Patent GB-1115427-A (GB)
Title: Process for the photochemical cross-linking of polymers
Inventor: DELZENNE GERARD ALBERT
IPC: C07D333/54
Filed: 1967-01-26
Abstract: A photo-curable polymer comprises a polymeric backbone carrying benzo[b]thiophen-1, 1-dioxide substituents pendant on the backbone. The polymer may be prepared by re-acting a polymer back-bone material possessing reactive groups with a benzo[b]thiophen-1, 1-dioxide containing substituents which are reactive with these reactive groups.  Suitable groups on the back-bone material are free anhydride groups, hydroxyl groups, amino or thiol groups.  Suitable substituents on the benzo[b]thiophen-1,1-dioxide are chlorocarbonyl, chlorosulphonyl, isocyanato or amine groups.  In examples, derivatives of a partly hydrolysed copolymer of ethylene and vinyl acetate, a partly hydrolysed copolymer of vinyl chloride and vinyl acetate, the polyether of 2,2-bis(4-hydroxy phenyl)-propane and epichlorohydrin, partly hydrolysed cellulose acetate, and a copolymer of styrene and maleic anhydride are made.  The polymer may be activated with an activating agent, e.g. p - dimethyl - amino - acetophenone, p - dimethylamino - benzophenone, p - nitrophenol, o,o1-dichloro-p-nitroaniline or anthraquinone.  In examples the polymers are also mixed with Michler's ketone and a black dye.  The benzo[b]thiophene-1, 1-dioxide derivatives used are the 2 - (p - isocyanatophenyl)-, 2 - (p - chlorocarbonyl - phenyl), 2 - (p - carboxy - p - phenyl) and 5-amino derivatives.  Compositions, which are used in the photo-chemical preparation of printing plates, also comprise cyclohexanone, pyridine, 1 - methyl - 2 - benzoyl - methylene-naphtho[1, 2-d]thiazoline, toluene, butyl acetate, dioxane and acetone.ALSO:2 - (p - Chlorocarbonylphenyl) - benzo[b] - thiophen-1,1-dioxide is prepared by (a) adding a suspension of p-bromoacetophenone in methanol to a solution of potassium hydroxide and thiophenol in methanol and refluxing to give the 41-bromo - 2 - phenylthioacetophenone intermediate; (b) adding a solution of this intermediate in chlorobenzene to a suspension of aluminium chloride in bromine chloride, followed by concentrated hydrochloric acid to give the 2-(p-bromophenyl)-benzo[b]thiophene intermediate; (c) heating a mixture of this intermediate with copper (I) cyanide and quinoline, extracting, dissolving with potassium hydroxide in glycol, heating and pouring into acidified water to yield the p-(2-benzo[b]thiophen)benzoic acid intermediate and (d) heating this intermediate with glacial acetic acid and hydrogen peroxide and then heating with thionyl chloride to give the product.  2 - (p - Isocyanato - phenyl)benzo[b]thiophen-1,1-dioxide is prepared by (a) adding a solution of p-nitrobenzyl chloride in methanol to a solution of sodium hydroxide and benzo[b]thiophen-2,3-dione in methanol, diluting and acidifying and refluxing with acetic anhydride and piperidine to give the 2-(p-nitrophenyl)-2-carboxybenzo[b]thiophen intermediate; (b) heating this intermediate with quinoline and copper powder and heating the product with glacial acetic acid and hydrogen peroxide to obtain the 2-(p-nitrophenyl)-benzo[b]thiophen-1,1-dioxide intermediate and (c) refluxing this intermediate, glacial acetic acid, tin (II) chloride and strong hydrochloric acid to obtain the amine, dissolving this in xylene and adding xylene saturated with phosgene to obtain the product.  5 - Amino - benzo[b]thiophen - 1,1 - dioxide is prepared by nitration of o-chlorobenzaldehyde, conversion with sodium sulphide and sulphur and ring closure of the disulphite formed, decarboxylation, conversion with hydrogen peroxide, and finally reduction of the nitro group to amino.