US 12,435,029 B2
Method for producing highly polymerizable N-vinyl carboxylic acid amide monomer
Takamitsu Kobayashi, Tokyo (JP); and Naoyuki Tanaka, Tokyo (JP)
Assigned to Resonac Corporation, Tokyo (JP)
Appl. No. 17/595,785
Filed by Resonac Corporation, Tokyo (JP)
PCT Filed Dec. 23, 2020, PCT No. PCT/JP2020/048225
§ 371(c)(1), (2) Date Nov. 24, 2021,
PCT Pub. No. WO2021/132365, PCT Pub. Date Jul. 1, 2021.
Claims priority of application No. 2019-236141 (JP), filed on Dec. 26, 2019.
Prior Publication US 2022/0220063 A1, Jul. 14, 2022
This patent is subject to a terminal disclaimer.
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 crystallization precipitation, and subjecting precipitated N-vinyl carboxylic acid amide monomer crystals to solid-liquid separation (step (A)), 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 methyl ethyl ketone and an aliphatic hydrocarbon having 6 to 7 carbon atoms, then performing solvent crystallization, performing solid-liquid separation, and recovering an N-vinyl carboxylic acid amide monomer purified product (step (B)), wherein
a mass ratio of methyl ethyl ketone:N-vinyl carboxylic acid amide monomer crystal in the step (B) is (0.01 to 0.5):1.0, 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 to 3.0):1.0.