14149-58-7Relevant academic research and scientific papers
Synthesis and examination of amine-cyanocarboxyboranes, the boron analogues of α-cyanocarboxylic acids: X-ray structural study of the first lactam containing a boron atom in the lactam ring
Gyori, Béla,Lázár, István,Berente, Zoltán,Király, Róbert,Bényei, Attila
, p. 3567 - 3581 (2004)
The first representatives of chiral boron atom-containing amine-cyanomethoxycarbonyl boranes (A·BH(CN)COOMe) have been synthesized either from the corresponding amine-bromocyanomethoxycarbonylborane complexes with [Bu4 or from Me3N·BH(CN)COOMe and an amine in a base-exchange reaction. Acid hydrolyses of methyl esters generated the free acids (A·BH(CN)COOH), which are isoelectronic to the α-cyano carboxylic acids. Their pKa values and hydrolysis half-lives in acidic medium (that is rate of proton reduction) have been determined. Similarly to the alpha cyano carboxylic acids, the cyano group attached to the boron (in alpha position to the COOH group) increased the acid strength of carboxy boranes with 2.0-2.5 orders of magnitude. Independently from the type of the amine, pKa values of the amine-cyanocarboxyboranes (6.34-5.82) decrease consistently with the increase of pKb values of the amines. Hydrolytic decomposition rate of the alkylamine complexes increases with increasing pKb values of the amines while the opposite was found for pyridine base complexes. When considering both types of the amines, hydrolysis half-lives of the complexes range over several orders of magnitude from 0.005 to 400 h. Based on these observations protonation of the amine nitrogen atom appears to be the rate determining step in the hydrolysis process. With loss of methanol, 2-NH2-py·BH(CN)COOMe transformed into a five membered lactam derivative. X-ray diffraction revealed that the pyridine ring is coplanar with the five membered lactam ring. In the crystal two molecules are connected in a head to tail arrangement by strong intermolecular H-bonds between N(2)-H and the carbonyl oxygen (O1) with a donor and acceptor distance of 2.867(3) A?. Three new cyanomethoxycarbonylborates having the composition of K[BHn (CN)3-nCOOMe] (n = 1, 2) and K[B(OH)(CN)2COOMe] have also been synthesized and their properties examined.
Highly selective extraction of Cu(II) and Zn(II) using [B(3-iPrpz) 4]- (iPrpz=isopropylpyrazolyl)
Kitano, Tsuyoshi,Sohrin, Yoshiki,Hata, Yasuo,Mukai, Hiroshi,Wada, Hiroki,Ueda, Kazumasa
, p. 283 - 289 (2004)
The solvent extraction of first-series transition metal ions {Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)} with [B(3-iPrpz)4] - (iPrpz=isopropylpyrazolyl) is reported. Although the previously reported tetrakis(pyrazolyl)borates, [B(pz)4]- and [B(3-Mepz)4]-, quantitatively extracted all the studied transition metal ions, [B(3-iPrpz)4]- extracted only Cu(II) and Zn(II). In order to elucidate the origin of the selectivity, the structures of the extracted species, [B(3-iPrpz)4]2Zn (1) and [B(3-iPrpz)4]Cu(OCOCH3) (2), were determined by single-crystal X-ray diffraction. Complex 1 has a tetrahedral geometry with each ligand having bidentate coordination. Complex 2 has a distorted square pyramidal geometry with [B(3-iPrpz)4]- having tridentate coordination and the acetate anion having asymmetric bidentate coordination. These structures of the extracted species are different from those of the previously studied tetrakis(pyrazolyl)borates, which are octahedral A 2M with each ligand having tridentate coordination (A -=tetrakis(pyrazolyl)borate, M2+=first-series transition metal ion). Because the bulky isopropyl groups at the 3-position of the pyrazolyl ring prevent octahedral geometry, the other metal ions cannot form stable and extractable complexes with [B(3-iPrpz)4]-.
A General Protocol for the Polycondensation of Thienyl N-Methyliminodiacetic Acid Boronate Esters to Form High Molecular Weight Copolymers
Carrillo, Josue Ayuso,Turner, Michael L.,Ingleson, Michael J.
supporting information, p. 13361 - 13368 (2016/10/22)
Thienyl di-N-methyliminodiacetic acid (MIDA) boronate esters are readily synthesized by electrophilic C-H borylation producing bench stable crystalline solids in good yield and excellent purity. Optimal conditions for the slow release of the boronic acid using KOH as the base in biphasic THF/water mixtures enables the thienyl MIDA boronate esters to be extremely effective homo-bifunctionalized (AA-type) monomers in Suzuki-Miyaura copolymerizations with dibromo-heteroarenes (BB-type monomers). A single polymerization protocol is applicable for the formation of five alternating thienyl copolymers that are (or are close analogues of) state of the art materials used in organic electronics. The five polymers were produced in excellent yields and with high molecular weights comparable to those produced using Stille copolymerization protocols. Therefore, thienyl di-MIDA boronate esters represent bench stable and low toxicity alternatives to highly toxic di-trimethylstannyl AA-type monomers that are currently ubiquitous in the synthesis of these important alternating copolymers.
Hydrolysis of thymidine boranomonophosphate and stepwise deuterium substitution of the borane hydrogens. 31P and 11B NMR studies
Li, Hong,Hardin, Charles,Shaw, Barbara Ramsay
, p. 6606 - 6614 (2007/10/03)
The α-P-boranophosphate nucleosides comprise a new class of modified nucleotides that may find use as therapeutic and DNA diagnostic agents. Hydrolysis of thymidine 5'-boranomonophosphate, d(p(B)T), has been studied in H2O and D2O using 1H, 31P, and 11B NMR spectroscopies. Although d(p(B)T) is quite stable at 25 °C, it hydrolyzes slowly at higher temperatures. At 50 or 60 °C, d(p(B)T) hydrolyzes first into thymidine (dT) and boranophosphate (O3P-BH33-), followed by subsequent hydrolysis of the O3P-BH33- to produce phosphonate and boric acid. A three-step deuterium substitution of the borane hydrogens in O3P-BH33- was detected in D2O by the presence of a 31P isotope shift. The 31P resonances shifted downfield by 0.14 ppm upon substitution of each of three 1H atoms by 2H. Exchange of the borane hydrogens with D2O occurs as sequential processes superimposed upon hydrolysis of O3P-BH33-. The hydrolysis and deuteration steps were characterized in terms of pseudo-first-order rate constants. Hydrolysis of O3P-BH33- is an order of magnitude slower than deuterium substitution.
Hydrolysis of (Trimethylamine)borane with Ion-Exchange Resins: Effect of Ionic Surfactants
Bromberg, Lev,Muraviev, Dmitri,Warshawsky, Abraham
, p. 13927 - 13930 (2007/10/02)
The hydrolysis of (trimethylamine)borane (TB) with the D+ form of ion-exchange resin suspended in organic solvent was studied.The hydrolysis retardation is observed in two cases: (i) due to inhibition by the hydrolysis side product, trimethylam
Infrared spectra of molecular B(OH)3 and HOBO in solid argon
Andrews, Lester,Burkholder, Thomas R.
, p. 7203 - 7210 (2007/10/02)
Anhydrous B(OH)3 was pressed into a pellet and sublimed at room temperature under vacuum to give molecular B(OH)3 for argon matrix infrared study.The spectrum showed sharp fundamentals without the effect of hydrogen bonding observed in the solid.Fermi resonances were characterized for two fundamentals.The observed frequencies for B(OH)3 and the three deuterium substituted molecules are in agreement with values from self-consistent field/double zeta plus polarization (SCF/DZP) calculations allowing for appropriate scale factors.The major thermal decomposition products from pulsed laser evaporation of B(OH)3 were H2O, B2O3, and HOBO.Molecular HOBO was characterized by a strong 2020 cm-1 fundamental, which was confirmed by SCF/DZP calculations.
