Organic Chemistry HCC H C C C CC C H H H H H H H O H H H H H C C C H H H H C C C H H H H H H H H

Compare and contrast the structure of aromatic and aliphatic hydrocarbons. Include: molecular models, structural formulas, common uses Additional KEY Terms resonance

Aliphatics - straight chains and cyclic-aliphatics. Aromatics- benzene and its derivatives (variations) - unsaturated - named because of their smell/odour All aromatic compounds contain a single modified benzene ring or groups of rings.

Benzene (C 6 H 6 ): simplest aromatic compound a known carcinogen colorless, highly flammable liquid naturally occurring in crude oil important industrial solvent and precursor in the production of drugs, plastics, rubber, and dyes…

Almonds Benzaldehyde C7H6O C7H6O Citrus fruits Limonene C 10 H 16

Spearmint / Caraway Carvone C 10 H 14 O Optical Isomsers

Liquorice Glycyrrhizin C 42 H 62 O 16

6 electrons (one from each carbon) participate in double bonds. These 6 e - are actually shared by all 6 carbons. Two different correct structures for benzene - RESONANCE - to show the movement of the 6e -.

H H H C C C C C C H H H

H H H C C C C C C H H H

Molecules with double bond resonance are more stable than molecules of similar size. Explains higher than expected melting point.

Naming compounds containing Benzene 1. Benzene is the parent chain when the ring is off an end carbon of an alkane. methylbenzene or "toluene" CH 3 butylbenzene CH 2 - CH 2 - CH 2 - CH 3

2.Benzene is a branch on ANY alkene / yne chain, OR when the benzene ring is in the middle of the alkane chain. Here the benzene ring is called a phenyl group CH 3 - CH 2 - CH - CH 3 2-phenylbutane CH 2 - CH = CH 2 3-phenylpropene

3.If there are two branches on an alkane, the alkane is the parent chain and the benzene ring is named as a phenyl. Even if the ring is on an end carbon The Alkane exception to the Rule 3-methyl-1-phenylbutane CH 2 - CH 2 - CH - CH 3 CH 3 -

When benzene has 2 identical branches on the ring, the positions are given special names. 1,2 - ortho1,3 – meta1,4 - para. H H CH 3 H H (o-xylene) 1,2-dimethylbenzene o-dimethylbenzene

1,3-dimethylbenzene m-dimethylbenzene (m-xylene) (p-xylene) 1,4-dimethylbenzene p-dimethylbenzene

methylbenzene CH 3 butylbenzene CH 2 - CH 2 - CH 2 - CH 3 CH 2 - CH = CH 2 3-phenylpropene CH 3 - CH 2 - CH - CH 3 2-phenylbutane

CAN YOU / HAVE YOU? Compare and contrast the structure of aromatic and aliphatic hydrocarbons. Include: molecular models, structural formulas, common uses Additional KEY Terms resonance