Abstract
The methylation of several organic potassium salts with 10-methylthioxanthenium tetrafluoroborate (2) was investigated in a solid state. The ground mixture of 2 and each one of the potassium salts of benzoic acid, p-nitrobenzoic acid, phthalimide, 1, 2-benzisothiazol-3(2H)-one 1, 1-dioxide, 2-acetyl-2, 3-dihydro-1H-inden-1-one, and 2-acetyl-1, 2, 3, 4-tetrahydronaphthalen-1-one was prepared. The temporal change of each ground mixture was followed by an infrared spectroscopy and an X-ray diffraction analysis at room temperature, 40°C, and 70°C. On standing at proper temperature the ground mixtures of 2 with each one of the above potassium salts in an agate mortar, the infrared spectroscopy and the power X-ray diffraction analysis indicate the appearance of the corresponding peaks attributable to a methylation product, the demethylated product (thioxanthene), and the ion exchanged product (KBF4) in a process of time. Next, the difference of the state of each mixture and the effet of grinding were confirmed by means of the differential thermal analysis. It turned out that the reaction temperature changed from the region of high to that of low with increasing grinding time. The solid-state reactions of 2 with free benzoic acid, and phthalimide did not proceed. From the facts described above, in the solid-state reaction of 2 with organic potassium salts, it became clear that every reaction gave methylation compound by the attack of the organic anion to the methyl group with the formation of the ion exchanged KBF4, moreover, the grinding activated the reaction system and facilitated the methylation at relatively low temperature.
