Synthesis of Bismuth Trifluoromethanesulfonate

Bismuth (III) trifluoromethanesulfonate, also known as bismuth triflate, is an economical, efficient, and environmentally friendly catalyst for the synthesis of organic products. Currently, bismuth triflate is not produced in Russia, so developing a technology for producing bismuth triflate is an important task. Bismuth triflate can be obtained using two methods: by reacting bismuth hydroxide with triflic acid, and by reacting bismuth oxide with triflic acid. The production of bismuth triflate from bismuth hydroxide is a long process that does not proceed to the end and has a yield of no more than 40%. The bismuth oxide obtained by thermal decomposition of bismuth hydroxide has several polymorphic modifications. Heating was carried out to 750 °C and cooled for 8 hours. The γ-bismuth oxide obtained in this way is dissolved in triflic acid for 2 hours and forms high-concentration solutions. The solubility values of bismuth triflate were determined at different acidity levels. X-ray analysis showed that bismuth nonahydrate triflate formed needle-like crystals. The α-phase of bismuth oxide obtained by decomposition of bismuth hydroxide at 450 °C did not dissolve completely in the acid. The process was carried out for 4 hours, and the yield was 92%. The resulting crystals of a bipyramidal shape were studied by differential thermal analysis, which showed that the crystals are pentahydrate of bismuth triflate, which loses crystallization water in the temperature range of 64-130 °C. Up to 320 °C, the substance is thermally stable. At a temperature of 327 °C, it melts with decomposition, which is accompanied by the formation of bismuth oxo-sulfates. According to X-ray diffraction data, the composition of the resulting phases is Bi28O32(SO4)10 and Bi34.7O100S16. Further heating to 380 °C leads to the decomposition of bismuth oxo-sulfates, resulting in the formation of the stable monoclinic modification of bismuth oxide, α-Bi2O3.