The OH group is attached with primary, secondary and tertiary alcohols with primary, secondary and tertiary carbon atoms respectively. In a primary (1°) alcohol, the carbon atom that carries the -OH group is only attached to one alkyl group. Example: Methanol, CH3OH.
In a secondary (2°) alcohol, the carbon atom with the -OH group attached is joined directly to two alkyl groups.
In a tertiary (3°) alcohol, the carbon atom holding the -OH group is attached directly to three alkyl groups.
Lucas test : With Lucas reagent tertiary alcohol gives turbidity immediately, secondary alcohol forms turbid within five minutes and primary alcohol shows no turbidity.
Victor Meyer test: In this test an unknown alcohol is converted into the corresponding nitro alkane which is then treated with nitrous acid followed by alkalizing the solution.
Result: Primary alcohol gives blood-red colour, secondary alcohol gives blue and tertiary alcohol remain colourless.