Sulfur dioxide oxidizing halides

Heating the adduct of ethylene oxide and sulfur dioxide with primary alcohols in the presence of alkali hydrides or a transition-metal halide yields dialkyl sulfites (107). Another method for the preparation of methyl alkyl sulfites consists of the reaction of diazomethane with alcoholic solutions of sulfur dioxide (108). 

Normally, the most practical vinyl substitutions are achieved by use of the oxidative additions of organic bromides, iodides, diazonium salts or triflates to palladium(0)-phosphine complexes in situ. The organic halide, diazonium salt or triflate, an alkene, a base to neutralize the acid formed and a catalytic amount of a palladium(II) salt, usually in conjunction with a triarylphosphine, are the usual reactants at about 25-100 C. This method is useful for reactions of aryl, heterocyclic and vinyl derviatives. Acid chlorides also react, usually yielding decarbonylated products, although there are a few exceptions. Likewise, arylsulfonyl chlorides lose sulfur dioxide and form arylated alkenes. Aryl chlorides have been reacted successfully in a few instances but only with the most reactive alkenes and usually under more vigorous conditions. Benzyl iodide, bromide and chloride will benzylate alkenes but other alkyl halides generally do not alkylate alkenes by this procedure. 

The substituted tricarbonyl complexes react in a similar fashion to the tetracarbonyl complexes with halogens, whereas electrochemical oxidation appears to cause the formation of a doubly charged cation, [M(CO)3 (triars)]2+, where M = Cr, Mo, W (67). Allyl halides react with the tripyridine-substituted carbonyls of the type Mo(CO)3(bipy)py [or Mo(CO)3 (phen)py phen = phenanthroline] to form a 77-allylic carbonyl cation, such as [Mo(CO),(bipy)py(7r-allyl)]+ (146). The cation reacts with sulfur dioxide to form Mo(CO)2(bipy)(S02)2 (147). 

Between 400 and 430° the hydrogen pressure reaches 1 atm. The melting point (under pressure) is above 800°. Sodium hydride dissolves in fused sodium hydroxide and in fused alkali halides. It is insoluble in liquid ammonia. Water decomposes it immediately and completely to hydroxyl ion and hydrogen. Although sodium hydride is said to be stable in dry oxygen to 230°, traces of elemental sodium present may cause its ignition at lower temperatures. Copper, lead, and iron oxides are reduced by the compound to the free metals. Sulfur dioxide, carbon monoxide, and the halogens are reduced by the hydride to dithionite, formate, and halide ions, respectively. 

DIPROPYL OXIDE (111-43-3) CeHj O Highly flammable, peroxidizable liquid. Forms explosive mixture with air (flash point 70°F/21°C Fire Rating 3). Forms xmstable and explosive peroxides, especially when anhydrous. Reacts violently with oxidizers, permanganates, peroxides and hydroperoxides, ammonium persulfate, bromine dioxide, acyl halides, strong acids sulfuric acid, nitric acid. On small fires, use dry chemical powder (such as Purple-K-Powder), alcohol-resistant foam, or COj extinguishers. 

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