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. 13, 1991
Filed:
Aug. 02, 1990
Ponnampalam Mathiaparanam, Appleton, WI (US);
Appleton Papers Inc., Appleton, WI (US);
Abstract
Preparation of novel symmetrical and unsymmetrical chromogenic di-[bis-(indolyl)ethylenyl]tetrahalophthalides is disclosed. Specifically these compounds are chromogenic di-[bis-(indolyl)ethylenyl]tetrahalophthalides of the formula ##STR1## wherein L and X are as hereinafter defined. The process disclosed involves condensing bis(indolyl)ethylenes with tetrahalophthalic anhydride in acetic anhydride, in the presence of an electron acceptor or preferably an acetate of Group I or II of the Periodic Table. Optionally, and preferably, where unsymmetrical di-[bis-(indolyl)ethylenyl]tetrahalophthalides are desired, indoles are reacted with an acylindole in the presence of a Vilsmeier reagent to form the starting bis(indolyl)ethylene.