Preparation of polyvinylpyridine N-oxides

Details Preparation of polyvinylpyridine N-oxides Preparation of polyvinylpyridine N-oxides

1995-08-24

1996-11-26

Lipman, Bernard

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

5253271, 525370, 525371, 525372, C08F 842

Patent

active

055786847

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for preparing polyvinylpyridine N-oxides by oxidizing polyvinylpyridines with aqueous solutions of hydrogen peroxide in the presence of acids at pH values below 7.
GB-A 1 097 450 discloses the preparation of polyvinylpyridine N-oxide by oxidizing poly-2-vinylpyridine in glacial acetic acid as solvent with a 30% strength aqueous solution of hydrogen peroxide at 50.degree. C. The industrial implementation of such a process entails difficulties because the separation of the carboxylic acids used from the polyvinylpyridine N-oxides is problematic and because during the preparation there is formation of unstable peracids which are capable of detonation and can be handled only with special safety precautions. Concerning the problems in the use of peroxyacetic acid in the preparation of N-oxides, reference is made to U.S. Pat. No. 3,047,579, lines 35-50. As is also stated therein, the formation of N-oxides in the reaction of tertiary aromatic amines with hydrogen peroxide in aqueous solution takes place so slowly as to be unsuitable for industrial preparation.
According to U.S. Pat. No. 3,047,579, tertiary amines are oxidized with hydrogen peroxide in glacial acetic acid or in aqueous solution in the presence of catalytic amounts of acid-forming elements of Groups 5b, 6b, 7b and 8 of the Periodic Table.
It is an object of the present invention to provide a process for oxidizing polymers which contain vinylpyridine units which can be implemented industrially.
We have found that this object is achieved by a process for preparing polyvinylpyridine N-oxides by oxidizing polyvinylpyridines with aqueous solutions of hydrogen peroxide in the presence of acids when the oxidation is additionally carried out in the presence of oxides or acids of elements of Groups 5b, 6b, 7b and 8 of the Periodic Table or of salts of these acids as catalyst, or when the oxidation is carried out in from 40 to 80% by weight aqueous solutions of at least dibasic carboxylic acids or of polymers of monoethylenically unsaturated carboxylic acids as solvent in the presence or absence of the catalysts. Oxides, acids or salts derived from tungsten, molybdenum or vanadium are preferably used as catalyst.
It is possible by the process according to the invention to oxidize both homo- and copolymers of vinylpyridines. The vinyl group can be in position 2, 3 or 4 of the pyriding ring. The preparation of homo- and copolymers from these monomers is known in the art. Copolymers of vinylpyridine contain at least 5% by weight of vinylpyridine units. Suitable comonomers are all monoethylenically unsaturated monomers which can copolymerize with vinylpyridine, for example vinyl esters such as vinyl acetate, vinyl propionate and vinyl butyrate, styrene, .alpha.-methylstyrene, divinylbenzene, monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid and crotonic acid, anhydrides of monoethylenically unsaturated carboxylic acids such as maleic anhydride or itaconic anhydride, esters of monoethylenically unsaturated carboxylic acids and C.sub.1 -C.sub.6 -alcohols, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylimidazole, N-vinylformamide, N-methyl-N-vinylacetamide, N-vinylacetamide and quaternized basic vinyl compounds such as N-vinyl-N-methylimidazole and N-alkylvinylpyridines with 1 to 12 carbon atoms in the alkyl group.
Polymers of 4-vinylpyridine are preferably oxidized. All polyvinylpyridines can be converted by the process according to the invention into the corresponding N-oxides. This applies both to low molecular weight and to very high molecular weight polyvinylpyridines. Suitable polyvinylpyridines have K values from 8 to 350. Polyvinylpyridines which have molecular weights from 1000 to 300 000 are preferably used. Such polymers have K values from 10 to 100 (determined by the method of H. Fikentscher in 1% strength solutions in ethanol at 25.degree. C.). The aqueous hydrogen peroxide solutions used in the process according to the invention normally

REFERENCES:
patent: 3047579 (1962-07-01), Witman
patent: 3159611 (1964-12-01), Dunn et al.

Affiliated with

Also associated with

Rating

Preparation of polyvinylpyridine N-oxides does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Preparation of polyvinylpyridine N-oxides, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Preparation of polyvinylpyridine N-oxides will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1973856