Study of the controlled temperature reaction between closo-decahydrodecaborate and alcohols in H2SO4 medium

The reactions of the ammonium salt of c/oso-decahydrodecaborate (NH4)(2)B10H10 with alcohols were studied in concentrated sulfuric acid medium. Alcohols ROH (R = CH3, C2H5, C3H7, iso-C3H7, C4H9, 2-C4H9, ter-C4H9, C5H11) played the role of solvent and ligand, simultaneously. These Electrophile Induced Nucleophilic Substitution Reactions were conducted at two different temperatures (25 degrees C or reflux) in atmospheric air and produced [2-B10H900-, [2,7(8)-B10H8(0R)212- and/or [B10H7(OR)(3)](2-). The rate of the reaction and the nature of the product formed depended on the temperature, on the alcohol, and on the reaction duration. The reactions at 25 degrees C, if proceeded, produced mainly the monoalkoxy derivative, [2-B10H900-. For the longer chain alcohols (4 carbons and above) the increase in the reaction duration and the temperature resulted in higher substitution, thus producing the dialkoxy [2,7(8)-B10H8(OR)(2)(2-) and trialkoxy [B10H7(OR)(3)](2-) derivatives. Meanwhile only the monoalkoxy [2-B10H9OR](-) plus the dialkyloxonium [2-B10H90R2] derivatives were produced with the shorter alcohols (1 to 3 carbons) at refluxing temperature. All these derivatives were isolated in their pure forms on DEAE-cellulose column with adequate yields, and characterized by B-11, C-13, H-1 NMR, negative ESI and TLC.