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131.
HongMinMA ZhanZhuLIU ShiZhiCHEN 《中国化学快报》2003,14(5):468-470
A new approach to synthesis of 6,7-dimethoxyisatin is reported.2-nitro-3,4-dimethoxy mandelonitrile in glacial acetic acid was treated with the solution of stannous chloride in hydrochloric acid to give 6,7-dimethoxyisatin in a high yield. 相似文献
132.
IntroductionOrganotincarboxylatesarewidelyusedasbiocides ,fungicideandashomogeneouscatalystsinindustry .1 6Inordertoexploretherelationshipsbetweenbiologicalactiv ityandstructure ,anumberofsuchmoleculeshavebeensynthesizedandstudiedinrecentyears .7 15Studieson… 相似文献
133.
KANG Qiao-xiang YANG Zhi-wang LI Cui-lin MA Heng-chang GUO Zhen WANG You-peng XU Da-hai LEI Zi-qiang 《合成化学》2004,12(Z1)
Oxidation of alcohols to the corresponding aldehydes or ketones is one of the most fundamental reactions in organic chemistry [1,2]. Some of the products of the oxidation exhibit an important role in the organic synthesis as well as pharmaceutical synthesis. In most reactions, the lanthanide complexes show satisfied catalytic activities for some compounds. Furthermore, there has been increasing interest in the lanthanide complexes and several reports have appeared in the literature [3, 4]. But the exploitation of these complexes for the oxidation of some organic substrates has been limited. Here we reported a method for the preparation and the catalytic properties as well as the recycling of lanthanide complexes in oxidation of alcohols.The synthetic procedure for the polymer supported lanthanide complexes is shown as following(scheme 1):●-NH2+CICH2COOH(C2Hs)3N→●-NHCH2COOHM=Ce(Ⅲ), Tb(Ⅲ), Sm(Ⅲ)scheme 1The oxidation of benzyl alcohol was carried out in the presence of iodosylbenzene by the polymer supported Ce(Ⅲ), Tb(Ⅲ) and Sm(Ⅲ) catalysts at 80℃ for 4.0h, the yields of benz-aldehyde are as following (table 1):Table 1 Oxidation of benzyl alcohol with the supported catalysts**Reaction condition: benzyl alcohol 0.1 mmol, iodosylbenzene 0.15mmol,catalyst 0.2mg, 80℃ for 4.0h in 1,2-dichloroethane.It can be seen from the table that the Tb(Ⅲ) complex shows higher catalytic activity for the oxidation of benzyl alcohol. Further investigation is now being carded on to optimize the results. 相似文献
134.
M. Akram N. U. Khattak A. A. Qureshi Arshid Iqbal K. Ullah I. E. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(2):429-435
Neutron induced radiography has been applied to the determination of boron concentrations in drinking water, collected from natural springs of Reshian and Muzaffarabad areas of Azad Kashmir, Pakistan, using CR-39 etched track detectors. The technique is based upon the simultaneous irradiation with thermal neutrons of a sample of unknown concentration and a standard of known boron concentration, fixed on a track detector. The subsequent counting of alpha and 7Li tracks in the detector resulting from the 10B(n,)7Li nuclear reaction is done after chemical etching. Boron concentration in the sample is determined by comparing 7Li and alpha-particle track density with that of a standard of known boron concentration. Boron concentrations in drinking water samples from Muzaffarabad and Reshian area of Azad Kashmir have been found to vary from (0.054±0.001) mg/l to (0.250±0.004) mg/l with an average of (0.16±0.002) mg/l. The observed concentration of boron in drinking water has been found to be less than the provisional Maximum Acceptable Concentration level (0.4 mg//l) of WHO. The drinking water from the reported area has been found to be within safe limits as far as boron related health hazards are concerned.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
135.
S. Z. Qureshi M. I. H. Helaleh N. Rahman R. M. A. Q. Jamhour 《Analytical and bioanalytical chemistry》1997,357(7):1005-1007
A spectrophotometric determination of trimethoprim is described based on the reaction of its amine group with persulfate
which acts as a strong oxidizing agent in alkaline media. The reaction produces a stable yellow colored compound after heating
in a boiling water bath for 30 min. At λmax 355 nm, Beer’s law is obeyed in the concentration range 10–60 μg ml–1 with a molar absorptivity of 2.7 × 103 l mol–1cm–1. The method is applied to formulations with sulfamethoxazole.
Received: 30 July 1996 / Revised: 16 October 1996 / Accepted: 22 October 1996 相似文献
136.
SHEN Jian-Ping MA Jun SUN Tie JIANG Da-ZhenDepartment of Chemistry Jilin University Changchun Jilin ChinaMIN En-ZeResearch Institute of Petroleum Processing Beijing China 《中国化学》1995,13(2):124-130
The effects of alkali metals (Na+,K+) on the exchange degree of Hβ zeolite under different conditions and the conversion of α(or β)-methylnaphthalene over the alkalized zeolites were studied. The results showed that the H+ of Hβ zeolite is totally replaced by the Na+ of NaCl solution, while partially exchanged by the K+ of KC1 solution, there is an exchange equilibrium between the H+ and K+ for Hβ zeolite (Si/Al=17.23) and the value of equilibrium is 88.39. The exchange degree also increases with increasing the Si/Al of the samples. It was suggested that these resluts are attributed to the electrostatic field in the pore of Hβ zeolite and the nature of zeolite and the properties of alkali metal. The isomerization of α(or β)-methylnaphthalene is the main reaction over the samples and it is more favour on the proper acid-base sites of KHβ zeolite. 相似文献
137.
通过仿真计算分析了激光在光束控制系统通道内传输所产生的热效应及其对远场光束质量的影响。激光传播由近轴波方程描述,用快速傅里叶变换技术求解;激光热效应引起的流场密度变化采用完全Navier-Stokes方程计算。计算给出了不同波长、不同吸收系数条件下的远场光斑情况。计算结果表明,在典型的工作条件和状态下,较高能量激光在光束控制系统通道内产生的热效应影响不容忽视,它会明显降低远场目标处的能量集中度,增大光斑的发散。 相似文献
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