NEW MATERIAL: A compound of formula I [R1 is (substituted)aryl, alkylaryl or aralkyl; Q is formula II (W1 and W2 are each electron-attracting group); Z1 and Z2 are each H, halogen or 1-4C alkyl].

EXAMPLE: N-(p-Chlorophenyl)-2-methyl-3-chloro-cis-3-thio-(1-acethylpropan-2-on-1-yl) acrylamide.

USE: Biocides and bactericides. The subject compound is introduced in or over aqueous system such as water-cooling or laundry-washing water, or oil/water system such as cutting oil or oil field, which is contaminated by bacteria or microorganisms, to inhibit or prevent growth of microorganisms at such introduced site.

PROCESS: A compound of formula I is obtained by reacting a (substituted)-4- isothiazolin-3-one with an equimolar nuleophilic agent of the formula, QH such as 2,4-pentanedione, etc., in anhydrous methanol in presence of a reaction promotor such as NaOC2H5, etc.