Comprehensive DFT and MO studies on glyoxilic acid oxime and related ions in gas phase and solution: Conformations,basicities and acidities

Density functional (BLYP, B3LYP and BHLYP) and highly correlated MP2 and CCSD(T) calculations have been performed to investigate conformers, energy barriers, intramolecular H-bond strength, gas-phase basicity and deprotonation energies of glyoxilic acid oxime (gao) and related ions in gas phase and in aqueous solution (SCRF-PCM method). BHLYP/6-311G(d,p) and B3LYP/6-31++G(d) predictions for the global minimum conformer of gao were consistent with experiment. BLYP level overestimated the H-bond and stabilized incorrectly the H-bonded conformer. The calculations in solution indicated destabilization of H-bonded conformers due to the small polarizability and weaken of the H-bond. The same global minimum structures in gas phase and aqueous solution were found for gao-neutral (ectt) and gao-dianion (e⁻²), whereas they were different for gao-anion because of the strong decrease of the conformational energies in solution. The global minimum structures of the neutral, anion and dianion of gao, obtained in solution, are in agreement with experiment. The gas-phase basicity (GB) and molecular electrostatic potential (MEP) calculations revealed the same sites for electrophilic attack, supported by the nature of HOMO: the carbonylic oxygen for the neutral, the carboxylic oxygen for the anion and the oxime nitrogen for the dianion. MEP results in gas phase and in solution suggested a region between the two atoms, but not on one atom in accordance with bidentate binding of gao ions to a metal. The BHLYP/6-31++G(d,p) molecular properties of gao were in best consistent with CCSD(T) results. The thermodynamical properties (GB and bond deprotonation energy) of gao were better estimated at B3LYP level.     

Synthesis of a potential reactivator of acetylcholinesterase—1-(4-hydroxyiminomethylpyridinium)-3-(carbamoylpyridinium)propane dibromide

Two methods for the synthesis of a new unsymmetric bispyridinium oxime-1-(4-hydroxyiminomethylpyridinium)-3-(carbamoylpyridinium)propane dibromide are described. In vitro efficacy of this new oxime to reactivate sarin-inhibited acetylcholinesterase has been evaluated.     

3-(水杨酰肼)-丁基-2-酮肟和两个镍的酮肟配合物的合成和晶体结构

合成了3-(水杨酰肼)-丁基-2-酮肟H₂L(1，C₁₁H₁₃N₃O₃)和2个镍的3-(水杨酰肼)-丁基-2-酮肟化合物[Ni(HL)(CH₃COO^-)(C₅H₅N)₂](2)和[Ni(HL)₂]·2C₃H₇NO（3）。化合物1晶体属单斜晶系，空间群为P2₁/n，晶体学参数为：a=0.451 87(2) nm，b=2.086 8(1) nm，c=1.224 48(9) nm，β=94.974(3)°，V=1.150 3(1) nm³，Z=4，D_c=1.358 g·cm^-3，μ=0.101 mm^-1，F(000)=496，R=0.0435，wR=0.142 5。化合物2晶体属单斜晶系，空间群为P2₁/n，晶体学参数为：a=1.362 39(8) nm，b=1.345 37(6) nm，c=1.438 54(7) nm，β=113.138(3)°，V=2.424 6(2) nm³，Z=4，D_c=1.398 g·cm^-3，μ=0.843mm^-1，F(000)=1 064，R=0.042 4，wR=0.116 6。化合物3晶体属单斜晶系，空间群为P2₁/c，晶体学参数为：a=1.104 22(7) nm，b=2.860 1(1) nm，c=1.114 13(7)nm，β=114.589(5)°，V=3.199 5(3) nm³，Z=4，D_c=1.398 g·cm^-3，μ=0.667 mm^-1，F(000)=1 416，R=0.057 6，wR=0.1535。在化合物1晶体中，酮肟分子之间通过分子间氢键形成二维网状结构。在化合物2中，每个镍(Ⅱ)离子由1个3-(水杨酰肼)-丁基-2-酮肟的2个氮原子和1个氧原子，2个吡啶分子中的2个氮原子和1个乙酸根中的1个氧原子形成畸变的NiN₄O₂八面体配位构型，存在分子内氢键O-H(肟)…O(乙酸根)和O-H(酚)…N(酰肼)。在化合物3晶体中，每个镍(Ⅱ)离子由2个3-(水杨酰肼)-丁基-2-酮肟的4个氮原子和2个氧原子配位，形成畸变的NiN₄O₂八面体配位构型。晶体中存在O-H…O和O-H…N两种分子内氢键和O-H…O分子间氢键。     

Effects of organic solvents on the structure stability of TS-1 for the ammoximation of cyclohexanone

The effects of organic solvents on the ammoximation of cyclohexanone to cyclohexanone oxime with H₂O₂and NH₃ over TS-1 were studied. To investigate the effects of ammonia and organic solvents on the structure stability of the catalyst, TS-1 samples were pretreated under severe conditions in ammonia solution or ammonia solution plus methanol, toluene or t-butanol, respectively, and then characterized bySEM, XRD, FTIR, etc. The results revealed that t-butanol is the best solvent for the ammoximation reaction; ammonia tends to destroy the active sites, -Ti-O-Si- structure in TS-1, but the presence of organic solvents remarkably limits this damaging effect of ammonia.     

三烃基锡肟类化合物的合成及生物活性

共合成了１３个未见文献报道的三烃基锡肟衍生物，测定了它们的＾１ｈ，（＾１３Ｃ，＾１１９Ｓｎ）ＮＭＲ，ＩＲ和ＭＳ。结果表明此类化合物为四配位锡单体结构，生物活性测定结果表明部分化合物同时兼有杀菌、杀螨、除草多种活性。     

Rearrangement ofO-perfluoroisobutenylacetone oxime. The structure of 2,2-bis(trifluoromethyl)-5-methyl-gD4-pyrrolin-3-one

Dehydrofluorination ofO-(-hydroperfluoroisobutyl)acetone oxime affords 2,2-bis(tri-fluoromethyl)-5-methyl-⁴-pyrrolin-3-one; the molecular structure of the latter was unambiguously established by X-ray diffraction method.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 951–953, May, 1994.     

Synthesis of new pyrrolo-[3,4-c]isoxazole, pyrrolo[2,3-d]-[1,2,3]triazole, triazolo[4,5-c]-pyridazine, and dipyrrolo-[3,2-b:3′,4′-d]pyran derivatives

New pyrrolo[3,4-c]isoxazole derivatives were synthesized from the key intermediates 4-cyanopyrrolidin-3-ones in two steps. Pyrrolo[2,3-d][1,2,3]triazoles and triazolo[4,5-c]pyridazine were obtained from 2-arylhydrazono-4-cyano-1-(4′-methoxyphenyl)-3-oxopyrrolidines by refluxing with phenylhydrazine in either ethanol or glacial acetic acid. Aldol self-condensation of 1-aryl-4-cyanopyrrolidin-3-ones afforded dipyrrolo-[3,2-b:3′, 4′-d]pyran derivatives. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1841–1848, December, 2007.     

Deactivation and regeneration of the B2O3/TiO2-ZrO2 catalyst in the vapor phase Beckmann rearrangement of cyclohexanone oxime

The deactivation and regeneration of B₂O₃/TiO₂-ZrO₂ catalyst for the vapor phase Beckmann rearrangement of cyclohexanone oxime to -caprolactam were studied. The fresh, deactivated and regenerated catalysts were characterized by using adsorption of nitrogen, X-ray diffraction (XRD), thermogravimetry (TG) and NH₃-temperature-programmed desorption (NH₃-TPD) techniques. The crystal structure and pore size distribution of the catalyst were retained after reaction, but the number of acid sites decreased significantly. There was a relationship between the amount of coke deposited on the catalyst and the decline in catalytic activity. These results suggest that the coke deposition on the surface of catalyst is mainly responsible for the catalyst deactivation. The catalytic activity can be recovered completely after calcining the deactivated catalyst in air flow at 600 °C for 8 h.     

Homogeneous liquid-liquid extraction method for the selective separation and preconcentration of ultra trace molybdenum

A new simple and efficient homogeneous liquid-liquid extraction method for the selective separation and preconcentration of molybdenyl ions was developed. α-Benzoin oxime (ABO) was investigated as a complexing ligand, and perfluorooctanoate ion (PFOA⁻) was applied as a phase-separator agent under strongly acidic conditions. Under the optimal conditions ([ABO] = 2.1 × 10⁻³ M, [PFOA⁻] = 1.8 × 10⁻² M, [HNO₃] = 1.7 M, [acetone] = 11.8% (v/v)), 10 μg of molybdenum in 5 ml aqueous phase could be extracted quantitatively into 40 μl of the sedimented phase. The maximum concentration factor was 125-fold. Thiocyanate was applied as a chromogenic reagent for the direct spectrophotometric determination of molybdenum in the sedimented phase. The reproducibility of the proposed method is at the most 2.4%.The influence of the type and concentration of acid solution, the concentration of ABO, the type and volume of the water-miscible organic solvent, the concentration of PFOA⁻, and the effect of different diverse ions on the extraction and determination of molybdenum(VI) were investigated. The proposed method was applied to the extraction and determination of molybdenum(VI) in natural water, Spinach, and Lucerne samples. A satisfactory agreement exists between the results obtained by the proposed method and those reported by GF-AAS.     

2-Trif luoromethyl-4H-thiochromen-4-one and 2-trif luoromethyl-4H-thiochromene-4-thione: Synthesis and reactivities

2-Trifluoromethyl-4H-thiochromene-4-thione obtained from 2-trifluoromethyl-4H-thiochromen-4-one and P₂S₅ reacts with aromatic amines, hydrazine hydrate, phenylhydrazine, and hydroxylamine at the C(4) atom of the chromene ring to give the corresponding anils, azine, hydrazones, and oxime of thiochromone. 2-Trifluoromethyl-4H-thiochromen-4-one is oxidized by hydrogen peroxide in AcOH into 4-oxo-2-trifluoromethyl-4H-thiochromene 1,1-dioxide and reduced by NaBH₄ to 2-trifluoromethyl-4H-thiochromen-4-ol or cis-2-(trifluoromethyl)thiochroman-4-ol. When treated with hydrazine hydrate, thiochromen-4-one gives 3(5)-(2-mercaptophenyl)-5(3)-trifluoromethylpyrazole. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 504–509, March, 2006.