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Organic Chemistry
NOMENCLATURE
-Hydrocarbonsorganic compounds that
contain carbon and
hydrogen only
Saturated
- only C-C and C-H bonds
- alkanes
- cycloalkanes
Unsaturated
- carbon-carbon double
and triple bonds
- alkenes
- alkynes
ALKANES are saturated hydrocarbons. They are specified by the parent name and suffix ane.
Figure 1: The most common parent names.
Source: http://www.wavesignal.com/o_chem/images/Stereo5.jpg
NOTE: Alkanes with 3 or more carbons have constitutional isomers (compounds that have the same
molecular formula but connect differently)
o ACYCLIC ALKANES
Example 1: Name the
following
1) Find the longest chain and number the carbon atoms in
the chain. Start numbering at the end which has the
closest branch.
2) Identify substituents if present and place them in
alphabetic order. For alkyl groups: parent + yl
Answer: 4-ethyl-3-methylheptane
o CYCLOALKANES
Example 2: Name the
following
1) Find parent chain and number the ring
** Number different substituents in such a way that
they have the lowest corresponding location number
possible
Answer: 1-isobutyl-2-methylcyclohexane
ALKENES & ALKYNES
Alkenes are hydrocarbons that contain carbon—carbon double bond, whereas alkynes contain carbon –
carbon triple bonds.
o ISOMERS
Geometric isomers (in which atoms are joined to one another in the same way but atoms occupy
different relative positions in space).
They are two very distinct compounds.
Constitutional isomers are compounds that have the same molecular formula, but the atoms are
connected in different ways.
COMPOUNDS THAT CONTAIN OXYGEN, HALOGEN or SULFUR
o ALCOHOLS
Alcohols have –OH as the functional group present. They take the suffix ol.
Nomenclature rules:
1) determine the longest chain with –OH attached
2) OH suffix must get the lowest number
3) Number the chain in the direction that will give the substituent the lowest possible number
4) If more than one, write the substituents in order
2-ethyl-1-pentanol
3,3-dimethylcyclohexanol
2-ethyl-4-methylcyclopentanol
o ETHERS
Ethers have an oxygen atom between to alkyl groups. The substituents take the parent name and the suffix
oxy.
2-methoxypentane
1-ethoxy-2-ethylbutane
2-butoxy-3-methylpentane
o ALKYL HALIDES
Primary alkyl halide
Secondary alkyl halide
Alkyl halides are named as substituted alkanes:
3-chloro-5-methyloctane
4-bromo-3-chloro-1methylcyclohexane
Tertiary alkyl halide
ALDEHYDES & KETONES
They both contain C=O (carbonyl) functional group. Aldehydes contain a carbonyl group with at least one
Hydrogen atom attached to it. Ketones contain a carbonyl group with two hydrocarbons attached to it.
ALDEHYDE
KETONE
ethanal
2-butanone
CARBOXYLIC ACIDS, ESTERS & AMIDES
Carboxylic acids are compounds that contain the carboxyl group –COOH.
Esters are compounds that contain –COO – between two alkyl groups. They are formed from a carboxylic
acid and an alcohol.
Amides are compounds that contain the H2NCOO— group. They are formed from ammonia and carboxylic
acids.
CARBOXYLIC ACID
ESTER
AMIDE
Ethanoic acid
Ethyl acetate
acetamide