CONFORMATIONAL POLYMORPHISM IN THIOPHENYL SUBSTITUTED QUINONES AND THE DISAPPEARING NMR-SPECTRUM

被引：6

作者：

KASHYAP, RP ^{[1
]}

SUN, DL ^{[1
]}

WATSON, WH ^{[1
]}

机构：

[1] TEXAS CHRISTIAN UNIV,DEPT CHEM,FT WORTH,TX 76129

来源：

JOURNAL OF CHEMICAL CRYSTALLOGRAPHY | 1995年 / 25卷 / 06期

关键词：

THIOPHENYLQUINONES; POLYMORPHISM; CONFORMERS; MOLECULAR MECHANICS;

D O I：

10.1007/BF01796060

中图分类号：

O7 [晶体学];

学科分类号：

0702 ; 070205 ; 0703 ; 080501 ;

摘要：

The stepwise addition of thiophenol to benzoquinone gives thiophenylbenzoquinone (1b), 2,5-and 2,6-di-(thiophenyl)benzoquinone (2,3),2,3,6-tri-(thiophenyl)benzoquinone (4) and 2,3,5,6-tetra-(thiophenyl)benzoquinone (5). Compounds 1-4 can be crystallized, and the C-13 NMR spectra are readily interpreted. Compound 5 could not be crystallized easily, and the NMR showed more than twice as many lines as the number of carbon atoms. Slow evaporation in an NMR tube produced three distinct crystals. X-ray analysis of two crystals (5a and 5c) showed the compounds to be conformational polymorphs. Direct synthesis of 5 from tetrachlorobenzoquinone and thiophenol yielded only conformer 5a, and the C-13 NMR spectrum showed only the 6 lines expected for four equivalent phenyl substituents on benzoquinone. Subjecting 5a to a variety of solvents, reagents and temperatures did not regenerate the original C-13 NMR spectrum. The crystal structures, conformations, and polymorphs are discussed.

引用

页码：339 / 349

页数：11

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