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Seven sulfonates of 4-chloro-3,5-dimethylphenol and seven sulfonates of 5-chloro-7-iodo-8-quinolinol were synthesized, characterized, and evaluated for antimalarial activity. None of the sulfonates was effective against Plasmodium berghei .

THERE has been some uncertainty about the fate of halogenated derivatives of oxine in the body1, but only a small part of an oral dose of Chlorhydroxyquinoline could be detected in the urines of rats1,2. In further experiments, traces were found in the blood of rats but the amount could not be estimated.

Two procedures have been developed for determining chlorhydroxyquinoline (halquinol) in pig feed medicated at a level of 120 p.p.m. The ultraviolet spectrophotometric procedure can be used to determine halquinol and the gas-liquid chromatographic procedure to determine specifically the 5,7-dichloro- and the combined 5- and 7-chloroquinolin-8-ol components. Halquinol was found to react with copper during the initial extraction with chloroform, thus preventing formation of the silyl ether prior to gas-liquid chromatography. Partitioning the chloroform extract with dilute mineral acid so as to cause dissociation of the chelate and adding EDTA before back-extraction into dichloromethane overcame this problem.

A method has been developed for the determination of chlorhydroxyquinoline (Halquinol) in medicated pig feeds. Because of the interference by feed constituents in simple spectrophotometric and polarographic assay procedures, a spectrofluorimetric procedure is recommended. Spectrofluorimetric measurements are taken in a methanolic solvent containing 5 per cent. of chloroform, and the fluorescence of chlorhydroxyquinoline, as its magnesium chelate, is measured at 500 nm, with an excitation wavelength of 402 nm. Cyanide is used to suppress interference from copper and zinc salts that are commonly added to these feeds. The procedure is not affected by the presence of other feed additives, such as dimetridazole and arsanilic acid.