Patent ID: 8039659

Claim:
A process comprising: reacting a dialkyl carbonate of the formula (II) and an aromatic hydroxy compound of the formula (III) in the presence of a transesterification catalyst in a first reaction column, the first reaction column comprising a top section, a bottom section, a rectifying section in an upper portion of the column and a reaction zone below the rectifying section, wherein R 1 and R 2 independently of one another represent linear or branched, optionally substituted C 1 -C 34 -alky, wherein R, R′ and R″ independently of one another represent H, linear or branched, optionally substituted, C 1 -C 34 -alkyl, C 1 -C 34 -alkoxy, C 5 -C 34 -cycloalkyl, C 7 -C 34 -alkylaryl, C 6 -C 34 -aryl or a halogen radical, and wherein R can also represent —COO—R′″, wherein R′″ can be H, linear or branched C 1 -C 34 -alkyl, C 1 -C 34 -alkoxy, C 5 -C 34 -cycloalkyl, C 7 -C 34 -alkylaryl or C 6 -C 34 -aryl; feeding a bottom product from the first reaction column to a further reaction column; the bottom product comprising a diaryl carbonate of the formula (I), an alkylaryl carbonate of the formula (IV), or both, and residual unreacted dialkyl carbonate and aromatic hydroxy compound; the further reaction column comprising a top section, a rectifying section in an upper portion of the column and a reaction zone below the rectifying section; and reacting the residual unreacted dialkyl carbonate and aromatic hydroxy compound in the further reaction column, wherein R, R′ and R″ have the meaning given for formula (III), and wherein R 1 has the meaning given for formula (II); feeding a process stream to a distillation column, the process stream comprising a mixture of unreacted dialkyl carbonate and one or more reaction-product alcohols drawn from the first reaction column, the further reaction column, or both, such that the unreacted dialkyl carbonate is separated from the one or more reaction-product alcohols; and recycling the separated, unreacted dialkyl carbonate to the first reaction column; wherein the further reaction column comprises one or more condensers, and heat of condensation from the one or more condensers is fed back into the process.