The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 24, 1976
Filed:
Apr. 01, 1974
Eva R Karger, Arlington, MA (US);
Paul T MacGregor, Lexington, MA (US);
Polaroid Corporation, Cambridge, MA (US);
Abstract
This invention relates to derivatives of phthalaldehydic and naphthalaldehydic acid useful as intermediates in the preparation of pH-sensitive phthalide and naphthalide indicator dyes. One class of intermediates provided by the present invention comprises compounds of the formula: ##SPC1## Wherein A represents 4'-hydroxy-1'-naphthyl and X represents the atoms necessary to complete a ring-closing moiety selected from a phthalide and a naphthalide and preferably is naphthalide. Another class of intermediates provided by the present invention comprises compounds of the formula: ##SPC2## Wherein A represents 4'-hydroxy-1'-naphthyl; B represents 4'-hydroxy-1'-naphthyl or indol-3-yl and C represents a 2-carboxy-1-phenyl radical or an 8-carboxy-1-naphthyl radical and preferably is 8-carboxy-1-naphthyl.