Unit 3Organic Chemistry

Chemistry 2202

Introduction

● Organic Chemistry is the study of the molecular compounds of carbon.eg. CH4 CH3OH CH3NH2

● Organic compounds exclude oxides of carbon and ions containing carbon.ie. CO CO2 KCN CaCO3

are NOT organic compounds!!

History of Organic Chemistry● Started when medicine men extracted

chemicals from plants and animals as treatments and cures

● First defined as a branch of modern science in the early 1800's by Jon Jacob Berzelius

● Berzelius believed in Vitalism - organic compounds could only originate from living organisms through the action of some vital force

● organic compounds originate in living or once-living matter

● inorganic compounds come from "mineral" or non-living matter

● In 1828, Friedrich Wöhler discovered that urea - an organic compound - could be made by heating ammonium cyanate (an inorganic compound).

NH4OCN(aq) (NH2)2CO(s)

inorganic organic

http://en.wikipedia.org/wiki/Urea

What’s this?

(NH2) 2CO - (NH2)2CO

di-urea

● organic chemistry branched into disciplines such as polymer chemistry, pharmacology, bioengineering and petro-chemistry

● 98% of all known compounds are organic

● The huge number of organic compounds is due mainly to the ability of carbon atoms to form stable chains, branched chains, rings, branched rings, multiple rings, and multiple bonds (double and triple bonds) to itself and to many other non-metal atoms.

Sources of Organic Compounds

1. Carbonized Organic Matter- fossil fuels such as coal, oil, and natural

gas - basis for the petrochemical industry

2. Living Organisms eg: - penicillin from mold - acetylsalicylic acid (Aspirin) from the

bark of a willow tree

3. Invention

- antibiotics, aspirin, insulin, vanilla flavoring, and heart drugs are manufactured from organic starting materials

- plastics

Structural Isomers

● Structures that have the same molecular formula, but different structural formulas are called structural isomers

eg. C4H10

Practice: Draw all structural isomers of C5H12 and C6H14

CH3 CH2

CH2

CH3

butane

CH3

CH

CH3

CH3

2-methylpropane

They have the same molecular formula (C4H

10), but

different structural formulas. They are isomers and are different compounds and have different properties such as boiling point.

Structural Isomers

● structural isomers have the same chemical formula but have different chemical and physical properties.

Classifying Organic Compounds Organic

Compounds

Hydrocarbons HydrocarbonDerivatives

• Alcohols• Ethers• Aldehydes• Ketones• Carboxylic Acids• Alkyl Halides• Esters• Amines• Amides

Aliphatic

AlkAnes

AlkEnes

AlkYnes

Aromatic (benzene based)

● hydrocarbons consist of carbon

and hydrogen atoms only

eg. Methane - CH4 ● hydrocarbon derivatives have one or

more hydrogen atoms replaced by another nonmetallic atom

eg. bromomethane - CH3Br

methanol - CH3OH

● aliphatic hydrocarbons have carbon atoms bonded in chains or rings with only single, double, or triple bonds

● aromatic hydrocarbons contain at least one 6 carbon benzene ring

Organic Worksheet #1

Aliphatic Hydrocarbons

1. Alkanes● Alkanes are hydrocarbons that have only

single bonds between carbon atoms

● general formula CnH2n+2

eg. C3H8 C6H14

IUPAC prefixes

Prefix # of carbon atoms

meth 1

eth 2

prop 3

but 4

pent 5

hex 6

hept 7

oct 8

non 9

dec 10

Complete this table for the first

10 alkanes

methane CH4

ethane

propane

methane CH4

ethane C2H

6

propane C3H

8

butane C4H

10

pentane C5H

12

hexane C6H

14

heptane C7H

16

octane C8H

18

nonane C9H

20

decane C10

H22

● A series of compounds which differ by the same structural unit is called a homologous series

eg. each alkane increases by CH2

What is the next member of this homologous series?

SiO2Si2O3 Si3O4 _____

Representing Alkanes (4 ways)

1. Structural formulas

eg. propane

H – C – C – C – H

HHH

HHH

● Hydrogen atoms may be omitted from structural formulas

eg. propane

– C – C – C –

2. Condensed Structural Formula

eg. propaneCH3-CH2-CH3

3. Line Structural Diagrams

eg: propane

(the endpoint of each segment is a carbon atom)

4. Expanded Molecular Formulas

eg. propane

CH3CH2CH3

● An alkyl group has one less hydrogen than an alkane.

● General Formula: CnH2n + 1

● To name an alkyl group, use the prefix to indicate the # of carbon atoms followed by the suffix –yl

eg. -C7H15 heptyl

Alkyl Groups

Alkyl Groups

methyl  -CH3

ethyl  -C2H5  or  -CH2CH3

propyl  -C3H7  or  -CH2CH2CH3

● Branched alkanes are alkanes that contain one or more alkyl groups

eg.

Alkyl Groups

2,4 - dimethylpentane

1. Find the longest continuous chain (LCC) of carbons(parent chain) and give it the alkane name.

2. Number the carbons in the parent chain starting from the end closest to branching. These numbers will indicate the location of alkyl groups.

Naming Branched Alkanes

Naming Branched Alkanes

3. List the alkyl groups in alphabetical order. Use Latin prefixes if an alkyl group occurs more than once. (di = 2, tri = 3, tetra = 4, etc. don't count for alphabetical order)

4. Use a number to show the location of each alkyl group on the parent.

5. Use commas to separate numbers, and hyphens to separate numbers and letters. 

Naming Branched Alkanes

eg.

4-ethyl-3-methylheptane

Naming Branched Alkanes

eg.

7 6 5 4 3 2 1

ethyl

methyl

4-ethyl-3-methylheptane

Naming Branched Alkanes

CH3

CH2

C CH2 CH2 C

CH2

CH3

CH3

CH3

CH3

CH3

CH3

CH2

C CH2 CH2 C

CH2

CH3

CH3

CH3

CH3

CH3

3,3,6,6-tetramethyloctane

Practice:● p. 336 - 339 #’s 5 – 11

(Answers on p. 375)

Naming Branched Alkanes

CH3 CH2 CH

CH2 CH CH2

CH CH3

CH2CH3CH3

CH2 CH3

4,6-diethyl-2-methyloctaneParent chain: Octane2-methyl4,6-diethyl

12

34

5

6

78

CH3 CH2 CH CH3

CHCH3 CH

CH3

CH2

CH

CH2 CH3

CH2CH2

CH3

CH3 CH

CH3

C

CH3

CH2 CH3

CH

CH2 CH2 CH3

CH2

CH2 CH3

CH3 CH2 CH2 CH

CH2 CH2 CH3

CH

CH2 CH2 CH3

CH2 CH CH3

CH3

7-ethyl-3,4,5-trimethyldecane

3-ethyl-2,3-dimethyl-4-propylheptane

2-methyl-4,5-dipropyloctane

3-ethyl-2,2-dimethylhexane

3 – ethyl – 5 – methyl – 4,4 - dipropylnonane

CH3 C

CH3

CH3

CH

CH2 CH3

CH2 CH2 CH3

CH3 CH2 CH

CH2 CH3

C

CH2 CH2 CH3

CH2 CH2CH3

CH

CH3

CH2 CH2CH2

CH3

Organic Worksheet #2

Alkenes and Alkynes

● saturated hydrocarbons contain only single bonds between carbon atoms

eg. alkanes● saturated hydrocarbons have the

maximum number of hydrogen atoms bonded to carbon atoms

Alkenes and Alkynes

● unsaturated hydrocarbons contain double or triple bonds between carbon atoms

eg. alkenes and alkynes

Alkenes and Alkynes

● General Formulas:

– AlkenesCnH2n

– Alkynes CnH2n - 2

At least one double bond

At least one triple bond

Naming Alkenes and Alkynes

1. Name the longest continuous chain that contains the double/triple bond.

2. Use the smallest possible number to indicate the position of the double or triple bond.

Naming Alkenes and Alkynes

3. Branches are named using the same rules for alkanes.

4. Number the branches starting at the same end used to number the multiple bond.

For you to do!!

Pg. 347 #'s: 17, 18, 19

Worksheet #3: Alkenes and alkynes

Cyclic Hydrocarbons

Cycloalkanes and cycloalkenes

cyclopentane

methyl

ethyl

1-ethyl-3-methylcyclopentane

3-ethyl-1-methylcyclopentane

1

2

3

methyl

1,2,3,4-tetramethylcyclohexane

Practice

Pg. 356 – 358 Pg. 358 #'s: 30-31

Worksheet #4

Aromatic Compounds

● Aromatic hydrocarbons contain at least one benzene ring.

● The formula for benzene, C6H6 , was determined by Michael Faraday in 1825.

● The structural formula was determined by August Kekulé in 1865.

Aromatic Compounds

Proposed formula:

Conflicting Evidence

● C=C double bonds are shorter than C-C single bonds. X-ray crystallography shows that all C-C bonds in benzene are the same length.

● Benzene reacts like an alkane, not like an alkene.

Modified structure

● Kekulé proposed a resonance structure for benzene.

● The resonance structure is an average of the electron distributions.

Aromatic Compounds

or

6 electrons shared6 carbon

atoms

Aromatic Compounds

● bonding electrons, once believed to be in double bonds, are delocalized and shared equally over the 6 carbon atoms

● the bonds in benzene are like “1½” bonds – somewhere between single and double.

Naming Aromatic Compounds● an alkyl benzene has one or more H

atoms replaced by an alkyl group.● name the alkyl groups, using numbers

where necessary, followed by the word benzene.

Aromatic Compounds

methylbenzene

propylbenzene

ethylbenzene

Aromatic Compounds

1,3-dimethylbenzene

1,4-dimethylbenzene

1,2-dimethylbenzene

Aromatic Compounds

● ortho- means positions 1 and 2 and is represented by "o"

● meta- means positions 1 and 3 and is represented by "m"

● para- means positions 1 and 4 and is represented by "p"

Aromatic Compounds

m-dimethylbenzene

p-dimethylbenzene

o-dimethylbenzene

Aromatic Compounds

● Benzene is treated as a branch if it is not attached to the terminal carbon of an alkyl group

● Benzene as a branch is called phenyl

Aromatic Compounds

CH2

CH2

CH3

CH3CHCH3

propylbenzene2-phenylpropane

Aromatic Compounds

CH3CHCHCH2CH2CH3

CH2CH3

3 – ethyl – 2 – phenylhexane

Aromatic Compounds

● Pg. 361 #’s 32 – 35

Geometric Isomers● Compounds with the same molecular formula, but different geometry of bonds

● Two types of shapes● Cis and Trans isomers● Cis – groups on the same side of the double bond

● Trans – groups on different sides of the double bond

● Cis/Trans written as part of the name● Ex: cis-2-butene or trans-2-butene

cis and trans isomers (p. 348)

cis and trans isomers (p. 348)

Properties of aliphatic hydrocarbons

● Because they are nonpolar, all hydrocarbons are insoluble in polar water.

● The boiling/melting point of alkanes is somewhat higher than alkenes but lower than alkynes.

● As the number of atoms in the hydrocarbon molecule increases, the boiling/melting point increases.

Hydrocarbon Production● Crude oil is a mixture of hydrocarbons.● Hydrocarbons are extracted from the ground at

well sites, then processed at refineries.● Fractional Distillation is a process used to

separate petroleum into its hydrocarbon components.

● This process relies on the different boiling points of each hydrocarbon.

substances with the highestboiling points condense closer to the bottom

Hydrocarbon Derivatives● Hydrocarbon Derivatives contain other

nonmetal atoms such as O, N, or halogen atoms.

● 9 types of derivatives:

(See p. 378 + ethers and organic halides)● the reactive group of atoms that gives a

family of derivatives its distinct properties is a functional group

Hydrocarbon Derivatives

● The general formula for a derivative is

R - functional group

where R stands for any alkyl group.

Hydrocarbon Derivatives

eg. ALCOHOLS R-OH

ethanol C2H5OH

propanol C3H7OH

CARBOXYLIC ACIDS R-COOH

ethanoic acid CH3COOH

propanoic acid C2H5COOH

1. Alcohols

● Have the hydroxyl functional group

General Formula: R - OH

Naming Alcohols (p. 387)

● The parent alkane is the longest chain that has an -OH group

● Replace the last -e in the alkane name with

the suffix -ol.● Add a number (smallest one) to indicate the

location of the -OH group.

C OH

H

H

H

CC O

H

H

H

H

H

H

methanol

ethanol

eg. CCC O

H

H

H

H

H

H

H

H

CCC

O

H

H

HH

H

H

H

H

propanol

2-propanol

2-methyl-2-butanol

Properties of Alcohols (p. 389)

● Alcohols have H-bonding which makes their mp and bp higher than the corresponding alkane.

● Polarity decreases as the # of carbon atoms increases

● Long chain alcohols are less soluble in water than short chain alcohols.

Reactions of alcohols

Combustion

R-OH + O2 → CO2 + H2O

eg. Write the equation for the burning of butanol.

Reactions of alcohols

Substitution

R-OH + H-X → R-X + H2O

eg. Use structural formulas to show the reaction between 2-pentanol and HBr.

Reactions of alcohols

Elimination (Dehydration)

eg.

CCC OH

H

H

HHH

HH

H2SO4

CCC HHH

HH

H

+ H2O

2. Ethers

● Composed of two alkyl groups bonded to an oxygen atom.

● General Formula: R1-O-R2

● Naming ethers: p. 395– IUPAC name– Common name

O C C

H

H

H

H

H

CH

H

H

O C C C C

H

H

H

H

H

H

H

H

H

CCC

H

H

H

H

H

H

H

1-methoxyethane or ethyl methyl ether

1-propoxybutane or butyl propyl ether

O C C

H

H

H

H

H

CC

H

H

H

H

H

P. 395, 396 #’s 20 – 23

Worksheet: Ethers

1-ethoxyethane or diethy ether

3. Aldehydes (p. 402)

● Contain a carbonyl functional group at the end of a carbon chain.

General Formula:=

HR-C

O

Naming:● Use the alkane name for the longest

continuous chain.● Remove the –e and add the suffix –

aleg.

butane →butanal

CCCC O

HH

H

H

H

H

H

H

2,3 - dimethylpentanal

3 – ethyl – 3 - methylhexanal

4. Ketones (p. 402)

● Contain a carbonyl functional group in the ‘middle’ of a carbon chain.

ie. NOT on carbon #1

General Formula: =O

- R2R1-C

Naming:● Use the alkane name for the longest

continuous chain.● Replace the –e with the suffix –one● Use the smallest possible number for the

position of the C=O group.

CCCC

O

H

H

H

H

H

H

H

H

CCCCC

O

H

H

H

H

H

H

H

H

H

H

2 – butanone & 2 - pentanone

3 – fluoro – 4 – methyl – 2 - hexanone

5. Carboxylic Acids (p. 405)

Contain a carboxyl functional group

ie. -COOH

General Formula:

=O

- OHR1-C

● The “C” of COOH is always #1● Find longest chain with COOH● Drop the “e” of alkane name and replace with “oic” acid● Don't need to use 1 in naming for COOH place● Branching is same as always

3 – ethyl – 3 – methylpentanoic acid

CCC OH

OH

H

H

H

H

C C C CO

O H

H

H

H

H

H

H

H

Propanoic acid

Butanoic acid

6. Alkyl Halides (p. 390, 391)

Contain at least one halogen atom

General Formula: R – X

(X is F, Cl, Br, or I)

● Naming alkyl halides is the same as naming all other pure hydrocarbons except now there are halogen atoms involved.

● The “ine” of the halogens are dropped for “o”● Bromine --> Bromo; chlorine --> chloro

2,4 – dichloro – 1 - methylcyclohexane4 – fluoro – 2 - pentene

CCCC

Br

Br

Br

H

H

HH

H

H

H

CCCCC

Cl

Br

BrBr

Br

H

HHH

H

H

H

2,2,3 – tribromobutane & 1,2,3,4 – tetrabromo – 4 - chloropentane

CCCC

Br

Br

Br

H

H

HH

H

H

H

CCCCC

Cl

Br

BrBr

Br

H

HHH

H

H

H