Preparation dimsyl sodium

A preparation of dimsyl sodium from sodium and DMSO, on 14 litre scale, overheated, then exploded causing two fatalities. It has not proved possible to duplicate the runaway. 

A solution of NaGaCH in DMSO may be prepared by reacting acetylene with dimsyl sodium (prepared from NaH and DMSO) in DMSO [39], other acetylenes can in principle be metallated in a similar way. The kinetic stability of NaC CCHjR in DMSO is limited, however. At somewhat elevated temperatures a slow isomerization to CHjCsCR occurs, whereby DMSO acts as the proton source [37]. 

Immonium salts can be used in the preparation of aporphines via benzyne intermediates. Treatment of salt 26 with dimsyl sodium in DM SO provided a 257o yield of dehydrodomesticine. ... 

Methylsulfinyl carbanion (dimsyl ion) is prepared from 0.10 mole of sodium hydride in 50 ml of dimethyl sulfoxide under a nitrogen atmosphere as described in Chapter 10, Section III. The solution is diluted by the addition of 50 ml of dry THF and a small amount (1-10 mg) of triphenylmethane is added to act as an indicator. (The red color produced by triphenylmethyl carbanion is discharged when the dimsylsodium is consumed.) Acetylene (purified as described in Chapter 14, Section I) is introduced into the system with stirring through a gas inlet tube until the formation of sodium acetylide is complete, as indicated by disappearance of the red color. The gas inlet tube is replaced by a dropping funnel and a solution of 0.10 mole of the substrate in 20 ml of dry THF is added with stirring at room temperature over a period of about 1 hour. In the case of ethynylation of carbonyl compounds (given below), the solution is then cautiously treated with 6 g (0.11 mole) of ammonium chloride. The reaction mixture is then diluted with 500 ml of water, and the aqueous solution is extracted three times with 150-ml portions of ether. The ether solution is dried (sodium sulfate), the ether is removed (rotary evaporator), and the residue is fractionally distilled under reduced pressure to yield the ethynyl alcohol. 

Besides solvation, a solvent can also participate in entrainment of ion-radical transformations. The reaction between tertiary aliphatic nitro compounds and the sodium derivative of nitromethane, NaCH2N02, is an example (Kornblum and Erickson 1981). To prepare NaCHjNOj, nitromethane is treated with sodium hydride. Then a tertiary aliphatic nitro compound is introduced into the solution formed. Several organic solvents were probed and CHjSOjCHj (DMSO) turned out to be the most effective. Kornblum and Erickson (1981) attributed this result to the formation of small amounts of NaCH2SOCH3 (sodium dimsyl) that was produced from DMSO as a result of its reaction with sodium hydride. Sodium dimsyl acts as a powerful one-electron reducer that induces the following chain anion-radical process ... 

Step 1 The diol E must be protected (acetal, in this example) for the Wittig reaction to proceed. The Wittig reagent is prepared from the phosphonium iodide using sodium dimsylate, NaCH2S(0)CH3. 

Table 4.4 lists some common bases used in organic chemistry. Although butyl-lithium behaves as a very strong base in many reactions, it also exhibits other chemistry, so it is usually used to prepare other strong bases listed in the table. Lithium diisopropylamide, sodium amide, dimsyl anion, and sodium hydride are often used to prepare the conjugate bases of aldehydes, ketones, and esters for use in reactions. Potassium fert-butoxide is employed when a base somewhat stronger than the conjugate bases of most alcohols is needed. 

Dimsyl anion was prepared from 10.2 g. (0.24 mole) (Note 10 of 66.8% sodium hydride, which was washed with pentane and vacuum dried, and 200 ml. of anhydrous dimethyl sulfoxide. The mixture was heated at 65-70° for about 50 minutes, until hydrogen evolution ceased. CaiUion This mixture should not he heated above 80°, because of the possibility of explosive decomposition. 

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