Patent ID: 9340496
Filing Date: 2016-05-17
CPC Classification: C07C

Claim Text:
1. A process for the production of 4,4′-dichlorodiphenyl sulfone in steps comprising: reacting dimethyl sulfate and sulfur trioxide to form a reaction mixture comprising dimethyl pyrosulfate; reacting the formed dimethyl pyrosulfate with unreacted sulfur trixoxide in the reaction mixture; reacting the reaction mixture with monochlorobenzene to form an isomeric mixture of dichlorodiphenyl sulfones; optionally removing unreacted dimethyl sulfate; isolating crude 4,4′-dichlorodiphenyl sulfone using a water miscible alkanol/water miscible alkanol-water mixture; recovering the solvent from mother liquor; optionally recovering the isomeric mixture of dichlorodiphenyl sulfones from mother liquor; optionally, converting the residual isomeric mixture of dichlorodiphenyl sulfones to a product selected from diphenyl sulfone, 2-aminodiphenyl sulfone; 2,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfone; optionally recovering monochlorobenzene sulfonic acid and/or monochlorobenzene from the mother liquor; optionally recovering sulfuric acid from the residual liquor; optionally recycling the solvent; and purifying 4,4′-dichlorodiphenyl sulfone from crude followed by crystallization and treating with one or more of a sequestering agent or activated carbon in the presence of a water immiscible solvent or a water immiscible solvent-water mixture, wherein catalyst is added in the step of reacting dimethyl sulfate and sulfur trioxide, the step of reacting the formed dimethyl pyrosulfate with unreacted sulfur trioxide, the step of reacting the mixture with monochlorobenzene, or at the end of the step of reacting the mixture with monochlorobenzene.