108203-18-5Relevant academic research and scientific papers
An improved synthesis of borazine with aluminum chloride as catalyst
Li, Jun-Sheng,Zhang, Chang-Rui,Li, Bin,Cao, Feng,Wang, Si-Qing
, p. 1763 - 1766 (2010)
Borazine is an excellent precursor for boron nitride. However the existing synthetic methods for the preparation of borazine have drawbacks such as relatively high reaction temperatures, side reactions, long reaction times, and low yields. An improved synthesis procedure was disclosed, which involved the use of aluminum chloride as a catalyst in the reaction of sodium borohydride with ammonium sulfate. The aluminum chloride catalyst: brought the reaction temperature down from 120-140 °C to 45 °C. Improved yields of borazine were obtained in comparison to the reaction without a catalyst. In addition, the reaction process was investigated in detail by 11B NMR spectroscopy and Fourier transform, infrared spectroscopy (FTIR). It was found that aluminum, borohydride formed in very small quantity when aluminum chloride was introduced, which plays an important role in the reaction.
Iridium-catalyzed dehydrogenation of substituted amine boranes: Kinetics, thermodynamics, and implications for hydrogen storage
Dietrich, Brandon L.,Goldberg, Karen I.,Heinekey, D. Michael,Autrey, Tom,Linehan, John C.
, p. 8583 - 8585 (2008)
Dehydrogenation of amine boranes is catalyzed efficiently by the iridium pincer complex (κ3-1,3-(OPtBu2) 2C6H3)Ir(H)2 (1). With CH 3NH2BH3 (MeAB)
Calorimetric process monitoring of thermal decomposition of B-N-H compounds
Wolf,Baumann,Baitalow,Hoffmann
, p. 19 - 25 (2000)
Borazane BH3NH3 is a crystalline solid with a high hydrogen content. It decomposes thermally activated already at temperatures below 410K. The thermal decomposition of BH3NH3 was studied by thermogravimetry (TG), differential scanning calorimetry (DSC), volumetric measurements and coupled TG/FTIR. Measurements were performed under isothermal conditions and in scanning mode. The enthalpy change at the exothermic decomposition reaction ΔrH was determined by use of DSC-technique. At different heating rates and temperatures a value of ΔrH=-(21.7±1.2)kJ/mol BH3NH3 was obtained. It can be pointed out that under appropriate conditions borazane decomposes completely below the melting temperature of T=385K given in the literature. As a consequence of the low decomposition rate a separation of different steps is possible only at low heating rates. The decomposition reaction is accompanied by hydrogen evolution. During this first decomposition step borazane releases approximately 1molH2 per mol BH3NH3. The other decomposition products are a solid residue of polymeric aminoborane (BH2NH2)x and a small amount of the volatile borazine B3N3H6. The solid aminoborane was characterised by X-ray powder diffraction measurements, IR-spectroscopy and elemental analysis. The small amount of borazine formed was detected by the coupled TG/FTIR-investigations. The mass of the hydrogen released below T=385K is about 6.5% of the initial sample mass. Due to the significant amount of evolved hydrogen and the exothermic character of the decomposition process the use of borazane as a source for hydrogen seems to be possible and interesting.
Ammonia Borane Dehydrogenation Promoted by a Pincer-Square-Planar Rhodium(I) Monohydride: A Stepwise Hydrogen Transfer from the Substrate to the Catalyst
Esteruelas, Miguel A.,Nolis, Pau,Oliván, Montserrat,O?ate, Enrique,Vallribera, Adelina,Vélez, Andrea
, p. 7176 - 7181 (2016)
The pincer d8-monohydride complex RhH{xant(PiPr2)2} (xant(PiPr2)2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) promotes the release of 1 equiv of hydrogen from H3BNH3 and H3BNHMe2 with TOF50% values of 3150 and 1725 h-1, to afford [BH2NH2]n and [BH2NMe2]2 and the tandem ammonia borane dehydrogenation-cyclohexene hydrogenation. DFT calculations on the ammonia borane dehydrogenation suggest that the process takes place by means of cis-κ2-PP-species, through four stages including: (i) Shimoi-type coordination of ammonia borane, (ii) homolytic addition of the coordinated H-B bond to afford a five-coordinate dihydride-boryl-rhodium(III) intermediate, (iii) reductive intramolecular proton transfer from the NH3 group to one of the hydride ligands, and (iv) release of H2 from the resulting square-planar hydride dihydrogen rhodium(I) intermediate.
Thermal decomposition of B-N-H compounds investigated by using combined thermoanalytical methods
Baitalow,Baumann,Wolf,Jaenicke-R??ler,Leitner
, p. 159 - 168 (2002)
The thermal decomposition of borazane BH3NH3 in the temperature range up to 500 K has been studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) combined with the FRIR spectroscopic and mass spectrometric analysis of the gas phase. Above 340 K borazane is decomposed in stages as the temperature is increased, The exothermic decomposition is accompanied by the release of approximately 2.2 mol H2/mol BH3NH3. This corresponds to a remarkable hydrogen storage density of 14.3 mass% related to the mass of borazane. In the gas phase above the solid decomposition residue monomeric aminoborane (BH2NH2), borazine (BHNH)3, which is the boron-nitrogen analog of benzene, and traces of diborane B2H6 were found beside hydrogen. The release of significant quantities of borazine was observed only at temperatures above 400 K.
Ruthenium complexes with cooperative PNP ligands: Bifunctional catalysts for the dehydrogenation of ammonia-borane
Kaess, Martina,Friedrich, Anja,Drees, Markus,Schneider, Sven
, p. 905 - 907 (2009)
(Chemical Equation Presented) G"Ru"vy reactivity: The new ruthenium(II) complex having cooperative PNP enamido ligand A reversibly activates two equivalents H2 under reversible hydrogenation of amido (B) and amino (C) complexes. B exhibits the
Non-noble metal doped perovskite as a promising catalyst for ammonia borane dehydrogenation
Salinas-Torres, David,Navlani-García, Miriam,Kuwahara, Yasutaka,Mori, Kohsuke,Yamashita, Hiromi
, p. 6 - 11 (2020)
Lanthanum Strontium Cobalt (LSC) perovskite-based catalysts were prepared and evaluated in the ammonia borane dehydrogenation reaction. Doping with additional non-noble metals, such as Ni or Cu greatly enhanced the catalytic performance, especially in the case of Cu. In order to evaluate the effect of the Cu loading, catalysts with various Cu contents ranging from 0.82 to 5.42 wt.percent were synthesized. It was found that the Cu-doped sample with a nominal formula of La0.7Sr0.3Co0.90Cu0.10O3 containing 2.72 wt.percent of Cu displayed the highest catalytic activity among investigated, which outperformed the counterpart Cu-supported catalyst (Cu/La0.7Sr0.3CoO3). La0.7Sr0.3Co0.90Cu0.10O3 showed good durability during five consecutive reaction runs, confirming the suitability of perovskite-type catalysts in stabilizing the catalytic active phase. The present catalytic system provides a cost-effective alternative to the noble-metal-based catalysts commonly used to catalyze the ammonia borane dehydrogenation reaction.
Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
supporting information, p. 5305 - 5316 (2021/04/12)
Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
Iron complex-catalyzed ammonia-borane dehydrogenation. A potential route toward B-N-containing polymer motifs using earth-abundant metal catalysts
Baker, R. Tom,Gordon, John C.,Hamilton, Charles W.,Henson, Neil J.,Lin, Po-Heng,Maguire, Steven,Murugesu, Muralee,Scott, Brian L.,Smythe, Nathan C.
, p. 5598 - 5609 (2012/05/20)
Ammonia-borane (NH3BH3, AB) has garnered interest as a hydrogen storage material due to its high weight percent hydrogen content and ease of H2 release relative to metal hydrides. As a consequence of dehydrogenation, B-N-containing oligomeric/polymeric materials are formed. The ability to control this process and dictate the identity of the generated polymer opens up the possibility of the targeted synthesis of new materials. While precious metals have been used in this regard, the ability to construct such materials using earth-abundant metals such as Fe presents a more economical approach. Four Fe complexes containing amido and phosphine supporting ligands were synthesized, and their reactivity with AB was examined. Three-coordinate Fe(PCy3)[N(SiMe3)2]2 (1) and four-coordinate Fe(DEPE)[N(SiMe3)2]2 (2) yield a mixture of (NH2BH2)n and (NHBH)n products with up to 1.7 equiv of H2 released per AB but cannot be recycled (DEPE = 1,2-bis(diethylphosphino)ethane). In contrast, Fe supported by a bidentate P-N ligand (4) can be used in a second cycle to afford a similar product mixture. Intriguingly, the symmetric analogue of 4 (Fe(N-N)(P-P), 3), only generates (NH2BH2)n and does so in minutes at room temperature. This marked difference in reactivity may be the result of the chemistry of Fe(II) vs Fe(0).
Catalytic redistribution and polymerization of diborazanes: Unexpected observation of metal-free hydrogen transfer between aminoboranes and amine-boranes
Robertson, Alasdair P. M.,Leitao, Erin M.,Manners, Ian
, p. 19322 - 19325 (2012/01/13)
Ir-catalyzed (20 °C) or thermal (70 °C) dehydrocoupling of the linear diborazane MeNH2-BH2-NHMe-BH3 led to the formation of poly- or oligoaminoboranes [MeNH-BH2]x (x = 3 to >1000) via an initial redistribution process that forms MeNH 2?BH3 and also transient MeNH=BH2, which exists in the predominantly metal-bound and free forms, respectively. Studies of analogous chemistry led to the discovery of metal-free hydrogenation of the B=N bond in the "model" aminoborane iPr2N=BH2 to give iPr2NH?BH3 upon treatment with the diborazane Me3N-BH2-NHMe-BH3 or amine-boranes RR′NH?BH3 (R, R′ = H or Me).
