title: The role of ammonia in promoting ammonia borane synthesis.
abstract: Ammonia promotes the synthesis of pure ammonia borane (AB) in excellent yields from sodium borohydride and ammonium sulfate in tetrahydrofuran under ambient conditions. An examination of the influence of added ammonia reveals that it is incorporated into the product AB, contrary to its perceived function as a catalyst or a co-solvent. Mechanistic studies point to a nucleophilic attack by ammonia on ammonium borohydride with concurrent dehydrogenation to yield AB.
authors.affiliation: Herbert C. Brown Center for Borane Research, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084, USA. chandran@purdue.edu.
authors.forename: P Veeraraghavan
authors.initials: PV
authors.lastname: Ramachandran
authors.affiliation: Herbert C. Brown Center for Borane Research, Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084, USA. chandran@purdue.edu.
authors.forename: Ameya S
authors.initials: AS
authors.lastname: Kulkarni