Introduction to Nitrogen Functional Groups

James Richard Fromm


Nitrogen can be attached to carbon in many ways. The organic compounds which contain nitrogen are essential to life. The most important organic nitrogen compounds are the amines and their derivatives the amides.

Amines

Substitution of an ammonia for hydrogen or carbon produces an amine group on an organic compound. Amines are classified as primary, secondary, or tertiary depending on the number of carbons which form bonds to the nitrogen. Following the normal organic practice of designating a carbon chain by the symbol R, a primary amine would be an amine with the structure RNH2; a secondary amine would have the structure R2NH; and a tertiary amine would have the structure

R3N. The carbon chains on a secondary or tertiary amine need not be identical.

Amines, like ammonia, can be protonated giving rise to alkylammonium ions. An example is the ethylammonium ion, CH3CH2NH3+, which is the conjugate acid of ethylamine. Amines are basic and form the largest and most significant class of organic bases.

Amides

A reversible reaction between an amine and a carboxylic acid causes loss of water and the formation of an amide; the reaction is:

RNH2 + R'COOH larrow.GIF (55 bytes)rarrow.gif (63 bytes) R'CONHR + H2O.

The amide bond is reasonably stable. When it forms between amino acids, in which both an amine group and a carboxylic acid group are present in the same molecule, the polymeric chain produced is a polypeptide. If the polypeptide chain is long enough, it is called a protein.


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Copyright 1997 James R. Fromm