In the solid state, a characteristic reaction is observed on heating of ground mixtures of 1-methyl-4-oxo-cis-2,6-diphenylthianium tetrafluoroborate (1) and alkali halides. These reactions occurred via ion exchange.These reaction products were 4-oxo-cis-2,6-diphenylthiane (6) and 5-(methylthio)-1,5-diphenyl-(E)-1-penten-s-trans-3-one (3) in KC1, mainly dibenzalacetone (4) in KBr, 1,5-bis(methylthio)-1,5-diphenylpentan-3-one (5), 3, 4, and 6 in KI, 3, 4, and 6 in NaCI, respectively, and different from those at room temperature. Moreover, the existence of three crystal forms (form I, II and III) and an amorphous form of 1 was confirmed by powder X-ray diffraction.Polymorphic transformations caused by heating, standing and by mechanical treatment such as grinding.In the solid-state reaction, grinding of mixture occurs the interaction such as adsorption.Moreover, thermal solid-state reaction by differential thermal analysis was affected by the grinding times and amount of alkali halide.

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Erhitzen der Thianiumtetrafluoroborate (I) mit Alkalimetallhalogeniden führt in einer Festkörperreaktion zu den Verbindungen (II)‐(V), die z.Tl. als Gemisch anfallen.

The solid-state reaction of ground mixture of 1-methy1-4-oxo-trans-2,6-diphenylthianium tetrafluoroborate (2) with some alkali halides (AX) has been investigated. In each system, an ion exchange reaction between 2 and AX occurred followed by the S-C bond cleavage in oxothianium ion. At room temperature, the ground mixture of 2 with KCl, KBr or NaCl gave 5-(methylthio)-1,5-diphenyl-(E)-1-penten-s-trans-3-one (3) and with KI gave 4-oxo-cis-2,6-diphenylthiane (5) in quantitative yield, respectively. When the ground mixtures were heated, the product was 3 in KCl and dibenzalacetone (6) in KBr, quantitatively. The products were 3 and 6 in NaCl and 3, 5, 6 and 1,5-bis(methylthio)-1,5-diphenylpentan-3-one (7) in KI. On heating system, activated hydrogen halide gas genreaction attacked 3 and produced 6. Stereomutation at C2 or C6 of oxothianium ion was observed accompanied by the ion exchange both in NaCl and KI media. It is considered that these stereomutation occurred via pyramidal inversion at the sulfonium carbanion.

Die Festkörperreaktion der trans‐Verbindung (I) mit Alkalimetallhalogeniden wird untersucht.