Sterling Drug Inc.

The Hilton-davis Chemical Co.

James E Kassner

Nicholas A Ambrosiano

Raymond E Werner

Robert W Rebhahn

Ramamurthi Kannan

Gordon J Sterken

This invention relates to improved processes for the manufacture of quinolinic acid run with a higher concentration of reactants in the initial step wherein quinoline is oxidized with hydrogen peroxide in an aqueous sulfuric acid solution in the presence of copper sulfate to prepare copper quinolinate, and in subsequent steps converting the copper quinolinate from the initial step to quinolinic acid by treating the copper salt with alkali to form the water soluble alkali salt form of quinolinic acid precipitating the copper as insoluble cupric oxide and thereafter treating the soluble alkali salt form with acid to obtain the quinolinic acid, the improvement whereby the reaction of the initial step is carried out in a thermally controllable and safe manner and the formation of by-products is minimized which comprises in the initial step adding separately either in portion-wise multiple and approximately equal portions or adding continuously and simultaneously over a period of time each of the following, the sulfuric acid, the quinoline and the hydrogen peroxide to an aqueous solution of the copper sulfate over such time intervals of sufficient length spaced between each group of portion-wise additions or at such a rate as to allow the hydrogen peroxide to react to maintain an unreacted hydrogen peroxide concentration in the reaction of between approximately three and approximately fifteen percent.

Process for preparing quinolinic acid

Substituted 2-benzoylbenzoic acids, useful as intermediates for preparing valuable chromogenic phthalide compounds, are prepared by reacting certain substituted 3,3-diphenylphthalides with a lower alkanoic acid and water.

Process for preparing 2-benzoylbenzoic acids

A multi-step process for the purification of Quinoline Yellow WS involves generating water-insoluble organic amine salts of sulfonated 2-(2-quinolinyl)-1,3-indandione from technical Quinoline Yellow WS followed by treatment of the amine salt with sodium hydroxide to regenerate Quinoline Yellow WS certifiable as a D&C color.

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Fort Mitchell, KY, United States of America

James E Kassner