Neutral coloring photochromic 2H-naphtho[1,2-b] pyrans and heterocyclic pyrans
US6248264A · kind A · utility
19Cited by
6References
10Claims
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Key dates
| Filing date | Nov 1, 1999 |
| Grant date | Jun 19, 2001 |
| Priority date | — |
| Expiry date | Nov 1, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D495/04
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Compositions comprising a naphtho [1,2-b]pyran of formula (I): ##STR1## wherein R.sup.7 and/or R.sup.9 is hydrogen or an amino group provided that R.sup.7 and R.sup.9 are not both hydrogen, and the other substituents are as defined in the specifcation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.