P.Nageswara Sarma

Determination of 2-methylpyrazine and pyrazinamide in reaction mixtures by gas and high-performance liquid chromatography☆

Abstract Pyrazinamide is an antitubercular drug, commonly prepared by ammoxidation of 2-methylpyraine (2-MP), which also may be prepared by several routes. Rapid, sensitive and selective analytical methods are essential for monitoring he reactions during process development. Methods based on gas chromatography were developed for monitoring the reactions during the preparation of 2-MP and a high-performance liquid chromatographic procedure was used to separate and determine the ammoxidation products of 2-MP. The methods were utilized successfully in analysing the reaction streams.

Determination of physicochemical properties of some fatty acid methyl esters by gas liquid chromatography

Physicochemical data such as vapor pressures (p0), heats of vaporization (ΔHv), activity coefficents at infinite dilution (γ∞) and excess partial molar entropy (ΔSe0) are considered important for conducting unit processes and designing reactor equipment. Scanty information regarding such data is available in the literature for the higher fatty acid methyl esters. The objective of this research was to determine the physicochemical properties of higher fatty acid methyl esters (C11–C23) by a gas-liquid chromatographic technique with SE-30 and diethylene glycol adipate as stationary phases. Correlations between carbon numbers and various thermodynamic properties have indicated definite trends, which could be useful in predicting the properties of unknown fatty acid methyl esters. The data generated may be useful to chemical engineers in the construction of storage tanks, solvent extractors and distillation columns.

Determination of chloropyridine isomers by gas chromatography and high-performance liquid chromatography in chlorpyrifos process development☆

Abstract Vapour phase chlorination of pyridine yields pentachloropyridine, and selective reduction of pentachloropyridine gives 2,3,5,6-tetrachloropyridine, both being important industrial intermediates. Various other isomeric chloropyridines may be formed during the chlorination reaction, and gas and high-performance liquid chromatographic methods are described for the separation and determination of chloropyridine isomers obtained during the vapour phase chlorination of pyridine. The methods have been successfully tested on the process development of the insecticide chlorpyrifos.

Separation and determination of reaction mixtures of anthraquinone by gas chromatography

Abstract Anthraquinone is a valuable organic intermediate commonly prepared by the reaction of phthalic anhydride with benzene and subsequent acid cyclization of the product obtained. Rapid, sensitive and selective analytical methods are essential for monitoring the reactions during process development. A gas Chromatographic method using an internal standard is described for the separation and determination of the reaction products obtained during the manufacture of anthraquinone.