The chemistry of small boranes and their anions Bi

Diborane occupies a special place because all the other boranes can be prepared from it (directly or indirectly) it is also one of the most studied and synthetically useful reagents in the whole of chemistry/ B2H6 gas can most conveniently be prepared in small quantities by the reaction of I2 on NaBH4 in diglyme [(MeOCH2CH2)20], or by the reaction of a solid tetrahydroborate with an anhydrous acid  

When B2H6 is to be used as a reaction intermediate without the need for isolation or purification, the best procedure is to add Et20Bp3 to NaBH4 in a polyether such as diglyme  

On an industrial scale gaseous BP3 can be reduced directly with NaH at 180° and the product trapped out as it is formed to prevent subsequent pyrolysis  

Some 200 tonnes per annum of B2H6 is produced commercially, worldwide. Care should be taken in all these reactions because B2H6 is spontaneously flammable its heat of combustion (—A//°) is higher per unit weight of fuel than for any other substance except 

22 in Mellor s Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. 5, Supplement 2, Part 2, pp. 52-162, Longmans, London, 1981. 

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