Ammonia borane as a reducing agent for organic functional groups

CHED 517

Kirsten N. Jaegersen and Paul Louis Gaus, gaus@wooster.edu. Department of Chemistry, The College of Wooster, 943 College Mall, Wooster, OH 44691
The utility of ammonia borane as a convenient reducing agent for a variety of organic functional groups has been investigated. Several ketones, aldehydes, epoxides, acid halides, etc. have been reacted with ammonia borane, at room temperature, in methanol. The reactions proceed smoothly to give the corresponding alcohols, which have been characterized by GC/MS techniques, which indicate a single product with a retention time and mass spectrum identical to that of a known sample. For instance, acetophenone, benzaldehyde, and cyclohexanone give sec-phenethyl alcohol, benzyl alcohol, and cyclohexanol, respectively. Two-thirds an equivalent of ammonia borane is sufficient to give full reduction of one equivalent of ketone or aldehyde. The selectivity of the reagent for various functional groups will be presented, as will a comparison of this reducing agent with the more traditional sodium borohydride.