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Kinetics of the direct borane reduction of pinacolone in THF

1997; Royal Society of Chemistry; Issue: 12 Linguagem: Inglês

10.1039/a703698a

2050-8239

Holger Jockel, Reinhard Schmidt,

Ammonia Synthesis and Nitrogen Reduction

The kinetics of the borane reduction of the ketone pinacolone in THF depend strongly on the borane reagent. NaBH4, which is present in commercial BH3–THF as stabilizer, strongly catalyzes the reaction. The use of commercial BH3–THF results in the borane reaction order of 1.6. In contrast, freshly prepared, pure BH3–THF yields kinetics for which the main reaction, the reduction of the ketone by BH3–THF forming the monoalkoxyborane, are first order in both reactants. Two further subsequent reactions have to be included in the reaction scheme in order to fit the kinetics by numerical integration. Results of semiempirical calculations are compared with experimental findings to eludicate the possible reaction mechanism of the main reaction.