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The review surveys the data on the synthesis of organosulfur, selenium, and tellurium compounds in basic reducing systems. Good prospects of the hydrazine hydrate-alkali system are demonstrated.

Thiylation of polyhaloalkanes and Paraform with elemental sulfur activated in hydrazine hydrate3organic amine systems is performed. Monoethanolamine, triethanolamine, and triethylamine were used as amines. The reactions gave thiocols of various structures. The products were characterized by elemental analysis and IR spectroscopy. Reductive cleavage of the synthesized thiocols was performed to obtain di-and polythiols.Previously we showed that sulfur is easily activated in hydrazine hydrate3alkali (NaOH, KOH) systems to form polydisulfide anions, which allowed such systems to be used for fast and complete dissolution of sulfur [1,2]. We also found that elemental sulfur is equally effectively activated in hydrazine hydrate3 organic amine systems. As the organic amines we tried primary, secondary, and tertiary amines, such as monoethanolamine, morpholine, triethylamine, triethanolamine, as well as pure hydrazine hydrate [3].Sulfur reacts with hydrazine hydrate (in the absence of bases) with heat release and vigorous evolution of hydrogen sulfide and ammonia, which condense at the outlet of the reactor as ammonium hydrosulfide. The reaction of sulfur with hydrazine hydrate3 alkali or hydrazine hydrate3amine systems begins at room temperature and occurs with warming-up of reaction mixture to 60365oC.The quantity of dissolved sulfur depends on the nature of the amine and the concentration of the latter in hydrazine hydrate, and reaches 70031300 g per 1 l of hydrazine hydrate. As the mole fraction of the amine increases from 5 to 50%, the maximum quantity of dissolved sulfur increases by a factor of about 1.5; therewith, primary amines are more active than secondary, and tertiary amines are the least active. The best results were obtained with hydrazine hydrate3alkali and hydrazine hydrate3monoethanolamine systems [4].We have thoroughly studied thiylation of polyelectrophilic reagent in solutions of sulfur in hydrazine hydrate3alkali systems and developed in the course of this research new synthetic approaches to thiocols of various structures [5]. However, alkalis are hard bases and may induce dehydrohalogenation of alkyl halides; at high concentrations, alkalis can cause corrosion of the reactor material. Therefore, we considered it promising to replace alkalis with amines which are free of the above disadvantages and studied sulfur reactions with polyelectrophilic reagents in hydrazine hydrate3amine systems. As the polyelectrophiles we used dichloromethane, 1,2-dichloroethane, 1-bromo-3-chloropropane, 1,2,3-trichloropropane, b,b`-dichloroethyl ether (Chlorex), and Paraform. We also studied the behavior of mixtures of organochlorine compounds: a fraction containing 78% of 1,2-and 1,3-dichloropropanes and a fraction containing 76% of 1,2,3-trichloropropane. These fractions are epichlorohydrin production wastes whose utilization is an urgent ecological problem [6]. As the amine in most experiments we used monoethanolamine. In addition, for the sake of comparison, the hydrazine hydrate3tri-ethanolamine and hydrazine hydr...