Process for the preparation of anthraquinone dispersions and their use in alkaline wood digestion processes
US4717451A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1985 |
| Grant date | Jan 5, 1988 |
| Priority date | — |
| Expiry date | Dec 18, 2005 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C46/00
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The process of making a wet or dry dispersion containing anthraquinone suitable for use in the alkaline digestion of wood comprising cyclizing ortho-benzoylbenzoic acid at a temperature of about 150.degree. to 180.degree. C. and at an absolute pressure between about 5 and 40 millibars in the presence of between about 0.05 to 2 parts by weight of sulfuric acid, having a concentration of at least about 95%, per part by weight of ortho-benzoylbenzoic acid to form a reaction mixture containing anthraquinone, bringing the reaction mixture to a pH of at least about 7 by addition thereto at a temperature between about ambient temperature and 100.degree. C. of an aqueous solution of sodium hydroxide or potassium hydroxide containing between about 10% to 40% hydroxide by weight, and then forming a dispersion thereof and using such dispersion in the alkaline digestion of wood.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.