Synthesis and Antimicrobial Activity of 3-[(2-R-oxyethoxy)methyl]benzazole-2-thiones

Compounds containing a bound formaldehyde moiety are one of the widely used classes of biocides for the protection of petroleum products from microbiological contamination. To obtain new formaldehyde-containing biocides, we studied the reaction of ethylene glycol monomethyl and monophenyl ethers with formaldehyde and 2-mercaptobenzazoles (2-mercaptobenzothiazole and 2-mercaptobenzoxazole). As shown by 13C NMR spectroscopy, potentially tautomeric 2-mercaptobenzazoles reacted in the thione form to afford the corresponding 3-[(2-R-oxyethoxy)methyl]benzazole-2-thiones. Microbiological evaluation of the synthesized compounds revealed their antimicrobial activity against microorganisms damaging to petroleum products. In particular, they protected M-12 motor oil from biodegradation at a concentration of 0.5%.