Process for the recovery of high purity diesters of terephthalic or isophthalic acids
US4032563A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 2, 1975 |
| Grant date | Jun 28, 1977 |
| Priority date | — |
| Expiry date | Sep 2, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C67/39
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process is disclosed for producing the dimethyl esters of aromatic dicarboxylic acids wherein the acid is esterified with a low molecular weight alcohol, the product is crystallized and separated to isolate a mass of the diester crystals and recover a mother liquor. An improvement in such process resides in the thermal oxidation with molecular oxygen of a mother liquor material to produce a mono methylphthalate from either p-methyl toluate or methyl-4-carboxybenzaldehyde. A portion of the oxidized mother liquor is recycled to the esterification zone wherein the mono methylphthalate can be esterified to the dimethyl ester while another portion of the oxidized mother liquor stream is passed to an evaporation treatment zone, preferably a wiped film evaporator, wherein overhead material is separated from a high boiling bottoms material and recycled to the esterification reaction zone. The high boiling bottoms stream from the evaporation treatment zone is purged from the system thereby removing from the overall process high boiling organics including ash.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.