Methyl-Substituted Biphenyl Compounds, Their Production and Their Use in the Manufacture of Plasticizers

A process for producing biphenyl esters, the process comprising:

• (a) contacting a feed comprising at least one aromatic hydrocarbon selected from the group consisting of toluene, xylene and mixtures thereof with hydrogen in the presence of a hydroalkylation catalyst under conditions effective to produce a hydroalkylation reaction product comprising (methylcyclohexyl)toluenes and/or (dimethylcyclohexyl)xylenes;
• (b) dehydrogenating at least part of the hydroalkylation reaction product in the presence of a dehydrogenation catalyst under conditions effective to produce a dehydrogenation reaction product comprising a mixture of methyl-substituted biphenyl compounds, wherein the dehydrogenation catalyst comprises an element or compound thereof from Group 10 of the Periodic Table of Elements dispersed on a refractory support;
• (c) contacting at least part of the dehydrogenation reaction product with an oxygen source under conditions effective to convert at least part of the methyl-substituted biphenyl compounds to biphenyl carboxylic acids;
• and
• (d) reacting the biphenyl carboxylic acids with one or more C4 to C14 alcohols under conditions effective to produce biphenyl esters.