O-S bonds

The broken bonds (boldface = dissociated atom or group) BDEs (boldface = recommended data reference in parentheses) Methods (reference in  

Phenyl phenylsulfonyl sulfate 0=S(0)(Ph)(PhS02) 122 510.4 Derived 1978BEN 

Methylthio peroxy OO-SCH3 11 46 Pulse laser photolysis 1992TUR/BAR 

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SuIfona.tlon, Sulfonation is a common reaction with dialkyl sulfates, either by slow decomposition on heating with the release of SO or by attack at the sulfur end of the O—S bond (63). Reaction products are usually the dimethyl ether, methanol, sulfonic acid, and methyl sulfonates, corresponding to both routes. Reactive aromatics are commonly those with higher reactivity to electrophilic substitution at temperatures > 100° C. Tn phenylamine, diphenylmethylamine, anisole, and diphenyl ether exhibit ring sulfonation at 150—160°C, 140°C, 155—160°C, and 180—190°C, respectively, but diphenyl ketone and benzyl methyl ether do not react up to 190°C. Diphenyl amine methylates and then sulfonates. Catalysis of sulfonation of anthraquinone by dimethyl sulfate occurs with thaHium(III) oxide or mercury(II) oxide at 170°C. Alkyl interchange also gives sulfation. 

Other examples of the successful displacement of tosylates are the preparation of 31 -, 16a-,16j - and27- labeled steroids. This displacement reaction fails, however, with certain C-18 and C-19 alcohol derivatives which give mainly O—S instead of C—O bond cleavage. Unsatisfactory results were also obtained with sterically hindered tosylate esters at C-11, C-12 and C-20, which give considerable amounts of olefinic products in addition to O—S bond cleavage. ... 

Correa and Waters50 also proposed a mechanistic scheme where the key step of the overall reaction involves the recombination of sulfonyl radicals to form an intermediate with an O—S bond, the decomposition of which yields a sulfinyl radical (ArSO ) and an oxygen-centered radical ArS020 Later this suggestion was further strengthened on the basis of ESR studies51 and thanks to the elucidation of the electronic structure of sulfonyl radicals. However, it seems to the author that the available literature data point to an overall mechanism for equation 17 more complex that the one suggested50 (cf., for... 

As esters of sulfuric acid, the hydrophilic group of alcohol sulfates and alcohol ether sulfates is the sulfate ion, which is linked to the hydrophobic tail through a C-O-S bond. This bond gives the molecule a relative instability as this linkage is prone to hydrolysis in acidic media. This establishes a basic difference from other key anionic surfactants such as alkyl and alkylbenzene-sulfonates, which have a C-S bond, completely stable in all normal conditions of use. The chemical structure of these sulfate molecules partially limits their conditions of use and their application areas but nevertheless they are found undoubtedly in the widest range of application types among anionic surfactants. 

Basically, the production of half esters of sulfuric acid involves the introduction of the -S03H group by replacement of the O-H bond with an O-S bond, according to the general reaction [Eq. (1)] ... 

Alcohol sulfates are half esters of sulfuric acid and contain a C-O-S bond in the molecule. This bond is only relatively stable in water and can hydrolyze, mainly under acidic conditions. The hydrolysis is favored by temperature as was proven in the study of Maurer et al. with octadecyl sulfuric acid [57]. They found that a 0.05 M solution in distilled water at 100°C hydrolyzed to 50% in less than 30 min, whereas at 60°C the hydrolysis was 10% after 3 h and 16% after 7 h. 

Heterocyclic compounds Heterocyclic C=N systems, such as benzoxazole and related thia-zoles, react with complex 2b to yield the ring-expanded adducts, e. g. complexes 90 and 91, by formal C-X (X = O, S) bond cleavage and coupling with the alkyne. In the case of benzisoxazole, the alkyne is not coupled but eliminated, and ring-enlargement of the ben-zisoxazole leads to the N-bridged dimer 92 [48]. 

Other useful correlations exists between SEj, and the ability of the metal to backbond to the nitrosyl as reflected in the Tc-NX (X = O, S) bond distance (see Fig. 5 [96] and the NO stretching frequency in Ru" amine complexes (Fig. 6). As EEl increases, the ability of the metal to backbond decreases and the coordinated NO becomes more like NO". Such correlations should prove useful not only for predicting the ability of metallonitrosyls to release NO, but also the tendency of the nitrosyl to undergo nucleophilic attack. 

X = O, S Bonds in heavy print are of highest order N, R, E show sites of reaction with nucleophiles, radicals... 

Reductive cleavage of O—O, O—N, O—S and S—N bonds is also possible. For example, the peroxide bond in the dioxazine (152) is cleaved by treatment with zinc in ethanolic potassium hydroxide, or by catalytic hydrogenolysis (64JOC291). Zinc in acid cleaves the S—N bond in (153) (68LA(715)223). Concomitant reduction of the sulfoxide also occurs, so that subsequent recyclization and aromatization with loss of ammonia leads to the ben-zothiazole (154). The O—S bond in (3) is reductively cleaved by sodium borohydride to give the alcohol (155) (77TL4245). 

In case (a), labelled secondary alkyl benzenesulfonates (alkyl = 2-adamantyl, 2-propyl, cyclopentyl, etc.) with 18-28% of lsO in the sulfonyl group were partially solvolysed in a range of solvents (SOH), and recovered unreacted alkyl benzenesulfonates were then subject to reductive cleavage of the O—S bond of the sulfonate ester [39]. For water as solvent, the... 

Tetracyanoethylene oxide (TCNEO) not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides with generation of two molecules of carbonyl cyanide (17). The reduction mechanism involves a zwitterion intermediate (15) that produces sulfide and two molecules of (17) by simultaneous cleavage of the C—C and O—S bonds. A mechanism (Scheme 14) that involves a zwitterion (16) as a common intermediate is proposed for the formation of ylide and sulfoxide.311... 

This difference is probably due to the fact that no O-S bonding can exist in 108, whereas it can for 110. Another point is that 108 is more polar than 109, probably because a zwitterion formula is more favored in 108 than in 109, the energy liberated by the transformation cyclo-hexadienone-phenol being larger than the energy liberated by the transformation anthrone-anthranol. 

Quantum-field chemistry concept [5-9] treat transport of molecules inside the condensed phases of water as conduction through emptiness of two kinds (see Fig. 2). It is intramolecular emptiness restricted by grid intramolecular hydrogen (O-H—O) a-bonds inside supermolecule and, secondly, it is supramolecular emptiness lying between supermolecules confined by network of supramolecular hydrogen (O-H... O) (S-bonds and electrostatic y-bonds. 

In protophilic media, amides exist as monomeric H-complexes with a two-centered H-bond and 1 2 H-complexes of the open-chair dimer with a bifurcated (three-centered) hydrogen bond. The formation of a strong bifurcated H-bond weakens the bridging N-H...O=S bond. 

The catalytic activity of these materials depends upon the sulfur content. When the sulfur loading in the catalyst increases, structures with S-O-S bonds similar to those in pyrosulfuric or higher polysulfuric acids may exist on the surface of the catalysts. 

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