Spectroscopic Studies on Dyes. V. Derivatives of cis-Indigo1
Spectroscopic Studies on Dyes. V. Derivatives of cis-Indigo1
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染料的光谱研究。
DOI：
10.1021/jo01018a055
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发表时间：
1965
影响因子：
3.6
通讯作者：
Anton F. Zenhäusern
中科院分区：
文献类型：
--
作者：
G. Wyman;Anton F. Zenhäusern
N，N‘-草酰亚胺的可见光谱与N，N’-二乙酰基二甘醇和N，N‘-双(三氟乙酰基)靛蓝的光化学生成的顺式异构体的光谱比较表明，这三个分子都是非共面的顺式构型。这一点在红外区的羰基伸缩频率的研究中得到了进一步证实。用分光光度技术研究了在苯和氯苯溶液中，由青黛和草酰氯生成草酰二硫的反应。结果表明，以-lt；RANS-N-(氯草酰基)青蓝为中间体的反应为两步反应。用类似的技术发现草酰二甘在二甲基甲酰胺水溶液中的碱性水解分两步进行，包括两个酰胺键的逐步水解。由于第二步反应的速度很慢，所以有可能确定中间阴离子的可见光谱，并根据吸收峰的长波(571微米)指定它的反式构型。(Heller以前在这个反应中观察到了一种蓝色中间体，他认为它是顺式的。)虽然人们很早就知道了蓝色的结构，而且人们认识到该分子具有反式构型，但文献5已经报道了3·4个As-Indigo的衍生物，也推测了顺式-Indigo的存在。6鉴于我们目前对共轭化合物顺反异构化的理解，认为不稳定的顺式异构体在环境中存在的可能性很小。
A comparison of the visible spectrum of N, N'-oxalylindigo with the spectra of the photochemically produced cis isomers of N, N'-diacetylindigo and N, N'-bis (trifluoroacetyl) indigo suggests a noncoplanar cis configuration for all three molecules. This was further substantiated by a study of the carbonyl stretching frequencies in the infrared region. Theformation of oxalylindigo from indigo and oxalyl chloride was studied in benzene and chlorobenzene solutions, using spectrophotometric techniques. The results indicate a two-step mechanism with< rans-N-(chlorooxalyl) indigo as the intermediate. By a similar technique the alkaline hydrolysis of oxalylindigo in aqueous dimethylformamide was found to proceed in twosteps involving the stepwise hydrolysis of the two amide linkages. Owing to the slowness of the second step it was possible to determine the visible spec-trum of the intermediate anion and to assign a trans configuration to it in view of the long wave length (571 µ) of the absorption maximum.(Heller had previously observed a blue intermediate in this reaction which he attributed to cis-indigo.)Although thestructure of indigo has long been known and it is recognized that the molecule possesses a trans configuration, 3· 4 derivatives of as-indigo have been reported in the literature5 and the existence of cis-indigo has also been postulated. 6 In view of our current understanding of the cis-trans isomerization of conjugated compounds, it is considered highly unlikely that the unstable cis isomer could exist at ambient