1823. KOCH, H., AND HILBERATH, F. [Literature Review and Comparative Investigations of Methods for Determining the Iodine Number of Hydrocarbons.] Brennstoff-Chem., vol. 21, 1940, p. 185-194; Chem. Abs., vol. 35, 1941, p. 7319.

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Literature Abstracts

Reviews 62 papers published since 1884. The Wijs, Kaufmann, and iodo-thiocyanate methods and the procedures of Hanus, Francis, and Grosse-Oetringhaus have been compared for 17 simple olefin hydrocarbons. For the exact determination of the I number of aliphatic monoolefins and hydrocarbon mixtures, the methods of Kaufmann and Grosse-Oetringhaus alone are suitable. For approximations, the KBr-KBO₃ method of Francis is suitable. The use of the Wijs, Hanus, and Kaufmann methods involves large substitution errors with tertiary or ditertiary olefins. These 3 methods can be used with olefins not branched at the double bond, as with the Kogasins. No general conclusions were reached for the determination of cyclic monoolefins because of few data: Cyclopentene and cyclohexene can be analyzed by the methods named, but side reactions were observed with certain unsaturated cyclic terpenes. Conjugated double bonds in dienes can be considered as having the I consumption of single double bonds with the iodo-thiocyanate, Wijs, and Hanus methods. On the other hand, the method of Francis, as modified by Cortese, produces complete saturation, and the method can be used in combination with the other methods to determine the content of conjugated double bonds in mixtures by difference. Few tests were made with acetylenes; the methods of Wijs and Hanus give 50% of the theoretical I-consumption; the method of Lucas and Pressman gives complete saturation in the absence of substitutable olefins. With synthetic Kogasin lubricating oils, the suitability of the iodo-thiocyanate method for the exact determination of double bonds and the Wijs method (limited to 2-3 min. reaction time) for approximations was shown.