Reduction of some ketones using sulphurated sodium borohydride (NaBH2S3) : kinetics and mechanism

Abstract

Rates of sulphurated sodium borohydride (NaBH₂S₃) reduction of some ketones (acetone, acetophenones, benzophenones, and fluorenone) in tetrahydrofuran have been measured. Results for the two series (acetophenones and benzophenones) studied fit the Hammett equation with high ρ⁺ values (+2.531 for acetophenones and +1.982 for benzophenones) thus suggesting that BH₂S₃-ion is a moderately strong nucleophile. Thermodynamic parameters have been evaluated and a suitable mechanism for these reactions has been proposed.