[1,2,5,6]Tetrathiocino-[3,4-c; 7,8-c']diisothiazole-3,8-dicarbonitrile
AssigneeE. I. Du Pont de Nemours and Company
InventorSusan Anne Vladuchick
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Abstract
Described is a process for preparing 3,4-dimercaptoisothiazole-5-carbonitrile disalt, preferably disodium salt, and its conversion to 1,4-dithiino[2,3-c; 6,5-c']-diisothiazole-3,7-dicarbonitrile through an intermediate dimeric structure believed to be [1,2,5,6]tetrathiocino-[3,4-c; 7,8-c']diisothiazole-3,8-dicarbonitrile. 3,4-Dimercaptoisothiazole-5-carbonitrile disodium salt and [1,2,5,6]tetrathiocino[3,4-c; 7,8-c']diisothiazole-3,8-dicarbonitrile are useful rubber curing agents, and 1,4-dithiino[2,3-c; 6,5-c']diisothiazole-3,7-dicarbonitrile is the immediate precursor of 1,4-dithiino[2,3-c; 6,5-c']diisothiazole-3,7-dicarboxylic acid, a yellow pigment.
Claims20
A process comprising (1) contacting a 1,2-dimercaptomaleonitrile salt of the formula ##STR18## where M is an alkali metal or bis[tetra(lower alkyl ammonium)], with sulfur in an alcohol solvent at a temperature of at least 50.degree. C and (2) contacting the resulting product with an oxidizing agent selected from the group consisting of bromine, hydrogen peroxide, iodine, sodium hypochlorite, sodium hypobromite, iron (III) chloride and potassium hexacyanoferrate (III) to form:
- ##STR19##
A compound having the formula ##STR21##
Dependencies are inferred from the claim text.