Oxidation of alcohol

Test to distinguish primary, secondary and tertiary alcohol

Oxidation of alcohols involves the formation of a carbon oxygen double bond with the cleavage of an O-H and C-H bonds.
The products of oxidizing reaction depends on the nature of alcohols (primary, secondary or tertiary nature of the carbon) and also the oxidizing agent used. Hence this reaction can be utilized for distinguishing the primary, secondary and tertiary alcohols from one another
A primary alcohol when treated with potassium to an aldehyde and then to an acid. Both the aldehyde and acid contain the same number of carbon atoms as the parent alcohol.


A secondary alcohol on oxidation with acidified K2Cr2O7 or chromium trioxide (CrO3) forms a ketone with the same number of carbon atoms as the parent alcohol. The ketone is further oxidized under strong conditions to form a mixture of acids, each containing lesser number of carbon atoms than the parent alcohol.


Tertiary alcohols do not undergo oxidation reaction under normal conditions since they have no hydrogen on carbon bearing the –OH group. But, when treated with strong oxidizing agents like HNO3 at elevated temperature they are oxidized to ketones first and then to acids, both containing fewer number of carbon atoms than the parent alcohol due to cleavage of various C-C bonds.

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