Selective aerobic oxidation of dimethylbiphenyls

A process for forming methylbiphenyl mono-esters, comprising:

• selectively oxidizing dimethyl-1,1′-biphenyl to form methyl-1,1′-biphenyl mono-carboxylic acids, by contacting a solution of dimethylbiphenyl isomers, including dimethyl-1,1′-biphenyl, in acetic acid in the presence of a Co(II) acetate catalyst and air, and optionally:
• (i) adding a co-solvent, or
• (ii) adding sodium or potassium acetate, and
• oxidizing the dimethyl-1,1′-biphenyl under time and temperature conditions sufficient to form one or more methyl-1,1′-biphenyl mono-carboxylic acid(s);
• and
• reacting the methyl-1,1′-biphenyl mono-carboxylic acids with C4 to C13 alcohols under esterification conditions, the process further comprising limiting the total conversion to 45-55% when the 3,3′-isomers of dimethylbiphenyl comprise between 10 and 30 wt % in the feed, so as to increase the overall yield of methyl-1,1′-biphenyl mono-carboxylic acids relative to other 1,1′-biphenyl oxygenates.

A process for selective oxidation of dimethyl-1,1′-biphenyl to form methyl-1,1′-biphenyl mono-carboxylic acid(s), comprising:

• contacting a solution of dimethylbiphenyl isomers, including dimethyl-1,1′-biphenyl, in acetic acid solvent in the presence of a Co(II) acetate catalyst and air, and optionally:
• (i) adding a co-solvent, or
• (ii) adding sodium or potassium acetate, and
• oxidizing the dimethyl-1,1′-biphenyl under time and temperature conditions sufficient to form one or more methyl-1,1′-biphenyl mono-carboxylic acid(s), the process further comprising limiting the total conversion to 30-45% when the 3,3′-isomers of dimethylbiphenyl comprise between 30 and 80 wt % in the feed, so as to increase the overall yield of methyl-1,1′-biphenyl mono-carboxylic acids relative to other 1,1′-biphenyl oxygenates.