US 11,718,579 B2
Method for producing highly polymerizable N-vinyl carboxylic acid amide monomer
Takamitsu Kobayashi, Tokyo (JP); and Naoyuki Tanaka, Tokyo (JP)
Assigned to SHOWA DENKO K.K., Tokyo (JP)
Appl. No. 17/595,783
Filed by SHOWA DENKO K.K., Tokyo (JP)
PCT Filed Dec. 23, 2020, PCT No. PCT/JP2020/048224
§ 371(c)(1), (2) Date Nov. 24, 2021,
PCT Pub. No. WO2021/132364, PCT Pub. Date Jul. 1, 2021.
Claims priority of application No. 2019-236790 (JP), filed on Dec. 26, 2019.
Prior Publication US 2022/0227697 A1, Jul. 21, 2022
Int. Cl. C07C 231/24 (2006.01); C07C 233/05 (2006.01)
CPC C07C 231/24 (2013.01) [C07C 233/05 (2013.01)] 7 Claims
 
1. A method for producing a highly polymerizable N-vinyl carboxylic acid amide monomer, comprising
(A) a step of melting a crude N-vinyl carboxylic acid amide monomer comprising 50 to 88 mass % of an N-vinyl carboxylic acid amide monomer by heating, followed by cooling for precipitation, and subjecting precipitated N-vinyl carboxylic acid amide monomer crystals to solid-liquid separation, and
(B) a step of further dissolving the N-vinyl carboxylic acid amide monomer crystals separated in the step (A) in a mixed solvent of acetonitrile and an aliphatic hydrocarbon having 6 to 7 carbon atoms, then performing crystallization, performing solid-liquid separation, and recovering an N-vinyl carboxylic acid amide monomer purified product, wherein
a mass ratio of acetonitrile/N-vinyl carboxylic acid amide monomer crystal in the step (B) is 0.01:1.0 or more and 0.5:1.0 or less, and
a mass ratio of aliphatic hydrocarbon having 6 to 7 carbon atoms/N-vinyl carboxylic acid amide monomer crystal in the step (B) is 0.5:1.0 or more and 3.0:1.0 or less.