Acceleration of Organic Reactions Using Microwave

The use of microwave technology in accelerating organic reactions has received intense attention leading to immense growth recently. Accordingly, we have been interested in improving the efficacy of organic processes by microwave irradiation. Here we report our results on the microwave assisted direct amide formation from carboxylic acid and amine, the hydrolysis of biopolymers, and nucleophilic aromatic substitution reaction. The reactions carried out under microwave irradiation, in general, …     

First synthesis of a malarial prototype: a fully lipidated and phosphorylated GPI membrane anchor

A strategy is described for syntheses of a fully lipidated and phosphorylated prototype of the GPI of Plasmodium falciparum, the causative agent of lethal cerebral, drug-resistant malaria. Orthoesters, prepared in four steps from d-mannose, and methyl α-d-glucopyranoside are the key starting materials. The latter furnishes the inositol moiety using Bender’s procedure, while the former gives the other four units of the pseudo-pentasaccharide. The strategy for installing the three biologically important acyl units of the phosphoinositide has been worked out. The critical, biosynthetically important C2-O-acyl group of the inositol is exceptionally stable, showing no tendency to migrate to the cis-related C3-OH in several test substrates.     

A Novel Green Synthesis of Quinolines through Acid-catalyzed Friedlander Reaction in Ionic Liquids

Quinoline derivatives were efficiently prepared through acid-catalyzed Friedlander reaction in ionic liquid ([bmim] [BF4]). It is shown that the proposed method is operationally simple and environmentally benign in that the reaction media and the catalyst can be recovered and be reused effectively for at least four times.     

影响β—环糊精及其衍生物对萘胺荧光增强效应的一些因素

研究一有机溶剂，无机盐，尿素对萘胺－β－环糊精及其衍生物荧光体系的影响，发现它们对萘胺有荧光增强效应，初步探讨了其中的作用机理。     

On Transition Structures for Hydride Transfer Step in Enzyme Catalysis. A Comparative Study on Models of Glutathione Reductase Derived from Semiempirical, HF, and DFT Methods

As a model of the chemical reactions that take place in the active site of gluthatione reductase, the nature of the molecular mechanism for the hydride transfer step has been characterized by means of accurate quantum chemical characterizations of transition structures. The calculations have been carried out with analytical gradients at AM1 and PM3 semiempirical procedures, ab initio at HF level with 3-21G, 4-31G, 6-31G, and 6-31G basis sets and BP86 and BLYP as density functional methods. The results of this study suggest that the endo relative orientation on the substrate imposed by the active site is optimal in polarizing the C4-Ht bond and situating the system in the neighborhood of the quadratic region of the transition structure associated to the hydride transfer step on potential energy surface. The endo arrangement of the transition structure results in optimal frontier HOMO orbital interaction between NADH and FAD partners. The geometries of the transition structures and the corresponding transition vectors, that contain the fundamental information relating reactive fluctuation patterns, are model independent and weakly dependent on the level of theory used to determine them. A comparison between simple and complex molecular models shows that there is a minimal set of coordinates describing the essentials of hydride transfer step. The analysis of transition vector components suggests that the primary and secondary kinetic isotope effects can be strongly coupled, and this prompted the calculation of deuterium and tritium primary, secondary, and primary and secondary kinetic isotope effects. The results obtained agree well with experimental data and demonstrate this coupling.     

Reactions of magnesium formate on supports

Thermal decomposition of supported magnesium formate has been studied by gas chro-matography.The reaction paths of decomposition of supported magnesium formate depend on thenature of the supports.For Mg(HCO_2)_2/HZSM-5,the zeolite behaves as a dehydration catalyst togive CO and H_2O at lower temperatures;when the zeolite is modified by phosphorus,the methanationreaction will be partly restrained.In the case of Mg(HCO_2)_2/AC,strong adsorption of CO_2 leadsto the formation of the shoulder peak of CO_2 at higher temperatures,however,CH_4 disappears aftermodified by phosphorus.For Mg(HCO_2)_2/Al_2O_3,the dehydrogenation of HCO_2~- takes place on thesurface of Al_2O_3.The decomposition of Mg(HCO_2)_2 on SiO_2 in hydrogen yields two peaks of COand only one appears after modified by phosphorus.When Mg(HCO_2)_2 decomposes on MgO,the firstpeak of CO_2 arises from the reaction of surface Mg~(2+) with HCO_2~- from dissociated Mg(HCO_2)_2.     

改性ZSM—5分子筛在甲苯一段硝化中的应用

对ＮａＺＳＭ－５分子筛进行改性，在其表面引入铁，镁离子，用作硝硫混酸对甲苯一段硝化反应的催化剂，明显提高产物中对硝基甲苯的生成比例，研究了影响反应结果的因素。     

丹宁纤维素富集-氢化物发生ICP-AES同时测定水中痕量锗

研究了丹宁纤维素富集10~(-11)g/ml级锗的条件,并考察了地下水中36种共存离子对磷酸介质中氢化物发生ICP-AES测定锗的干扰和消除,应用于测定地下水中的超痕量锗,结果满意,检出限为15ng/L。     

Suppressed Blinking in Single Quantum Dots (QDs) Immobilized Near Silver Island Films (SIFs)

In this report, we use single-molecule spectroscopic method to study emission behaviors of streptavidin conjugated quantum dots immobilized on biotinylated-BSA (bovine serum albumin) monolayer near non-continuous rough silver nanostructure. We observed greatly reduced blinking and enhanced emission fluorescence of quantum dots next to silver island films.     

Differential pulse polarographic determination of salicylaldehyde as its Girard-P derivative

A method for the determination of salicylaldehyde (2 × 10^–6–10^–4 M) by differential-pulse polarography, based on the in situ formation of its Girard-P derivative in aqueous solution at pH 2.5, is proposed. The relative standard deviation was 1.5% (ten determinations of 4 × 10^–5 M level). The applicability of this method was checked in synthetic samples containing salicyl alcohol,o-aminophenol, 2-methylphenol, salicylic acid and 4-aminobenzoic acid.