Sulfones sulfoxides

Formation of C-C Bonds by Addition to Olefinic Double Bonds Enimines, Nitroalkenes, 4,5-Dihydrooxazoles, a,/MJnsaturated Sulfones, Sulfoxides and Sulfoximines... 

Of the two classes, the sulfones have received more study, but there is enough information on the sulfoxides to provide a meaningful comparison between them. Such a comparison is made more complete by including the corresponding sulfides and indeed the sulfone/sulfoxide/sulfide structural variations will be one of the central considerations of our treatment. 

FIGURE 20. Sulfur bond lengths in analogous sulfones/ sulfoxides/sulfides with various ligands (cf. Reference 5). 

FIGURE 23. Representation of sulfones, sulfoxides and sulfides as AX4, AX3E, and AX2E2 systems. 

Syntheses of Sulfonates, Sulfinates, Sulfonamides, Sulfoxylates, Sulfones, Sulfoxides, Sulfites, Sulfates, and Sulfanes... 

In ODS, sulfur compounds present in fuels are oxidized to more polar sulfones / sulfoxides to facilitate their removal by solvent extraction or adsorption. Various oxidation systems have been reported in the literature for this transformation. Among these oxidants like hydrogen peroxide (H2O2) and carboxylic acid as catalyst3"5. For the chemical industry, it becomes more and more important to develop cleaner technologies. Solvent extraction processes are used to separate sulfones / sulfoxides from oxidized fuels. These processes required suitable and selective solvents for separation of oxidized sulfur compounds from petroleum feedstocks. 

Fig. 18a. The bond angles X-S-X in a series of sulfones, sulfoxides, and sulfldes ...

According to Marshall [23] and Beech [26], the oxidation of the thiophenol linker would increase the reaction rate. To study this effect, the linker in resin (35) was oxidized to sulfone/sulfoxide using mCPBA. Cleavage reaction of resin (35) -OX with n-butylamine went to completion in less than 4 min (Fig. 12.20), compared with 24 h needed for this resin under the same conditions without oxidation. The rate constant was determined to be 0.0179, which was a 580-fold increase compared with the unoxidized form. This result indicated that a linker oxidation was preferred for high yield when the products will not be affected by oxidation conditions. 

Plant. Oat plants were grown in two soils treated with [ Ciphorate. Most of the residues remained bound to the soil. Less than 2% of the applied [ Ciphorate was recovered from the oat leaves. The major residues in soil were phorate and the corresponding oxon, sulfone, oxon sulfone, sulfoxide, and oxon sulfoxide (Fuhremann and Lichtenstein, 1980). These compounds were also found in asparagus tissue and soil treated with the insecticide (Szeto and Brown, 1982). 

The established mechanism of sulfide photo-oxidation in solution invokes the novel formation of two intermediates a persulfoxide. A, and a hydroperoxy sulfonium ylide, B, (Fig. 13A) [25], In this mechanism the sulfide substrate intercepts the second intermediate, k o, and does not competitively inhibit the predominant sulfone forming pathway, kso2. As a consequence, the sulfone/sulfoxide ratio is independent of sulfide concentration. In contrast, the results in the zeolite are inconsistent with this mechanism but are consistent with the trapping of a single intermediate with both sulfide and adventitious sulfoxide (Fig. 13B). 

SULFONES, SULFOXIDES, SULFONIC ACIDS AND THEIR DERIVATIVES... 

Key H atoms not shown aromatic bonds Nitrogroups 0-N=0 Sulfones, sulfoxides,... 

The conjugate addition of heteronucleophiles to activated alkenes has been used very often in organic synthesis to prepare compounds with heteroatoms [3 to various activating functional groups, e.g. ketones, esters, nitriles, sulfones, sulfoxides and nitro groups. As in the Michael reaction, a catalytic amount of a weak base is usually used in these reactions (with amines as nucleophiles, no additional base is added). 

Corynebacterium equi IF0 3730 gave high enantioselectivity in the oxidation of aryl alkyl sulfides [106], The results listed in Scheme 6C, 11 arise from experiments with no formation of sulfone, which occurs quite easily in several cases. Thio ketals and thio acetals were oxidized into mono S-oxides by various fungal species with enantioselectivity up to 70% ee [107]. Corynebacterium equi was very successfully used in the oxidation of formaldehyde dithioacetals to mono S-oxide or sulfone-sulfoxide, depending on the substrates. Thus n-Bu-S-CH-S-n-Bu was transformed to n-Bu-S02-CH2-S(0)-n-Bu with more than 95% ee in 70% yield. 

Other classes of sulfur-bound CF3 groups include sulfones, sulfoxides, and sulfoximines, examples of which are given in Scheme 5.17. 

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