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:
Jan. 23, 1990
Filed:
Mar. 11, 1988
Karl Schmeidl, Ludwigshafen, DE;
BASF Aktiengesellschaft, Ludwigshafen, DE;
Abstract
Completely esterified rhodamine dyes of the formula ##STR1## where R, R.sup.2 and R.sup.4 are independently of one another methyl or ethyl, R.sup.1 and R.sup.3 are independently of one another hydrogen, methyl or ethyl, R.sup.5 and R.sup.6 are independently of one another hydrogen or methyl and A.sup..crclbar. is an anion, are prepared from compounds of the formula II ##STR2## or from the corresponding water addition products by esterification with dialkyl sulfates in solvents by using .gamma.-butyrolactone, alkylene carbonates, dialkyl carbonates, methoxypropyl acetate or dialkyl phthalates as solvent and working in the presence of an excess of a base, based on dialkyl sulfate.