Distinguish between primary (1°) Secondary(2°) Tertiary(3°) Alcohols

 

The following tests are used to distinguish between the primary, secondary and tertiary alcohols.

Lucas test:-

Alcohols are treated with a solution of HCl and ZnCl saves as a catalyst.

The three types of alcohols undergo this reaction at different rates.

Tertiary alcohols react with Lucas's reagent very rapidly, secondary alcohols react somewhat slower, primary alcohols react with Lucas's reagent even more slowly.

(a) With tertiary alcohols cloudiness appear immediately.

(b) With secondary alcohols cloudiness appears in 5 minutes.

(c) With primary alcohols the solution remains clear, this is because primary alcohols do not react with Lucas reagent at room temperature high temperatures needed.

Dichromatic test:-

This test is based on the fact different types of alcohols give different products on oxidation, the alcohol is treated at room temperature with sodium dichromate in sulphuric acid 

a) Primary alcohols give a carboxylic acid-containing some number of carbons there will be a change in color of the solution are more strongly held  by the carbon nucleus, this makes is easier to remove the hydrogen as a proton (C ≡ CH) 1 alkyne 

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