PURPOSE: To isolate a dimethyl 4,4'-biphenyldicarboxylate from residues and flow of secondary products of DMT production.
CONSTITUTION: Process for isolating dimethyl 4,4'-biphenyldicarboxylate from residues and flow of secondary products of DMT production, which comprises distilling the residues or materials of flow of secondary products at a pressure of at most 7 mbar at a boiler temperature from 200 to 350°C, subsequently treating the distilate for 10 to 60 minutes with 0.7 to 10 times the amount of an organic solvent at 70 to 180°C, if required, separating the clear solution from undissolved components, cooling the removed clear solution to 45 to 65°C and allowing it to crystallize at this temperature, resulting in a suspension of dimethyl 4,4'-biphenyldicarboxylate crystals from which the crystals are isolated by the conventional method and washing one or more times with the same or a different organic solvent and drying.
URURIHI HERUTENSHIYUTAIN
RAINAA SHIYARAA
