Process for the preparation of N-substituted methacrylamides and acrylamides

A process for preparing N- alkylamides of acrylic acid or methacrylic acid, wherein acrylonitrile or methacrylonitrile is reacted with a compound having an optionally substituted alkyl group with 3 to 40 carbon atoms, capable of forming an alkyl carbonium ion under the effect of sulphuric acid, is characterized in that the nitrile together with the alkyl group containing compound is added to a quantity of concentrated sulphuric acid, in a mole ratio of sulphuric acid to added nitrile of from about 1:1 to 2:1, which is at reaction temperature, and then the mixture is left to react at a reaction temperature of from 10 to 100 DEG C and after dilution, e.g. with water, the unsaturated N-alkylamides are isolated, if required, by extraction with an inert extracting agent which is immiscible with the dilute sulphuric acid.