Study of the mechanism of the antioxidant action of ethoxyquin

L. Taimr
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引用次数: 8

Abstract

A study has been carried out of the reaction of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (ethoxyquin, I) with alkylperoxyls. In the presence of a relatively low concentration of 1-cyano-1-methylethylperoxyl, I reacts to form dimer IV (8-(6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinolin-1-yl)-6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline) as the main product and quinoline derivative III (2,4-dimethyl-6-ethoxyquinoline), as a side product, i.e., substances formed by the conversion of the aminyl II (6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinolin-1-yl) alone. Smaller amounts of p-quinoneimine VI and o-quinoneimine VIII (2,2,4-trimethyl-2,6-dihydro-6-quinolone and 6-ethoxy-2,2,4-trimethyl-2,8-dihydro-8-quinolone) have been found; these substances are formed by further oxidation of II. In the presence of relatively high concentrations of tert-butylperoxyls, peroxide IX (6-tert-butylperoxy-6-ethoxy-2,2,4-trimethyl-2,6-dihydroquinoline) is formed as the main product. Substance IX thermally decomposes to form VIII, while in the presence of weak acids IX is converted into VI as the main product. Dimer IV is a medium-strength antioxidant which is gradually converted into 8-(6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinolin-1-yl)-2,2,4-trimethyl-6-quinolone (XI) and 8-(6-ethoxy-3-hydroxy-2,2-dimethyl-4-methylene-1,2,3,4-tetrahydroquinolin-1-yl-)-2,2,4-trimethyl-2,6-dihydro-6-quinolone) (XII). The methyl group in XI actively participates in the antioxidation process. When formed, nitroxide V (6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinolin-N-oxyl) acts as an efficient antioxidant which, however, does not participate in the cyclic mechanism that is employed to explain the action of antioxidants of the HALS type. The antioxidant properties were evaluated on the basis of their effect on the course of the autoxidation of squalene.
乙氧基醌抗氧化作用机理的研究
研究了6-乙氧基-2,2,4-三甲基-1,2-二氢喹啉(乙氧基醌,I)与烷基过氧基的反应。在1-cyano-1-methylethylperoxyl浓度相对较低,我反应形成二聚体IV (8 - (6-ethoxy-2 2 4-trimethyl-1 2-dihydroquinolin-1-yl) 6-ethoxy-2, 2, 4-trimethyl-1, 2-dihydroquinoline)为主要产品和喹啉衍生物III (2, 4-dimethyl-6-ethoxyquinoline),作为一个副产品,例如,物质形成的转换aminyl II (6-ethoxy-2 2 4-trimethyl-1 2-dihydroquinolin-1-yl)。发现了少量的对喹奈亚胺VI和邻喹奈亚胺VIII(2,2,4-三甲基-2,6-二氢-6-喹诺酮和6-乙氧基-2,2,4-三甲基-2,8-二氢-8-喹诺酮);这些物质是由II进一步氧化形成的。在较高浓度的叔丁基过氧基存在下,生成过氧化物IX(6-叔丁基过氧基-6-乙氧基-2,2,4-三甲基-2,6-二氢喹啉)作为主要产物。物质IX热分解生成VIII,而在弱酸存在下IX作为主要产物转化为VI。氮氧化物V(6-乙氧基-2,2,4-三甲基-1,2-二氢喹啉- n-氧)在形成时作为一种有效的抗氧化剂,但不参与解释HALS型抗氧化剂作用的循环机制。根据其对角鲨烯自氧化过程的影响来评价其抗氧化性能。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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