In the IUPAC system, the monocarboxylic acids are named as alkanoic acids. The name of the acid is derived by replacing the terminal 'e-' of the corresponding alkane with '-oic acid'. Carboxyl carbon is always given number one while numbering the carbon atoms of the parent chain.Examples:
In the common system, cyanides are named by any of the following methods:(i) By using suffix cyanide after the name of alkyl and aryl group.
or(ii) By adding the suffix o-nitrile in place of ic - acid in the common name of the corresponding acid produced by the hydrolysis of the cyanide compound.
For e.g., CH3 CN on hydrolysis gives CH3 COOH i.e., acetic acid.So the common name of the compound is methyl cyanide or Acetonitrile as derived from acetic acid.
In the IUPAC system, suffix nitrile is added to the name of the hydrocarbon atoms ie they are named as Alkanenitriles. The carbon atom of the -CN group is also counted in the parent chain. For determining the position of the substituent in a chain, the nitrile carbon is numbered as 1.Example: