Sulphoxides reactions with magnesium

DIMETHYL SULPHOXIDE (67-68-5) Forms explosive mixture with air (flash point 203°F/95°C oc). Violent or explosive reaction with oxidizers, acryl halides, aryl halides and related compounds, p-bromobenzoyl acetanilide, boron compounds, iodine pentafluoride, magnesium perchlorate, methyl bromide, perchloric acid, periodic acid, silver fluoride, sodium hydride, potassium permanganate. Forms powerfully explosive mixtures with metal salts of oxoacids. 

Optically active sulphoxides 311 and 312 have been prepared stereospecifically either by hydrolysis of the optically active sulphonium salt 313 or by the reaction of p-tolyl magnesium bromide with optically active sulphinate 314, respectively377 (equations 167 and 168). 

The stereospecific conversion of menthyl arenesulphinates into chiral aryl methyl sulphoxides may also be achieved by means of methyllithium . The reaction of methyllithium with diastereoisomerically or enantiomerically pure arenesulph-inamides 283 was found to give optically active aryl methyl sulphoxides 284 (equation 156). The preparation of optically active sulphoxides 285 and 286, which are chiral by virtue of isotopic substitution (H - D and - respectively), involves the reaction of the appropriate non-labelled menthyl sulphinates with fully deuteriated methyl magnesium iodide (equation 157) and with benzylmagnesium chloride prepared from benzyl chloride labelled with carbon (equation 158). 

Hexanedinitrile (adiponitrile). Use 150 ml of dry dimethyl sulphoxide, 21.2 g (0.17mol) of 1,4-dichlorobutane (Expt 5.52) and 20g (0.41 mol) of dried sodium cyanide. Maintain the reaction temperature at 90 °C for a further 15 minutes after the initial exothermic reaction has subsided. Add 150 ml of dichloromethane to the cooled reaction mixture and pour into an excess of saturated sodium chloride solution in a separatory funnel. Add just sufficient water to dissolve precipitated salts and separate the dichloromethane layer. Extract the acqueous layer once with dichloromethane, wash the combined extracts twice with salt solution, dry over magnesium sulphate and remove the solvent using a rotary evaporator. Fractionally distil the residue under reduced pressure and collect the adiponitrile as a fraction of b.p. 140-141 °C/ 1.5mmHg. The yield is 14.6g (81%). Some dimethyl sulphoxide (b.p. 40-42°C/1.5mmHg) may be obtained as a forerun. 

Stir 2.35 g (0.011 mol) of sodium metaperiodate (Section 4.2.55, p. 454) in 45 ml of a 1 1 mixture of water and methanol held at 0°C. Add portionwise 2.14 g (0.01 mol) of dibenzyl sulphide (Expt 5.204) and continue to stir the mixture at 0 °C for several hours, preferably overnight. Extract the reaction mixture (which contains precipitated sodium iodate) with three 20 ml portions of chloroform. Dry the combined chloroform extracts over magnesium sulphate and remove the solvent on a rotary evaporator. Recrystallise the product from ethanol. The yield of dibenzyl sulphoxide is 2.2 g (96%), m.p. 135 °C. 

The synthesis of the 3- and 4- pyridyl Grignard reagents (120) and (121) has been achieved by reaction of the corresponding phenyl pyridyl sulphoxide with phenyl magnesium bromide (Scheme 34). The pyridyl Grignards were trapped with aldehydes and ketones, and the... 

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