unit a: organic chemistry - …organic... · unit a: organic chemistry . ... structural formulas 1....

Innisfail High School

Chemistry 30

Ms. Littke

Spring 2014

Unit A: Organic Chemistry

Assessment

Formative

Students must participate in lessons

- complete daily notes and examples.

Students are expected to self assess and seek help if

necessary

Complete daily activities and review new concepts regularly

F/S - Quizzes will be given periodically throughout

the unit

You should use these to your advantage as they test

smaller sections of the curriculum and help prepare you

for the Unit Exam

Labs – 2 labs per unit

Summative Unit Exam – test format will be given to

you later

Unit A: Chapters 9 and 10

Organic Chemistry

Today’s Objectives:

1) Define organic compounds as compounds containing carbon, recognizing inorganic

exceptions such as carbonates, cyanides and carbides

2) Identify and describe significant organic compounds in daily life, demonstrating

generalized knowledge of their origins and applications

3) STS: Demonstrate an understanding that science and technology are developed to

meet societal needs and expand human capability

Section 9.1 (pg. 354-361)

Organic

Introduction Today’s Agenda:

1) Introduce organic chemistry and review the origins and

applications of some major organic compounds

2) “Carbon – The element of life” video

3) Are You Ready pg. 354 #1-6 – due tomorrow

What is Organic Chemistry?

The early definition related to compounds obtained only from

living things.

Today, it is a major branch of chemistry that deals with

compounds of carbon, called ORGANIC compounds*.

*Carbon compounds that are exceptions and considered

INORGANIC are compounds like:

Oxides carbon monoxide (CO(g) ) and carbon dioxide (CO2(g) ), and

Ionic compounds of carbon-based ions, such as carbonate CO32-,

cyanide CN-, and carbide ions, SiC (silicon carbide)

The major source of carbon compounds is still living or

previously living things, such as plants, animals and all types

of fossil fuels.

Organic or Inorganic??

Formula Organic or Inorganic?

CaCO3(s) Inorganic (carbonate ion)

C25H52(s) Organic

Ca2C(s) Inorganic (carbide ion)

CCl4(l) Organic

CH3COOH(l) Organic

CO2(g) Inorganic (oxide)

KCN(s) Inorganic (cyanide)

C12H22O11(s) Organic

Why is carbon special?

There are millions or organic compounds and only a thousand

inorganic compounds. WHY?

Carbon has a bonding capacity of 4

Remember Lewis Dot Diagrams from Chem 20??

This means carbon can bond extensively and can bond

together to form chains effectively = called Polymerism

Carbon covalently bonds by sharing 4 pairs of electrons.

These bonds may be single, double or triple, all producing

stable compounds

Compounds can form with same number of each type of atom

but different structures = Isomerism

So why do we care about bonding capacity?

If we know how many bonding e-’s an atom has, we can predict what structure a molecular compound will have

Determining Lewis Formulas

Atom Number of valence electrons

Number of bonding electrons

Bonding capacity

carbon 4 4 4

nitrogen 5 3 3

oxygen 6 2 2

halogens 7 1 1

hydrogen 1 1 1 H

I.e. Carbon can form 4 single bonds, 2 double bonds, 1 triple and 1 single, or 1 double and 2 singles

Polymers

Examples of repeating carbon chains:

Isomers

Compounds with the same number of each type of

atom but different structures (C4H10)

We will talk about this in more detail later

Importance of Organic Chemistry

Building units of all living matter: carbohydrates, proteins, fats

All foods are organic compounds

Photosynthesis is a reaction that makes carbon a part of our food. Carbon is passed along through food chains and sugar from photosynthesis is modified and combined with other materials.

Dead organisms are food for other organisms, or are buried in the earth and converted to fossil fuels like peat, coal and petroleum

Petroleum is the source of fuel and starting material for plastics, fabrics and industrial chemicals

The carbon cycle is

an illustration of the

interrelationship of

all living things with

the environment and

with technologies

that refine and use

fossil fuels

We will continually

outline the

importance of

organic compounds

in our daily lives

Carbon: The Element of Life

Complete the worksheet provided as you watch

the following video (20 min)

Today’s homework

Ensure video worksheet is complete and

in your notes to review later

Work on Are you Ready pg. 354-355

# 1- 6 – due tomorrow

What is coming up tomorrow?

Naming alkanes, branched alkanes and

cycloalkanes

Section 9.2 (pg. 366-374)

Naming Organic

Compounds Today’s Objectives:

1) Name and draw structural, condensed structural, and line diagrams and

formulas for saturated and unsaturated aliphatic (including cyclic)

• Containing up to 10 carbon atoms in the parent chain/cyclic structure

• Containing only one type of a functional group or multiple bond

• Using the IUPAC nomenclature guidelines

2) Identify types of compounds from the functional groups, given the structural

formula

3) Define structural isomerism and relate to variations in properties

Four Types of Formulas

1. Molecular Formulas C5H10(g) Not very useful for organic

compounds because so many

isomers can exist

2. Structural Formulas

1. Condensed Structural Formulas

2. Line Diagrams

– end of line segment represents carbon

– it is assumed to satisfy each carbon’s octet

Naming Organic Compounds

Aliphatic Hydrocarbons – contains only hydrogen and carbon atoms

Straight line chains of carbon atoms

Alicyclic hydrocarbons have carbon atoms forming a closed ring. Still

considered aliphatic

Alkanes Alkenes Alkynes

Only single C-C

bonds

Double C-C Bond

present

Triple C-C bond

present

General formula

CnH2n+2

General formula:

CnH2n

General formula:

CnH2n-2

Saturated Unsaturated Unsaturated

In organic chemistry, names

have a root and a suffix.

The root describes the number

of carbons present in the chain

or ring.

The suffix describes the type of

compound it is.


Naming ALKANES

1. Find the parent chain (the longest continuous chain

of carbon atoms). Use the appropriate root and

the suffix-ane.

Naming ALKANES

1. Find the parent chain. Use the appropriate root and suffix.

2. Number the carbon atoms, starting from the end closest to the

branch(es) so that the numbers are the lowest possible

3. Identify any branches and their location number on the parent chain

(us the suffix –yl for branches)

4. Write the complete IUPAC name, following the format: (number of

location, if necessary) – (branch name) (parent chain)

2-methylheptane

If more than one of the same branch exist, use a multiplier to

show this (di, tri). Remember to include all numbers

Draw 2,4,6-trimethylheptane

Naming ALKANES

If different branches exist, name them in alphabetical order

ethyl before methyl (e before m in the alphabet)

Naming ALKANES

If there is more than one

branch of the same type, a

locating number is given to

each branch and a prefix

indicating the number of that

type of branch is attached to

the name.

This numbering prefix does

not affect the alphabetical

order of the branches

Draw the structural formula

for 3,4-dimethylhexane

Naming ALKANES

Summary of Naming Alkanes

1. Find the parent chain. Use the appropriate root and suffix.

2. Number the parent chain carbon atoms, starting from the end

closest to the branch(es) so that the numbers are the lowest

possible

3. Identify any branches and their location number on the

parent chain (us the suffix –yl for branches)

4. If more than one of the same branch exist, use a multiplier

(di, tri) to show this. Remember to include all numbers

5. If different branches exist, name them in alphabetical order

6. Separate numbers from numbers using commas, and

numbers from words using dashes (no extra spaces)

Don’t forget

Questions will specifically

ask about structural,

condensed structural or

line structural formulas.

You must be comfortable

drawing any of the three

Practice

Write the IUPAC name for the following

2,5-dimethyl-4-propyloctane

Correct the following names:

4-ethyl-2-methylpentane

ACTUALLY 2,4-dimethylhexane

ALWAYS LOOK FOR LONGEST CHAIN!!

Correct the following name:

4,5-dimethylhexane

Actually 2,3-dimethylhexane

**Want branch numbers to be as low as possible

CYCLOALKANES

Based on evidence, chemists believe that organic carbon compounds

sometimes take the form of cyclic hydrocarbons:

Cycloalkanes: Alkanes that form a closed ring

General Formula CnH2n

Two less hydrogens are present than in straight chain alkanes because

the two ends of the molecule are joined

Are these considered saturated?? Yes, because they have only single

bonds and the max amount of hydrogen's bonded to the carbons

Cyclo-compounds will have a higher boiling point than their straight

chain partners (because there is an additional bond present)

Cycloalkanes are named by placing the prefix cyclo in front

of the alkane name, as in cyclopropane and cyclobutane

If branches are present, treat the cycloalkane as the parent

chain and identify the branches.

Since there is no end at which to start the numbering, use the

lowest numbers possible

Naming CYCLOALKANES

Name the following:

1. 2.

1,2-dimethylcyclopentane ethylcyclohexane

**Why don’t we need a number?

Today’s homework

Pg. 370 – 71 #7 – 11

Pg. 372 #5-6


Naming Alkenes, Alkynes, Cycloalkenes and

Cycloalkynes

Comparing properties of Isomers

Section 9.3 (pg. 374-380)

Naming Organic

Compounds:

Alkenes and Alkynes Today’s Objectives:


formulas for saturated and unsaturated aliphatic (including cyclic

• Containing up to 10 carbon atoms in the parent chain/cyclic structure

• Containing only one type of a functional group or multiple bond



formula


Review:

Find and name all of the isomers of pentane (C5H12(l))

Structural Isomerism

Compound with the same molecular formula but

different structures

They will have different chemical and physical

properties – based on their different structures

Alkenes and Alkynes

Alkenes – hydrocarbons containing a double C-C bond

General formula (CnH2n) - (like cycloalkanes)

Alkynes – hydrocarbons containing a triple C-C bond

General formula (CnH2n-2) – (like cycloalkenes)

Alkenes and Alkynes are considered unsaturated

compounds. They do not have the maximum number of

hydrogen atoms surrounding each carbon.

Reactivity: Alkynes (highest), Alkenes, Alkanes (lowest)

Naming Alkenes and Alkynes

1. Find the parent chain. It MUST contain the multiple bond.

If the bond is a double, the suffix for the parent chain will be -ene

If the bond is a triple, the suffix for the parent chain will be –yne

2. Count carbon atoms so that the multiple bond will be on the lowest

possible number. Indicate the number that the multiple bond falls on

directly before the suffix

3. Name branches as before


Draw the following as condensed structural formulas:

4-methylpent-2-yne

methylpropene

(why don’t we need a number?)


Name the following:

3-methylbut-1-ene

5-methylhex-2-ene


4. It is possible for a molecule to have more than one

double bond. These are called alkadienes and have

the same general formula as alkynes (CnH2n-2)

If this is the case, indicate both numbers where the

double bond is formed, and change the suffix to –diene.

a) Draw buta-1,3-diene:

b) What is the IUPAC name for the following:

buta-1,2-diene

Cycloalkenes and -ynes

The rules for naming cycloalkenes and cycloalkynes

are the same as naming cycloalkanes

The numbering for the carbon atoms begins with the

double bond; the carbons of the double bond are

carbons 1 and 2; lowest numbers possible

Draw 3-methylcyclohexene

as a condensed structural

formula

Today’s homework

Pg. 377 #1-5

Pg. 380 #6, 7, 11


Hydrocarbon Quiz #1

Naming Aromatics

Boiling point and Chemical Properties Analysis

Section 9.4 (pg. 381-385)

Naming Organic

Compounds:

Aromatics



formulas for aromatic carbon compounds



formula


Hydrocarbon Quiz #1

Aromatics

Originally, organic compounds with an aroma or

odour were called aromatic compounds

Now, aromatics refer to compounds containing a

benzene-ring structure

Benzene’s formula is C6H6, which would suggest a highly

unsaturated and reactive compound

Benzene is actually quite unreactive and is considered

more stable than alkenes and alkynes

Did You Know?? Benzene is a carcinogen and is found

naturally in petroleum – why would this be a problem?

What do we know about benzene? Formula is C6H6 (3D link)

Unreactive – so no true double or triple bonds

Carbon-carbon bonds are the same length and strength

Each carbon is bonded to a hydrogen

So what does benzene look like??

The three double bonds resonate resulting in an overall

bond length somewhere in between a single and a

double bond, explaining benzene’s stability

We will use this line

structural formula to

represent benzene in

compounds

http://www.nelson.com/ABchem20-30/teacher/protect/otr/chem2030OTR/attachments/l_animations_simulations/MMDB/dswmedia/database.htm

Common Aromatic Compounds

Include Aspirin and Vanillin (one of the flavour molecules in vanilla)

You will notice many aromatic molecules are often depicted

using a condensed structural formula except for the benzene

ring, which is shown as a line structural formula.

This combination is commonly used by chemists, and we will use

this method when drawing aromatics.

Naming Aromatics

1. If an alkyl branch is attached to a benzene ring, the

compound is named as an alkylbenzene.

Alternatively, the benzene ring may be considered as a

branch of a large molecule: in this case, the benzene ring

is called a phenyl branch. Which has a phenyl branch?

An alkylbenzene Contains a phenyl branch

Naming Aromatics

2. If more than one alkyl branch is attached to a benzene

ring, the branches are numbered using the lowest

numbers possible, starting with one of the branches.

Given the choice between two sets of lowest numbers, choose the

set that is in both numerical and alphabetical order

1-ethyl-2,4-dimethylbenzene 3-phenyl-4-propyloctane

Practice Naming Aromatics

Draw 1,2-dimethylbenzene

Are there any isomers of this compound?

There is also classical way of naming these isomers. The

arrangements are denoted by the prefixe:s ortho (o), meta (m) and

para (p). These names are still used in industry so you may

encounter them in other references.

1,2-dimethylbenzene 1,3-dimethylbenzene 1,4-dimethylbenzene

o-dimethylbenzene m-dimethylbenzene p-dimethylbenzene


Draw the line structural formula for 1-ethyl-3-methylbenzene

Draw the line structural formula for 2-phenylpentane


Draw 3-phenylpent-2-ene

Name the following

propylbenzene

Why is no number needed?

Are the hydrogen’s

wrong??

Summary

We have now learned about both aliphatic and

aromatic hydrocarbons. You will need to be

comfortable naming all of the following:

Teacher Note:

End if not enough time for two dry labs

Can use during the Station Lab Periods

Review of Intermolecular Forces

London Forces – temporary dipoles resulting from an

uneven distribution of e- in all molecules

Temporary (-) end will repel e- in neighbouring molecules

and so on

Depends on size of molecule (number of e-’s)

Weakest of the intermolecular forces

Dipole-Dipole – only exists in polar molecules

Attraction between + and – ends of molecule

Hydrogen Bonding – super strong force

Only exists when H-N, H-F, H-O bonds are present

Applications Read pg. 384 Lab Exercise 9.A – complete the parts in red

Purpose: To test the generalization that aromatic hydrocarbons

react like saturated rather than unsaturated hydrocarbons

Design: cyclohexane, cyclohexene and benzene are all mixed

with potassium permanganate (purple). Evidence for a reaction

is a change in the initial purple colour of the solution.

Prediction: Based on your current knowledge, predict the order

in which the compounds will react, from least reactive to most

reactive. Explain your reasoning.

Analysis: On the basis of the evidence, determine the order of

the reaction rate for the three compounds.

Evaluation: Determine if your prediction was verified or

falsified. Was the generalization about aromatic hydrocarbons

acceptable based on the evidence? Was the purpose of the

investigation accomplished?

Sample lab report for 9.A

Applications Read pg. 384 Lab Exercise 9.B – complete the parts in red

Purpose: To test the ability of the concept of London forces to predict

the relative boiling points of aliphatic and aromatic compounds

(Remember: the more electrons in a compound = the stronger the

intermolecular forces = the higher the boiling point needed to pull the

molecules apart)

Problem: What is the relative order of the boiling points of hexane,

hex-1-ene, cyclohexane, cyclohexene, and benzene?

Prediction: Determine the number of electrons in each molecule and

use these numbers to determine the order of boiling points

Analysis: On the basis of the evidence given, determine the order of

the boiling points. (from lowest to highest)

Evaluation: Determine if your prediction was verified or falsified.

Was the predictive power of the concept of London forces judged to

be acceptable based on the evidence? Was the purpose of the

investigation accomplished?

Extra Practice for Lab Reports

Complete pg. 355 #6

Complete the prediction, analysis and evaluation

Remember lab report guidelines in textbook starting on

pg. 790

Today’s homework

Pg. 385 #3-5 – due tomorrow


Review Aromatic and Aliphatic Compounds

Section 10.2 and 10.3 (pg. 417-435)

Organic Chemistry:

Organic Halides and Alcohols


1) Name and draw structural, condensed structural and line diagrams and

formulas for organic halides and alcohols

2) Identify types of compounds from their functional groups, given the structural

formula and name of the functional groups

Today’s Agenda: Review

You will have another Hydrocarbon Quiz next

class covering all aliphatic and aromatic

compounds

Today’s agenda:

Review Quiz – go over common mistakes

Pg. 385 #6-8

**7d) 4-methyl (not 3-methyl)

Make the change in your book if not done

already

Aliphatic and Aromatic Compounds

Hydrocarbon Quiz #2

Review of Intermolecular Forces

London Forces – temporary dipoles resulting from an

uneven distribution of e- in all molecules

Temporary (-) end will repel e- in neighbouring molecules

and so on

Depends on size of molecule (number of e-’s)

Weakest of the intermolecular forces

Dipole-Dipole – only exists in polar molecules

Attraction between + and – ends of molecule

Hydrogen Bonding – super strong force

Only exists when H-N, H-F, H-O bonds are present

Organic Halides

Organic compounds where one or more hydrogen

has been replaced with halogens (F, Cl, Br, I)

Common example: CFC (chlorofluorocarbons)

Nomenclature is similar to naming branch chains of

hydrocarbons, but the branch name used is based

on the halogen used

chloro-, fluoro-, bromo-, iodo-

Organic Halides

What do you need to know about organic halides?

May by polar or nonpolar molecules or may have a

relatively nonpolar (hydrocarbon) end and a polar

(halide) end (**Remember Electronegativity differences)

Have higher boiling points than similar hydrocarbons

Have very low solubility in water but higher solubility

than similar hydrocarbons

Are typically good solvents for organic materials such

as fats, oils, waxes, gums, resins or rubber

Usually toxic or ecologically damaging (DDTs and PCBs)

Practice Naming Organic Halides

Draw 1,2-dichloroethane

Draw 2,2,5-tribromo-5-methylhexane

Practice Naming Organic Halides

Name the following:

CH2Cl2

1,2-dibromoethene

Bonus: Try 1,2-dibromo-1,2-dichloroethene

chlorobenzene

dichloromethane

Did You Know?

There is always a

new concept to

learn that extends

what you have

already learned.

In addition to the

structural isomers

that you know

about, there are cis

and trans isomers

Stop and Practice

Alcohols

An alcohol is an organic compound that contains the –OH

functional group (hydroxyl)

General formula is R-OH (R = rest of molecule)

Alcohols are classified as primary, secondary or tertiary

depending on the number of carbons bonded to the carbon

that contains the hydroxyl group

Common Alcohols

Methanol (also called wood alcohol) is extremely toxic, causing

death and blindness

Ethanol (also known as grain alcohol) is the alcohol found in

alcoholic beverages and is used in the production of vinegar

Gas line antifreeze,

windshield de-icer,

windshield washer

fluid – all contain

methanol

Naming Alcohols

1. Locate the longest chain that contains an –OH group attached to

one of the carbon atoms. Name the parent alkane

2. Replace the –e at the end of the name of the parent alkane with

–ol (i.e. butane becomes butanol)

3. Add a position number before the suffix –ol to indicate the

location of the –OH group

REMEMBER to number the main chain of the hydrocarbon so that

the hydroxyl group has the lowest possible position number

propan-1-ol

Naming Alcohols

4. If there is more than one –OH group (called polyalcohols), leave

the –e in the name of the parent alkane and put the appropriate

prefix before the suffix –ol (i.e. diol, triol, tetraol)

4. Name and number any branches on the main chain. Add the

names of these branches to the prefix.

Draw 2,3-dimethylbutan-2-ol

Practice Naming Alcohols

Draw line structural formulas for:

1. cyclohexanol

2. phenol

1. The three isomers of C5H11OH that are pentanols

These are the

only two cyclic or

aromatic alcohols

you will need to

know as they get

very complicated

Alcohols

What do you need to know about alcohols?

Question: Why is the propane used in a barbecue a gas at

room temperature, but propan-2-ol (also known as rubbing

alcohol) a liquid at room temperature?

Answer: Propane is a non-polar hydrocarbon with weak

intermolecular forces, thus it has a low boiling point and is a

gas at room temperature.

Propan-2-ol is an alcohol, with a polar hydroxyl group and

strong intermolecular forces, thus it has a higher boiling point

than propane and is a liquid at room temperature

Alcohols

What do you need to know about alcohols?

Question: Glycerol (propane-1,2,3-triol) is more viscous than

water, and can lower the freezing point of water. When

added to biological samples, it helps to keep the tissues from

freezing, thereby reducing damage. From your knowledge of

the molecular structure of glycerol, suggest reasons to account

for these properties of glycerol.

Answer: Each molecule of glycerol contains three hydroxyl

groups which can hydrogen-bond with water, interfering with

the attractions between water molecules and thus interfering

with the freezing of water. When water in tissues does not

freeze, there is less damage to the tissues.

Application Question

Predict the order of increasing boiling points for the

following compounds, and give reasons for your answer.

butan-1-ol pentane 1-chlorobutane

Answer: (Lowest b.p.): pentane, 1-chlorobutane, butan-1-ol

Why? All molecules have a similar number of electrons.

Pentane has the lowest boiling point, because it is non-polar so

will only have London forces between the molecules. 1-

chlorobutane is polar so will have dipole-dipole forces as well

as London forces. Butan-1-ol has the highest boiling point

because its molecules will have all three intermolecular forces,

most importantly, hydrogen bonding

Today’s homework

Pg. 418 #1-5

Pg 422 #6-8

Pg. 430 #5,6,7a,9a

Due tomorrow


Carboxylic Acids and Esters

Section 10.4 (pg. 436-443)

Organic Chemistry:

Carboxylic Acids and Esters


1) Name and draw structural, condensed structural and line diagrams and

formulas for carboxylic acids and esters

2) Identify types of compounds from their functional groups, given the structural

formula and name of the functional groups

Carboxylic Acids

A carboxyl group is composed of a carbon atom double

bonded to an oxygen atom and bonded to a hydroxyl

group (-COOH)

Note: Because the carboxyl group involves three of the

carbon atom’s four bonds, the carboxyl is always at the end

of a carbon chain or branch

methanoic acid ethanoic acid

Examples:

Carboxylic acids are

weak organic acids

Naming Carboxylic Acids

1. Name the parent alkane

2. Replace the –e at the end of the name of than parent

alkane with –oic acid

3. The carbon atoms of the carboxyl group is always given

position number 1. Name and number the branches that

are attached to the compound.

Draw 3-methylbutanoic acid

HOOC

Remember COOH or HOOC

can also represent the

carboxyl group

Naming Carboxylic Acids

1. Draw trichloroethanoic acid (key ingredient in chemical peels)

CCl3COOH

2. Draw 3-propyloctanoic acid

Do you need the CH3 here?

No – but sometimes you will

see it written this way. Don’t

be confused because it doesn’t

change the meaning

Esters

The reaction between a carboxylic acid and an alcohol produces

an ester molecule and a molecule of water

This reaction is known as a condensation or esterification reaction

The ester functional group –COO– is similar to that of a carboxylic

acid, except that the H atom of the carboxyl group has been

replaced by a hydrocarbon branch.

Esters are responsible for natural and artificial fragrance and

flavourings in plants and fruits.

In naming an ester you have to recognize that an ester

has 2 distinct parts. The main part contains the C=O

group which comes from the parent acid. The second

part is the alkyl group.

Esters

Naming Esters

1. Identify the main part of the ester, which contains the C=O group.

This part comes from the parent acid.

2. Begin by naming the parent acid but replace the –oic acid ending

of the name with –oate. (propanoic acid becomes propanoate)

3. The second part is the alkyl group that is attached to the single

oxygen atom. Name this as you would any other alkyl group (in

this case = methyl)

4. Put the names together. Note that esters are named as two words.

Naming Esters

Name the following ester and the acid and alcohol from

which it can be prepared.

ethyl butanoate

ethanol butanoic acid

water

Tip: The branch attached to the oxygen (of the –COO) comes first in the

name, the chain attached to the carbon (of the –COO) comes second

A strong acid catalyst,

such as H2SO4(aq) is used

along with some heating

to increase the rate of the

organic reaction

Naming Esters

Name the following ester and the acid and alcohol from

which it can be prepared.

ethyl benzoate ethanol benzoic acid water

What is missing from this esterification reaction?

Today’s homework

Pg. 438 #1,2

Pg. 441 #3-5, 6(a-c only)

Due tomorrow


Physical Properties of Organic Compounds

Crude Oil Refining

Full Naming Quiz (in two days)

Section 9.5 and 9.6 (pg. 386-400)

Properties of Organic

Compounds & Crude Oil

Refining Today’s Objectives:

1) Compare boiling points and solubility of organic compounds

2) Describe fractional distillation and solvent extraction

3) Describe major reactions for producing energy and economically important

compounds from fossil fuels

Physical Properties of Simple Hydrocarbons

Alkanes Non-polar molecules

Only intermolecular forces are London Force

Boiling point and melting point increase with number of carbons

All insoluble in water (like dissolves like) – nonpolar and polar don’t mix

1-4Cs = gas, 5-16Cs = liquid 17 and up = solid at SATP

Alkenes Non-polar molecules, therefore insoluble in water

Boiling points slightly lower than alkanes with the same number of carbons

due to less electrons (unsaturated), resulting in lower London Forces

Alkynes Non-polar molecules, therefore insoluble in water

Higher boiling points than alkanes and alkenes with similar C #s

Accepted explanation: Linear structure around triple bond allows electrons to

come closer together than in alkanes/enes, resulting in greater London Force

Branching The more branching, the less significant the London Force (~lower b.p.)

- more surface area in straight chain hydrocarbons allows more

separation of charge, resulting in greater London Force

- see Table #3 pg. 378 (i.e. pentane (with 5Cs) has a b.p. of 36oC

which is much higher than dimethylpropane (5Cs) -12oC) = because

branching decreased the strength of the London force

Physical Properties of Hydrocarbon Derivatives

Alcohols Much higher boiling points than hydrocarbons (1-12Cs are liquids at SATP)

due to hydrogen bonding between hydroxyl groups of adjacent molecules

Small alcohols are totally miscible in water, but the larger the hydrocarbon

part of the alcohol (nonpolar part), the more nonpolar the alcohol is

Carboxylic

Acids

Like alcohols they have hydrogen bonding, but is more significant due to the

C=O. This means greater bps and solubility than alcohols with same number

of Cs.

Carboxylic acids with 1-4Cs are

completely miscible in water

Esters Fruity odour in some cases

Polar but they lack the –OH bond therefore do not have hydrogen bonding, so

lower bps than both alcohols and carboxylic acids

Esters with few carbons are polar enough to be soluble in water

Compound Boiling Point (oC)

butane -0.5

butan-1-ol 117.2

butanoic acid 165.5

Summary Table - Organic

In your homework book (pg. 7), there is a summary table

of all of the organic compounds we have studied. This

will be a good page to reference when studying

Sample Question

Predict the relative order of boiling points of the following

compounds (lowest to highest). Explain your reasoning.

butanol but-1-ene cyclobutane butanoic acid butane

Lowest -------------------------------------------------------------> Highest

but-1-ene butane cyclobutane butanol butanoic acid

Reasoning: but-1-ene has lower LF’s for than butane because it is

unsaturated, cyclobutane has an additional bond because cyclic,

butanol has H-bonding, butanoic acid has stronger H-bonding)

Which would be soluble in water?

Butanol and butanoic acid – because they are the only polar molecules

and like dissolves like!

Crude Oil Refining

Crude oil is a complex mixture of hundreds of thousands

of compounds, all of which have different boiling points

We can take advantage of these different b.p.’s and

physically separate the different components using heat

This process is called fractional distillation or fractionation

A fractional distillation tower

contains trays positioned at

various levels.

Heated crude oil enters near

the bottom of the tower.

The bottom is kept hot, and the

temperature gradually

decreases toward the top of

the tower.

As compounds cool to their

boiling point, they condense in

the cooler trays. The streams of

liquid (called fractions) are

withdrawn from the tower at

various heights along the tower.

Electronic Visual

http://science.howstuffworks.com/environmental/energy/oil-refining4.htm

A more detailed look…

The vaporized components of the

crude oil rise and gradually cool.

To get from one level to the next, the

vapours are forced to bubble through

the liquid condensed in each tray.

The figure shows the bubble caps used

to allow this to happen.

If a gas cools to its boiling point, it will

condense and be piped out through

the draining tube

Q: How does the number of carbon atoms in a hydrocarbon chain

affect its boiling point?

Smaller molecules have fewer electrons, so weaker London forces

compared with larger molecules. The fractions with higher boiling points

are found to contain much larger molecules (see Table 1 pg. 387)

Crude oil is heated in the

fractionation tower without air being

present to reduce the risk of mixtures

starting to burn or explode

Cracking

Cracking: large hydrocarbons are broken into smaller fragments

Historically, thermal cracking used extremely high temperatures but

created large quantities of solid coke.

Now, catalytic cracking uses a catalyst to speed up the reaction and

produce less residual products like tar, asphalt and coke

Example: C17H36(l) C9H20(l) + C8H16(l) + C(s)

larger molecules smaller molecules + carbon

In 1960, hydrocracking was developed, which combines catalytic

cracking and hydrogenation and produces no coke.

Example: C17H36(l) + H2(g) C9H20(l) + C8H16(l)

larger molecule + hydrogen smaller molecules

Oil Refining

The refining of crude oil can be divided into two main categories:

1. Physical Processes

Fractional Distillation: see previous slides

Solvent Extraction: solvent is added to selectively dissolve and

remove an impurity or to separate a useful product from a

mixture

2. Chemical Processes

Cracking – larger molecules are broken down into smaller ones

Reforming – large molecules are formed from smaller ones

These chemical processes are needed because fractional distillation

does not produce enough of the hydrocarbons that are in demand

(i.e. gasoline) and produces too much of the heavier fractions

Catalytic Reforming and Alkylation

Catalytic Reforming: improves the quality of the gasoline

aliphatic molecule aromatic molecule + hydrogen

Alkylation: increases the branching; improves the quality of the fuel

aliphatic molecule more branched molecule

(AKA: isomerization because it converts molecules into a branched isomer)

FYI pg. 392 on

Octane Numbers

Combustion Reactions

Burning of hydrocarbons in the presence of oxygen

Complete Combustion: abundant supply of oxygen;

products are carbon dioxide, water vapour and heat

Ex. C3H8(l) + 5O2(g) 3CO2(g) + 4H2O(g)

Incomplete Combustion: limited supply of oxygen; products

are carbon monoxide, soot (pure carbon) or any

combination of carbon dioxide, carbon monoxide and soot

in addition to water vapour and heat

Ex. 2C8H18(l) + 17O2(g) 16CO(g) + 18H2O(g)

OR 2C8H18(l) + 9O2(g) 16C(s) + 18H2O(g)

** Assume complete combustion unless specified otherwise

Balancing FYI

Ex. 2C8H18(l) + 17O2(g) 16CO(g) + 18H2O(g)

Can also be balanced using a fraction (you need to be

comfortable using this method) – divide each number by 2

C8H18(l) + 17/2 O2(g) 8CO(g) + 9H2O(g)

Ex. 2C8H18(l) + 9O2(g) 16C(s) + 18H2O(g)

can also be balanced as …

C8H18(l) + 9/2 O2(g) 8C(s) + 9H2O(g)

Today’s homework

Read pages 410-416

Pg. 388 #2

Pg. 391 #11

Pg. 397 #4 b, c, d only

Pg. 430 #11


Chapter 9 Exam Review (Unit A Part 1)

Exam on Friday

After the Break

Hydrocarbon Reactions

Addition, Substitution and Elimination

unit a: organic chemistry - …organic... · unit a: organic chemistry . ... structural formulas 1....

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