Benzopyran compounds
Patent 5552091 Issued on September 3, 1996. Estimated Expiration Date: 
June 30, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
June 30, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3562172 3567605 3578602 Photochromic compounds Photochromic compounds Photochromic compound and articles containing the same Photochromic spiro(indoline)benzoxazines Photoreactive lenses with adamantane spiro compounds Photochromic spiropyran compounds Photochromic plastic article and method for preparing same InventorAssigneeApplicationNo. 497516 filed on 06/30/1995US Classes:252/586, Displaying color change548/440, The five-membered hetero ring shares ring carbons with two benzene rings (i.e., carbazoles)549/42, Tetracyclo ring system having the hetero ring as one of the cyclos549/383, Tetracyclo ring system having the hetero ring as one of the cyclos549/389, Naphtho-pyrans (including hydrogenated)549/457Tetracyclo ring system having the hetero ring as one of the cyclosExaminersPrimary: Tucker, PhilipAttorney, Agent or FirmForeign Patent References
International ClassesG02B 005/23C07D 209/82 C07D 333/50 C07D 311/78 AbstractDescribed are novel reversible photochromic benzopyran compounds, examples of which are compounds substituted at the 2-position of the pyran ring with a dibenzo-fused 5 member heterocyclic compound; other enumerated substituents at the other 2-position of the pyran ring; and a substituted or unsubstituted benzo, benzothieno or benzofurano group fused to the benzo portion of the benzopyran. Also described are organic host materials that contain or that are coated with such compounds. Articles such as ophthalmic lenses or other plastic transparencies that incorporate the novel benzopyran compounds or combinations thereof with complementary photochromic compounds, e.g., spiro(indoline) type compounds, are also described.Other References
Field of SearchDisplaying color changeTetracyclo ring system having the hetero ring as one of the cyclos Tetracyclo ring system having the hetero ring as one of the cyclos Naphtho-pyrans (including hydrogenated) Tetracyclo ring system having the hetero ring as one of the cyclos The five-membered hetero ring shares ring carbons with two benzene rings (i.e., carbazoles) |
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