Classification of Organic Compounds

a) Acyclic or open chain compounds:  These contain alkanes, alkenes, alkynes and their derivatives. These are also called aliphatic compounds.

b) Cyclic or closed chain compounds:

IUPAC Nomenclature of Organic Compounds:

a) Nomenclature of saturated hydrocarbons:

b) Nomenclature of compounds containing functional group or multiple bonds:

Functional group Secondary suffix Functional group Secondary suffix
Alcohols (-OH) -ol Aldehydes (-CHO) -al
Ketones (>C=O) -one Carboxylic acids (-COOH) -oic acid
Amines (-NH2 ) -amine Acid amides (-CONH2 ) -amide
Acid chlorides (-COCL) -oyl chloride Esters (-COOR) -oate
Nitrites (-C=N) -nitrite Thioalcohols (-SH) -thiol

Nomenclature of compounds having polyfunctional groups:

When an organic compound contains two or more functional groups, one group is called the principal functional group while the others are called the secondary functional groups and are treated as substituents: The order of preference for principal group is: Carboxylic acid > acid anhydrides > esters > acid halides > amides > nitrites > aldehydes > ketone > alcohols > amines > double bond > triple bond

When the functional groups act as substituents, they ar named as:

Functional group Prefix Functional group Prefix
- COOH Carboxy -CHO Formyl
-COOR Alkoxy cabonyl or Carbalkoxy >CO Oxo or Kelo
-COCL Chloroformyl -OH Hydroxy
-CONH2 Carbamoyl -SH Mecaplo
-CN Cyano -NH2 Amino
-OR Akoxy =NH Imino
-X Halo -NO2 Nitro

Nomenclature of simple aromatic compounds:

a) Nuclear substituted: In these the functional group is directly attached to the benzene ring. Most of these compounds are better known by their common and historical names. In the IUPAC system, they are named as derivatives of benzene.

b) Side chain substituted: In these the functional group is present in the side chain of the benzene ring. Both in the common and IUPAC systems, these are usually named as phenyl derivatives of the corresponding aliphatic compounds.