# US 5,708,167 A · Method for the preparation of an N-vinyl compound

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- Number: US 5,708,167 A
- Document ID: US5708167A
- Status: Granted
- Kind: A
- Application number: 08/518,365
- Filed: 1995-08-23
- Granted: 1998-01-13
- Earliest claimed: 1994-08-31
- Assignees: Shin-Etsu Vinyl Acetate Co., Ltd.
- Inventors: Yoshihiro Honma; Shozo Tanaka; Mitsuyoshi Oshima; Soji Tanioka; Fumiaki Kawamoto
- Web page: https://patentgrep.com/patent/US5708167A

## CPC

- C07D 207/267: with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to the ring nitrogen atom
- C07D 211/76: attached in position 2 or 6
- C07D 223/10: attached in position 2
- C07D 263/22: with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to other ring carbon atoms
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

Proposed is a novel and very efficient method for the preparation of an N-vinyl compound such as N-vinyl-2-pyrrolidone and N-vinyl-N-ethyl acetamide by the thermal decomposition of an N-(.alpha.-acyloxyethyl) compound which is a novel compound obtained by the addition reaction between an NH group-containing compound such as 2-pyrrolidone and N-ethyl acetamide and a vinyl carboxylate, e.g., vinyl acetate, in the presence of an alkali, e.g. alkali metal hydroxide. The reaction mixture after completion of this addition reaction as such, i.e. without isolating the N-(.alpha.-acyloxyethyl) compound, such as N-(.alpha.-acetoxyethyl)-2-pyrrolidone and N-(.alpha.-acetoxyethyl)-N-ethyl acetamide, is heated to effect in situ formation of the desired N-vinyl compound which can then be isolated by distillation under reduced pressure in a very high overall yield.

## Claims

### Claim 1

A method for the preparation of an N-vinyl compound represented by either one of the formulas ##STR4## in which R.sup.1 is a hydrogen atom or a monovalent hydrocarbon group, R.sup.3 is a monovalent hydrocarbon group, the subscript p is 0 or 1 and the subscript n is a positive integer not exceeding 10, which comprises the steps of:
(a) mixing an NH group-containing compound represented by the formula ##STR5## respectively, in which each symbol has the same meaning as defined above, and a vinyl carboxylate represented by the formula
R.sup.2 --CO--O--CH.dbd.CH.sub.2
in which R.sup.2 is a hydrogen atom or a monovalent hydrocarbon group, in the presence of an alkaline substance which is an alkali or alkaline earth metal compound to form an N-(.alpha.-acyloxyethyl) compound represented by the formula ##STR6## respectively, in which each symbol has the same meaning as defined above, as an addition product between the NH group-containing compound and the vinyl carboxylate in the mixture; and
(b) heating the mixture containing the N-(.alpha.-acyloxyethyl) compound to effect thermal decomposition of the N-(.alpha.-acyloxyethyl) compound.

### Claim 2 (depends on 1)

The method for the preparation of an N-vinyl compound as claimed in claim 1 in which heating of the mixture in step (b) is performed under concurrent distillation of the N-vinyl compound as produced from the N-(.alpha.-acyloxyethyl) compound in the mixture.

### Claim 3 (depends on 1)

The method for the preparation of an N-vinyl compound as claimed in claim 1 in which the temperature in step (b) is in the range from 80.degree. to 140.degree. C.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the alkaline substance is an alkali metal or alkaline earth metal hydroxide, carbonate, hydrogen carbonate, hydrogen phosphate, acetate or alcoholate.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the alkaline substance is an alkali metal hydroxide.

### Claim 6 (depends on 1)

The method according to claim 1, where unreacted vinyl carboxylate from step (a) is removed prior to heating in step (b).