Dimethyl sulfoxide basic

A number of chemiluminescent reactions may proceed through unstable dioxetane intermediates (12,43). For example, the classical chemiluminescent reactions of lophine [484-47-9] (18), lucigenin [2315-97-7] (20), and transannular peroxide decomposition. Classical chemiluminescence from lophine (18), where R = CgH, is derived from its reaction with oxygen in aqueous alkaline dimethyl sulfoxide or by reaction with hydrogen peroxide and a cooxidant such as sodium hypochlorite or potassium ferricyanide (44). The hydroperoxide (19) has been isolated and independentiy emits light in basic ethanol (45). 

Vinyl chloride reacts with sulfides, thiols, alcohols, and oximes in basic media. Reaction with hydrated sodium sulfide [1313-82-2] in a mixture of dimethyl sulfoxide [67-68-5] (DMSO) and potassium hydroxide [1310-58-3], KOH, yields divinyl sulfide [627-51-0] and sulfur-containing heterocycles (27). Various vinyl sulfides can be obtained by reacting vinyl chloride with thiols in the presence of base (28). Vinyl ethers are produced in similar fashion, from the reaction of vinyl chloride with alcohols in the presence of a strong base (29,30). A variety of pyrroles and indoles have also been prepared by reacting vinyl chloride with different ketoximes or oximes in a mixture of DMSO and KOH (31). 

Dried with Linde type 5A molecular sieves or Na2S04 and fractionally distd at reduced pressure. Alternatively, it was refluxed with, and distd from, BaO. Also purified by fractional crystn from the melt and distd from zinc dust. Converted to its phosphate (m 135°) or picrate (m 223°), which were purified by crystn and the free base recovered and distd. [Packer, Vaughn and Wong J Am Chem Soc 80 905 1958.] The procedure for purifying via the picrate comprises the addition of quinoline to picric acid dissolved in the minimum volume of 95% EtOH to yield yellow crystals which are washed with EtOH and air dried before recrystn from acetonitrile. The crystals are dissolved in dimethyl sulfoxide (previously dried over 4A molecular sieves) and passed through a basic alumina column, on which picric acid is adsorbed. The free base in the effluent is extracted with n-pentane and distd under vacuum. Traces of solvent are removed by vapour phase chromatography. [Mooman and Anton J Phys Chem 80 2243 1976.]... 

Phenol Acidic Dimethyl sulfoxide Bifunctional (leans basic)... 

VV -values for bromoform and pyrrole, acidic liquids, against poly(vinyl chloride), an acidic polymer, and dimethyl sulfoxide, a predominantly basic liquid, against polyfmethyl methacrylate), a basic polymer, but large values for the acidic liquids against PMMA and the basic liquid against PVC. 2-Iodoethanol, a bifunctional liquid, showed appreciable -values with both polymers. Despite these results in line with expectations, other results based on wettability measurements are not so clear-cut. For example, Vrbanac [94] found significant apparent acid-base interactions of various aromatic liquids against poly(ethylene), presumably a neutral substrate. 

On treatment with a strong base such as sodium hydride or sodium amide, dimethyl sulfoxide yields a proton to form the methylsulfinyl carbanion (dimsyl ion), a strongly basic reagent. Reaction of dimsyl ion with triphenylalkylphosphonium halides provides a convenient route to ylides (see Chapter 11, Section III), and with triphenylmethane the reagent affords a high concentration of triphenylmethyl carbanion. Of immediate interest, however, is the nucleophilic reaction of dimsyl ion with aldehydes, ketones, and particularly esters (//). The reaction of dimsyl ion with nonenolizable ketones and... 

G(CH3S02 ) is the yield of CH3S02 radicals, AOH- and AH+ are the decrease and increase of the conductivity in basic and acidic solutions respectively, l is the specific conductivity and l(Haq+) and i(OH ) are known to be 315 and 178 fl-1 cm2, respectively. For dimethyl sulfoxide G(RS02 ) was found to be 5.46 comparing this to G(OH) = 6.0 for N20 -saturated aqueous solution leads to the conclusion that 91% of the OH radicals were added to the sulfoxide bond. There is no proof for the fate of the other 9% it is probable that they abstract hydrogen atoms from the methyl groups. 

Bordwell and coworkers63 87 have studied the reaction of 9-fluorenyl carbanions (9-RFP) with a series of electron acceptors and in particular a-halosulfones and sulfoxides, in dimethyl sulfoxide solution. The overall reaction is characterized by the formation of the 9,9 -bis-fluorenyl derivative and the reduction of the halogenated acceptor. A family of 9-substituted fluorenyl carbanions covering a basicity range of 9.1 pKa units was used and... 

Allyl anion is too strongly basic to be studied as the free anion in solution. Bordwell developed an acidity scale based on equation 1 in dimethyl sulfoxide (DMSO) at 25 °C3 and applied the method to a number of more acidic substituted allylic systems. A summary of some results is shown in Table 10. DMSO is sufficiently polar that there is little ion... 

Aromatic nucleophilic radiofluorinations are usually performed in aprotic polar solvents, such as dimethyl sulfoxide (DMSO), sulfolane or dimethylacetamide, and often under basic conditions (because of the presence of Kryptofix-222 / potassium carbonate). Completion of the p F]fluoride incorporation often requires moderate to high temperatures (100-170 °C) for 10-30 min. Microwave technology can be a successful application here, resulting in improved yields and shorter reaction times [29,170-173],... 

Oxidation of diphenylmethane in basic solutions involves a process where rate is limited by and equal to the rate of ionization of diphenylmethane. The diphenylmethide ion is trapped by oxygen more readily than it is protonated in dimethyl sulfoxide-text-butyl alcohol (4 to 1) solutions. Fluorene oxidizes by a process involving rapid and reversible ionization in text-butyl alcohol solutions. However, in the presence of m-trifluoromethylnitrobenzene, which readily accepts one electron from the carbanion, the rate of oxygen absorption can approach the rate of ionization. 9-Fluorenol oxidizes in basic solution by a process that appears to involve dianion or carbanion formation. Benzhydrol under similar conditions oxidizes to benzophenone by a process not involving carbanion or dianion formation. 

TITTe have reported that the triphenylmethide ion in dimethyl sulfoxide (DMSO) solution reacts with oxygen at a rate approaching the diffusion-controlled limit (k > 109 liters/mole sec.) (16). The triphenylmethide ion is actually more reactive toward molecular oxygen than the triphenylmethyl radical. Because of the reactivity of the triphenylmethyl anion toward molecular oxygen, it is possible to measure the rate of ionization of triphenylmethane in basic solution by the rate of oxygenation. 

L = dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), and triphenylphos-phine oxide (OPPh3). The former illustrates how simple polyethers may stabilize the hydrated dioxomolybdenum(VI) bromide core. The others are representative examples of addition compounds with ligands that are able to displace water from the coordination sphere of molybdenum but at the same time are not sufficiently basic toward the proton to cause formation of hydrobromides and molybdates. 

Isatin, JV-methylisatin, and JV-hydroxyisatin can be reduced to semidiones by treatment with the enolate anion of propiophenone in dimethylsulfoxide.258 Nitroxides are prepared from iV-hydroxyisatin by treatment with lead dioxide in dioxan, while another nitroxide was formed spontaneously from iV-hydroxyisatin in basic dimethyl sulfoxide solution in the presence of oxygen.256... 

In this protocol additional steps are taken to eliminate starch from the isolated cell wall material to minimize erroneous estimations of glucose in later analytical procedures. In some plant material only small numbers of very tiny starch granules may be found after staining with iodine in potassium iodide (see Basic Protocol 1) and these may be deemed too few to warrant the drastic action necessary to remove the large amounts of starch found in cells of potatoes for example. If the starch granules are small in size (e.g., <10 pm), then they are likely pass though the 11 -pm nylon mesh and be lost from the cell wall material however, to remove large amounts of starch, additional treatments with dimethyl sulfoxide (DMSO) and/or a-amylase are required. 

There has been a review of die effects of high pressure on the substitution reactions of amines witii haloaromatic compounds, including polyhalobenzenes.17 Nucleophilic substiditions by amines often proceed readily hi dimethyl sulfoxide (DMSO). The pKa values, hi DMSO, have been reported for some ammonium ions derived from amines widely used as nucleophiles in 5nAt reactions.18 Correlations have been established19 between die oxidation potentials and the basicities of some arylamhie and diarylamine anions and die rate constants for dieir reactions with aiyl halides in DMSO. 

There have been two additional experiments which verified this basic picture of the nuclear hyperfine interaction in hemins. Johnson (78) increased the spin-lattice relaxation time by performing the Mossbauer experiment under field and temperature conditions which provide a large value of H/T. At 1.6 °K and in an applied field of 30 kG, a magnetic hyperfine interaction corresponding to that expected for high spin Fe(III) and for the g-values is measured experimentally. Recently, Lang et al. have found that a portion of hemin chloride dissolved in tetrahydro-furan at 1 mM concentration displays a hyperfine interaction at 4 °K in zero applied magnetic field. Their conclusion is that a portion of the hemin is present in a monomeric form in this solvent, a situation which is not apparent to any extent in water, acetic acid, chloroform, or dimethyl sulfoxide (77) at any concentrations used. 

---