Alkylamides

Alkylamides are a class of amides in which the nitrogen atom of the amide group is substituted by one or more alkyl groups. In practice, the common usage refers to N-alkylamides with the general formula R-CO-NR'R'' (where R, R' and R'' are alkyl groups). Primary amides (R-CO-NH2) and arylamides are related but not typically described as alkylamides.

Chemically, the amide bond features resonance between the carbonyl and the nitrogen; N-alkyl substitution reduces the hydrogen-bond donating ability and affects basicity and hydrolysis rate. Tertiary amide derivatives (N,N-dialkyl) lack N-H and are often strong polar aprotic solvents with high boiling points. Common examples include N,N-dialkylformamides and N,N-dialkylacetamides.

Preparation generally involves coupling of carboxylic acids with alkylamines using activating reagents (such as DCC, EDC, or other coupling systems), or reaction of acyl chlorides with alkylamines. Secondary amides can be prepared by alkylation of primary amides, though this route is less common. In practice, N-alkylamides are frequently encountered as intermediates in pharmaceutical synthesis and polymer chemistry.

Applications and occurrence: N-alkylamides are widely used as solvents and reaction media, with examples including dimethylformamide and dimethylacetamide. They also serve as intermediates in the synthesis of pharmaceuticals, agrochemicals, and polymers. Safety considerations include toxicity and potential irritation; many N,N-dialkylamides require careful handling and appropriate ventilation.