Process for preparing 2-chloro-3-alkoxy-4-alkylsulfonyl-benzoic acids and esters

A process for preparing a substituted benzoic acid or benzoate ester compound of the formula:

• wherein
• Z represents Cl or OR and R represents a C1-C4 alkyl group optionally substituted with a C1-C4 alkoxy or C1-C4 alkylthio group or with a 3-6 membered alicyclic moiety composed of one oxygen or sulfur atom and 2-5 carbon atoms or represents a 3-6 membered alicyclic moiety composed of one oxygen or sulfur atom and 2-5 carbon atoms;
• R′″ represents C1-C4 alkyl;
• and
• R″ represents H or lower alkyl which process comprises contacting a chloro compound of the formula:
• wherein R′″ and Z are as defined hereinabove with carbon monoxide under 300 to 5,000 kiloPascals pressure at a temperature of about 100° C. to about 150° C. in the presence of water or a lower alkyl alcohol, a base, a catalytic amount of a palladium II halide or C1-C8 alkanoate, a trihydrocarbylphosphine chelant selected from a triphenylphosphine, a diphenylcyclohexylphosphine, 1,3-bis (diphenylphosphino) propane, and 1,4-bis (diphenylphosphino) butane or a preformed palladium II halide or C1-C8 alkanoate salt:trihydrocarbylphosphine complex prepared therefrom, and, optionally, a phase transfer catalyst and, when R″ represents hydrogen, subsequently acidifying the reaction mixture obtained.