Welcome to Chem 36!Organic Chem Lab

Dr. Katie Masters

Chem 36 Info…

Day/Time Lab: M/T/R/F, 9:35 am - 12:35 pm

Faculty Dr. Katie Masters Dr. Jackie Bortiatynski in Director, Organic Labs Director, Instrumentation

Charge 218 Whitmore Lab 211D Whitmore LabPhone: 863-3319 Phone: 865-2772kmasters@psu.edu jackie@chem.psu.edu

Office Hours Thursday, 3:00 pm - 5:00 pm

Website http://courses.chem.psu.edu/chem36

Required Materials

Lab Guide for Chemistry 35 & Chemistry 36: Introductory OrganicLaboratory Minard, Masters, Halmi & Williamson, 2004-2005 Edition,Hayden McNeil

Organic Chemistry Laboratory Notebook, 1st Edition, R. Minard, Hayden McNeil

Eye Protection - Eye Protection is required at all times in lab!

Organic Lab Equipment Kit

Combination or key lock

Lab apron and rubber gloves (optional)

Lab Assignments

5 Technique Experiments• Recrystallization & Melting Point*• Distillation & Boiling Point• Liquid/Liquid Extraction• Thin-Layer Chromatography (TLC)• Column Chromatography

5 Synthetic ExperimentsAssigned experiments; Downloadfrom the course website.

Spectral Unknown ExperimentDetermine an unknown’s structure

Quizzes5 quizzesEach worth 20 pts

Lab:5 Technique Experiment PreLabs 400 points*5 Technique Experiment Final Reports 400 points5 Synthetic Experiment Prelabs 500 points5 Synthetic Experiment Final Reports 500 pointsSpectral Unknown Determination 100 pointsTA Evaluation 100 pointsQuizzes 100 pointsMaximum Lab Points 2100 points

*Chapter 4 PreLab and Final Report do not count towards the final grade

Breakdown of the Course Points…

Lab Assignments: PreLabs and Final Reports

• PreLabs must be handed in BEFORE running the experiment. Please write them neatly!

• Late work is subject to a 10-point deduction the first day late and a 2-point deduction each additional day

• See Chapter 3 (Lab Guide) for details on PreLabs and Final Reports

• Course website has examples of PreLabs and Final Reports

• Grade sheets are to be attached to the front of the PreLabs and Final Reports; use them as a guide to include all important sections; they are located at the end of each experiment chapter

PreLab Sections

• Summary

• Goals

• Diagrams of Special Apparatus/Reaction Schemes

• Chemical Data Table

• Spectral Comparison*

• Chromatography Behavior Comparison*

• Explanation of “Work-Up”*

• PreLab Exercise

*Not for all PreLabs

PreLab: Summary Section

• Should be ~ 2 paragraphs long

1st paragraph:• Theory• Relevance/significance of technique, compound or reaction being studied.

2nd paragraph:• Concise description of the experiment being done• Do NOT include experimental detail!• Include specific compound being investigated, special techniquesused, spectral data to be acquired• Include a reference

PreLab: Summary Section

Example Summary for a Technique Experiment:

Small samples of impure solids can be purified by sublimation, or vaporization followed by condensation. The impure solid is heated on a warm surface, evaporates, and condenses (solidifies) on a cold surface. Once on the cold surface, the purified compound can be carefully collected, leaving the impurities behind on the warm surface. Sublimation is a useful purification technique if the impurities are essentially nonvolatile and if the desired substance has a vapor pressure of at least a few Torr at its melting point. Sublimation is best used on small amounts of sample since product loss in transfer and collection is minimal.

This experiment focuses on the purification via sublimation of an unknown substance, which will be one of the following compounds: 1,4-dichlorobenzene, naphthalene, 1-naphthol, acetanilide, benzoic acid, salicylic acid, camphor, or caffeine. Once the sublimation of the unknown compound is complete, its identity will be determined via melting point. The weight and percent recovery will also be determined to investigate the efficiency of sublimation as a purification technique.Reference: Lab Guide for Chemistry 35 & 36, Minard, et al, page 1000.

PreLab: Summary SectionExample Summary for a Synthetic Experiment:

Sulfanilamide, or p-aminobenzenesulfonamide, was first synthesized in 1908. It was discovered that sulfanilamide has antibacterial properties, and the mode of action has been determined. Bacteria must synthesize folic acid in order to grow. Sulfanilamide inhibits the formation of folic acid, and therefore, stops the growth of bacteria. Since humans do not synthesize folic acid (must be acquired in food), only bacteria are affected by the use of sulfanilamide. Thus, there is no negative side effect to taking sulfanilamide since it does not disrupt any critical biological action in the body.

This experiment focuses on the three-step synthesis of sulfanilamide, starting with acetanilide. The synthetic scheme is shown in the “Diagrams of Special Apparatus/Reaction” section of this PreLab. In this three-step route, acetanilide is subjected to chlorosulfonation, which is then followed by sulfonamide formation,and finally, reduction of the acetyl amide to yield sulfanilamide. The final product, sulfanilamide, will be crystallized and weighed to determine the percent yield of the pure product. The melting point and IR spectrum will be acquired to verify the purity and identity of sulfanilamide.Reference: Handout downloaded from the Chem 36 website, www.courses.chem.psu.edu/chem36.

PreLab: GoalsAt least 3 goals. Some examples:

•To purify an unknown by sublimation.•To observe the sand bath temperature at which sublimation starts and finishes.•To identify an unknown by melting point.•To synthesize sulfanilamide via a three-step process starting with acetanilide.•To purify sulfanilamide via recrystallization. •To achieve a 90% recovery (as reported in the experimental procedure) for the recrystallization of the crude product.•To verify sulfanilamide’s purity and identity via melting point and IR analysis.

PreLab: Diagrams of Apparatus

•Include hand-drawn, labeled pictures of equipment that you havenever used in this course. Thus, if first time use, then draw it. If you have used the equipment/technique in the past, do not draw it.

• When you run a reaction, include the overall reaction scheme in this section.

PreLab: Chemical Data Table (Notebook)

• Include chemicals that you may work with: chemical name, structure, FW, bp/mp, density, gram amount, mmol amount waste category, flammability, toxicity, comments. Use the Aldrich catalog to find this information.

• How to find mmol amount?

Gram amount to be used X (1/FW) X 1000 = mmol

• Waste category: Please refer to the Lab Guide to see how compoundsare disposed of.For example:Hexanes - NHO (non-halogenated organics)Acetone - D (drain)Dichloromethane - HO (halogenated organics)HCl (aq) - D (drain with lots of water)Used syringe/needle - Sharps container

Common Shelf Chemical Data Table - fill out and hand in a copy with PreLab 5. If a chemical appears on this list, do not include in regular table

Chemical Data Table

Note:

When using Aldrich, pick the chemical entry that does NOT haveisotopic labeling, e.g, d, 15N, 13C. These are more expensive and willhave different FWs. Aldrich will also tell you if a chemical is flammable or toxic or an irritant.

Typically, use the last entry that gives all necessary data for thetable.

Final Reports (Post Labs) Sections

• Observations/Data: be as detailed as possible

• Results/Discussion: presentation of your findings, interpretation of your results, statement of whether goals were met

• PostLab Questions

• Attach the in-lab notebook pages. Make sure your TA signs your notebook pages at the end of each lab session.

Final Reports: Observations/Data Example

Fifty milligrams of an impure unknown solid (slightly yellowed white solid) was placed into a 25-mL Erlenmeyer filter flask. (Note: the solid smells like moth balls).The side arm of the flask was closed off with a pipette bulb. Ice water was placed in the centrifuge tube. The system was carefully heated on a sand bath until sublimation began. Sublimation was noted by observing small needles condensing onto the cooled centrifuge tube. At times, small needles were seen on the sides of the upper part of the flask. In order to ensure condensation on the centrifuge (and not on the sides of the flask), a loose fitting of aluminum foil was placed on the sides of the flask to cause the crystals to sublime from the sides of the flask and condense on the centrifuge tube.

The temperature was maintained, and sublimation was complete when there was a small amount (~10-12 mg) left on the bottom of the filter flask. The centrifuge tube was carefully lifted out of the filter flask, and the white crystals were carefully scraped off the centrifuge tube and weighed. Note: there was a small amount of product loss during the collection/scraping of the crystals. Thirty-two milligrams of white solid compound were collected, and its melting point was determined to be 79-81°C.

Final Reports: Results/Discussion Example

Based on the experimental melting point data, the unknown white solid has been identified as naphthalene, which has a melting point of 82°C. The percent recovery is calculated below:

% recovery = 32 mg/50 mg X 100 = 64%

Sublimation has proved to be an effective method for purifying a small amount of impure solid. The experimental melting point, 79-81°C, is extremely close to the theoretical melting point of naphthalene. Also, naphthalene is reported to appear as pure white crystals, which is what was observed after sublimation, and is the main component of moth balls. The percent recovery, 64%, although not excellent, is fair; it would have been higher if loss of product did not occur.

Overall, sublimation is a fast, efficient way to purify solids. The set-up of apparatus is simple as is the process of sublimation and collection of pure product.

Important Safety Rules

• Always wear eye protection when in the lab!

• Use gloves when appropriate; wash hands often.

• All chemistry must be done in the fume hoods.

• Your TA must be present when you are in the lab.

• If you wear shorts that are above the knee, you must wear a lab apron.

• No bare midriffs or open-toed sandals.

• Report accidents immediately to your TA.

• Keep coats and book bags on the shelves above your desk - keep them out of the aisles!

Courtesy in the Lab

• Return all reagent and solvent bottles to their proper place on the sideShelves or in the refrigerator immediately!

• Keep your area clean. Your TA will assign one person to do a generalLab clean-up after each lab session.

• Show up prepared and on time.

• Keep the Instrument Room clean (room 206 Whitmore).

• Avoid floods.

• Keep balances clean!

• Treat everyone with respect.

Instrument Room

• NMR Spectrometer• IR• UV/Vis• RI (refractive index)• Polarimeter• GC• GC-MS

Chem 36 TAs will hold their office hours in this room.

**You are required to get all spectra signed and dated by a TA in theInstrument Room as soon as you acquire them.**

Course Schedule & Syllabus

Note the following:

• Dates of all quizzes. Quizzes are given at the beginning of lab.

• One “Catch-Up” Lab.

• The 1st half of this semester, you will learn fundamental techniques. In the2nd half, you will apply those techniques when doing synthetic reactions.

Next Lab Session

1. Come to lab with the PreLab for Chapter 4.

2. Quiz 1 - Safety (Ch 2) and Ch 4 material.

3. Have your TA initial and date your notebook pages before leaving; do thisat the end of each session.

You will get a Spectral Unknown (Ch 10) within the first two sessions. Start working on that ASAP; sign up for instrument time. Note the date when the Progress Check is due for this experiment.