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TABLE OF CONTENTS
CHEMISTRY 2231 LABORATORY SCHEDULE
LAB
PERIOD EXPERIMENT PAGE
1
2
3
4
5
6
7
8
9,10
11,12
13
14
GENERAL INFORMATION ................................................................... 4
MELTING POINT ................................................................................ 12
RECRYSTALLIZATION ......................................................................... 16
DISTILLATION .................................................................................... 20
RESOLUTION OF RACEMIC PHENYLSUCCINIC ACID ............................. 23
SYNTHESIS OF TERTIARY BUTYL CHLORIDE ......................................... 26
SYNTHESIS OF 2-METHYL-2-BUTENE .................................................. 29
SYNTHESIS OF 2,4,4-TRIMETHYL-2-PENTENE AND ISOMER ................. 32
OXIDATION OF CYCLOHEXENE TO ADIPIC ACID .................................. 35
SYNTHESIS OF 2-METHYL-4-HEPTANONE ........................................... 38
SYNTHESIS OF ETHYL IODIDE ............................................................. 43
CHECK OUT ....................................................................................... 46
ORGANIC POLYMERS ......................................................................... 47
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TABLE OF CONTENTS
CHEMISTRY 2241 LABORATORY SCHEDULE
LAB
PERIOD EXPERIMENT PAGE
1
2
3
3
3
4
5
4
6
7
8
9
9
10
11
12
13
14
GENERAL INFORMATION ................................................................... 4
COLUMN CHROMATOGRAPHY .......................................................... 52
SYNTHESIS OF 1,4-DI-T-BUTYL-2,5-DIMETHOXYBENZENE ................... 55
THE CANNIZZARO REACTION ............................................................. 58
PART I ............................................................................................... 59
PART II .............................................................................................. 59
PART III ............................................................................................. 60
SPECTROCOPY ................................................................................... 62
SYNTHESIS OF BENZOPHENONE OXIME ............................................. 67
THE REARRANGEMENT OF BENZIL ..................................................... 70
PREPARATION OF METHYL BENZOATE ............................................... 73
SYNTHESIS OF LIDOCAINE .................................................................. 77
Parts I & II ......................................................................................... 78
Part III ............................................................................................... 79
SYNTHESIS OF DIBENZALACETONE ..................................................... 85
-D-(+)-GLUCOSE PENTAACETATE ...................................................... 88
CHECK OUT ....................................................................................... 91
THE SYNTHESIS OF ASPIRIN ............................................................... 92
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USEFUL INFORMATION
SAFETY ............................................................................................. 4
GRADING .......................................................................................... 5
LABORATORY NOTEBOOK ................................................................. 5
USING THE BALANCES ....................................................................... 6
HEATING IN THE LAB ......................................................................... 6
BUNSEN BURNERS ............................................................................ 7
DISTILLATION TECHNIQUE ................................................................. 7
REFLUX TECHNIQUE .......................................................................... 8
RECRYSTALLIZATION TECHNIQUE ...................................................... 8
FILTERING AND DRYING SOLID: ......................................................... 8
FILTER AID ........................................................................................ 9
DRYING ORGANIC LIQUIDS (THE REMOVAL OF WATER) ..................... 9
DRYING GLASSWARE ......................................................................... 9
USES OF THE SEPARATORY FUNNEL: .................................................. 9
THEORETICAL YIELD .......................................................................... 10
PERCENTAGE YIELD ........................................................................... 11
HANDING IN PRODUCTS .................................................................... 11
Figure 1. Recrystallization technique (diagrammed). ......................... 95
Figure 2. Reflux Set-up. .................................................................... 96
Figure 3. Simple Distillation Set-up. .................................................. 97
Figure 4. Unpacked Column Distillation Set-up. ................................ 98
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GENERAL INFORMATION
SAFETY
SAFETY IS THE NUMBER ONE PRIORITY. Always read and understand the
experiment before coming to lab. Follow the procedure and the directions of the
instructor exactly. If you do not understand what you doing, stop and ask the instructor.
Some of the laboratory rules and regulations are:
YOU MUST:
WEAR SAFETY GOGGLES AT ALL TIMES.
WEAR APPROPRIATE CLOTHING, NO SHORTS OR SANDALS.
WORK ONLY DURING SCHEDULED LAB PERIODS.
KNOW WHAT YOU ARE DOING AT ALL TIMES.
BE ALERT AT ALL TIMES.
NO MATTER HOW MINOR, REPORT ALL ACCIDENTS.
KNOW THE LOCATIONS OF THE SAFETY EQUIPMENT.
KEEP YOUR WORK SPACE AND THE HOODS CLEAN.
YOU MUST NOT:
EAT, DRINK, OR SMOKE IN THE LAB.
PERFORM UNAUTHORIZED EXPERIMENTS.
ACT IN A LOUD OR DISRUPTIVE MANNER.
REMOVE ANY CHEMICALS OR EQUIPMENT FROM THE LAB.
IN ADDITION:
CONTACT LENSES SHOULD NOT BE WORN IN THE LAB
DO NOT PUT ANY SOLIDS IN THE SINKS, THIS INCLUDES
BOILING CHIPS, RUBBER BANDS, AND BROKEN GLASS.
ALL IRONWARE AND HOSES MUST BE RETURNED TO THE SIDE
DRAWERS AFTER EACH LAB, IN THE CORRECT DRAWER.
DISCARD ALL CHEMICALS AS DIRECTED BY YOUR INSTRUCTOR.
VISITORS ARE NOT ALLOWED IN LAB.
DO NOT START AN EXPERIMENT OVER WITHOUT YOUR INSTRUCTOR'S
PERMISSION.
EACH STUDENT IS EXPECTED TO CONCENTRATE ON THEIR OWN
WORK AND NOT CARRY ON CONVERSATIONS WITH THEIR
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NEIGHBORS. ANY QUESTIONS ARE TO BE DIRECTED TO THE
INSTRUCTOR.
IF A STUDENT HAS TO LEAVE THE LABORATORY FOR SOME
REASON, PERMISSION MUST BE OBTAINED FROM THE
INSTRUCTOR FIRST.
NEVER RETURN EXCESS CHEMICALS TO THE CONTAINER, PASS THEM
ON TO THE NEXT PERSON OR PROPERLY DISPOSE OF THEM. PUT TOPS
ON CONTAINERS IMMEDIATELY AFTER USE. THE TOPS ARE NOT USED
FOR ANYTHING ELSE, DON'T PUT CHEMICALS IN THEM.
STOP AND CLEAN UP IMMEDIATELY ANY SPILLAGE.
CLOSE THE ICE MACHINE DOOR AFTER YOU TAKE THE ICE.
SAFETY IS ALWAYS THE NUMBER ONE PRIORITY.
GRADING
The laboratory grade will count 25 % of the final Organic Chemistry lecture grade.
The laboratory grade is based on the experiments (each worth ten points), quizzes, and
notebook. The experiments are graded on the basis of the quality and quantity of the
product, and your technique. All experiments will count towards the final laboratory
grade; no experiments will be dropped. If you miss an experiment, speak with your
instructor as soon as possible, otherwise a grade of zero will be given for that experiment.
LABORATORY NOTEBOOK
Learning how to keep a proper lab notebook is part of your scientific training and you
will be expected to maintain a lab notebook for this Organic lab course. Part of your final
lab grade will be based on the adequacy of this notebook. A small bound composition
notebook (9 3/4 X 7 1/2 inches) is required. It will be graded during the semester and/or
collected at the end of the semester. It should be kept up to date at all times. Folders or
spiral notebooks are not acceptable. The notebook must include the following
information on numbered pages, unless specified differently by your instructor:
1) Start each new experiment on a new page.
2) Write the title of the experiment and the date it is preformed.
3) Write the balanced equation.
4) List the reactants, including the number of grams and moles of each. A reactant is any
reagent to the left of the arrow in the balanced equation.
5) Calculate the theoretical yield, showing all calculations.
6) Briefly outline the procedure.
7) Copy the class notes, including precautions and changes.
8) Record your results, including your actual yield and percent yield.
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Steps one through six should be done before coming to class. Step seven
is written at the start of class and step eight is entered into your notebook
at the end of the experiment.
USING THE BALANCES
1) Start with the balance reading 0.00, press tare if it is not reading 0.00. The letter "g"
(grams) should always appear on the upper left hand of the display.
2) Place a large piece of paper and a beaker on the balance (always weigh solids in a
beaker, the paper is there in case you spill a chemical, it will be caught by the paper and
not corrode the pan of the balance).
3) Press tare so that balance again is reading 0.00.
4) Add the solid to be weighed out into beaker until desired weight is displayed.
5) Stop and clean up any spills immediately.
6) Never return excess chemicals to the container, pass them on to the next person or
dispose of them properly. Put tops on the containers immediately after use. The tops are
not used for anything else, don't put chemicals in them.
7) Remove the beaker, press tare to return balance to 0.00.
HEATING IN THE LAB
You will be required to use flask heaters, or a Bunsen burner flame as a heat
source throughout the two semesters of Organic Chemistry Lab. Read the procedures and
precautions for each experiment, to determine which heat source is necessary for that
experiment. If a Bunsen burner flame is to be used, make sure that no flammable
material, such as, solvents is in your hood. Also, make sure clothing (for example, shirts,
sweaters, and ties) and long hair, especially if you lean over, are kept away from the
flame. Never heat anything in a completely closed system.
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BUNSEN BURNERS
1) Attach a hose from the Bunsen burner to the gas outlet (indicated by a blue color)
2) Adjust the bottom valve of the Bunsen burner so that it is open slightly.
3) Turn the gas on.
4) Using the gas lighter, light the Bunsen burner. If the burner will not light, open the
bottom valve of the burner or the gas outlet valve a little more.
5) After the burner is lit, turn the bottom valve to adjust the height of the flame and rotate
the barrel of the burner to adjust the flame size and intensity.
6) Always turn the Bunsen burner off by using the gas outlet. Always use a wire gauze
when using a flame as a heat source.
FLASK HEATERS
Never plug the Flask Heaters directly into an outlet, always use a Heat Control, which is
plugged into an outlet. Usually a setting of 15 is sufficient to heat most reaction mixtures
to boiling. Do not get the flask heater wet.
DISTILLATION TECHNIQUE
1) Always use a boiling chip, never add a boiling chip to a hot liquid.
2) Distill slowly, 1-2 drops per second.
3) The distillation receiver is always a round bottom flask.
4) All glass joints must fit tightly together, use rubber bands.
5) The tip of the temperature probe should be positioned properly (see page 95).
6) When collecting an organic product, the entire distillation apparatus must be dry.
7) Cooling water for the condenser, enters at the lower end of the condenser and exits at
the top. Use a reasonable, low pressure rate of water flow.
8) Distillation products to be submitted for grading must be dry (not cloudy). If the
product is cloudy, dry it with a drying agent and then decant the product into a dry bottle
before handing it in to the instructor.
9) Never leave a distillation unattended.
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REFLUX TECHNIQUE
Reflux (see Figure 2, p. 95) is a method used to heat a reaction mixture to its boiling
point without losing any of this mixture through evaporation. The heat
provides the energy necessary for product formation. A good rate of reflux is
a mixture that is gently boiling, with vapor condensing no faster than 1
drop/second from the condenser. Follow the same rules as if distilling.
(boiling chips, grease, etc.) Vapors should never reach more than one quarter
of the way up the condenser. If vapors go higher in the condenser or come out
the top of the condenser, remove the heat source immediately.
RECRYSTALLIZATION TECHNIQUE
1) Steps one and two (see Figure 1, p. 94) should be set up before starting the
recrystallization process.
2) In a beaker add two boiling chips, the solid to be recrystallized, and the minimum
amount of solvent or in the amount directed. The minimum amount of solvent is the
amount of solvent that will dissolve the solid at the boiling point of the solvent, plus
approximately 10%.
3) If directed, let the liquid cool for two minutes and add a spatula full of charcoal, then
heat the mixture back to boiling. The charcoal is used to remove impurities.
4) Filter the mixture through a pre-heated powder funnel to remove any undissolved
impurities and the charcoal. The mixture that is being filtered must remain at or just
below its boiling point during the entire filtration. If solid starts to recrystallize in the
powder funnel, notify the instructor. Use a "Hot Hand" to grab the hot beaker.
5) Cool the collected liquid in an ice/water bath (use approximately 50% ice and 50%
water) until the entire contents of the beaker is ice cold (feel the outside of the beaker).
Occasionally stir the cooling solution.
6) Vacuum filter the cold mixture, rinsing the beaker with the filtrate if necessary, and
save the purified solid.
FILTERING AND DRYING SOLID:
1) Make sure the filtration apparatus is set-up as shown on p. 94, Figure 1, step 4.
2) Turn on the vacuum and mat down the filter paper with the solvent you are using
before starting to filter.
3) When beginning to filter, make sure that there is a proper seal between the funnel and
the filter flask by pushing down on the funnel.
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4) When all of the liquid has filtered into the filter flask, it is usually a good idea to press
down the solid in the funnel with a clean cork or large spatula.
5) When finished filtering then close the vacuum.
6) Remove the solid from the filter paper and store it in a large beaker.
FILTER AID
This is a solid that sits on the filter paper and acts as a barrier to protect the filter paper
from the solid to be filtered out. It is used because the compound to be filtered consists
of very small particles that would clog up or go through the filter paper.
DRYING ORGANIC LIQUIDS (THE REMOVAL OF WATER)
A drying agent (ex. sodium sulfate) is a solid that removes water from an organic
liquid. The organic liquid is dry if it is clear and some of the drying agent swirls freely.
Start by adding a small spatula full of the drying agent to the liquid to be dried. If the
liquid is cloudy or all of the drying agent clumps together or sticks to the Erlenmeyer
flask, then there is still water present and more drying agent is needed. Add another
spatula full. The drying of an organic liquid should always be done in a stoppered
Erlenmeyer flask, not in a beaker. Always put the top back on the drying agent bottle
immediately after use.
DRYING GLASSWARE
1) Use the plastic squeeze bottle with acetone located at the front desk.
2) Squeeze acetone through the equipment needed to be dried and collect it in a beaker
(place this used acetone in the recycling container). This washes out the water.
3) Using an air jet (indicated by an orange color), gently blow air through the piece of
equipment so that the acetone evaporates. It should only take 10-15 seconds to evaporate
the acetone.
USES OF THE SEPARATORY FUNNEL:
1) To mix reagents.
2) To separate a liquid from another insoluble liquid.
3) To add a reagent dropwise to a reaction mixture.
Always remove the hollow stopper before dispensing any liquid from the separatory
funnel. In addition, drain the bottom layer and pour the top layer from the funnel.
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THEORETICAL YIELD
The theoretical yield (TY) of a reaction is calculated before the start
of the experiment so that the student can know how much product to expect if
100 % of the reactants react to give the desired product. The calculation of
the theoretical yield can be performed in the following three steps:
1) Balance the equation.
2) Calculate the number of moles for each reactant using the following formula:
moles = grams / molecular weight
3) Calculate the TY based on each reactant using the following equation:
TY = (moles of reactant) (MW of product) {(moles of product)/(moles of reactant)}
The last term in this equation, the ratio {(moles of product)/(moles of reactant)} is
obtained from the coefficients of the balanced equation.
EXAMPLE
What is the theoretical yield of ethyl iodide given the following information:
The procedure calls for the addition of 7.9g of ethanol, 1.4g of phosphorus, and 10g of
iodine.
STEP 1: The equation is already balanced.
STEP 2: Calculate the number of moles for each reactant. Only compounds to the left of
the reaction arrow are reactants. Calculating the number of moles of ethanol,
phosphorus, and iodine:
Moles of ethanol = 7.90 / 46.07 = 0.171 moles
Moles of phosphorus = 1.40 / 30.97 = 0.0452 moles
Moles of iodine = 10.00 / 253.81 = 0.03940 moles
6CH3CH2OH 2P + 3I2+ + H3PO3I6CH3CH2Ethanol Ethyl iodide
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STEP 3: Calculation of the TY based on ethanol:
TY = (0.171) (155.97) (6/6) = 26.6g of ethyl iodide
Calculation of the TY based on phosphorus:
TY = (0.0452) (155.97) (6/2) = 21.1g of ethyl iodide
Calculation of the TY based on iodine:
TY = (0.03940) (155.97) (6/3) = 12.29g of ethyl iodide
The correct TY is the lowest number of grams calculated in step 3, therefore, the limiting
reagent for this reaction is iodine and the correct TY for ethyl iodide is: 12.29g
PERCENTAGE YIELD
The percentage yield (%Y) is calculated at the end of the experiment to
show the student how well he or she performed the experiment and about the
limitations of the experiment imposed by the nature of the reaction.
Calculate the percentage yield using the following equation:
%Y = (Actual Yield)/(Theoretical Yield) x 100
HANDING IN PRODUCTS
Unless otherwise instructed, the product prepared is given to the instructor in a labeled
bottle or envelope. On the label is neatly printed the student's name, the name of the
product, the actual yield, and the percent yield.
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MELTING POINT
INTRODUCTION
The melting point and the freezing point can be defined as the temperature at which a
liquid and a solid phase of a compound exist in equilibrium at a pressure of one
atmosphere. The purpose of this experiment is to gain experience in the use of the mel-
temp apparatus and to learn what useful information melting points can tell us. Organic
chemist use this physical constant for two important reasons. Because it is highly
unlikely that two substances would have the exact same melting point, the possible
identity of an unknown pure solid can be determined by simply taking its melting point.
The second reason why chemists use melting points is to determine if a substance is pure
or impure. A pure substance will have a sharp narrow range (2-3C) melting point,
while an impure substance will have a lower, wider range melting point.
Throughout both semesters of organic chemistry lab, students will be synthesizing
different solid compounds. One method to determine if the correct compound has been
synthesized and that the purity of this compound is acceptable is to take a melting point.
The student will be asked to take a melting point, before submitting certain products that
they make in future labs, therefore, learning the correct method to determine the melting
point now, will save you a lot of time and aggravation in the future.
A mixed melting point is a method used to positively identify an unknown solid.
This is done by mixing your unknown compound with a known compound that you think
could be your unknown. If the unknown and the known that you mixed with it are the
same compound, then you will get a sharp melting point range, identical to the melting
point of the unknown taken by itself. However, if you mixed your unknown with a
known compound that is different from your unknown, you introduced an impurity into
your unknown and the melting point will be lower and have a wide range. A good
example of this last fact is that salt (the impurity) is placed on icy roadways (the ice is
assumed to be pure and will melt at 0) to melt the ice because the ice will now melt at a
lower temperature.
PRECAUTION - parts of the DigiMelt apparatus are hot and will easily burn you.
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HOW TO TAKE A MELTING POINT
1) Place a small amount of a sample into a capillary tube that is open only at one end.
Either by gently tapping the capillary tube on the bench top or by gently vibrating the
tube with a file, allow the sample to travel to the closed end of the tube. There should be
approximately 5 mm. of sample in the capillary tube, just enough to see it clearly.
2) Turn the switch on the DigiMelt apparatus to the "on" position.
3) The START temperature should read at least 30 below the melting point of the
sample.
4) The STOP temperature should be 10C above the melting point.
5) The rate of heating called the RAMP rate should be 2C / minute.
6) Record the melting point range of your sample. The low end of this temperature range
is when the sample first starts to melt and the high end is when all of the sample has
melted.
PROCEDURE
1) Before class, record the literature melting points for all the compounds listed on the
back of the Melting Point Data Sheet. Record the source of this information.
2) Take the melting point of any three known compounds that are found under the hood.
Record all of your results in your notebook and then on the Melting Point Data Sheet.
3) Take the melting point of the unknown that was given to you. Set the START at
80C, the STOP at 170C RAMP rate at 10C / minute.
4) Take a second, more accurate melting point of your unknown by setting, the START
temperature should read at least 30 below the melting point of the sample the STOP
temperature should be 10C above the melting point the rate of heating called the RAMP
rate should be 2/ minute. Repeat this step with a new sample of your unknown to verify
your results.
5) Take a mixed melting point by placing a small amount of unknown on your watch
glass and adding about 1/5 as much of a known compound. This known compound
should hav
5). Mix them well and take its melting point. Do as many mixed melting points as
needed to identify your unknown, but at least two mixed melting points should be done.
6) Write your results in your notebook and then on the data sheet which will be
submitted to your instructor.
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NAME_________________________
Pre-lab
LITERATURE MELTING POINTS OF SOME
ORGANIC COMPOUNDS
COMPOUND LITERATURE MELTING POINT, C
Acetanilide __________
Fluorene __________
Benzoic Acid __________
Benzamide __________
Urea __________
Glucose Pentaacetate __________
Phenacetin __________
Benzoin __________
o-Chlorobenzoic Acid __________
Anthranilic Acid __________
Benzilic Acid __________
Adipic Acid __________
Salicylic Acid __________
Benzanilide __________
Source________________________________________________________
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NAME_________________________ LOCKER NUMBER _______
DATE ________________ LAB DAY AND TIME ______________
MELTING POINT DATA SHEET
Results of Three Known Compounds listed in the Table on the Back
Results of Unknown
Unknown M.P. Range (taken quickly) _______________
Unknown M.P. Range (taken slowly) 1)_______________
2)_______________
Results of Mixed Melting Points
UNKNOWN NUMBER __________
NAME OF UNKNOWN ____________________________
GRADES: Pre-Lab (20):_____ Experimental Technique (30):_____
Yield & Purity (30):_____ Post Lab Questions (10):_____ Lab Report Grade = _____
Known Compound Literature M.P. Observed M.P. Range
Compound Mixed with Unknown Observed M.P. Range
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RECRYSTALLIZATION
INTRODUCTION
The purpose of this lab is to learn the technique of recrystallization and how to choose
a recrystallization solvent. Recrystallization is a process used to purify solid
compounds. In addition you will identify your unknown based on melting point.
In future experiments, you will be synthesizing different solid compounds. To assure
yourself and your lab instructor that these compounds are pure, you will be required to
perform a recrystallization at the end of each lab, before handing in your product for
grading. Therefore, it is important that you understand this technique and have this
procedure written down in your notebook so that you can refer back to it when necessary.
Before we look at recrystallization in detail, it is necessary to define the term
solubility. Solubility is the extent to which a substance (called a solute) mixes with a
liquid (called a solvent) to produce a homogeneous system (called a solution). The
importance of solubility can be seen in every experiment preformed in this class and in
many aspects of every day life. Reactants, used in future experiments, will be dissolved
in a suitable solvent. This lowers the activation energy so that the reaction can proceed to
products more easily. Solubility also plays an important roll in both chromatography
experiments. Pharmacy students, in future courses, will learn that drugs taken orally need
to be water soluble and fat-soluble at the same time for optimal adsorption in the blood.
The first part of today's experiment deals with the solubility of a pure solid compound
in a wide range of polar and nonpolar solvents (the compounds in the chart of the Data
Sheet are in increasing polarity order). The degree of solubility is important to determine
a good recrystallization solvent for this solid if it needs to be purified. The definition of a
good Recrystallization Solvent is:
1) A solvent that will dissolve a large amount of the solute (the compound to be purified)
when the solvent is hot and only a very small amount of solute when the solvent is cold.
2) Impurities will not dissolve in hot or cold solvent.
3) Ideally the solvent should also be cheap, nontoxic, and nonflammable.
In the second part of this experiment you will recrystallize an impure solid compound
using the best recrystallization solvent. The two unknowns are either benzoic acid or
acetanilide. The recrystallization process can be summed up as follows. The solid to be
purified is dissolved in a minimum amount of boiling solvent. The boiling mixture is
filtered to remove all insoluble impurities. The filtrate (the liquid that was collected after
the filtering) is cooled to precipitate the solid. The solvent is filtered off, leaving the
purified solid. One can see that recrystallization works because most compounds are
more soluble in hot solvent than in cold solvent. Finally the melting point can be used to
determine if your unknown is benzoic acid or acetanilide.
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PROCEDURE
To prepare for this experiment properly, read how to use the balances (page 5),
filtering and drying solids (page 8) and the recrystallization technique (pages 7 and 93).
PART 1: SOLUBILITY TEST FOR THE SOLID TO BE PURIFIED
KEY:
S = soluble (all solid dissolves in 3 mL of solvent)
I = insoluble (not all solid dissolves in 3 mL of solvent)
1) Before lab, record on the Solubility Data Sheet, the literature boiling points for the
solvents used in this experiment.
2) Add 0.1 grams of the solid to be purified in a test tube. Add 3 ml of solvent. Stir with
wood sticks and record if S or I. If S, then repeat step 1 using the next solvent. If I, then
proceed to step 3.
3) Heat the test tube with a beaker of very hot water, stir, realizing that if you heat the
test tube too long, some low boiling point solvents will evaporate. Record: S if all solid
dissolves or I if some solid does not dissolve.
4) Repeat steps 1 and 2 for every solvent that the instructor has (usually petroleum ether,
acetone, ethyl acetate, ethanol, and water are the solvents tested) directed you to test.
5) All results should be recorded in your notebook and then on the solubility data sheet.
PRECAUTION: All of the solvents used in Part 1, except water, are flammable. Do not start Part 2 until you are directed to do so by the instructor.
PART 2: RECRYSTALLIZATION OF AN IMPURE SOLID (see Figure 1, page 94)
1) Place 1.0 gram of impure solid into a 250 mL beaker. Add 20 mL of the
recrystallization solvent and 2 boiling chips to the beaker. Do not take the pure solid that
was used for the solubility tests.
2) Set-up steps one and two of the apparatus as shown in Figure 1, page 94.
3) Heat the contents of the beaker to boiling with either a flask heater or Bunsen burner
as advised by your instructor; observe the sample! If your sample hasn't completely
dissolved after the mixture has been boiling for a couple of minutes,
add an additional 10 mL of solvent; reheat to boiling temperature and observe again.
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It may be necessary to add more solvent to dissolve the crystals ( add in 10 mL
increments). As the beaker is being heated, heat the powder funnel and filter paper with
gentle steam.
4) As soon as the crystals have been dissolved in the hot solvent, add a small amount of
charcoal using a micro spatula, continue to heat for 1 minute, then shut off the heating
source.
5) Without letting the contents of the beaker cool down, pour the mixture in the beaker
through the preheated powder funnel that contains the filter paper. Use the "Hot Hand"
to grab the hot beaker. If crystals are formed during filtration, reheat to a boil then allow
the solution to cool by itself very slowly. After the beaker that contains the filtrate has
cooled to close to room temperature and crystals have formed, cool this beaker an
ice/water bath until it is as cold as the ice water.
7) Filter the purified solid through your Buchner funnel. This is done by wetting the
filter paper in the Buchner funnel with the solvent used to crystallize. Turn the vacuum
(yellow handle) on. When you are sure that the filter paper is matted down, pour the
solid mixture in your beaker, into the Buchner funnel. The solvent should drain into the
filter flask and the solid should be caught on the filter paper in the funnel. You should
see no solid in the filter flask. If you can't get all of crystals out of the beaker, pour some
or all of the filtrate (the solvent that drained into the filter flask) back into the beaker, stir,
and filter again.
8) Store your purified solid in a clean, dry 50 mL beaker in your locker until the
following lab period.
9) Please note this procedure should be applied whenever you recrystallize a solid.
10) Next lab period, you will take a melting point of your dried solid to check its purity.
Identify your unknown based on melting point. You will also measure the weight of the
purified solid and hand it in using a sample vial or envelope. Put a label on the vial with
the following information:
Your Name
Product Name
M.P. Range = _______C
% Recovered =_________
The % Recovered is calculated as follows:
% Recovered = (final weight/starting weight) X 100
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NAME_________________________ LOCKER NUMBER _______
DATE ________________ LAB DAY AND TIME ______________
SOLUBILITY DATA SHEET
CHART OF SOLUBILITIES TO DETERMINE THE BEST
RECRYSTALLIZATION SOLVENT FOR ____________________
KEY: S = very soluble (all solid dissolves in 3 mL of solvent)
I = insoluble (not all solid is soluble in 3 mL of solvent)
Solvent Boiling Point Cold Hot Good Recrystal. Solvent (yes/no)
Petroleum
Ether
Acetone
Ethyl Acetate
Ethanol
Water
Which of the solvents listed above is the best recrystallization solvent for the solid
you tested? Why?
Weight of Crude Solid ______________g
Weight of Recrystallized Solid ____________g
Melting Point Range _________________C
Percent Recovered ______________%
Name of unknown__________________
GRADES: Pre-Lab (20):_____ Experimental Technique (30):_____
Yield & Purity (30):_____ Post Lab Questions (10):_____ Lab Report Grade = _____
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20
DISTILLATION
INTRODUCTION
Distillation is a process used to purify a liquid. The purpose of todays experiment is for the student to become familiar with how to set-up the apparatus used in a distillation and
to compare two different types of distillations. These two different types are called
simple distillation and distillation with an unpacked column.
The reason why distillation works can easily be expressed by looking at Raoult's Law,
which states that the vapor above a boiling solution will always contain more of the lower
boiling point component than the solution that is boiling. In today's experiment we will
start with a 50/50 solution of acetone (B.P.= 56C) and water (B.P.= 100C). As the
solution is heated and starts to boil, the vapor above the boiling solution will contain
more acetone, the lower boiling point liquid. As this acetone rich vapor moves away
from the heat source and cools, this new solution still contains more acetone and less
water. Eventually, this acetone rich solution will be vaporized again. This vapor will
contain even more acetone and less water. Depending upon the amount of surface area
between the boiling liquid and the water cooled condenser, many of these vaporizations /
condensations can take place. Therefore, the more surface area, the greater the separation
of the two liquids.
In today's experiment, the student will distill a solution of acetone (some students will
be familiar with acetone as it is the solvent used to remove nail polish) and water, trying
to separate, as best as possible, the two liquids. This will be accomplished by collecting
three fractions and measuring their volumes. Fraction I will be collected from a
temperature range of 56 to 62, therefore, this fraction contains only acetone. Fraction II
will be collected between 63 to 90. This second fraction contains a mixture of acetone
and water. The last fraction, fraction III, is the residue. This fraction contains only water.
Ideally, to achieve the best separation, one should get all the acetone in fraction I, no
fraction II, and all the water in fraction III.
WHEN DISTILLING, ALWAYS:
1) Add two boiling chips to the distilling flask. Never add a boiling chip to a hot liquid.
2) Use a thin film of grease whenever glass touches glass. All glass joints must fit tightly
together, use rubber bands.
3) Insert thermometer probe into the adapter. The tip of the probe should be just below
the junction in the three way connecting tube.
4) Cooling water for the condenser enters at the lower position and exits at the top, turn it
on slowly.
5) A good rate of distillation is 1 drop/second.
6) The distillation receiver is always a round bottom flask.
7) Never leave your distillation unattended.
-
21
PRECAUTION Acetone is flammable, it should not be left in an open container on the bench top. The
joints of the distillation set-up must be tightly fitted together.
PROCEDURE
1) Add 15 mL acetone, 15 mL of water, and 2 boiling chips to a 100 mL round bottom
flask (RBF).
2) Set-up the apparatus as shown for a simple distillation (Figure 3, page 96). Make sure
all glass joints are tight.
3) Turn on the water very slowly, until you see a slow, but steady stream of water
coming out of the condenser.
4) Get your apparatus checked by your instructor.
5) Heat the solution with a flask heater and heat controller so that the rate of distillation
is one drop per second.
6) At a temperature of just above 62C, turn off the heat controller and change the
receiving flask from a 50 mL to a 25 mL RBF. Make sure you did not loosen any glass
joints and then start to heat again.
7) At 90C, turn off the heat controller. Let the residue in the 100 mL RBF cool.
8) Measure and record the three volumes that were collected. Dispose of the fractions as
directed.
9) Repeat this procedure, but set-up an unpacked column distillation apparatus in step 2
(Figure 4, page 97). It is not necessary to clean or dry any equipment.
10) Obtain an unknown acetone/water solution from your instructor and measure the
volume (do not add any additional water). Determine the amount of acetone present in
your unknown solution by using distillation through an unpacked column, as in step 9.
11) Record your results in your notebook and then on the data sheet.
-
22
NAME_________________________ LOCKER NUMBER _______
DATE ________________ LAB DAY AND TIME ______________
DISTILLATION DATA SHEET
SIMPLE DISTILLATION (NO COLUMN)
VOLUMES COLLECTED
T = 56 to 62C _________mL
T = 62 to 90C _________mL
T = 90 to 100C ________mL
UNPACKED COLUMN VOLUMES COLLECTED
T = 56 to 62C _________mL
T = 62 to 90C _________mL
T = 90 to 100C ________mL
UNKNOWN SOLUTION DISTILLATION Starting Volume __________mL
Volume Collected between 56 to 62C___________mL
Percent acetone in unknown solution ______________%
Which method of distillation (no column or unpacked column) was the best? Why?
GRADES
Pre-Lab (20):_____ Experimental Technique (30):_____
Yield & Purity (30):_____ Post Lab Questions (10):_____ Lab Report Grade = _____
-
23
RESOLUTION OF RACEMIC PHENYLSUCCINIC ACID
INTRODUCTION Because enantiomers have mostly identical chemical and physical properties, their
separation (called a resolution) requires special techniques. Resolution via
diastereeomeric salt formation, first accomplished in 1853 by the father of
stereochemistry, Louis Pasteur, will be the method of resolution demonstrated in this
experiment. Racemic phenylsuccinic acid (RS-PSA) will be resolved using the optically
pure base, S-(-)-Proline (S-Pro)* or R(+)-Proline (R-Pro).. The optical purity of some
samples can be determined using a technique called polarimetry. We will not be telling
you whether you are using S-Pro or R-Pro ! - you will use polarimetry of the PSA sample
that you isolate to discover the stereochemistry of the Proline that you used.
When an acid is mixed with a base, a salt results and this is the case when RS-PSA is
mixed with S-Pro, using isopropanol as a solvent. Two different salts form. The first salt
consists of (S-PSA)-(S-Pro)2, that is, for every one molecule of S-PSA, there are two
molecules of S-Proline associated with it. The second salt is composed of (R-PSA)-(S-
Pro). These two salts can now be separated because of their solubility difference in
isopropanol. The (S-PSA)-(S-Pro)2 salt, being less soluble in the isopropanol,
precipitates out of solution and can be isolated by filtration. The more soluble (R-PSA)-
(S-Pro) salt remains dissolved in the filtrate. The S-PSA can be liberated from its proline
salt form by the addition of hydrochloric acid. The converse happens with RS-PSA and
R-Pro (see diagram above!).
The resolution of enantiomers is a very important topic, especially when dealing with
chiral drugs. For example, with Ibuprofen (Motrin, Advil), the S-enantiomer has all of
the anti-inflammatory activity, while the R-enantiomer has no effect. With
Chlorpheniramine (Chlortrimeton), the S-enantiomer contains all of the antihistamine
activity, while the R-enantiomer has a sedative side effect.
*Stephani, R. and Cesare, V. J. Chem. Educ., 1997, 74, 1226.
** S-(-)-Proline is also called L-(-)-Proline , R-(+)-Proline is also called D-(+)-Proline
-
24
PROCEDURE (Review the reflux technique (p. 7) and set-up (Figure 2, p. 95), (All equipment should be dry through step 5)
1) Weigh out 1.94g of racemic phenylsuccinic acid in a 150 mL beaker and dissolve it in
50 mL of 2-propanol. Transfer this solution to a clean and dry 100 mL RBF using your
long stem funnel.
2) Add 1.15g of unknown proline (break up any clumps) to the 100 mL round bottom
flask (RBF) using your powder funnel. Use 10 mL of 2-propanol to rinse the small
amount of proline that remains in the beaker. Swirl the flask for several minutes. All of
the proline will not dissolve. Obtain a stir bar from the instructor.
3) Reflux (Figure 2, p. 95) and stir with magnetic stir bar (and stir plate) and with a flask
heater and heat controller for 20 minutes.
4) Air cool the flask to room temperature. This takes about 10 to 15 minutes.
Occasionally swirl the mixture during this time. A lot of solid should be seen when the
flask reaches room temperature. Remove the magnetic stir bar with a magnetic stir
and return the stir bar to the instructor.
5) Stir the mixture in the flask for one minute and then vacuum filter the mixture through
clean, dry equipment. The filter paper should be matted down with 2-propanol. Use the
filtrate to remove all of solid from the flask. Discard the filtrate as directed by the
instructor. Wash the solid with 2 x 15 mL of acetone. Leave the vacuum on for 2 minutes
after the second acetone wash and then press down the solid with a hollow stopper to
remove as much liquid as possible. Dry the solid between two pieces of filter paper.
Discard the acetone filtrate as directed by your instructor.
6) Add 10 mL of 6M HCl to a 100 mL beaker and clamp it in an ice/water bath. When
this solution is cold, add all of the solid from step 5. Stir for about 5 minutes.
7) Vacuum filter the mixture (clean the filtration apparatus with water and mat down the
filter paper with water, the equipment does not have to be dry). Wash the solid in the
Buchner funnel with 2 x 15 mL of water. Let the solid dry in a large beaker until the next
lab period. Discard the filtrate as directed by your instructor.
8) After recording the weight, use a polarimeter to measure the optical rotation, a, of your
phenylsuccinic acid. Do this by adding all of your PSA to a 10 mL graduated cylinder,
add 7 to 8 mL of acetone and stir to dissolve all of the solid. Then add more acetone until
the solution is exactly to the 10 mL mark of the cylinder, stir again. Add this solution to
the polorimeter cell until it is full. Place the cell into the polarimeter record the observed
Be sure to determine whether the optical rotation is plus + or minus-.
Calculate the specific rotation [] and the percent optical purity (% OP) using the formulas shown on the data sheet. Determine if you have resolved R-Phenyl succinic
acid or S-Phenyl succinic acid.
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25
NAME________________________________ LOCKER #______________
DATE________________ LAB DAY AND TIME_________________
RESOLUTION OF PHENYLSUCCINIC ACID
DATA SHEET
OVERALL RESOLUTION EQUATION:
DATA FOR PHENYLSUCCINIC ACID
[]max = + _173.3_ (c = 1, acetone) (from CRC Handbook of Chemistry and Physics)
Theoretical Yield = ________g
RESULTS
Weight of (+)-PSA Recovered =_________g
Percent Yield = __________
Observed Rotation = ___________ Record if it is plus + or minus-.
[] = ____________ (c = _________, acetone)
% Optical Purity = _________
My resolved Phenylsuccinic acid is R or S.CIRCLE THE CORRECT ISOMER.
[] = / (lc) where l = length of the cell in decimeters (10 cm = 1 dm) c = concentration in g/mL
% OP = ([]/[ ]max) x 100 where []max = [] of optically pure PSA in acetone
GRADES: Pre-Lab (20):_____ Experimental Technique (30):_____
Yield & Purity (30):_____ Post Lab Questions (10):_____ Lab Report Grade = _____
-
26
SYNTHESIS OF TERTIARY BUTYL CHLORIDE
INTRODUCTION
In this experiment, the student will see that tertiary alcohols react almost
instantaneously with hydrohalic acids at room temperature to form an upper layer of an
alkyl halide. The student will also become familiar with some of the uses of the
separatory funnel and also how to dry organic liquids using drying agents. Before
coming to lab, read the uses of the separatory funnel (page 8) and drying organic liquids
(page 8).
PRECAUTIONS
1) Concentrated hydrochloric acid can cause severe burns.
2) Tertiary butyl chloride is very flammable, therefore, no flames are to be used today.
3) Always vent the separatory funnel when mixing compounds and remove the hollow
stopper when dispensing liquids from it.
PROCEDURE
1) To your separatory funnel add 7.86 g (10 mL) of tert-butyl alcohol and 25 mL of
concentrated hydrochloric acid. (Concentrated hydrochloric acid has a molarity of
12.4M. Knowing this value and that M = mol/L, the number of moles can easily be
calculated. Knowing that the MW of HCl is 36.46g/mol., the number of grams of HCl
also be calculated.
* J.F. Norris, et al, Org. Syn., 1928, 8, 50.
C
CH3
CH3
CH3
Cl+ HCl
tert-Butyl Alcohol tert-Butyl ChlorideHydrochloric Acid
+ H2OCCH3
CH3
CH3
OH
-
27
2) Gently swirl the contents of the separatory funnel for one minute, then stopper it with
your hollow stopper. Invert and vent the separatory funnel by opening the stopcock to
release the pressure. Make sure you hold the hollow stopper in place when you invert the
funnel. Repeat the shaking, inverting, and releasing of pressure, slowly at first. As the
pressure decreases, gradually increase the shaking. This is done for approximately five
minutes.
3) Clamp the stoppered funnel to a ring stand and let it stand until both layers are clear.
This will take at least 20 minutes. During this time, the student should set up the
distillation apparatus used later in this experiment.
4) When both layers are clear, drain off and discard the lower layer.
5) Add 10 mL of saturated sodium bicarbonate solution to the top layer in the separatory
funnel. Gently swirl the unstoppered funnel for two minutes, and then stopper it, invert,
and release the pressure. This is again repeated, gradually increasing the shaking. Be
sure to frequently vent the funnel.
6) After letting the layers separate for one minute, drain off the lower bicarbonate layer
and discard it.
7) Add 10 mL of water to the top layer, stopper, invert, and vent several times as done
previously.
8) Let the layers separate for one minute and then drain off and discard the lower water
layer.
9) Transfer the top tert-butyl chloride layer to an Erlenmeyer flask and dry it with
sodium sulfate (see page 8).
10) Using your long stem funnel with a very small piece of glass wool, decant the t-butyl
chloride from the sodium sulfate into your 50 mL round bottom flask (RBF).
11) Distill tert-butyl chloride using a simple distillation set-up (Figure 3, page 96) with a
flask heater and heat controller. Collect the product up to and including 52C or until the
distillation stops. Use a 25 mL RBF cooled with ice water as the receiving flask.
12) Pure tert-butyl chloride is a clear, colorless, liquid. If your product is cloudy, dry it
with sodium sulfate before handing it in.
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28
ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT
NAME_____________________________________ LOCKER #__________
DATE________________ LAB DAY AND TIME_____________________
TITLE OF EXPERIMENT____________________________________________
BALANCED EQUATION:
NAME OF PRODUCT____________________________________
Molar Mass ___________ M.P(solid)e or B.P.(liquid)
e__________
a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.
b. Moles = Grams/Molar Mass.
c. Coefficients from the balanced equation.
d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.
e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.
GRADING: Pre-Lab (20):_____ Experimental Technique (30):_____
Yield & Purity (30):_____ Post Lab Questions (10):_____ Lab Report Grade = _____
Name of
Reactant
Grams MM Moles
Product Coeff .
Reactant
Coeff.
Moles
of Produc
t
a b
c d
RESULTS:
Actual Yield _________g Percent Yield _________% Melting Point______oC
-
29
SYNTHESIS OF 2-METHYL-2-BUTENE
INTRODUCTION
In this experiment, 2-methyl-2-butene, an alkene, will be synthesized, by the sulfuric
acid catalyzed dehydration of 2-methyl-2-butanol. This reaction demonstrates that the
more highly branched alkene will be the major product because the hydrogen nucleus on
the number 3 carbon is the easiest to remove. Can you name the minor product in this
reaction?
PRECAUTIONS
1) 2-methyl-2-butene and 2-methyl-2-butanol are flammable, therefore, no flames are to
be used today.
2) Be careful when using the sulfuric acid solution and the sodium hydroxide solution,
both will burn the skin.
3) The product, 2-methyl-2-butene, boils at a low temperature, therefore, it evaporates
very quickly. Do not leave it open to the air. You will notice that the receiving flasks
during the distillations are packed in ice/water. This is to keep the product from
evaporating.
* Whitmore, F.C., Rowland, C.S., Wrenn, S.N., Kilman, G.W., J. Am. Chem. Soc., 1942,
64, 2970.
CH3 CH2 C
CH3
CH3
OH
H2SO4
H2OCH3 CH C
CH3
CH3 + H2O
2-Methyl-2-Butanol (t-Amyl Alcohol)
2-Methyl-2-Butene
-
30
PROCEDURE
1) Set up a simple distillation (Figure 3, page 96) with the following changes: use a 50
mL RBF that is packed in ice/water as a receiving flask and a 100 mL RBF as the
distilling flask. Use the large condenser and the hollow stopper in the set up. None of
this equipment has to be dry.
2) Add 20.0 mL of the sulfuric acid solution (34 %) to a 125 mL Erlenmeyer flask and
cool it in a beaker of ice water.
3) Slowly, with swirling and continued cooling of the flask, add 10.0 mL of 2-methyl-2-
butanol (tertiary amyl alcohol) to the 125 mL Erlenmeyer flask.
4) Using a long stem funnel, transfer the contents of the Erlenmeyer flask to the 100 mL
RBF of the distillation set-up.
5) Using a flask heater, distill until distillate is no longer obtained. This usually takes
between 10 to 20 minutes if the rate of distillation is one to two drops per second. There
will be liquid left in the 100 mL RBF. Remember that a good rate of distillation is 1 drop
per second!
6) Transfer the contents of the 50 mL RBF to a separatory funnel and add 5 mL of 10 %
NaOH solution. Swirl the unstopped funnel for one minute and then stopper it with your
hollow stopper and shake the funnel with frequent venting. Clamp the separatory funnel
to a ring stand and let the two layers separate. Drain off and discard the lower aqueous
layer as directed by your instructor.
7) Pour the top layer (2-methyl-2-butene) into a clean, dry 50 mL Erlenmeyer flask.
Cork and cool the flask in and ice/water bath and dry the product with sodium sulfate.
8) Decant the liquid through a clean, dry, long stem funnel that contains a small amount
of glass wool into a 50 mL RBF and distill using simple distillation (Figure 3, page 96)
with a flask heater and controller. All equipment must be clean and dry. Use the west
(thin) condenser and a 25 mL RBF that is packed in ice/water as a receiving flask.
Collect up to 43C as pure product.
9) Hand in the product today, as directed by your instructor.
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31
ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT
NAME_____________________________________ LOCKER #__________
DATE________________ LAB DAY AND TIME_____________________
TITLE OF EXPERIMENT____________________________________________
BALANCED EQUATION:
NAME OF PRODUCT____________________________________
Molar Mass ___________ M.P(solid)e or B.P.(liquid)
e__________
CALCULATION OF THEORETICAL YIELD
Lowest moles of product ________ X MM of Product ___________=
RESULTS
ACTUAL YIELD ___________G PERCENT YIELD ___________%
a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.
b. Moles = Grams/Molar Mass.
c. Coefficients from the balanced equation.
d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.
e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.
GRADING: Pre-Lab (20):______ Experimental Technique (30):_____
Yield & Purity (30):______ Post Lab Questions (10):_____ Lab Report Grade = ______
Name of
Reactant
Grams MM Moles
Product Coeff .
Reactant
Coeff.
Moles
of Produc
t
a b
c d
-
32
SYNTHESIS OF 2,4,4-TRIMETHYL-2-PENTENE AND ISOMER
INTRODUCTION
When tert-butyl alcohol is heated in the presence of sulfuric acid, 2-methyl propene
(isobutylene) is produced. The mechanism for this reaction is similar to the synthesis of
2-methyl-2-butene, the last experiment.
Isobutylene has a boiling point of -7C, therefore, it is a gas at room temperature.
This isobutylene gas, if left in the presence of the sulfuric acid solution, will react further
and dimerize to give the following two isomers: 2,4,4-trimethyl-2-pentene and 2,4,4-tri-
methyl-1-pentene. If hydrogen gas and a catalyst, such as nickel, were allowed to react
with these two pentenes, 2,2,4-trimethylpentane would form. 2,2,4-trimethylpentane has
the common name iso-octane or synthetic gasoline. It has been assigned an octane
number of 100. Compare this rating, to the octane number of the gasoline that you use in
your car. Most unleaded gasoline has an octane rating between 87 and 92.
When calculating the TY for this experiment, since both pentene products are
collected together, add the theoretical yield of both pentene products to get the correct
overall TY. This is done because both of the pentenes boil within 5C of each other and
would be difficult to separate using simple or column distillation.
* Whitmore, F.C., Ind. Eng. Chem., 1934, 26(1), 94-95.
Overall equation:
4 CCH3
CH3
CH3
OHH2SO4
H2OCH3 C
CH3
CH2 + H2O4 4Isobutylene
4 CH3 C
CH3
CH2H2O
H2SO4CH3 C
CH3
CH3
CH2 C
CH3
CH2 + CCH3
CH3
CH3
CH C
CH3
CH3
CCH3
CH3
CH3
OHH2SO4
H2OCCH3
CH3
CH3
CH C
CH3
CH3+CH3 CCH3
CH3
CH2 C
CH3
CH2
tert-Butyl Alcohol 2,4,4-Trimethyl-1-Pentene 2,4,4-Trimethyl-2-Pentene
+ 4 H2O4
-
33
PRECAUTIONS
1) Be careful with the sulfuric acid solution, it burns.
2) Both tert-butyl alcohol and the two pentene products are flammable. Use a flask
heater for the reflux and the distillation, do not leave them unattended. Make sure glass
joints are fitted tightly together.
PROCEDURE
1) Clamp a 100 mL RBF to a ring stand and add 28 mL of 50 % aqueous sulfuric acid
solution to it.
2) Slowly add 10.0 mL of tert-butyl alcohol and immediately attach a reflux condenser.
3) Using the flask heaters and controller, gently reflux (Figure 2, page 95) the solution
for 30 minutes. A good rate of reflux for this reaction is a gentle boil. During this time,
you can see the formation of an upper layer, which is the pentene products.
4) Cool the reaction mixture to room temperature by lowering the 100 mL RBF into an
ice/water bath. Leave the condenser on and the water running until the reaction mixture
is cool.
5) Add the reaction mixture to a separatory funnel and drain off and discard the lower
layer as directed by your instructor.
6) Add 20 mL of water to the top layer in the separatory funnel. Shake the funnel with
venting.
7) Drain off and discard the lower aqueous layer as directed by your instructor.
8) Add the top layer to an Erlenmeyer flask and dry it with a small spatula full of sodium
sulfate.
9) Decant the dried liquid through a long stem funnel that contains a small amount of
glass wool into a clean, dry 50 mL RBF.
10) Set-up a simple distillation (Figure 3, page 96) with a flask heater and controller, use
a 25 mL RBF as a receiving flask. The position of the temperature probe is important.
All equipment must be clean and dry. If you have some unreacted tert-butyl alcohol, it
will distill over at approximately 82C. Change the receiving flask at 90C if any alcohol
did distill over. Collect between 100 - 108C as pure product. The alkenes should be
clear and colorless, hand it in as directed by your instructor.
-
34
ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT
NAME_____________________________________ LOCKER #__________
DATE________________ LAB DAY AND TIME_____________________
TITLE OF EXPERIMENT____________________________________________
BALANCED EQUATION:
NAME OF PRODUCT____________________________________
Molar Mass ___________ M.P(solid)e or B.P.(liquid)
e__________
CALCULATION OF THEORETICAL YIELD
Lowest moles of product ________ X MM of Product ___________=
RESULTS
ACTUAL YIELD ___________G PERCENT YIELD ___________%
a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.
b. Moles = Grams/Molar Mass.
c. Coefficients from the balanced equation.
d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.
e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.
GRADING: Pre-Lab (20):______ Experimental Technique (30):_____
Yield & Purity (30):______ Post Lab Questions (10):_____ Lab Report Grade = ______
Name of
Reactant
Grams MM Moles
Product Coeff .
Reactant
Coeff.
Moles
of Produc
t
a b
c d
-
35
OXIDATION OF CYCLOHEXENE TO ADIPIC ACID
INTRODUCTION
Double bonds can be cleaved by several oxidizing agents. The oxidizing agent to be
used in this experiment is potassium permanganate. The mechanism of this oxidation
involves the initial formation of a cis-glycol. The carbon-carbon bond of the glycol is
then further oxidized by the permanganate and is cleaved to yield the dicarboxylic acid,
adipic acid. Adipic acid is used in the manufacturing of nylon.
PRECAUTIONS
1) Be careful with the potassium permanganate, it stains clothes and skin.
2) Be careful with the concentrated hydrochloric acid, is severely burns.
PROCEDURE
1) In a 100 mL RBF, dissolve 4.13 g of potassium permanganate in 75 mL of hot tap
water (stir for 4 or 5 minutes with a magnetic stirrer).
2) Make a solution of 1.0 mL of cyclohexene in 5 mL of acetone. In approximately one
milliliter increments, add this solution into the 100 mL RBF (use a transfer pipet for the
addition). Gently stir the flask with the magnetic stirrer throughout the addition.
3) After the addition is complete, attach your large condenser to the RBF. With water
running up through the condenser, heat the flask very gently with flask heater for 20
minutes, continue the stirring. During this time, in a 400 mL beaker, dissolve 3 g of
sodium bisulfite in about 200 mL of hot water. Save this solution to clean all of your
equipment that will have a brown manganese dioxide stain throughout this experiment.
4) Allow the reaction mixture to air cool for 5 minutes.
* Golendeev, V.P., Trudy Gor'kovsk. Politekh. Inst., 1955, 11, 5-11.
4
PotassiumPermanganate
Cyclohexene
Adipic Acid
3 HOOC CH2 CH2 CH2 CH2 COOH
HCl
2 KOH+3 8 2H2O+MnO2+-- C
O
O K+
)CH2(K+ O C
O
KMnO4+ 83
-
36
5) Remove the condenser and add 2.0 g of sodium bisulfite in small increments over 10
minutes to the hot reaction mixture (use your powder funnel). Swirl and stir the mixture
for 4 or 5 minutes, then cool it in an ice bath to below room temperature.
6) While the flask is cooling, add 5 or 6 large spoonula's full of celite (see page 8, filter
aid) to 40 mL of water in a 100 mL beaker.
7) Using water, mat down a small piece of filter paper on the Buchner funnel of your
filtration equipment. With the vacuum on swirl and pour the celite/water mixture from
step six into the Buchner funnel. The 40 mL of water will filter through into the filter
flask and the celite should form a layer that completely covers the filter paper. Slowly
release the vacuum and discard the 40 mL of water from the filter flask.
8) Filter the cooled reaction mixture through the Buchner funnel that contains the celite.
Never fill the Buchner funnel much more than half way. The filtrate must be colorless.
9) Add 20 mL of water to the 100 mL RBF to rinse it. Pour this 20 mL of water onto the
brown solid (MnO2) in the Buchner funnel. Transfer the filtrate (the liquid in the filter
flask) to a 150 mL beaker (the beaker should be pre-marked for 15 mL) and give it to
your instructor until next lab period. Leave it uncovered.
NEXT LAB PERIOD (review recrystallization, pages 7 and 93)
10) Concentrate the filtrate to until 15 mL of liquid remains in the 150 mL beaker. Use
the Bunsen burner as a heat source.
11) As soon as you can, transfer the hot 15 mL of solution remaining in your 150 mL
beaker into a clean 100 mL beaker. Cool this solution in an ice/water bath until it is
below room temperature.
12) Acidify the 15 mL of solution in the 100 mL beaker until the pH = 1-2 by dropwise
adding concentrated hydrochloric acid. Stir the mixture after adding each drop of acid
and check the acidity using EMD pH strips. White crystals of adipic acid will precipitate
from the water. Cool this solution in an ice/water bath with occasional stirring until it is
below room temperature.
13) Vacuum filter the mixture and then combine your adipic acid with your lab hood
partner and recrystallize the adipic acid using about 5 to 10 mL of water as the
recrystallization solvent, did you look at pages 7 and 93?
14) Let the pure adipic acid dry in your locker in an open beaker until next period. Clean
and dry all glassware for next period.
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37
ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT
NAME_____________________________________ LOCKER #__________
DATE________________ LAB DAY AND TIME_____________________
TITLE OF EXPERIMENT____________________________________________
BALANCED EQUATION:
NAME OF PRODUCT____________________________________
Molar Mass ___________ M.P(solid)e or B.P.(liquid)
e__________
CALCULATION OF THEORETICAL YIELD
Lowest moles of product ________ X MM of Product ___________=
RESULTS
ACTUAL YIELD ___________G PERCENT YIELD ___________%
a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.
b. Moles = Grams/Molar Mass.
c. Coefficients from the balanced equation.
d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.
e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.
GRADING: Pre-Lab (20):______ Experimental Technique (30):_____
Yield & Purity (30):______ Post Lab Questions (10):_____ Lab Report Grade = ______
Name of
Reactant
Grams MM Moles
Product Coeff .
Reactant
Coeff.
Moles
of Produc
t
a b
c d
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38
SYNTHESIS OF 2-METHYL-4-HEPTANONE
INTRODUCTION
Many times starting materials are not readily available to synthesize the desired
product in one step. It is first necessary to synthesize, in one or more steps, compounds
that can then be converted into the final product. This experiment is an example of a
multi-step synthesis to obtain the desired product, 2-methyl-4-heptanone. Infrared
spectroscopy (IR) will be used to determine if the reactions were successful.
One of the most versatile synthetic reagents in organic chemistry is the alkyl or
aryl magnesium halide: the Grignard reagents. Grignard reagents were discovered by P.
A. Barbier and their chemistry was worked out extensively by his student, Victor
Grignard (Noble Prize, 1912).
In today's experiment, you will use one of two different "routes" to make the same
compound. Which Grignard and alkyl halide you use will depend on the Route you are
assigned! The First reaction involving the Grignard reagent is split into two steps:
In the first step, the Grignard reagent is prepared by reacting an alkyl halide, with
magnesium under anhydrous (no water) conditions (first equation). In the second step,
the Grignard reagent is allowed to react with an aldehyde to obtain the salt of 2-methyl-4-
heptanol. The salt is easily hydrolyzed by the addition water (second equation).
Finally, this alcohol will be converted to the corresponding ketone, 2-methyl-4-
heptanone, using sodium hypochlorite as the oxidizing agent (third equation).
* J. Chem. Educ., 1991, 68, 71.
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39
PRECAUTIONS
1. Diethyl ether is extremely flammable; NO BUNSEN BURNERS are to be used
today.
2. All reactions are exothermic, add reagents cautiously and as directed.
3. Sodium hypochlorite is a bleaching agent, wear your lab coat.
4. When mixing in the separatory funnel, swirl gently with the stopper off. When
shaking, vent the separatory funnel frequently.
PROCEDURE
DO NOT CLEAN OR RINSE OUT ANY GLASSWARE UNTIL AFTER STEP #10
1) All apparatus must be cleaned and dried the lab period before starting this experiment.
2) Carefully insert the prepared calcium chloride tube into your thermometer adapter.
3) Set-up the apparatus as follows: clamp a 100-mL RBF to a ring stand and attach a
claisen connecting tube. To the side opening of the tube attach the large condenser. Place
the calcium chloride tube on top. To the opening of the claisen tube that is directly over
the flask, place a separatory funnel, which will function as an addition funnel. This set-
up remains the same until step #11.
4) Weigh out magnesium turnings (1.9 g) and grind them with a mortar and pestle for
approximately one minute, then transfer then to the 100 mL RBF. Add and a few crystals
of iodine. Carefully, place a magnetic stir bar into your 100 mL RBF.
5)Route A: Make a solution of 1-chloropropane (4.07 g, 4.54 mL) in 15 mL of diethyl
ether in the separatory funnel
Route B:Make a solution of 1-chloro-2-methylpropane (4.81 g, 5.45 mL) in 15 mL of
diethyl ether in the separatory funnel. Swirl the apparatus to make sure the halide/ether
solution is well mixed.
(Review precautions). Turn on the water to the condenser.
6) Begin adding, DROPWISE, a small amount of the 1-chloro-2-methylpropane/ether
solution to the flask (approx 40 drops). The contents of the flask should become cloudy,
small bubbles should appear, the ether should begin to boil and reflux and the iodine
brown color should disappear. Be patient, if after 5 minutes there is no sign of a reaction,
notify your instructor. Then begin stirring with magnetic stir bar. Make sure the flask is
centered relative to the stir plate.
7) Keeping the reaction under control, add the rest of the 1-chloroalkane/ether solution, a
portion at a time, to maintain a steady rate of reflux. (Approx. 1-2 drops/sec) After all
has been added, close the separatory funnel and heat the flask by using a beaker of hot
water so that the reaction mixture gently continues to reflux for 20 minutes.
-
40
8) Cool the reaction mixture in an ice/water bath to room temperature.
9) Route A: Make a solution of 3-methylbutanal (2.84g, 3.61 mL) in 15 mL of ether in
the separatory funnel
Route B: Make a solution of butanal (2.40g, 2.92 mL) in 15 mL of ether in the separatory
funnel
and then dropwise, add this solution to the 100 mL RBF with stirring. After the addition
is complete, reflux the reaction mixture with a beaker of hot water for 15 minutes. Cool
the reaction mixture to below room temperature before proceeding to the next step.
10) Carefully, with constant stirring, add 10 mL of water, in small portions, from the
separatory funnel to the reaction mixture. Stir for several minutes. IF you have time
AND the solution above the solids is clear, complete steps 11-14. If not, stopper the
flasks loosely, and continue at the next lab. Return the magnetic stir bar to the instructor.
PART 2
11) Decant the solution from the unreacted magnesium into a separatory funnel, it maybe
necessary to add 20-40 mL of additional ether to the reaction flask, add 10mL of water to
the separatory funnel, shake and vent, allow layer separation and discard the lower
aqueous layer in the waste container (NOT THE SINK).
12) Add 30 mL of 5 % sodium hydroxide (NaOH) solution, shake and vent, allow layer
separation, discard the aqueous bottom layer as above and transfer the top ether layer to a
100 mL RBF.
13) Distill the ether from a 100-mL RBF using hot water bath. (simple distillation; see
diagram on page 95 lab text, you can substitute a glass stopper for the thermometer) Your
product is the residue of the distillation; the ether, which distills over, is collected in the
"recovered ether" bottle. Cool the receiver with ice water.
14) Add 10 mL of acetic acid to the 100-mL flask that contains the 2-methyl-4-heptanol.
Clamp this flask in a small beaker of ice water for 2-3 minutes. With the flask still in the
ice water, carefully add 30-mL aqueous 2.1M sodium hypochlorite solution, in small
portions, gently stirring (with a magnetic stir bar) the mixture after each addition.
15) Remove the flask from the ice water and swirl the solution carefully while it returns
to room temperature. Return the magnetic stir bar to your instructor.
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41
EXTRACTION TECHNIQUES USING DICHLOROMETHANE
Dichloromethane is denser than water and most organic compounds and will therefore
appear in the lower layer of the extraction. When you extract an aqueous layer 2 times,
you remove the lower layer after the first extraction, SAVE IT, and re-extract the
remaining upper aqueous layer with a fresh amount of dichloromethane. You will then
combine the two lower layers, which contain dichloromethane and whatever was
extracted into it. The upper layer is then disposed of properly.
16) Add 30 mL of water to the reaction in step #16 and transfer it to a separatory funnel.
Extract the aqueous solution 2 times with 30 mL of dichloromethane. Add 5 mL of water
to the combined dichloromethane extracts, shake and separate the lower organic layer.
17) Dry the dichloromethane layer with sodium sulfate, decant and distill off the
dichloromethane using a simple distillation. Cool the receiver with ice water bath. Distill
the light fractions (the low boiling point compounds) up to a thermometer temperature of
60O
C, 20 degrees above the boiling point of dichloromethane. The 2-methyl-4-heptanone
remains as the residue of the distillation. Take an IR of this product. Label the key
peaks in the IR. Hand in the product as directed. Put the dichloromethane in the bottle
labeled "Recovered Dichloromethane".
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42
ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT
NAME_____________________________________ LOCKER #__________
DATE________________ LAB DAY AND TIME_____________________
TITLE OF EXPERIMENT____________________________________________
BALANCED EQUATION:
NAME OF PRODUCT____________________________________
Molar Mass ___________ M.P(solid)e or B.P.(liquid)
e__________
CALCULATION OF THEORETICAL YIELD
Lowest moles of product ________ X MM of Product ___________=
RESULTS
ACTUAL YIELD ___________G PERCENT YIELD ___________%
a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.
b. Moles = Grams/Molar Mass.
c. Coefficients from the balanced equation.
d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.
e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.
GRADING: Pre-Lab (20):______ Experimental Technique (30):_____
Yield & Purity (30):______ Post Lab Questions (10):_____ Lab Report Grade = ______
Name of
Reactant
Grams MM Moles
Product Coeff .
Reactant
Coeff.
Moles
of Produc
t
a b
c d
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43
SYNTHESIS OF ETHYL IODIDE
INTRODUCTION
This experiment demonstrates a second method that an alkyl halide can be
synthesized. Compare this method to the method used to synthesize t-butyl chloride. In
this experiment the student is actually performing two reactions. The first reaction is the
synthesis of phosphorus triodide. As soon has the phosphorus triodide is formed, it will
react with the ethyl alcohol to produce the alkyl halide, ethyl iodide. When the product
of a first reaction (phosphorus triodide) is used, without isolation or purification, as a
reactant in the formation of a second product (ethyl iodide), then these two reactions are
said to be done "In situ".
To calculate the theoretical yield of ethyl iodide, use the bottom, overall equation.
PRECAUTIONS
1) Phosphorus, Iodine, and Ethyl Iodide are dangerous. Avoid contact of these three
chemicals with the skin. Avoid breathing these chemicals.
2) Ethyl alcohol and ethyl iodide are flammable. During the reflux and both distillations,
all glass joint must be tightly fitted together.
* King, H.S., Org. Syn., 1933, 13, 60 - 65.
Phosporus triodide
2PI3
6CH3CH2OH + 2PI3
6CH3CH2OH
2P + 3I2
2P + 3I2+
+ H3PO3I6CH3CH2
+ H3PO3I6CH3CH2
Overall equation:
Ethanol Ethyl iodide
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44
PROCEDURE 1) Clamp a 250 mL round bottom flask (RBF) to a ring stand and add 1.4g of red phosphorus (0.045 moles) and 10 mL of absolute ethanol (0.17 moles)
using a powder funnel. Don't forget to add two boiling chip to the flask.
2) Slowly, a spatula-full at a time, add 10g (0.04 moles) of iodine through the powder
funnel and into the 250 mL RBF. Swirl the reaction mixture after each addition, gently
rocking the ring stand from side to side for 30 seconds. The RBF should get warm, due to
the exothermic reaction taking place. If the reaction mixture begins to boil, cool the flask
in 600 mL beaker of ice/water until the boiling stops, then re-start the addition of iodine.
3) After all of the iodine has been added, attach a reflux condenser (the "fat" condenser)
and swirl the mixture for several minutes.
4) Reflux (Figure 2, page 95) with a flask heater and controller for 30 minutes.
5) Cool the reaction mixture in ice/water, without removing the condenser, until the
contents of the flask are approximately at room temperature.
6) Distill the contents of the 250 mL flask. Set up a simple distillation (Figure 3, page
96). Use a flask heater and controller. Use a hollow stopper instead of a thermometer
adapter and thermometer. Use the same condenser that was used for the reflux, no need
to clean it. Use a 100 mL RBF as a receiving flask. Distill until there is no liquid left in
the 250 mL RBF. You will see a dark colored solid in the distilling flask and a yellow,
red or orange colored distillate in the 100 mL receiving flask.
7) Transfer the impure ethyl iodide from the 100 mL RBF to a separatory funnel and add
10 mL of 3% sodium hydroxide. Put the hollow stopper on the funnel. Invert and vent
the funnel several times. Shake the funnel more vigorously and continue to vent. Clamp
the funnel to a ring stand and allow the contents of it to separate into two layers.
8) Drain the lower layer (impure ethyl iodide) & save it. Discard the top aqueous layer.
9) Put the bottom layer back into the separatory funnel and add 10 mL of water. Shake
and vent the funnel several times, then let the two layers separate.
10) Drain the lower layer into an Erlenmeyer flask and dry it with sodium sulfate.
Discard the top, water layer.
11) Distill the dried ethyl iodide using a flask heater and a simple distillation (Figure 3,
page 96). Use a 50 mL RBF as a distilling flask and a 25 mL (RBF) as a receiving flask.
Use the west ("thin") condenser, the thermometer adapter, and the 150 degree
thermometer. All of the equipment must be clean and dry. Collect up to 73C as pure
product.
12) Ethyl iodide is a clear colorless liquid. Hand in the product in a 30 mL sample bottle
with the usual label.
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45
ORGANIC CHEMISTRY PRE-LAB AND DATA REPORT
NAME_____________________________________ LOCKER #__________
DATE________________ LAB DAY AND TIME_____________________
TITLE OF EXPERIMENT____________________________________________
BALANCED EQUATION:
NAME OF PRODUCT____________________________________
Molar Mass ___________ M.P(solid)e or B.P.(liquid)
e__________
CALCULATION OF THEORETICAL YIELD
Lowest moles of product ________ X MM of Product ___________=
RESULTS
ACTUAL YIELD ___________G PERCENT YIELD ___________%
a. Use atomic weights rounded off to the nearest 0.1 atomic mass unit.
b. Moles = Grams/Molar Mass.
c. Coefficients from the balanced equation.
d. Moles of Prod.= (Product Coefficient/Reactant Coefficient) X Moles of Reactant.
e. From the Handbook of Chemistry and Physics, the Aldrich Catalog, or a website.
GRADING: Pre-Lab (20):______ Experimental Technique (30):_____
Yield & Purity (30):______ Post Lab Questions (10):_____ Lab Report Grade = ______
Name of
Reactant
Grams MM Moles
Product Coeff .
Reactant
Coeff.
Moles
of Produc
t
a b
c d
-
46
CHECK OUT
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47
ORGANIC POLYMERS THE SYNTHESIS OF NYLON AND THE IR ANALYSIS OF POLYMERS
Objective
The purpose of this experiment is to synthesize the polymer, Nylon-6,10, and to
determine the identity of an unknown polymer using infrared spectroscopy.
Introduction
Polymers are very large molecules composed of repeating subunits called
monomers. Polymers can either be synthesized through addition reactions of alkenes or
via condensation reactions. In addition reactions, the carbon-carbon double bond within
the alkene is broken and a new covalent bond between the two monomers is formed. In
the second type of reaction, two monomers condense together to form the polymer and
water as a by-product. In this experiment, Nylon-6,10 (an amide) will be synthesized by
reacting an amine with an acid chloride.
Nylon-6,10 is a polyamide formed from the reaction of a diamine, an amine that
has an NH2 group at each end, with a diacid chloride, which has a COCl group at each end. Nylon-6,10 is named based on the structure of its amide monomer unit. The
diamine used is hexamethylene diamine, which consists of six carbons while the diacid
used is sebacoyl chloride, a component containing ten carbons. When the diamine and
diacid condense, HCl is formed as a by-product, which can cause undesirable side
reactions. As a result, the diamine is dissolved in a sodium hydroxide solution such that
it neutralizes the HCl as soon as it is formed.
Nylon is a very versatile substance. It is strong enough to be used in tires, but can
also be spun fine enough to be used in hosiery. It is also very durable as it washes and
dries easily, and holds shape well, which is why it is used in fabrics.
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48
The identification of various compounds including polymers can be attained using
infrared (IR) spectroscopy. Since the absorption of infrared light can result in the
vibration of bonds, and the absorption of different bonds occurs at different frequencies,
the different functional groups present in the molecule can be identified from its IR
spectrum. IR spectroscopy is especially used in the waste management industry to aid
recyclers in identifying plastics that are missing their identification code. Plastics are
synthetic polymers that can be distinguished from each other based on the IR absorption
frequencies of the functional groups present in their monomeric units. In this experiment,
you will obtain the IR spectrum of an unknown synthetic polymer and confirm its identity
using Table 1.
Table 1: Structure of the Monomer Unit of Recycled Synthetic Polymers
Name of
Plastic
Identification
Code Structure of monomer
Poly(ethylene
terephthalate)
Polyethylene
Poly(vinyl
chloride)
Polypropylene
Polystyrene