Sir: A previous publication describes procedures for the quantitative separation of lead and barium, of cadmium and mercury, of lead and zinc, and the semiquantitative separation of cadmium and zinc (3). Since this technique is simple and rapid and does not require elaborate equipment, the investigation was continued to develop procedures for the reduction of the coinage metals.EXPERIMENTAL Apparatus and Reagents. The pH of the solutions was determined with a Beckman Zeromatic pH meter.Sodium Borohydride.Approximately 1% aqueous solution was prepared just before use from 98+% sodium borohydride purchased from Metal Hydrides, Inc. Solution concentrations were approximated on a weight basis-for example, 1% Na-I3H4 was made by dissolving 1 gram of NaBH4 in 100 ml. of solution.Gold(III) Chloride. Stock solutions of gold chloride, approximately 0.06 7, were prepared by dissolving pure metallic gold in chlorine water and diluting to 1 liter. The 0.1 A7 solutions of copper chloride, copper nitrate, copper sulfate, and silver nitrate were standardized using established procedures described in the literature {2).Procedure.
As reported in the literature, borazine reacts with excess methanol at room temperature to form a 1:3 adduct, Pyrolysis of this adduct at 100°has been reported to give 3 moles of H2 per mole of adduct and a volatile monomer CH3OBNH, which would represent the only case of a monomeric species of empirical formula corresponding to a borazine derivative. Our repeated pyrolyses of B3N3He-3CH3OH gave the predicted amount of H2. The other products observed are ammonia-trimethoxyborane, H3NB(OCH3)3 (which has a gas phase molecular weight close to that calculated for CH3OBNH), B-trimethoxyborazine [B3(OCH3)3N3H3], a little methanol and a non-volatile white solid of composition intermediate between BN and [B(OCH3)NH]*. B3(OCH3)3N3H3 sublimes in vacuo at 60°, reacts quantitatively with methanol at 100°to produce H3NB(OCH3)3, and changes to a non-volatile solid when heated alone at 100°. It appears highly improbable that a stable CH3OBNH monomer can be prepared by reaction of borazine and methanol. The reaction of borazine on mixing with ethanol is similar to that with methanol except that partial ethanolysis to break the borazine ring occurs at room temperature and even lower. B-Triethoxyborazine may be obtained from borazine-ethanol mixtures by heating at 100°. The same compound melting at 53-54°was prepared for comparison by the interaction of B3Cl3NiH| with NaOCaHa.
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