4.2.5 Nomenclature of Carbon Compounds

. . Nomenclature of Carbon Compounds The names of compounds in a homologous series are based on the name of the basic carbon chain modified by a “prefix” “phrase before” or “suffix” “phrase after” indicating the nature of the functional group. For example, the names of the alcohols taken in Activity .

are methanol, ethanol, propanol and butanol. Naming a carbon compound can be done by the following method – (i) Identify the number of carbon atoms in the compound. A compound having three carbon atoms would have the name propane. In case a functional group is present, it is indicated in the name of the compound with either a prefix or a suffix (as given in Table .

). (iii) If the name of the functional group is to be given as a suffix, and the suffix of the functional group begins with a vowel a, e, i, o, u, then the name of the carbon chain is modified by deleting the final ‘e’ and adding the appropriate suffix. For example, a three-carbon chain with a ketone group would be named in the following manner – Propane – ‘e’ = propan + ‘one’ = propanone. (iv) If the carbon chain is unsaturated, then the final ‘ane’ in the name of the carbon chain is substituted by ‘ene’ or ‘yne’ as given in Table .

. For example, a three-carbon chain with a double bond would be called propene and if it has a triple bond, it would be called propyne. Calculate the difference in the formulae and molecular masses for (a) CH OH and C H OH (b) C H OH and C H OH, and (c) C H OH and C H OH. Is there any similarity in these three?

Arrange these alcohols in the order of increasing carbon atoms to get a family. Can we call this family a homologous series? Generate the homologous series for compounds containing up to four carbons for the other functional groups given in Table . .