Dimethyl sulfone

Perfluorosulfonyl fluorides have also been prepared by dkect fluotination, although ki general yields are lower than preparation by ECF. Perfluoromethanesulfonyl fluoride has been produced ki 15% yield from dkect fluotination of dimethyl sulfone (16). Perfluoro-2-propanesulfonyl fluoride was prepared ki 29% yield from propanesulfonyl fluoride (17). Dkect fluotination of tetramethylene sulfone leads to the kitact perfluorkiated sulfone ki 28% yield and the ting-opened product (perfluorobutanesulfonyl fluoride) ki 10% yield (eq. 10) (17). 

Trifluorobenzene. This compound is formed ia low yield (13—24%) from l,2,3-trichloroben2ene or 2,3-difluorochloroben2ene and KF/CsF ia dimethyl sulfone (204). Likewise, low yields are reali2ed when the Bal2-Schiemann reaction is appHed to 2,3-difluoroaniline or... 

Thermal Stability. Dimethyl sulfoxide decomposes slowly at 189°C to a mixture of products that includes methanethiol, formaldehyde, water, bis(methylthio)methane, dimethyl disulfide, dimethyl sulfone, and dimethyl sulfide. The decomposition is accelerated by acids, glycols, or amides (30). This product mixture suggests a sequence in which DMSO initially undergoes a Pummerer reaction to give (methylthio)methano1, which is labile and reacts according to equations 1—3. Disproportionation (eq. 4) also occurs to a small extent ... 

Dimethyl sulfone [67-71-0] M 94.1, m 109 . Crystd from water. Dried over P2O5. 

The catalytic effect of aromatic nitro groups in the substrate and product or in an added inert nitro compoimd (e.g., w-dinitrobenzene in 18) has been observed in the reaction of 2,4-dinitrochlorobenzene with an amine in chloroform. Hydrogen bonding to benzil or to dimethyl sulfone and sulfoxide also provided catalysis. It is clear that the type of catalysis of proton transfer shown in structure 18 will be more effective when hydrogen bonding is to an azine-nitrogen. 

Data on entropies and heat capacities, which are available only for dimethyl sulfoxide and dimethyl sulfone, can be found elsewhere19. 

The geometric parameters of the three-membered ring sulfones and sulfoxides have been determined via X-ray diffraction techniques and gas-phase microwave spectroscopy. The accumulated data for some selected thiirane and thiirene oxides and dioxides (16-19) as well as for the corresponding thiirane (20) and the acyclic dimethyl sulfone (for the sake of comparison) are given in Table 3, together with the calculated values. 

As in the acyclic series, there is a lengthening of the sulfur-oxygen bond as the sulfur is oxidized from the sulfoxide to the sulfone in both the thiirane (i.e. 16a - 17a) and the thiirene (i.e. 18a - 19b) series. Unexpected, however, is the substantial decrease in the OSO angle of the sulfone group in thiirenes compared with that of the thiiranes (e.g. [Pg.387]

The NMR spectra of the corresponding dimethyl sulfide and dimethyl sulfone consist of two singlets at 1.27, 2.92 and 1.43, 3.80 ppm, respectively (in CDC13), most probably implying a rapid interconversion of puckered conformations66. 

When a mixture of p-anisaldehyde and dimethyl sulfone was treated with excess potassium t-butoxide in DMF at 60-65 °C, bis-unsaturated sulfone 277 was obtained. In the reaction at 50 °C using a small amount of base, the main product was a heterocyclic compound, i.e., 2,4-di-p-methoxyphenyl-l,4-oxathiane 4,4-dioxide 278358. 

The formation of dimethyl sulfide, dimethyl sulfone, and methane (by H-abstraction) observed in these photolyses is thus accounted for. Hydrogen abstraction by the methylsulfinyl radical affords methanesulfenic acid, CH3SOH, a very reactive molecule, which rapidly undergoes a series of secondary reactions to produce the methanesulfonic acid, methyl methanethiolsulfonate (CH3S02SCH3), and dimethyl disulfide which were also observed during these photolyses. 

Nelson54 studied the products of radiolysis of aqueous solution by variable-field CIDNP pulse radiolysis. On the basis of the chemical shifts the following products were identified methyl methanesulfinate, methanol, l,2-bis(methylsulfinylethane) [CH3S(0)CH2CH2S(0)CH3], dimethyl sulfone, dimethyl sulfide, methane and ethane. The high field polarization was used to study the mechanism of formation of polarized products. 

Although S02, RH and RR are the major products, they are not the only ones and for radiolysis of dimethyl sulfone Bowmer and O Donnell70 identified another twenty products. 

Ce4+ is a versatile one-electron oxidizing agent (E° = - 1.71 eV in HC10466 capable of oxidizing sulfoxides. Rao and coworkers66 have described the oxidation of dimethyl sulfoxide to dimethyl sulfone by Ce4+ cation in perchloric acid and proposed a SET mechanism. In the first step DMSO rapidly replaces a molecule of water in the coordination sphere of the metal (Ce v has a coordination number of 8). An intramolecular electron transfer leads to the production of a cation which is subsequently converted into sulfone by reaction with water. The formation of radicals was confirmed by polymerization of acrylonitrile added to the medium. We have written a plausible mechanism for the process (Scheme 8), but there is no compelling experimental data concerning the inner versus outer sphere character of the reaction between HzO and the radical cation of DMSO. 

Generally, higher catalyst concentration leads to side reactions. An efficient approach to minimize the side reactions is to use the minimum amounts of Friedel-Crafts catalyst (e.g., FeCl3, 0.1-4 wt%). The reaction can be performed either in bulk or in solution using, for example, nitrobenzene, dimethyl sulfone, or chlorinated biphenyls as the reaction media. 

Other carbanionic groups, such as acetylide ions, and ions derived from a-methylpyridines have also been used as nucleophiles. A particularly useful nucleophile is the methylsulfinyl carbanion (CH3SOCHJ), the conjugate base of DMSO, since the P-keto sulfoxide produced can easily be reduced to a methyl ketone (p. 549). The methylsulfonyl carbanion (CH3SO2CH2 ), the conjugate base of dimethyl sulfone, behaves similarly, and the product can be similarly reduced. Certain carboxylic esters, acyl halides, and DMF acylate 1,3-dithianes (see 10-10. )2008 Qxj(jatjye hydrolysis with NBS or NCS, a-keto aldehydes or a-... 

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