Bis-indolyl phthalides and naphthalides
US4124592A · kind A · utility
2Cited by
3References
41Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1973 |
| Grant date | Nov 7, 1978 |
| Priority date | — |
| Expiry date | Oct 23, 1993 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B11/26
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
This invention relates to indole phthalein indicator dyes including phthalides and naphthalides wherein one of the indol-3-yl radicals is substituted with a hydrogen-bonding group on a carbon atom adjacent to the nitrogen atom of the indole ring. In a preferred embodiment, one of the indol-3-yl radicals is substituted with a hydrogen-bonding group and the other indol-3-yl radical is substituted with a hydrogen-bonding group or with an electron-withdrawing group. These indicator dyes, especially those of the preferred embodiment, possess a relatively high pKa and a relatively broad absorption spectrum in the visible range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.