Organic ChemistryThe study of carbon compounds.

Over 10 million compounds naturally existMore than 300 000 are synthesized

Inorganic vs Organic

– oxides of carbon (CO2, CO)

– carbonates,bicarbonates (NaHCO3,CaCO3)

– cyanides (NaCN, etc)

– any carbon attached to a metal and no H

• Hydrocarbons containing CxHy

Origin of organic compoundsOrigin of organic compounds• Originally from “organic” meaning life• Not just chemistry of life, chemistry of carbon

• Naturally occurring organic compounds are found in plants, animals, and fossil fuels

• All of these rely on the “fixing” of C from CO2

• Synthetic organic compounds are derived from fossil fuels or plant material

The diversity of carbon compounds is based on the fact carbon atoms Form 4 Bonds

• Forms strong covalent and nonpolar bonds with itself and other elements

Review:• Lewis Structure, Structural formula, Line diagrams

Carbon molecules form complex 3-D shapes

Common Molecular Shapes

• Tetrahedral

• Trigonal planar

• Linear

• Angular

• Trigonal pyramidal

Simplest HydrocarbonsSimplest HydrocarbonsC C C C

C C

C

C

C

C

C

C

H

H

H

H

H

H

C C C C C

H

H

H

H

H H

H

H

H

H

H

H

Alkanes Alkenes

Alkynes Aromatics

C C C C C

H

H

H

H

H

H

H

H

H

H

C C C C CH

H

H

H

H

H

H

H

Naming Hydrocarbons (nomenclature)

Naming: common vs. IUPAC• Common names used in the 1800’s are still used for some

compounds today: eg.

H C C HCommonly known

as Acetylene

• The International Union of Pure and Applied Chemistry (IUPAC) was established in 1900s

• Systematic method allows an infinite number of compounds to be named given a few rules

IUPAC: Ethyne

Mnemonic for first four prefixes

First four prefixes• Meth-

• Eth-

• Prop-

• But-

Monkeys

Eat

Peeled

Bananas

?Decade

Decimal

Decathalon

Other prefixes

• Pent-

• Oct-

• Dec-

• Hex-, Hept-, Non-

Alkanes

• Are straight or branched-chain containing only single bonds

• Are a homologous series –a group of compounds whose members differ by the addition of the same structural group

• Named by using prefix and ending -ane

TASK

• Write chemical and structural formula for all alkanes that contain up to 10 carbons

• Methane CH4 • Ethane CH3CH3

• Propane CH3CH2CH3

• Butane CH3CH2CH2CH3

• Pentane• Hexane• Heptane• Octane• Nonane• Decane• This is just the beginning……………………………………………………………..

You may have noticed that branching creates enormous variation

Try Naming TheseTry Naming These

CH3

CH2CH2

CH2CH2

CH2CH2

CH2CH2

CH3

Structural Isomers

• Substances with the same chemical formula by different arrangements of atoms

• Eg. Butane & 2 methyl-propane

***Isomers have different physical and chemical properties

TASK: Draw all the isomers for pentane and hexane

Did you know?• 3 isomers of pentane• 5 isomers of hexane• Heptane-9 • Octane-18 • Nonane-35 • Decane-75 • making a total of 150 different possible alkane

compounds containing 10 carbons.

C

C

C

CC H

HHH

H

H

HH H

H

Greater complexity exists because organic compounds can form Cyclic (ring) structures?

• Cyclic structures are circular• Have “cyclo” in name

• Eg. Cyclopropane Cyclopentane

CH2

CH2

CH2

TASK

• Study the following graphic.

• What 2 trends can be identified?

• Hypothesize why these trends exist.

• TASK 2: Compare, contrast and explain the physical properties of the first 10 alkanes

Background: formulas for HxCy

• CH single bonds Alkanes= CnH2n+2,

• CH with one double bond Alkenes= CnH2n,

• CH with two double bonds Alkynes= CnH2n-2

• Q - How many hydrogens in each of these:Alkane C6H

Alkene C22HCH3 CH3

Basic names of hydrocarbons• Hydrocarbon names are based on:

– 1) class – 2) # of C, – 3) side chain type – 4) position

Q - What names would be given to these:7C, 9C alkane2C, 4C alkyne1C, 3C alkene

heptane, nonaneethyne, butynedoes not exist, propene

Numbering carbonsQ- draw penteneA- Where’s the bond?

We number C atoms

• Always start numbering for the carbon nearest the double bond the lowest number

• Q - Name these

C C C CCH3

H

H

H

H H H

HCH31

C2

C3

C4

C5

H

H

H

H H H

HCH35

C4

C3

C2

C1

H

H

H

H H H

H

Ethene

3-nonyne

2-buteneCH3

CH

CH

CH3

CH3 CH3

C2H4

1-pentene

Multiple multiple bonds

• Rules• Give 1st bond lowest #• include di, tri, tetra, penta, etc. before ene/yne• Comma between #s, hyphen between #-letter

2,3-heptadieneCH3CH3

CH3

CH2CCCCCCCH32,4,6-nonatriyne

C C C C

H

H

H

H

H

H

CH3CH2CH2CH=C=CH2

CH2CCH

CHCH2

2-butyne

1,2-hexadiene1,2,4-pentatriene

Cyclic structuresQ- Draw these:

cyclobutene 1,3-cyclopentadiene cyclopropane

CH2

CH

CH2

CHCC

C CCH

H H

H

H H

CH2

CH2

CH2

CH3 CH3

CH3

CH3Naming side chains

• Names are made up of: side chains, root

• Root is the longest possible HC chain• Must contain multiple bonds if present• Add -yl to get name of side chain

• Common side chains include:CH3- methyl CH3CH2- ethyl

CH3CH2CH2- propyl (CH3)2CH- isopropyl

• 2,3-dimethylpentane

CH3 CH3

CH3

CH3

CH3CH

CH3

*

ene

Naming side chainsExample: use the rules on the bottom of

handout to name the following structure

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

Rule 1: choose the correct ending

ene

Rule 2: longest carbon chain

Naming side chains

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

1-hexene ene

Rule 3: attach prefix (according to # of C)

Naming side chains

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

Rule 4: Assign numbers to each carbon

1-hexene

Naming side chains

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

Rule 4: Assign numbers to each carbon

CH3 CH2 C2

CH21

CH23

C4

CH25

CH3

CH3

CH36

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

1-hexene 1-hexene

Naming side chains

CH3 CH2 C2

CH21

CH23

C4

CH25

CH3

CH3

CH36

Rule 5: Determine name for side chains

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

1-hexene 1-hexene

Naming side chains

ethyl

methyl

methyl

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

CH3 CH2 C2

CH21

CH23

C4

CH25

CH3

CH3

CH36

1-hexene2-ethyl-4-methyl-4-methyl-1-hexene

Naming side chains

ethyl

methyl

methyl

Rule 6: attach name of branches

Rule 7: list alphabetically

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

CH3 CH2 C2

CH21

CH23

C4

CH25

CH3

CH3

CH36

1-hexene2-ethyl-4-methyl-4-methyl-1-hexene

Naming side chains

ethyl

methyl

methyl

Rule 8,9: group similar branches

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

CH3 CH2 C2

CH21

CH23

C4

CH25

CH3

CH3

CH36

1-hexene2-ethyl-4-methyl-4-methyl-1-hexene

Naming side chains

ethyl

methyl

methyl

Rule 8,9: group similar branches

CH3 CH2 C

CH2

CH2 C

CH2

CH3

CH3

CH3

CH3 CH2 C2

CH21

CH23

C4

CH25

CH3

CH3

CH36

2-ethyl-4,4-dimethyl-1-hexene

Naming side chains

ethyl

methyl

methyl

Try Naming Side Chains

CH3 CH2

CH CH3

CH2CH2

CH3

CH3 CH

CH

CH3

CH

CH3

CH2 CH2 CH3

CH2 CH3

CH3CH2CH CH CH CH2CH CH3

CH3

CH2CH3

CH3 CH3

3-methylhexane4-ethyl-2,3-dimethylheptane

5-ethyl-2,4,6-trimethyloctane

Naming side chains

3-ethyl-2-methylpentane

3-ethyl-1,5,5-trimethylcyclohexene

CH3CH

CHCH2

CH3

CH3

CH2CH3

CH3 CH3

CH3CH3

Name the structures below

Try Drawing These2,2-dimethyloctane

1,3-dimethylcyclopentane

1,1-diethylcyclohexane

6-ethyl-5-isopropyl-7-methyl-1-octene

Try Naming Try Naming

CH3 CH3

CH3

CH3

CH3

CH3

Aromatic Hydrocarbons

• Aromatic compounds contain benzene ring structures and their derivatives.

• Benzene (C6H6)• most commonly used organic (nonpolar)

solvent• very stable substance, unreactive • toxic if inhaled -carcinogenic• produced by processing coal, crude oil,

gasoline or the combustion of rubber tires

• if it occurs as a side chain it is called a phenyl group

Resonance• The properties of this compound can be explained by following theory:

-the chemical bonds between carbon atoms are not single or double-all bonds between carbons in the benzene ring are identical in length and strength -there is an even distribution of valence electrons around the entire molecule.

• The resonance of the single and double bonds accounts for the stability of aromatic compounds.

• This is illustrated by resonance structures:

There are 2 naming methods1) Numbering carbons2) ortho, meta, para (stomp)

Aromatic nomenclature

CH3

Ortho

Para

ST Meta

CH3

CH3

CH3

CH3

CH3CH3

1,2-dimethylbenzeneorthodimethylbenzene

1,3-dimethylbenzenemetadimethylbenzene

1,4-dimethylbenzeneparadimethylbenzene