Novel spiro-heterocyclic compounds, their preparation, and use thereof in a thermographic recording material
US4052218A · kind A · utility
8Cited by
5References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 19, 1975 |
| Grant date | Oct 4, 1977 |
| Priority date | — |
| Expiry date | May 19, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D277/64
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
The invention relates to novel thermochromic spiro heterocyclic compounds having one or the other of the following formulae: ##STR1## where R.sub.1 denotes hydrogen atoms or one or more electron-donor groups in positions 5, 6, 7 and 8 in formula (1); R.sub.i ' denotes hydrogen atoms or one or more electron-donor or electron-acceptor groups in positions 4', 5', 6' and 7' and 4", 5", 6" and 7" in formulae (1) and (2); and R.sub.j denotes hydrogen atoms or one or more electron-donor groups in positions 5, 6, 7, 8, 9 and 10 in formula (2). Use in thermographic recording material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.