Pyrolysis of the Borazine-Methanol Adduct

Abstract

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.

Blending materials composed of boron, nitrogen and carbon to transform approaches to liquid hydrogen stores

“…S5 †). Earlier work has shown that borazine 51 and AB spent fuel 52 can be digested by methanol, and the present results confirm that the mixed trimers can be easily digested to simpler borates. Hydrogenation of these borates using metal hydrides has been previously reported, and so regeneration of the fuel blend can be accomplished.…”

Synthesis and Applications of Organic Borazine Materials

“…Synthesis of B-trimethoxyborazine through formation of borazine-methanol adduct and a subsequent thermolytic dehydrocoupling. [78] ered from the liquid mixture by fractionation distillation though it was not possible to obtain pure compounds.…”

Synthesis and Reactions of Borazines

“…Another important type of substitution reaction of B -trichloroborazine involves the alkylation or arylation of boron by Grignard or lithium reagents. 91 106 107 These reactions provide access to various kinds of B -trialkylborazines and B -triarylborazines from B -trichloroborazines. Typically, the B -trichloroborazine reacted with freshly prepared Grignard reagent or lithium reagent (3 equiv to 4 equiv) in dry diethyl ether to give the corresponding B -functionalized borazines 117 and 82 (Schemes 61 and 62).…”

“…For example, in a 1960 report by Haworth and Hohnstedt, pyrolysis of the reaction mixture was necessary to afford the corresponding B -functionalized borazines, when ethylmagnesium iodide or phenylmagnesium iodide was employed for the reaction. 107 In contrast substitution reactions with in situ generated Grignard reagent generated from alkyl or aryl bromides and magnesium turnings only required heating of the reaction to the reflux temperature of diethyl ether to afford the product. 106…”

“…28 In 1959, Haworth and Hohnstedt pyrolyzed this adduct at 100 °C to obtain ammonia–trimethoxyborane­ complex NH 3 ·B(OMe) 3 as the resulting product. 136…”