Process for the production of 4-alkoxy-2(5H) thiophenones

Process for the production of a 4-alkoxy-2(5H) thiophenone of the formula:

• ##STR4## wherein R.sub.1 is a straight-chain or branched alkyl having 1 to 4 carbon atoms, comprising reacting a 3-alkoxy-4-halo-2E-butenoic acid alkyl ester of the formula:
• ##STR5## wherein R.sub.1 and R.sub.2 each is the same or different straight-chain or branched alkyl having 1 to 4 carbon atoms and Hal is chlorine or bromine, either (a) with an alkali salt of thioacetic acid to a 3-alkoxy-4-thioacetoxy-2E-butenoic acid alkyl ester, isolating the 3-alkoxy-4-thioacetoxy-2E-butenoic acid alkyl ester and further converting the 3-alkoxy-4-thioacetoxy-2E-butenoic acid alkyl ester with an alkali hydroxide to the 4-alkoxy-2(5H) thiophenone or (b) directlywith an alkali hydrogen sulfide to the 4 alkoxy-2(5H) thiophenone.