有機硫黄化合物の研究(第7報)cis-およびtrans-1-Thioniabicyclo-[4.4.0]decane Iodide結晶の熱異性化反応

抄録

The thermal behavior of cis-1-thioniabicyclo [4.4.0] decane iodide (cis-TBD-I) and its trans isomer (trans-TBD-I) were investigated in comparison with those of cis- and trans-TBD-Br (Miyoshi, Yakugaku Zasshi, 101, 891 (1981) by means of differential thermal analysis, X-ray diffraction and infrared absorption spectrometry. cis-TBD-I, having a monoclinic C-lattice at room temperature, is transformed into an orthorhombic F-lattice at 47°C. The cis-TBD cations in this orthorhombic F-lattice gradually isomerizes into an equilibrium state in the range of 130 to 180°C. This state contains cis- and trans-TBD cations in an approximately 3 : 2 molar ratio in the case of TBD-Br. This equilibrated compound also forms α-TBD-I crystal in the same way as in α-TBD-Br, in which isomeric cis- and trans-TBD cations are statistically distributed and have statistical orientations. trans-TBD-I, having an orthorhombic C-lattice at room temperature, corresponds to a super lattice of the high temperature phase. It is transformed into an orthorhombic F-lattice at 49°C, and isomerizes into α-TBD-I in the range of 120 to 180°C. On the other hand, cis- and trans-TBD-I form the face-centered orthorhombic mixed crystals which contain 3 to 40 mol percent of cis-TBD-I. From these results, it is concluded that α-TBD-I is one of the mixed crystals in which the content of cis-TBD-I is enriched up to 60 mol percent by thermal isomerization in the crystalline state.