Method of purifying carbazole ester precursors of 6-chloro-alpha-meth yl-carbazole-2-acetic acid

A process of purifying a (6-chloro-2-carbazolyl)methyl-malonic acid di(C1 -C6 alkyl) ester of Formula (I): wherein Ra and Rb must be the same and are selected from the group consisting of C1 -C6 alkyl; comprises phase separating one or more impurities from said carbazole ester at least once wherein...

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Bibliographic Details
Main Authors KEITH MICHAEL DEVRIES, DIANE MARIE RESCEK, PETER ROBERT ROSE, PHILIP DIETRICH HAMMEN, JOHN LLOYD TUCKER
Format Patent
LanguageEnglish
Published 23.12.1999
Edition6
Subjects
CHEMISTRY
HETEROCYCLIC COMPOUNDS
METALLURGY
ORGANIC CHEMISTRY
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Summary:A process of purifying a (6-chloro-2-carbazolyl)methyl-malonic acid di(C1 -C6 alkyl) ester of Formula (I): wherein Ra and Rb must be the same and are selected from the group consisting of C1 -C6 alkyl; comprises phase separating one or more impurities from said carbazole ester at least once wherein the solvent used to carry out said phase separation is acetic acid. In a preferred embodiment said acetic acid is glacial acetic acid which is maintained at a temperature of from about 30 DEG to about 110 DEG C and said carbazole ester is obtained in a purity of at least 99. 90% by weight, so that the amount of impurities present therein is 0.10% or less by weight. In a more preferred embodiment of said process, said temperature is from about 50 DEG to about 70 DEG C, and said phase separation is carried out only once.
Bibliography:Application Number: AU19990035038