Polysulfanes synthesis

Soluble low-valent metal alkoxides can also be synthesized by replacing small alkoxy group OR by bulky polydentate ligands such as 2-methoxyethanol CH3OC2H4OH. This solvent is currently used to prevent polymerization and get soluble molecular precursors with low-valent metal cations such as Cu + in the sol-gel synthesis of advanced ceramics such as high Tc superconductors YBa2Cu307 j (see Sulfur Organic Polysulfanes) ... 

In general, the sulfanes have a less well-developed chemistry, partly because of the difficulty in isolating them pure, although they have been used for the synthesis of some organosulfur compounds see Sulfur Organic Polysulfanes). 

The condensation of thiols or monoorganylsulfanes with sulfenyl chlorides, usually carried out in dry ether at 20 °C, allows the synthesis of symmetrically or unsymmetrically substituted polysulfanes. R and R may be alkyl, aryl, or acyl groups " yields can be as high as 90%. 

The use of iV,iV -dibenzimidazolyl sulfide for the synthesis of cyclic polysulfanes by reaction with dithiols has been explored. In many cases, oligomers or low-molecular mass polymers are formed, however, Q ,Q -dimercaptoxylene yields the benzotrithiepin shown in equation (113) when stirred at 20 °C with the imidazolyl sulfide in benzene. ... 

J. Albertsen, Synthesis and characteristics of new chalcogen-rich heterocycles with organoelement compounds of the 4th main group and purification of bisorganic polysulfanes using titanocene chalcogenide chelate complexes. Doctoral Dissertation, Technical University of Berlin, 1993. 

Preparation of S12 from S2CI2 and a polysulfane mixture H2S sulfanes H2S and dichlorosulfanes S Cl2 react with each other with elimination of HCl forming new S-S bonds. Since piue sulfanes with more than two sulfur atoms are difficult to prepare, this synthesis uses a mixture of sulfanes, called crude sulfane oil , which can easily be prepared from aqueous sodium polysulfide and concentrated hydrochloric acid at 0 °C [39, 40] ... 

Polysulfanes are compounds of the general type H2S, where x>2 (see structure 15.6). Sulfur dissolves in aqueous solutions of group 1 or 2 metal sulfides (e.g. Na2S) to yield polysulfide salts, (e.g. Na2S, ). Acidification of such solutions gives a mixture of polysulfanes as a yellow oil, which can be fractionally distilled to yield H2S c (x = 2-6). An alternative method of synthesis, particularly useful for polysulfanes with X > 6, is by condensation reaction 15.40. 

Polysulfide ions [8 ] are not prepared by deprotonation of the corresponding polysulfanes. Instead, methods of synthesis include reactions 15.18 and 15.41, and that of H2S with S suspended in NH4OH solution which yields a mixture of [NH4]2[S4] and [NH4]2[S5]. 

Although Se and Te analogues of polysulfanes do not extend beyond the poorly characterized H2Se2 and H2Te2, the chemistries of polyselenides, polytellurides and their metal complexes are well established. Equations 16.44—16.47 illustrate preparations of salts of [Se ] and [Te ] see Section 11.8 for details of crown ethers and cryptands. Solvothermal conditions may also be used for the synthesis of [Se ] and [Te ] anions. For example, when CS2CO3 and Se react in superheated MeOH solution, the CS2CO3 facilitates the disproportionation of Se to and 0x0-... 

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