Phthalic anhydride formation and separation
US4233227A · kind A · utility
5Cited by
2References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 5, 1979 |
| Grant date | Nov 11, 1980 |
| Priority date | — |
| Expiry date | Oct 5, 1999 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C51/573
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Undesirable discoloration of resultant phthalic anhydride and decomposition thereof and/or o-phthalic acid accompanying dehydration of o-phthalic acid to its anhydride in the presence of oxidation catalyst components Co, Mn and Br can be avoided by the rapid dehydration of o-phthalic acid and rapid vaporization of its anhydride occurring at a reduced pressure of downward from 760 mm Hg down to 40 mm Hg and at a temperature of from 180.degree. C. up to 250.degree. C. under continuous flow conditions which permit rapid removal of anhydride as vapor stream from catalyst components remaining as part of a fluid residue.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.