Sulphur-based stabilizers for 3-isothiazolones

A method of protecting against chemical degradation an isothiazolone of the formula:

• ##STR4## wherein Y is (C.sub.1 -C.sub.18)alkyl or (C.sub.3 -C.sub.12)cycloalkyl each optionally substituted with one or more of hydroxy, halo, cyano, alkylamino, dialkylamine, arylamino, carboxy, carbalkoxy, alkoxy, aryloxy, alkylthio, arylthio, haloalkoxy, cycloaklylamino, carbamoxy, or isothiazolonyl;
• an unsubstituted or halo-substituted (C.sub.2 -C.sub.8) alkenyl or alkynyl;
• a (C.sub.7 -C.sub.10)aralkyl optionally substituted with one or more of halogen, (C.sub.1 -C.sub.4)alkyl or (C.sub.1 -C.sub.4)alkoxy;
• or an aryl optionally substituted with one or more of halogen, nitro, (C.sub.1 -C.sub.4)alkyl, (C.sub.1 -C.sub.4)alkyl-acylamino, carb(C.sub.1 -C.sub.4)alkoxy or sulfamyl;
• and
• R and R.sup.1 are each independently H, halogen, (C.sub.1 -C.sub.4) alkyl, (C.sub.4 -C.sub.8) cycloalkyl or joined together to form a phenyl;
• comprising incorporating therewith an organic sulphur-containing compound, or an alkaline metal or amine salt thereof, capable of forming an adduct with said isotiazolone which is reversible upon hydrolysis, said sulfur-containing compound being selected from the group consisting of mercaptobenzothiazole, the sodium salt of 2-mercaptopyridine-N-oxide, 2-mercaptopyridine, 4-mercaptopyridine, benzothiazole, 2-thiohydantoin, L-cystin, methylenebis-thiocyante, 2-methylthiobenzothiazole, 4-methyl 4-H-1,2,4-triazole-3-thiol, 4-R-(thiazolidinethione)-4-carbonic acid, and 2-mercaptopyrimidine.