Organic Chemistry

The study of carbon-based compounds and their properties.

Historically the distinction between inorganic and organic substances was based on whether or not they were produced by living systems. It was believed that some sort of “life force” was needed to synthesize them.

In 1828, the German chemist Freidrich Wohler (1800-1882) prepared urea from the inorganic salt ammonium cyanate by simple heating.

NH4OCN H2N—C—NH2

O

urea

Hydrocarbons: contain only hydrogen and carbon

Hydrocarbons

Aliphatic Aromatic

Alkanes Alkenes Alkynes Cyclic

Hydrocarbons can be divided into different types, depending on their bonding.

Naming Organic Molecules

Alkanes - - Carbon chain, no double or triple bonds. All single bonds (saturated)

Alkenes - - Carbon chain, contains double bond(s) (unsaturated)

Alkynes - - Carbon chain, contains triple bond(s) (unsaturated)

Naming Organic Molecules

There are two parts to the main name of each molecule…

prefix: tells the # of carbons in main chain or ring

suffix: tells the type of bonding in the chain or ring

Prefix: indicates number of carbon atoms in the main chain or ring

1 meth-

2 eth-

3 prop-

4 but-

5 pent-

6 hex-

7 hept-

8 oct-

9 non-

10dec-

Suffix: indicates types of bonds present

Alkanes: (all single bonds) ___ -ane

Alkenes: (double bond) ___ -ene

Alkyne: (triple bond) ___ -yne

Saturated Hydrocarbons: the ALKANES: chains of carbon

connected by single bonds: contain only single C-C bonds

Saturated v. Unsaturated fats

Saturated with H

Single bonds are free to rotate, so these fats can pack tightly (solid @ room temp)

Which one is saturated?

For a bit of a demonstration… Good Eats fat train analogy

Watch episode from 1:30 to 5:00

ALKANES

ALKANES

ALKANESpropane, C3H8

ALKANESbutane, C4H10

ALKANESpentane, C5H12

ALKANEShexane, C6H14

ALKANESoctane, C8H18

Don’t write this example down, but watch to see where we’re going with this…

(Although you will be required to include the H’s if you take IB Chemistry)

“Normal” v. Branched

“normal” hydrocarbons are straight chains; no branching

Branched-chain hydrocarbons – isomers of “normal” hydrocarbons; have same formula, but different structures

n-butane

2-methlypropane

n-pentane

2-methylbutane

Are there any other pentane isomers?

Another branched alkane:

2,2-dimethylpentane

cyclopentane

Cycloalkanes

Cycloalkanes cyclobutane

Cycloalkanes ________________________

methyl-

ethyl-

1

2

3

3

2

1

green or red?

-ethyl- -methylcyclopentane1 3

Unsaturated Hydrocarbons: ALKENES – contain C-C double bonds

2-pentene

Unsaturated Hydrocarbons: ALKENES – contain C-C double bonds

2,4-hexadiene

Unsaturated Hydrocarbons: ALKYNES – contain C-C triple bonds

1-butyne

Unsaturated Hydrocarbons: ALKYNES – contain C-C triple bonds

3-ethyl-1-pentyne

Aromatic Hydrocarbons:

benzene – the simplest aromatic hydrocarbon; has a symmetrical ring structure

Aromatic Hydrocarbons:

benzene – can be drawn like this…

Derivatives of benzene:

1-ethyl-2-methylbenzene

Derivatives of benzene:

1,2-dimethyl-4-propylbenzene

For your homework:

If a halogen is attached, use the following prefixes:

fluoro- chloro-bromo-iodo-

(instead of methyl-, ethyl-, propyl-, etc.)