- Dehydrocoupling reactions of secondary and primary amine-borane adducts catalyzed by half-sandwich carbonyl complexes, [CpMn(CO)3], [(η6-C6H6)Cr(CO)3], and [CpV(CO)4]
-
Dehydrocoupling reactions of amineborane adducts catalyzed by half-sandwich carbonyl complexes are described. Secondary amine-borane adducts released H2 with catalytic action of [CpMn(CO)3] (Cp: η5-C5H5/su
- Kakizawa, Taeko,Kawano, Yasuro,Naganeyama, Kohsuke,Shimoi, Mamoru
-
-
Read Online
- Molecular Quadrupole Moments, Magnetic Anisotropies, and Charge Distributions of Borazine, B-Trichloroborazine, N-Trimethylborazine, and B-Trichloro-N-trimethylborazine. Comparison with Benzene and Its Derivatives.
-
Measurements of the dilute-solution molar Kerr constants, field-gradient birefringence constants, and Cotton-Mouton constants of borazine and three substituted borazines as solutes in cyclohexane or carbon tetrachloride at 25 deg C are reported.The observations yield the first direct experimental values of the effective polarizability anisotropies, electric quadrupole moments, and magnetic anisotropies, which are important descriptors of the molecular charge distributions.A comparison of the results for borazine with literature data for benzene shows that all three properties have the same signs in the two species but that all are considerably smaller in magnitude in borazine than in benzene.An analysis of the magnetizabilities indicates that the extent of electron delocalization in borazine is only about one-third of that in benzene, a conclusion which is consistent with a range of other evidence.
- Dennis, Gary R.,Ritchie, Geoffrey L. D.
-
-
Read Online
- Photoactivated, iron-catalyzed dehydrocoupling of amine-borane adducts: Formation of boron-nitrogen oligomers and polymers
-
Dehydrogenation chemistry with iron: The first examples of efficient iron-catalyzed dehydrocoupling/dehydrogenation of amine-boranes at ambient temperature have been reported. In the case of the primary amine-borane adduct MeNH2·BH3, both the polymer and/or N-alkyl borazine can be obtained (see scheme; 1=[{CpFe(CO)2}2]). Copyright
- Vance, James R.,Robertson, Alasdair P. M.,Lee, Kajin,Manners, Ian
-
-
Read Online
- Possible intermediates in the formation of 1,3,5-trimethylborazine
-
The 110° pyrolysis of H2B(NH2CH3)2+Cl -, H2CH3NBH2NHCH3BH2NH 2CH3+Cl-, and mixtures of (H2BNHCH3)3 and CH3NH3Cl give H3B3N3(CH3)3, CH3NH3Cl, and H2. The intermediates in the formation of the borazine ring have been investigated by studying the conversion of H2B(NH2CH3)2+Cl - to H3B3N3(CH3)3 in a mass spectrometer and by attempting to prepare possible intermediates. The current experimental evidence suggests that an initial intermediate is a linear, six-membered boron-nitrogen chain. Then, an intramolecular dehydrogenation ring-closure reaction between the ends of the chain leads to a species analogous to cyclohexenes. The more stable borazine ring is then formed from the cyclohexene type of species by the rapid loss of H2.
- Beachley Jr.
-
-
Read Online
- Rhodium-catalyzed formation of boron-nitrogen bonds: A mild route to cyclic aminoboranes and borazines
-
Secondary amine-borane adducts R2NH·BH3, which are stable to H2 elimination below 100 °C, undergo efficient catalytic dehydrocoupling at 25-45 °C in the presence of RhI or RhIII complexes to quantitatively form cyclic aminoboranes [NR2-BH2]2 (1: R = Me or 2: cyclo-C4H8); under similarly mild conditions, the analogous adducts NH3·BH3 and MeNH2·BH3 yield borazines [RN-BH]3 (3: R-H or 4: R = Me) in yields limited by intermolecular coupling reactions.
- Jaska,Temple,Lough,Manners
-
-
Read Online
- Catalytic dehydrocoupling of amine-borane adducts to form aminoboranes and borazines
-
A mild, catalytic dehydrocoupling route to aminoboranes and borazine derivatives from either primary or secondary amine-borane adducts has been developed using late transition metal complexes as precatalysts. The dehydrocoupling of Me2NH·BHsub
- Jaska, Cory A.,Temple, Karen,Lough, Alan J.,Manners, Ian
-
-
Read Online
- Bis-BN cyclohexane: A remarkably kinetically stable chemical hydrogen storage material
-
A critical component for the successful development of fuel cell applications is hydrogen storage. For back-up power applications, where long storage periods under extreme temperatures are expected, the thermal stability of the storage material is particularly important. Here, we describe the development of an unusually kinetically stable chemical hydrogen storage material with a H2 storage capacity of 4.7 wt%. The compound, which is the first reported parental BN isostere of cyclohexane featuring two BN units, is thermally stable up to 150 °C both in solution and as a neat material. Yet, it can be activated to rapidly desorb H2 at room temperature in the presence of a catalyst without releasing other detectable volatile contaminants. We also disclose the isolation and characterization of two cage compounds with S4 symmetry from the H2 desorption reactions.
- Chen, Gang,Zakharov, Lev N.,Bowden, Mark E.,Karkamkar, Abhijeet J.,Whittemore, Sean M.,Garner, Edward B.,Mikulas, Tanya C.,Dixon, David A.,Autrey, Tom,Liu, Shih-Yuan
-
-
Read Online
- Transition metal-catalyzed formation of boron-nitrogen bonds: Catalytic dehydrocoupling of amine-borane adducts to form aminoboranes and borazines
-
A mild, catalytic dehydrocoupling route to aminoboranes and borazine derivatives from either primary or secondary amine-borane adducts has been developed using late transition metal complexes as precatalysts. The adduct Me2NH·BH3 thermally eliminates hydrogen at 130 °C in the condensed phase to afford [Me2N-BH2]2 (1). Evidence for an intermolecular process, rather than an intramolecular reaction to form Me2N=BH2 as an intermediate, was forthcoming from "hot tube" experiments where no appreciable dehydrocoupling of gaseous Me2NH·BH3 was detected in the range 150-450 °C. The dehydrocoupling of Me2NH·BH3 was found to be catalyzed by 0.5 mol % [Rh(1,5-cod)(μ-Cl)]2 in solution at 25 °C to give 1 quantitatively after ca. 8 h. The rate of dehydrocoupling was significantly enhanced if the temperature was raised or if the catalyst loading was increased. The catalytic activity of various other transition metal complexes (Ir, Ru, Pd) for the dehydrocoupling of Me2NH·BH3 was also demonstrated. This new catalytic method was extended to other secondary adducts RR′NH·BH3 which afforded the dimeric species [(1,4-C4H8)N-BH2]2 (2) and [PhCH2(Me)N-BH2]2 (3) or the monomeric aminoborane iPr2N=BH2 (4) under mild conditions. A new synthetic approach to the linear compounds R2NH-BH2-NR2-BH3 (5: R = Me; 6: R = 1,4-C4H8) was developed and subsequent catalytic dehydrocoupling of these species yielded the cyclics 1 and 2. The species 5 and 6 are postulated to be intermediates in the formation of 1 and 2 directly from the catalytic dehydrocoupling of the adducts R2NH·BH3. The catalytic dehydrocoupling of NH3·BH3, MeNH2· BH3, and PhNH2·BH3 at 45 °C to give the borazine derivatives [RN-BH]3 (10: R = H; 11: R = Me; 12: R = Ph) was demonstrated. TEM analysis of the contents of the reaction solution for the [Rh(1,5-cod)(μ-Cl)]2 catalyzed dehydrocoupling of Me2NH·BH3 together with Hg poisoning experiments suggested a heterogeneous catalytic process involving Rh(0) colloids.
- Jaska, Cory A.,Temple, Karen,Lough, Alan J.,Manners, Ian
-
-
Read Online
- Mechanistic studies of the dehydrocoupling and dehydropolymerization of amine-boranes using a [Rh(Xantphos)]+ catalyst
-
A detailed catalytic, stoichiometric, and mechanistic study on the dehydrocoupling of H3B·NMe2H and dehydropolymerization of H3B·NMeH2 using the [Rh(Xantphos)]+ fragment is reported. At 0.2 mol % catalyst loadings, dehydrocoupling produces dimeric [H2B-NMe2]2 and poly(methylaminoborane) (Mn = 22 700 g mol-1, PDI = 2.1), respectively. The stoichiometric and catalytic kinetic data obtained suggest that similar mechanisms operate for both substrates, in which a key feature is an induction period that generates the active catalyst, proposed to be a Rh-amido-borane, that reversibly binds additional amine-borane so that saturation kinetics (Michaelis-Menten type steady-state approximation) operate during catalysis. B-N bond formation (with H3B·NMeH 2) or elimination of amino-borane (with H3B· NMe2H) follows, in which N-H activation is proposed to be turnover limiting (KIE = 2.1 ± 0.2), with suggested mechanisms that only differ in that B-N bond formation (and the resulting propagation of a polymer chain) is favored for H3B·NMeH2 but not H 3B·NMe2H. Importantly, for the dehydropolymerization of H3B·NMeH2, polymer formation follows a chain growth process from the metal (relatively high degrees of polymerization at low conversions, increased catalyst loadings lead to lower-molecular-weight polymer), which is not living, and control of polymer molecular weight can be also achieved by using H2 (Mn = 2 800 g mol-1, PDI = 1.8) or THF solvent (Mn = 52 200 g mol-1, PDI = 1.4). Hydrogen is suggested to act as a chain transfer agent in a similar way to the polymerization of ethene, leading to low-molecular-weight polymer, while THF acts to attenuate chain transfer and accordingly longer polymer chains are formed. In situ studies on the likely active species present data that support a Rh-amido-borane intermediate as the active catalyst. An alternative Rh(III) hydrido-boryl complex, which has been independently synthesized and structurally characterized, is discounted as an intermediate by kinetic studies. A mechanism for dehydropolymerization is suggested in which the putative amido-borane species dehydrogenates an additional H3B·NMeH2 to form the real monomer amino-borane H2B=NMeH that undergoes insertion into the Rh-amido bond to propagate the growing polymer chain from the metal. Such a process is directly analogous to the chain growth mechanism for single-site olefin polymerization.
- Johnson, Heather C.,Leitao, Erin M.,Whittell, George R.,Manners, Ian,Lloyd-Jones, Guy C.,Weller, Andrew S.
-
-
Read Online
- Method of manufacturing Alkylborazine-N
-
PROBLEM TO BE SOLVED: To provide a method for producing a borazine compound, with which the reaction yield and the purity of the end product are further improved.SOLUTION: A reaction is conducted by supplying raw material slurry to be added including one of a metal borohydride or an amine salt represented by (RNH)X (in formula, R represents a hydrogen atom, an alkyl group, or a cycloalkyl group, X represents a sulfate group or a halogen atom, and n is 1 or 2) and a solvent to an initially prepared liquid including the other of the metal borohydride and the amine salt and the solvent in a reaction vessel via a feed nozzle 120a. Here, a tip of the feed nozzle is located at a position within a range, corresponding to a distance Lfrom the liquid level of the reaction liquid, of 30-100% of a maximum distance Lin the vertical direction from the liquid level to the inside upper face of the reaction vessel, and the tip of the feed nozzle is located in a region with a similarity ratio of a horizontal plane including the tip of the feed nozzle to the horizontal cross-sectional shape of the reaction vessel of 0-0.8 when the center of gravity of the cross-sectional shape is set to be a center of similitude.
- -
-
Paragraph 0052; 0053; 0056; 0057; 0060
(2017/04/05)
-
- Mechanisms of the thermal and catalytic redistributions, oligomerizations, and polymerizations of linear diborazanes
-
Linear diborazanes R3N-BH2-NR2-BH 3 (R = alkyl or H) are often implicated as key intermediates in the dehydrocoupling/dehydrogenation of amine-boranes to form oligo- and polyaminoboranes. Here we report detailed studies of the reactivity of three related examples: Me3N-BH2-NMe2-BH3 (1), Me3N-BH2-NHMe-BH3 (2), and MeNH 2-BH2-NHMe-BH3 (3). The mechanisms of the thermal and catalytic redistributions of 1 were investigated in depth using temporal-concentration studies, deuterium labeling, and DFT calculations. The results indicated that, although the products formed under both thermal and catalytic regimes are identical (Me3N·BH3 (8) and [Me2N-BH2]2 (9a)), the mechanisms of their formation differ significantly. The thermal pathway was found to involve the dissociation of the terminal amine to form [H2B(μ-H)(μ-NMe 2)BH2] (5) and NMe3 as intermediates, with the former operating as a catalyst and accelerating the redistribution of 1. Intermediate 5 was then transformed to amine-borane 8 and the cyclic diborazane 9a by two different mechanisms. In contrast, under catalytic conditions (0.3-2 mol % IrH2POCOP (POCOP = κ3-1,3-(OPtBu 2)2C6H3)), 8 was found to inhibit the redistribution of 1 by coordination to the Ir-center. Furthermore, the catalytic pathway involved direct formation of 8 and Me2Ni - BH2 (9b), which spontaneously dimerizes to give 9a, with the absence of 5 and BH3 as intermediates. The mechanisms elucidated for 1 are also likely to be applicable to other diborazanes, for example, 2 and 3, for which detailed mechanistic studies are impaired by complex post-redistribution chemistry. This includes both metal-free and metal-mediated oligomerization of MeNHi - BH2 (10) to form oligoaminoborane [MeNH-BH 2]x (11) or polyaminoborane [MeNH-BH2] n (16) following the initial redistribution reaction.
- Robertson, Alasdair P. M.,Leitao, Erin M.,Jurca, Titel,Haddow, Mairi F.,Helten, Holger,Lloyd-Jones, Guy C.,Manners, Ian
-
supporting information
p. 12670 - 12683
(2013/09/23)
-
- Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors
-
Metal-free transfer hydrogenation of polarized olefins (RR′ CCEE′: R, R′ = H or organyl, E, E′ = CN or CO2Me) using amine borane adducts RR′NH-BH3 (R = R′ = H, AB; R = Me, R′ = H, MAB; R = tBu, R′ = H, tBAB; R = R′ = Me, DMAB) as hydrogen donors, were studied by means of in situ NMR spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the HN transfer is in agreement with a concerted transition state. The very reactive intermediate [NH2BH2] generated from AB was trapped by addition of cyclohexene into the reaction mixture forming Cy2BNH2. The final product borazine (BHNH)3 is assumed to be formed by dehydrocoupling of [NH2BH2] or its solvent stabilized derivative [NH2BH2]-(solvent), rather than by dehydrogenation of cyclotriborazane (BH2NH 2)3 which is the trimerization product of [NH 2BH2].
- Yang, Xianghua,Fox, Thomas,Berke, Heinz
-
p. 852 - 860
(2012/02/05)
-
- Catalytic redistribution and polymerization of diborazanes: Unexpected observation of metal-free hydrogen transfer between aminoboranes and amine-boranes
-
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).
- Robertson, Alasdair P. M.,Leitao, Erin M.,Manners, Ian
-
p. 19322 - 19325
(2012/01/13)
-
- Catching the first oligomerization event in the catalytic formation of polyaminoboranes: H3B·NMeHBH2·NMeH 2 bound to iridium
-
We report the first insertion step at a metal center for the catalytic dehydropolymerization of H3B·NMeH2 to form the simplest oligomeric species, H3B·NMeHBH2· NMeH2, by the addition of 1 equiv of H3B·NMeH 2 to [Ir(PCy3)2(H)2(η 2-H3B·NMeH2)][BArF 4] to give [Ir(PCy3)2(H)2(η 2-H3B·NMeHBH2·NMeH 2)][BArF4]. This reaction is also catalytic for the formation of the free linear diborazane, but this is best obtained by an alternative stoichiometric synthesis.
- Johnson, Heather C.,Robertson, Alasdair P. M.,Chaplin, Adrian B.,Sewell, Laura J.,Thompson, Amber L.,Haddow, Mairi F.,Manners, Ian,Weller, Andrew S.
-
p. 11076 - 11079
(2011/09/14)
-
- Reactions of amine-and phosphane-borane adducts with frustrated Lewis pair combinations of Group 14 triflates and sterically hindered nitrogen bases
-
The ability of trialkyl Group 14 triflates in combination with amine and pyridine bases to dehydrogenate amine-and phosphane-borane adducts has been investigated. By using multinuclear NMR spectroscopy, it has been shown that Me2NH ·BH3 (11) is efficiently converted to [Me2N-BH2]2 (12) by the so-called "frustrated Lewis pair" (FLP) of nBu3SnOTf (4, -OTf = -OSO2CF3) and 2,2,6,6-tetramethylpiperidine (6). Within the scope of the study, exchange of the Lewis acid effects the rate of dehydrogenation in the order: 4 gt; Me3Si-OTf (2) gt; Et 3SiOTf (3). Exchange of the Lewis base for 2,6-di-tert-butylpyridine (5) has also been shown to reduce the rate of reaction, whereas 1,3-di-tert-butylimidazol-2-ylidene (7) reacted directly with 2 to afford 1,3-bis-tert-butyl-4-(trimethylsilyl)imidazolium triflate (8[OTf]). For FLP combinations for which dehydrogenation reaction times are longer, detectable quantities of [H2B(μ-H)(μ-NMe2)BH2] (14) are observed. Both the dehydrogenation reaction and competitive formation of this product are proposed to proceed by initial hydride abstraction by the Lewis acid, followed by deprotonation by the Lewis base, or combination with further dimethylamine-borane and elimination of [Me2NH2]OTf (18[OTf]), respectively. In contrast to 11, MeNH2·BH 3 (22) was not found to cleanly dehydrogenate to either [MeNH-BH 2]3 or [MeN-BH]3 under the same conditions. An alternative reaction pathway was observed with either 2 or 4 and 6 with Ph 2PH ·BH3 (23), resulting in P-silylation or P-stannylation of the phosphane-borane, respectively.
- Whittell, George R.,Balmond, Edward I.,Robertson, Alasdair P. M.,Patra, Sanjib K.,Haddow, Mairi F.,Manners, Ian
-
experimental part
p. 3967 - 3975
(2011/01/11)
-
- Amino-borane oligomers bound to a Rh(I) metal fragment
-
Coordination complexes of previously observed intermediates, H 3B·NMe2BH2·NMe2H and [H2BNMeH]3, in the transition metal catalysed dehydrocoupling of H3B·NMe2H and H 3B·NMeH2 have been isolated and structurally characterised using the [Rh{PR′2(η2-C 5H7)}]+ fragment. Their onward reactivity shows that further dehydrogenation is not a simple intramolecular process. The Royal Society of Chemistry 2010.
- Dallanegra, Romaeo,Chaplin, Adrian B.,Tsim, Jennifer,Weller, Andrew S.
-
p. 3092 - 3094
(2010/07/06)
-
- Bis(a-amine-borane) complexes: An unusual binding mode at a transition-metal center
-
Getting a fix: Bis(?-amine-borane) rhodium complexes featuring a new binding mode (two amine-borane ligands) have been prepared (see picture; Rh yellow, P green, B pink, N blue). These complexes undergo dehydrocoupling to afford di- or trimeric cyclic ami
- Dallanegra, Romaeo,Chaplin, Adrian B.,Weller, Andrew S.
-
supporting information; experimental part
p. 6875 - 6878
(2010/01/15)
-
- Dehydrocoupling reactions of borane-secondary and -primary amine adducts catalyzed by group-6 carbonyl complexes: Formation of aminoboranes and borazines
-
Photoirradiation of a solution of BH3·NHR2 (1a: R = Me, 1b: R = 1/2C4H8, 1c: R = 1/2C 5H10, 1f: R = Et) containing a catalytic amount of a group-6 metal carbonyl complex, [M(CO)6] (M = Cr, Mo, W), led to dehydrogenative B-N covalent bond formation to produce aminoborane dimers, [BH2NR2]2 (2a-c, f), in high yield. During these reactions a borane σ complex, [M(CO)5(η1- BH3·NHR2)] (3), was detected by NMR spectroscopy. Similar catalytic dehydrogenation of bulkier amineboranes, BH 3·NHiPr2 (1d) and BH3· NHCy2 (1e, Cy = cyclo-C6H11), afforded monomeric products BH2=NR2 (4d, e). The reaction mechanism of the dehydrocoupling was investigated by DFT calculations. On the basis of the computational study, we propose that the catalytic dehydrogenation reactions proceed via an intramolecular pathway and that the active catalyst is [Cr(CO)4]. The reaction follows a stepwise mechanism involving NH and BH activation. Dehydrocoupling of borane-primary amine adducts BH 3·NH2R (1g: R = Me, 1h: R = Et, 1i: R = tBu) gave borazine derivatives [BHNR]3 (5g-i).
- Kawano, Yasuro,Uruichi, Mikio,Shimoi, Mamoru,Taki, Seitaro,Kawaguchi, Takayuki,Kakizawa, Taeko,Ogino, Hiroshi
-
experimental part
p. 14946 - 14957
(2010/01/16)
-
- Homogeneous catalytic dehydrogenation/dehydrocoupling of amine-borane adducts by the Rh(I) Wilkinson's complex analogue RhCl(PHCy2) 3 (Cy ) cyclohexyl)
-
The Rh(l) complex RhCI(PHCy2)3 (1) (Cy = cyclohexyl, C6H11) has been investigated as a catalyst for the dehydrogenation/dehydrocoupling of dimethylamine-borane adduct Me 2NH·BH3 (3) at 20 °C to afford the cyclic dimer [Me2N-BH2]2 (4). Unlike previously studied neutral and Cationic Rh(l) precatalysts such as [{Rh(μ-CI)(1,5-cod)} 2] and [Rh(1,5-cod)2]OTf (1,5-cod = 1,5-cyclooctadiene, C8H12, OTf = OSO2CF3) with weakly electron-donating ligands at the metal center, which are reduced to catalytically active Rh(0) species, catalytic dehydrogenation of 3 using 1 was found to occur in a homogeneous manner according to nanofiltration experiments, Hg(0) poisoning and kinetic studies. Moreover, the presence of the sterically bulky ligand PHCy2 in complex 1 has been found to significantly increase the rate of reaction previously reported for Wilkinson's catalyst RhCI(PPh3)3. The catalytic activity of 1 toward a range of other amine-borane adducts RR'NH · BH3 (e.g., RR' = 'Pr 2, MeBz, MeH) at 20 °C was also investigated. The third row transition metal analogue of 1, the lr(l) complex lrCI(PHCy2) 3 (2), was also explored as a catalyst for the dehydrocoupling of 3 and was found to exhibit much reduced catalytic activity compared to 1 but proved significantly more active for sterically encumbered substrates. Addition of the strong Lewis acid B(C6F5)3 as a co-catalyst to both 1 and 2 has been found to significantly increase the rate of the dehydrocoupling reactions in all cases. The Rh(l) complex 1 (but not the lr(l) analogue 2) was also found to be active for the catalytic dehydrocoupling of the phosphine-borane adduct Ph2PH·BH3 (14) at 60-90 °C to afford linear dimer Ph2PH-BH2-PPh 2-BH3 (15).
- Sloan, Matthew E.,Clark, Timothy J.,Manners, Ian
-
p. 2429 - 2435
(2009/08/08)
-
- Method for producing a purified borazine compound, method for filling a container with a borazine compound and container for preserving a borazine compound
-
On producing a purified borazine compound, a borazine compound is filtrated under an atmospheric condition of a water content of not higher than 2000 volume ppm. Or, on filling a borazine compound into a container, the above described borazine compound is filled into the above described container under an atmospheric condition of a water content of not higher than 2000 volume ppm. Or, as a container for preservation for preserving a borazine compound, a container for preserving a borazine compound, which has withstanding pressure of not lower than 0.1 MPa, is used.
- -
-
Page/Page column 8-11
(2008/06/13)
-
- Synthesis of B-trisubstituted borazines via the rhodium-catalyzed hydroboration of alkenes with N,N′,N″-trimethyl or N,N′,N″-triethylborazine
-
Hydroboration of terminal and internal alkenes with N,N′,N″-trimethyl- and N,N′,N″-triethylborazine was carried out at 50 °C in the presence of a rhodium(I) catalyst. Addition of dppb or DPEphos (1 equiv.) to RhH(CO)(PPh3)3 gave the
- Yamamoto, Yasunori,Miyamoto, Kazuo,Umeda, Junko,Nakatani, Yasutaka,Yamamoto, Tetsuya,Miyaura, Norio
-
p. 4909 - 4917
(2007/10/03)
-
- Method for producing borazine compound
-
In a synthesis of a borazine compound by a reaction of an alkali boron hydride represented by ABH4 (A represents lithium atom, sodium atom or potassium atom) and an amine salt represented by (RNH3)nX (R represents a hydrogen atom or an alkyl group, X represents a sulfate group or a halogen atom, and n is 1 or 2), or b) diborane (B2H6) and an amine represented by RNH2 (R represents a hydrogen atom or an alkyl group), a water content of raw material is controlled below a prescribed value; mixed solvents containing solvents each having a prescribed boiling point are used as a solvent for reaction; or a raw material is gradually fed to a reactor in a reaction. Or, a borazine compound is subjected to distillation purification treatment and filtration treatment. By such a method, a high purity of borazine compound can be produced safely and in a high yield.
- -
-
Page/Page column 10-12
(2008/06/13)
-
- METHOD FOR PRODUCING HEXAALKYLBORAZINE
-
The invention relates to a method for producing hexaalkylborazine represented by formula 2 from a borazine represented by the formula 1, an alkene and a ligand transition-metal complex catalyst. For both formulas 1 and 2, R1 represents an alkyl group and may be the same or different. R2 represents a hydrogen atom or an alkyl group, and may be the same or different, and at least one of the R2 is a hydrogen atom, and R3 represents a an alkyl group, and may be the same or different.
- -
-
Page/Page column 17-18
(2008/06/13)
-
- Intermediates in the formation of N-methylaminoborane trimer and N,N-dimethylaminoborane dimer
-
Experimental evidence for the intermediates in the formation of N-methylaminoborane trimer, (H2BNHCH3)3, and N,N-dimethylaminoborane dimer, (H2BN(CH2)2)2, has been obtained by synthetic methods and trapping procedures. The pyrolysis of methylamine borane, H3BNH2CH3, yields the six-membered ring of (H2BNHCH3)3 by initially forming H2B(NH2CH3)2+BH 4-, then [H2CH3NBH2NHCH3BH2NH 2CH3]+BH4- through a series of successive dehydrogenation condensation reactions. The final step of the proposed mechanism is ring closure by dehydrogenation. The new compound, [H2CH3NBH2NHCH3BH2NH 2CH3]+Cl-, was prepared by heating a mixture of H2B(NH2CH3)2+Cl - and H3BNH2CH3 and was characterized by elemental analysis, its reactions with FeCl3 and NaBH4, and its pmr spectrum. The experimental evidence for the intermediates during the pyrolysis of dimethylamine borane to form (H2BN(CH3)2)2 is consistent with monomeric H2BN(CH3)2 species which then associate to give the dimer.
- Beachley Jr.
-
p. 870 - 874
(2007/10/05)
-