From organoboranes oxidation

Hydroboration-oxidation is now a standard method for anb -Markovnikov s cis-hydration [1] of alkenes from the less hindered side of the double bond. The hydroboration of olefins, mainly in THF solvent, affords conveniently the corresponding organoboranes. Oxidation of the intermediate organoboranes is most conveniently carried out by successive addition of 3 M NaOH and 30% hydrogen peroxide (depicted as [O], Eq. 6.1). Other oxidation procedures, e.g., HjOj in buffer solutions, HjOj in NaOAc, per acids, and trimethyl-N-oxides are used in certain cases when the organoboranes are unstable to water or contain functionalities sensitive to alkaline medium. 

An improved procedure for the synthesis of alkyl iodides from organoboranes (and thus ultimately from alkenes), involving the use of iodine and sodium meth-oxide, has been shown to entail inversion at the C-B bond, and is employed in a new route to optically active iodides from alkenes e.g. Scheme 30). A similar sequence for conversion of alkenes to primary halides via hydrozirconation (Scheme 31) has been reviewed. Zr also catalyses addition of lithium aluminium hydride to alkenes under mild conditions, and the alanes so formed can likewise be converted into alkyl halides (Scheme 32). 

The combination of hydroboration and oxidation leads to the overall hydration of an alkene. Notice, however, that water is not a reactant. The hydrogen that becomes bonded to carbon comes from the organoborane, and the hydroxyl group from hydrogen peroxide. 

The main chemical products produced from these minerals are (a) boron oxides, boric acid and borates, (b) esters of boric acid, (c) refractory boron compounds (borides, eu .), (d) boron halides, (e) boranes and carbaboranes and (f) organoboranes. The main industrial and domestic uses of boron compounds in Europe (USA in parentheses) are ... 

Distillation of the product from the crude reaction mixture at this stage gives somewhat lower yields. Therefore, residual organoboranes are oxidized prior to isolation of product. 

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