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|Section2= |Section3= |Section4= |Section5= |Section8= }} Dimethylborane, (CH3)2BH is the simplest dialkylborane, consisting of a methyl group substituted for a hydrogen in borane. As for other boranes it normally exists in the form of a dimer called tetramethyldiborane or TMDB (CH3)2BH)2. Other combinations of methylation occur on diborane, including monomethyldiborane, trimethyldiborane, 1,2-dimethylborane, 1,1-dimethylborane and trimethylborane. At room temperature the substance is at equilibrium between these forms.〔 The methylboranes were first prepared by H. I. Schlesinger and A. O. Walker in the 1930s.〔 〕 ==Formation== Dimethylborane is formed when lithium dimethylborohydride Li(CH3)2BH2 reacts with an acid. The lithium dimethylborohydride can be made from a dimethylborinic ester and lithium monoethoxy aluminium hydride.〔 Methylboranes are also formed by the reaction of diborane and trimethylborane. This reaction produces four different substitutions of methyl with hydrogen on diborane. Produced is 1-methyldiborane, 1,1-dimethyldborane, 1,1,2-trimethyldiborane and 1,1,2,2-tetramethyldiborane. The latter is maximised when trimethylborane is six times the concentration of diborane. Other methods to form methyldiboranes include reacting hydrogen with trimethylborane between 80 and 200°C under pressure, or reacting a metal borohydride with trimethylborane in the presence of hydrogen chloride, aluminium chloride or boron trichloride. If the borohydride is sodium borohydride, then methane is a side product. If the metal is lithium then no methane is produced.〔 dimethylchloroborane and methyldichloroborane are also produced as gaseous products.〔 Atomic hydrogen converts trimethylborane on a graphene monolayer surface to dimethylborane which dimerises to tetramethyldiborane.〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tetramethyldiborane」の詳細全文を読む スポンサード リンク
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