Method of producing N-vinylcarboxylic acid amide
A method for producing an N-vinylcarboxylic acid amide is provided, the method focusing on unsaturated aldehydes that are contained as impurities generated during a reaction. The method for producing an N-vinylcarboxylic acid amide includes a step for controlling the contained amount of unsaturated aldehydes in the N-vinylcarboxylic acid amide to be not more than 20 mass ppm.
1. 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 R 1 represents an alkyl group having 1 to 5 carbon atoms, R 2 independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R 3 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.
2. The method of producing N-vinylcarboxylic acid amide according to claim 1 , further comprising:
a step of producing the N-(1-alkoxyethyl) carboxylic acid amide from carboxylic acid amide, acetaldehyde and alcohol; or from carboxylic acid amide and acetaldehyde dialkyl acetal.
3. The method of producing N-vinylcarboxylic acid amide according to claim 1 ,
wherein the N-vinylcarboxylic acid amide is a N-vinylacetamide.
4. The method of producing N-vinylcarboxylic acid amide according to claim 1 ,
wherein the unsaturated aldehydes comprises at least one selected from the group consisting of crotonaldehyde, 2-ethyl-2-butenal, 2-methyl-2-pentenal, 2-hexenal, 2,4-hexadienal, 2,4-octadienal, 2,4,6-octatrienal, and trans-2-octenal, and
an amount of the unsaturated aldehyde is a total amount of crotonaldehyde, 2-ethyl-2-butenal, 2-methyl-2-pentenal, 2-hexenal, 2,4-hexadienal, 2, 4-octadienal, 2,4,6-octatrienal and trans-2-octenal.
5. The method of producing N-vinylcarboxylic acid amide according to claim 1 , wherein the N-vinylcarboxylic acid amide is purified by crystallization.