Processes for the preparation of benzotriazole UV absorbers
US6815550B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 10, 2002 |
| Grant date | Nov 9, 2004 |
| Priority date | — |
| Expiry date | Dec 10, 2022 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C245/08
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Provided is a process for preparing 2H-benzotriazole UV absorbers containing a perfluoroalkyl moiety at the 5-position of the benzoic ring, for example a trifluoromethyl group, which involves digitizing the perfluoroalkyl substituted o-nitroaniline using concentrated sulfuric acid plus sodium nitrite or nitrosylsulfuric acid to form the corresponding monoazobenzene intermediate via the diazonium salt intermediate which is reduced to the corresponding 5-perfluoroalkyl substituted 2H-benzotriazole UV absorber compound by conventional reduction means. Also provided is a novel one-pot, multiphase reaction for the preparation of 2(2-nitrophenylazo) substituted phenols, which are precursors for 2H-benzotriazole UV absorbers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.