Chemistry ORGANIC CHEMISTRY – SOME BASIC PRINCIPLES AND TECHNIQUES

### Topics to be covered

=> Classification of organic compounds

### CLASSIFICATION OF ORGANIC COMPOUNDS

Organic compounds are broadly classified as follows:

I. color{red}("Acyclic or open chain compounds")

These compounds are also called as color{green}("aliphatic") compounds and consist of straight or branched chain compounds, for example:

II color{red}("Alicyclic or closed chain or ring compounds")

Alicyclic (aliphatic cyclic) compounds contain carbon atoms joined in the form of a ring (homocyclic). Sometimes atoms other than carbon are also present in the ring (heterocylic). Some examples of this type of compounds are:

color{green}("These exhibit some of the properties similar to those of aliphatic compounds.")

star color{red}("Aromatic compounds")

These include benzene and other related ring compounds (benzenoid). Like alicyclic compounds, aromatic comounds may also have hetero atom in the ring. Such compounds are called hetrocyclic aromatic compounds. Some of the examples of various types of aromatic compounds are:

star color{red}("Non-benzenoid compound")

star color{red}("Heterocyclic aromatic compounds")

Organic compounds can also be classified on the basis of functional groups, into families or homologous series.

star color{red}("Functional Group")
The functional group may be defined as an atom or group of atoms joined in a specific
manner which is responsible for the characteristic chemical properties of the organic compounds. The examples are hydroxyl group color{red}((–OH)), aldehyde group color{red}((–CHO)) and carboxylic acid group color{red}((–COOH)) etc.

star color{red}("Homologous Series")

A group or a series of organic compounds each containing a characteristic functional group forms a homologous series and the members of the series are called homologues. The members of a homologous series can be represented by general molecular formula and the successive members differ from each other in molecular formula by a color{red}(–CH_2) unit.