Gamma,delta-unsaturated beta-diketones by acylation of ketones

[reaction: see text] Gamma,delta-unsaturated beta-diketones have been prepared by the acylation of ketones with N-acylbenzotriazoles of various aliphatic and aromatic alpha,beta-unsaturated carboxylic acids.     

Polarographic study of the dipropyldithiophosphinate complexes of Pd(II), Pb(II), Cd(II), and Zn(II) ions

The complexes of the dithiophosphinic acids with Pd(II), Pb(II), Cd(II), and ZN(II) in a toluene-ethanol medium produce single polarographic waves. The half-wave potential is a linear function of the ligand concentration. The stabilities of these chelates, which are characterized by a sulphur-metal bond, are in the order: Pd(II) > Pb(II) > Cd(II) > Zn(II).     

Synthesis of benzothiazoles via ipso substitution of ortho-methoxythiobenzamides

An efficient route to the synthesis of benzothiazoles from ortho-methoxythiobenzamides via the ipso substitution of an aromatic methoxy group is presented, and the mechanism of the Jacobson synthesis of benzothiazoles is further investigated.     

HNCS与C_2H(X~2Π)反应微观动力学的理论研究

用量子化学密度泛函理论的UB3LYP/6-311 G鄢鄢方法和高级电子相关的UQCISD(T)/6-311 G鄢鄢方法研究了异硫氰酸(HNCS)与乙炔基自由基(C2H(X2Π))反应的微观机理.采用双水平直接动力学方法IVTST-M,获取反应的势能面信息,应用正则变分过渡态理论并考虑小曲率隧道效应,计算了在250～2500K温度范围内反应的速率常数.研究结果表明,HNCS与C2H(X2Π)反应为多通道、多步骤的复杂反应,共存在三个可能的反应通道,主反应通道为通过分子间H原子迁移,生成主要产物NCS C2H2.反应速率常数随温度升高而增大,表现为正温度效应.速率常数计算中变分效果很小.在低温区隧道效应对反应速率的贡献较大,反应为放热反应.     

Conversion of ammonia to dinitrogen in wastewater by Nitrosomonas europaea

Because Nitrosomonas europaea contains ammonia-oxidizing enzyme, nitrite reductase, and nitrous oxide reductase, the conversion of ammonia to dinitrogen was tried with different reaction conditions. In aerobic reaction conditions, ammonium was converted to nitrite (NO ₂ ⁻ ), while under oxygen-limiting or oxygen-free conditions, NO ₂ ⁻ -N formed from ammonia oxidation by N. europaea was reduced to N₂O and dinitrogen with 22% conversion. During denitrification, optimal pH for the production of N₂O and dinitrogen was found to be 7.0–8.0. Dinitrogen was not produced in acidic pH<7.0. A low partial oxygen pressure as well as oxygen-free conditions are favorable for high production of dinitrogen.     

Determination of tungsten in rocks and minerals by chelate extraction and atomic-absorption spectrometry

An atomic-absorption method for determination of tungsten in rocks and minerals is proposed. The method involves sample decomposition by acid digestion or by pyrosulphate fusion, followed by chelate extraction of tungsten by N-benzoylphenylhydroxylamine in toluene. Atomic-absorption measurements are made on the organic phase aspirated into a nitrous oxide-acetylene flame. Quantitative extraction with efficient separation from other elements is achieved in a single extraction from strong acid media. The method is rapid and reliable in terms of precision and accuracy and is applicable to rocks and minerals containing tungsten in the range from 100 ppm to 15%.     

Synthesis of trans-(3S)-amino-(4R)-alkyl- and -(4S)-aryl-piperidines via ring-closing metathesis reaction

[reaction: see text] trans-(3S)-Amino piperidines bearing various alkyl and aryl substituents at the C-4 position were synthesized via a ring-closing metathesis reaction. The absolute stereochemistry was controlled using a protected D-serine as a starting material. Stereoselective hydrogenation of allylamines provided trans-(3S)-amino-(4R)-alkyl- and -(4S)-aryl-piperidines. This procedure presents the first method for the asymmetric synthesis of 4-substituted 3-amino piperidines.     

Wolff Rearrangement of 2-diazo-1(2H)-naphthalenone induced by nonresonant two-photon absorption of NIR radiation

The irradiation of 2-diazo-1(2H)-naphthalenone (1), the common component of positive photoresists, with 800 nm pulses of ultrafast laser results in Wolff rearrangement via nonresonant two-photon absorbance of light. The 10% conversion of starting material resulting in the formation of methyl 1H-indene-3-carboxylate (2) was achieved after 11 min of irradiation of the methanol solution of 1 with an unfocused beam of a Ti:Sapphire laser operating at 1 kHz. The two-photon cross-section of the diazonaphthoquinone 1 at 800 nm was calculated to be sigma = 2.2 x 10-51 cm4 s photon-1 (0.2 GM).     

Derivative spectrophotometric determination of copper(II) in non-ionic micellar medium

A photometric method for trace analysis of Cu(II) with 1-(2-pyridylazo)-2-naphthol (PAN) in presence of a neutral surfactant, Triton X-100, has been reported in normal and derivative modes. The molar absorption coefficient () and Sandell's sensitivity (S) of PAN-Cu(II) complex at 555 nm is 5.21 x 10(4) l mol(-1) cm(-1) and 1.22 ng cm(-2) respectively. The detection limit of Cu(II) is 4.0 ng ml(-1) and Beer's law is obeyed in the range 0.08-4.00 mug ml(-1) of the analyte. Copper content of a number of commercially available alcoholic beverages, biological and standard alloy samples is reported. The results obtained are in excellent agreement with those obtained using AAS.