Iodination of Carboxylic Acid Chlorides
Abstract Generated abstract
This study examines whether a direct iodination method previously developed for aromatic compounds can be applied to fatty acid derivatives. Acid chlorides of acetic, propionic, and butyric acids were reacted with iodine in the presence of a sulfuric and nitric acid mixture, followed by hydrolysis, extraction, vacuum distillation, and recrystallization of the resulting products. The procedure afforded the corresponding alpha iodo carboxylic acids, with reported yields of 55 percent for iodoacetic acid, 45 percent for alpha iodopropionic acid, and 40 percent for alpha iodobutyric acid, calculated relative to iodine used. The work presents this route as an extension of direct iodination to aliphatic acid chlorides and compares it implicitly with earlier methods giving variable or unspecified yields.
Full Text
IODINATION OF CARBOXYLIC ACID CHLORIDES
A. N. Novikov, P. I. Siyanko
(Presented by the scientific-methodological seminar of the Faculty of Chemical Technology)
The purpose of this work was to extend the method of direct iodination of aromatic compounds, developed by B. V. Tronov and A. N. Novikov [1, 2], to derivatives of fatty acids. The acid chlorides of acetic, propionic, and butyric acids were subjected to direct iodination in the presence of a sulfuric–nitric acid mixture. In this process the corresponding α-iodo derivatives of the acids were obtained. According to the literature, α-iodo derivatives of fatty acids are obtained by the action of ICl on acid chlorides [3], by KI on the corresponding chloro derivatives of acids [4, 5] with yields of 30–75%, and also by direct iodination of acid anhydrides in a mixture of fuming nitric and nitrosylsulfuric acids with yields of 15–40% [6]. In subsequent years patents appeared on the preparation of iodoacetic acid: by halogenation of acetic acid in a flame [7], and by reaction of ketene with ICl [8]. The yields of the acid are not indicated.
Experimental Part
The syntheses were carried out in a flask equipped with a stirrer, a reflux condenser, and a dropping funnel. Iodine, sulfuric acid of density \(d\ 1.83\), which in some cases was omitted, and the acid chloride were charged into it successively. The mixture was heated on a bath to 50–60°C, and, with vigorous stirring, nitric acid of density \(d\ 1.4\) was added dropwise over the course of an hour. After the system became transparent and yellow in color, 10 ml of water was slowly added and the mixture was stirred for another 10 min. The mixture was then treated three times with chloroform, and the extracts were dried with fused calcium chloride. After distilling off the chloroform, the acid mixture was separated by vacuum distillation. Upon cooling, the iodo derivatives of the acids crystallized; the crystals were washed with petroleum ether (fraction 40–60°C) and filtered off. The products were recrystallized from petroleum ether. The conditions and results of the syntheses are summarized in the table. The yields of substances were calculated based on the iodine taken into the reaction.
Conclusions
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The method of direct iodination of aromatic compounds has been extended to acid chlorides of fatty acids.
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By direct iodination of the acid chlorides of acetic, propionic, and butyric acids, aqueous acetic, propionic, and butyric acids were obtained with yields of 55, 45, 40%.
References
- B. V. Tronov, A. N. Novikov. Proceedings of Higher Educational Institutions. Chemistry and Chemical Technology, 3, 872, 1960.
- A. N. Novikov, V. T. Slyusarchuk, Journal of General Chemistry, 37, 1323, 1967.
- V. Zernov, Journal of Physical Chemistry, 32, 804—819, 1901.
- I. Guben, Methods of Organic Chemistry, 3, 447, 1935.
- Fukui, Kitano, Yoshimura; Japanese patent 4322, 1958; RZhKhim., 48799 II, 1960.
- P. S. Varma, V. T. S. Menon, J. Ind. Chem. Soc., 10, 592, 1933; Chem. Zbl., 1, 2105, 1934.
- Cleaver C. S. U.S. Patent 2833822, 1958; RZhKhim., 10L94, 1961.
- Schnizer A. W. U.S. Patent 2820057, 1958; RZhKhim., 49427II, 1959.