Organic Chemistry: Names of Compounds

Definitions

Organic chemistry is the study of carbon compounds, excluding carbides, carbonates, and oxides.
A hydrocarbon is an organic compound entirely made up of hydrogen and carbon.
The carbon chain is the continuous line of carbon atoms in a molecular structure.
Alkanes are saturated hydrocarbons with single bonds. They follow the general formula CnH2n+2.
Alkenes are unsaturated hydrocarbons with double bonds. They follow the general formula CnH2n.
Functional group refers to a group of atoms responsible for the characteristic reactions of a particular compound.

Naming Organic Compounds

The first step in naming an organic compound is identifying the longest carbon chain in its structure. This defines the base name of the compound.
The next step is to identify any functional groups attached to this carbon chain. Their presence modifies the base name.
Prefixes denote functional groups that are set before the base name. For example, an alcohol contains the OH- functional group, which is denoted by the prefix ‘hydroxy-‘.
Suffixes indicate functional groups that replace the ‘-ane’ ending in alkanes; for example, ‘-ene’ for alkenes.
Numerals in the compound name indicate the position of the functional group on the carbon chain. The carbon atoms on the chain are numbered from the end closest to the first functional group.
When multiple identical functional groups are present, prefixes such as di-, tri-, tetra-, etc., are used based on the number of times the group appears.

Examples of Organic Compounds

Methane (CH4) is the simplest alkane with one carbon atom.
Ethene (C2H4) is an example of an alkene with a double bond.
Ethanol (C2H5OH) is an example of an alcohol, denoted by the ‘-ol’ suffix and presence of OH- functional group.
Propane (C3H8) is an alkane with three carbon atoms in its chain.
But-1-ene (C4H8) is an example of an alkene where the double bond is on the first carbon atom.
2,2-dimethylpentane is an example of an alkane where two methyl (CH3) groups are attached to the second carbon of a pentane (5-carbon) chain.

Important Functional Groups

Alcohols have an -OH group. eg. methanol (CH3OH)
Aldehydes have a -CHO group. eg. methanal (HCHO)
Ketones have a >C=O group. eg. propanone (CH3COCH3)
Carboxylic acids have a -COOH group. eg. ethanoic acid (CH3COOH)
Esters have a -COO- group. eg. methyl methanoate (HCOOCH3)
Halogens can also act as functional groups. Chloro-, bromo-, iodo- prefix denotes the presence of Cl-, Br- and I- respectively.
Ethers have an -O- group. eg. methoxy methane (CH3OCH4)