Method of producing N-vinylcarboxylic acid amide

A method of producing N-vinylcarboxylic acid amide, comprising:

• a step of obtaining N-vinylcarboxylic acid amide by using the de-alcoholization reaction from N-(1-alkoxyethyl) carboxylic acid amide,
• wherein the N-(1-alkoxyethyl) carboxylic acid amide is a compound represented by the following general formula (I),
• wherein R1 represents an alkyl group having 1 to 5 carbon atoms, R2 independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R3 represents an alkyl group having 1 to 5 carbon atoms;
• and
• a step of controlling an amount of unsaturated aldehydes in N-vinylcarboxylic acid amide to 20 mass ppm or less,
• wherein the step of controlling an amount of unsaturated aldehydes comprises steps of
• obtaining a second crude N-(1-alkoxyethyl) carboxylic acid amide by adjusting a pH of a first crude N-(1-alkoxyethyl) carboxylic acid amide to 8.0 to 8.5 by using 30 to 48% by mass of one selected from the group consisting of a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution;
• and
• purifying the N-(1-alkoxyethyl) carboxylic acid amide by distilling the second crude N-(1-alkoxyethyl) carboxylic acid amide.