# US 11,299,454 B2 · Method of producing N-vinylcarboxylic acid amide

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- Number: US 11,299,454 B2
- Document ID: US11299454B2
- Status: Granted
- Kind: B2
- Application number: 15/999,787
- Filed: 2017-01-16
- Published: 2021-07-15
- Granted: 2022-04-12
- Earliest claimed: 2016-02-22
- Assignees: Showa Denko K.K.
- Applicants: Showa Denko K.K.
- Inventors: Naoyuki Tanaka
- Web page: https://patentgrep.com/patent/US11299454B2

## CPC

- C07C 231/12: by reactions not involving the formation of carboxamide groups
- B01J 21/04: Alumina
- B01J 23/42: Platinum
- C07C 231/08: from amides by reaction at nitrogen atoms of carboxamide groups
- C07C 231/24: Separation; Purification
- C07C 233/18: having the carbon atom of the carboxamide group bound to a hydrogen atom or to a carbon atom of an acyclic saturated carbon skeleton
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

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.

## Claims

### Claim 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 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

The method of producing N-vinylcarboxylic acid amide according to claim 1,
wherein the N-vinylcarboxylic acid amide is a N-vinylacetamide.

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

The method of producing N-vinylcarboxylic acid amide according to claim 1, wherein the N-vinylcarboxylic acid amide is purified by crystallization.