Impulse-optimal controlling moment of solid body spatial turning

Kiev Construction Engineering Institute. Translated from Prikladnaya Mekhanika, Vol. 24, No. 5, pp. 99–104, May, 1988.     

Electrochemical Production and Examination of Redox Conversions of 2,4-Diphenyl-6H-cyclopenta[b]thiopyran and 2,4-Diphenylcyclopenta[b]thiopyrilium Perchlorate

The mechanism governing the formation of 2,4-diphenyl-6H-cyclopenta[b]thiopyran and corresponding thiopyrilium perchlorate from 1,3-diphenyl-3-(2-oxocyclopentyl)-1-propanon in conditions of oxidative activation of hydrogen sulfide is considered. The process of oxidation of 2,4-diphenyl-6H-cyclopenta[b]thiopyran in a nonaqueous environment is shown to proceed stepwise through the intermediate formation of a radical cation, radical, and anhydrobase, to aromatic system 2,4-diphenylcyclopentadieno[b]thiopyranilidene. A similar product is obtained when oxidizing the 2,4-diphenylcyclopenta[b]thiopyrilium cation. Reduction of thiopyrilium perchlorate was observed to lead to the formation of a 2,4-diphenylcyclopenta[b]thiopyranyl radical, which is confirmed by an ESR method. The mechanism of redox conversions of thiopyran and thiopyrilium salt is substantiated by a quantum-chemical calculation.     

The radical cation of hydrogen sulfide and related organic reactions

The electrochemical and chemical oxidation (by hinderedo-benzoquinones or NOClO₄) of H₂S in nonaqueous solutions (MeCN) proceeds with the donation of one electron. The formation of the unstable radical cation of hydrogen sulfide was detected by cyclic voltammetry. The radical cation decomposes to form H⁺ and the HS^. radical. The generation of the hydrogen sulfide radical cation was confirmed by ESR spectroscopy in a frozen Freon matrix. The possibility of using the hydrogen sulfide radical cation in the synthesis of organosulfur compounds under mild conditions was studied. The concept of the work was proposed by Prof. O. Yu. Okhlobystin. The first electrochemical experiments were performed when he was alive. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1182–1188, July, 2000.