Polysulfane oxide

The materials obtained by this idealized equation have also been termed polysulfuroxides in the older hterature. However, more recent results showed that they also contain hydrogen and therefore are probably polysulfane oxides of the types HS(S 0)xSH or HS(S 0)xOH [3, 88]. Due to the simultaneous thermal decomposition with formation of SO2 the sulfur content is higher than expected from Eq. (38) and from the general formula. All these compounds produce S2O on heating in a high vacuum which is a typical reaction for compounds containing oxidized sulfur chains or rings. 

The stereochemistry of organic sulfur compounds was reviewed very extensively by Laur in 1972 and that of organic polysulfides by Rahman et in 1970. Since those days, however, considerable progress has been made. The molecular and crystal-structures of more than 60 cyclic and acyclic polysulfanes of type R-S -R have been determined by X-ray diffraction on single crystals. In rare cases, electron diffraction of the vapor of R-S -R molecules has been used to determine the structure (see Diffiaction Methods in Inorganic Chemistry). In addition, the structures of several acyclic polysulfane oxides such as RS-SO-SR and RS02-S -S02R (n = 1, 2, 3), and of the trisulfane cation (MeS)3+, have been determined. 

Purification is by low-pressure distillation. Some physical properties are in Table 15.12. Polysulfanes are readily oxidized and all are thermodynamically unstable with respect to disproportionation ... 

A few mechanisms were postulated for this reaction (6). No matter what mechanism is considered, the oxidation of elemental sulfur or thiosulfate is accompanied by reductive cleavage of the sulfur-sulfur bridges. In the case of sulfur, the intermediate involved is a cyclic form of sulfur, probably Ss, although there is little difference observed for different allotrophic forms of sulfur such as rhombic, precipitated, and amphorous. These cyclic sulfides form the basis of polysulfanes and polythionates which could be metabolized readily by Thiobacilli (as shown in Figure 3). Actually, sulfur oxidation begins with its reduction, in which the gluathione-sulfhydryl groups located near the cell surface take part ... 

Since the chemistry of organic polysulfanes is closely related to their oxidized derivatives, Table 2 presents the well-characterized species with up to three sulfur atoms in the chain. The systematic nomenclature based on the lUPAC recommended name sulfanes is also given in Table 2. In addition, conventional names for some of these compounds are shown in brackets. 

Table 2 Nomenclature of polysulfanes and their oxidized derivatives (trivial names are given in parentheses) ...

Thiols are powerful reducing agents, which may be oxidized by O2, peroxides, halogens, sulfoxides, or metal ions in high oxidation states [FeCb, Pb(02CMe)4] usually disulfanes are formed in these reactions. Oxidation of thiols by sulfur(IV) or sulfur(Vl) compounds often results in mixtures of polysulfanes. 

Of the many reactions known for polysulfanes, only the following types will be dealt with since they are of general importance for inorganic and organic polysulfur compounds interconversion and sulfur transfer reactions, nucleophilic displacement reactions, and oxidation reactions with conservation of chain length. 

Oxidation of organic polysulfanes by an excess of peroxy acid results in disulfones (polysulfane tetroxides) (equation 153). Polysulfane 1,1-dioxides (monosulfones) may be prepared by reaction of monoorganylthiosulfates with sulfenyl chlorides (equation 156). ... 

Coordination OrganometalUc Chemistry Principles Electron Transfer Reactions Theory Macrocyclic Ligands Metal Ion Toxicity Oxides Solid-state Chemistry Polynuclear Organometallic Cluster Complexes Sulfur Organic Polysulfanes Thallium Organometallic Chemistry. 

A recent study on the reactivity of the parent benzo-l,2-dithiolan-3-one 1-oxide 79a (R = R = H) and o- and /i-substituted derivatives 79b-g with -propyl thiol in acetone/water mixture (7/3) was prompted (Table 5) by the observation that the DNA-cleaving activity and antitumor activity of leinamycin 5 depends, in part <2005JOC6968>, on initial thiol attack on its l,3-dioxo-l,2-dithiolane functionality. Experimental results have proved that the presence of chlorine as an electron acceptor in the /i ra-position relative to the sulfmyl sulfur S-1 of precursor 79e and ortho-substituents with lone electron pairs in the case of precursors 79b and 79d are responsible for increased product formation of polysulfanes 80 and 81. A rationale in terms of substituent effects, operating through-space and through-bond of the intermediates a and b, respectively, was suggested. In other words, the reaction is favored by ortho-substituents with lone pair electrons next to the dithiolanone-oxide (S-1) reaction center or a decrease of the electron density at the /i ra-position. 

Photoreaction 63 Photosynthesis 171 Plastic sulfur 43 Poly electrolytes 174 Polymer adsorption 174 -, preparation 87 -, rate of formation 90 -, structure 42 Polymerization theory 81 Polysulfanes 92-93 Polysulfide 176, 179, 183 -, oxidation 184... 

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