Process for the purification of dimethyl terephthalate

US5116518A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Wilfried Bachmann · Frankfurt am Main, DE
• Rolf Bader · Riehen, CH
• Horst Buttner · Bad Soden am Taunus, DE
• Edgar Wetzel · Heusenstamm, DE

Key dates

• Filing date: Dec 3, 1990
• Grant date: May 26, 1992
• Expiry date: Dec 3, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C67/52
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

In the process for the purification of diemthyl terephthalate (DMT) by recrystallization from methanolic solution, the mother liquor containing the impurities, substantially the isomers DMI, DMO and aldehydes, is separated off and passed to a workup tank. The moist crystals are dried by melting with the evaporation of methanol. The mother liquor is then separated off by filtration, and the moist crystals obtained from the separation are washed before melting. The washing liquid is recycled together with a portion of the separated mother liquor into the recrystallization tank.