Dimethyl sulphoxide anion

Corey and Chaykovsky were the first to investigate the reaction of dimethyl sulphoxide anion (dimsyl anion) with aldehydes and ketones400,401. They found that the reaction with non-enolizable carbonyl compounds results in the formation of /1-hydroxyalkyl sulphoxides in good yields (e.g. Ph2CO—86%, PhCHO—50%). However, with enolizable carbonyl compounds, particularly with cycloalkanones, poor yields of hydroxyalkyl products are observed (e.g. camphor—28%, cyclohexanone—17%, but... 

Dihydrodithiin sulphoxides, synthesis of 243 Dihydrothiophene dioxides, reactions of 653 /(,/( -Dihydroxyketones 619 Dimerization, photochemical 877, 884 Dimethyl sulphoxide anion of - see Dimsyl anion hydrogen bonding with alcohols and phenols 546-552 oxidation of 981, 988 photolysis of 873, 874, 988 radiolysis of 890-909, 1054, 1055 self-association of 544-546 Dimsyl anion... 

Anions of hydroperoxides may be used to successfully obtain sulphones by the oxidation of sulphoxides in non-aqueous media, without the use of transition metal catalysts. This is in contrast to oxidations with peracids where aqueous media are invariably used. Thus, dimethyl sulphoxide was oxidized by the anion of cumene hydroperoxide in ethanol or benzene solution at room temperature in 90% yield66. The yield is very much dependent on the base used and decreases along the series ... 

Bordwell (Bordwell and Bausch, 1986) has developed a method to determine C—H BDEs from a combination of p ha values and oxidation potentials (E ) of the corresponding anions in dimethyl sulphoxide solution. These acidity-oxidation potentials (AOP) are taken as measures for BDEs and are related to the stabilization of the radicals formed. This procedure has been recently applied to the subject of captodative stabilization (Bord-well and Lynch, 1989). Values of ABZ) relative to the C—H BDE in methane are calculated according to (13). These values are set equal to the... 

Thus, Table 1 reports chemical shift changes found by the addition of anion salts to calix[4]pyrrole and its derivatives relative to those for the free ligand in acetonitrile-d3 and dimethyl sulphoxide-d6 at 298 K. These data reveal that the... 

H NMR data in dimethyl sulphoxide-d6 are also shown in Table 1. For the interaction of 1 and 2 with the halide ions, A values in this solvent relative to acetonitrile-d3 reflect the medium effect on the complexation process. The data reveal that in moving from acetonitrile-d3 to dimethyl sulphoxide-d6, there is a substantial decrease in the strength of complexation of these ligands with these anions, although the selectivity trend remains unaltered. 

Table 2. Thermodynamic parameters of complexation of calixpyrrole receptors with halides and dihydrogen phosphate anions (tetra-n-butylammonium as counterion) in acetonitrile, dichloromethane, A/,A/-dimethylformamide, dimethyl sulphoxide and propylene carbonate... 

Table 3. Selectivity factor SF-/x2 of calix[4]pyrrole ligands for fluoride anion relative to other anions (X2 = Cl-, Br , I- and H2PO4) in acetonitrile (MeCN), di-chloromethane (DCM), A/,A/-dimethylformamide (DMF), dimethyl sulphoxide (DMSO) and propylene carbonate (PC)...

Thus, fluoride and calixpyrrole receptors (1, 16, and 18) are more stable in acetonitrile than in dichloromethane (Table 4). The stability of the fluoride anion and 2 is greater in acetonitrile than in dimethyl sulphoxide and propylene carbonate by factors of 1349 and 8, respectively. The same analysis carried out for fluoride anion and receptors 1, 2 and 8-atx.pp shows that the stability of this anion and these receptors is greater in A/,A/-dimethylformamide than in acetonitrile (Table 4). 

Inspection of Table 4 reveals that the electrochemical processes limiting the use of a particular combination involve either solvent or supporting electrolyte. In, e.g., acetonitrile (nos. 10-19) the anodic limit is dependent on the nature of the anion and the cathodic one on the nature of the cation. On the other hand, in a solvent like dimethyl sulphoxide the anodic limit is due to oxidation of solvent for anions which are difficult to oxidize (nos. 25, 26 cf. also Table 5) and of anions in cases of easily oxidizable ones, whereas the... 

Effect of Added Dimethyl Sulphoxide on the Rate Coefficients, k2, for the Reaction of Benzyl Chloride with the 9-Cyanofluorenyl Anion at 35 7°... 

A recent study of the interaction of superoxide anion with Fe(II) porphyrins in dimethyl sulphoxide or acetonitrile has suggested the formation of an complex (por-phyrin)Fe02, which is formulated on the basis of infra-red, U.V.-visible, n.m.r., and E.P.R. spectroscopic measurements as (porphyrin)-Fe (high spin)-02 . The E.P.R. spectrum differs from that of other high spin ferric porphyrin complexes but is... 

A recent modification [la] uses potassium tert-butoxide in anhydrous dimethyl sulphoxide, when reaction is rapid even at room temperature. The enhanced rate is attributed to the high reactivity of anions in this solvent (c/. p. 45). The reaction is usually formulated as a prototropic rearrangement of the hydrazone to give a diimide (i), followed by fragmentation of the diimide anion (2) to give a nitrogen molecule and the carbanion (3) [2], Rapid protonation then affords the reduced product. A recent study [3] oi solvent effects on the reduction... 

Enolate anions from ketones, and carbanions from other compoimds containing activated hydrogen such as dimethyl sulphoxide and fluorene, can also donate one electron to suitable acceptors (e.g., nitrobenzene and phenylglyoxal) (Russell and Janzen, 1962 Russell et al., 1962 Russell et al., 1966a). One example is the generation of the p-nitrotoluene radical-anion fromp-nitrotoluene in base the formation... 

The ease of loss of the substituent decreases in the order, o-, m-, p-1 > o-Br >p-Br >o-Cl>m-Br >m-, p-Cl, indicating that steric effects are important. The authors of this Review have observed that the reduction of ethyl o-nitrophenylacetate by electron transfer in a basic solution of dimethyl sulphoxide gives rise to the nitrobenzene radical-anion it seems probable that in this case the enolate anion, CHg.COaEt, is the leaving group. In a related reaction, Rieger et al. (1963) observed that p-cyanofluorobenzene, when reduced electrochemically, gives the radical-anion of 4,4 -dicyanobiphenyl, probably as follows ... 

A determination of the stability constants of aquo-complexes of Eu " in acetone showed that as the concentration of water in the solution of europium nitrate in acetone was increased, the first co-ordination sphere of europium(iii) became occupied by three water molecules which replaced three acetone molecules, and only then did the replacement of NO3 anions by water occur. An n.m.r. study of the hydration of lutetium(iii) nitrate in aqueous acetone showed the co-ordination number of lutetium to tend to six with increasing water concentration. The coexistence of several aquo(methyl sulphoxide)lutetium(iii) complexes were identified in the study of the complex formation between lutetium and dimethyl sulphoxide in acetone. 

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