离子色谱法测定酸雨中的阳离子

用离子色谱法测定酸雨中的Na^ 、NH4^ 、K^ 、Mg^2 、Ca^2 等阳离子，并同时用原子吸收分光光度法进行了对比实验。结果表明，利用离子色谱法测定阳离子，方法简便、快捷，能一次同时测定多种离子，测定结果和原子吸收法相符。     

氢转移反应HNCO+CH_x(x=1～3)的MP2和QCISD计算研究

在UMP2（FULL）/6-311（d,p）计算水平上,计算并讨论了碳氢自由基(CH_x) 和异氰酸（HNCO）发生氢转移反应位能面上驻点的结构和分子结构变化,并依据 UMP2的优化构型,进一步采用UQCISD（T）方法对反应途径上的驻点进行了单点能 量计算。研究指出,HNCO同CH_2,CH_3自由基反应时,氢转长期过程在分子间以新 的C-H键生成和旧的N-H键的断裂的协同方式进行,反应途径上均存在弱的氢键超分 子复合物;而HNCO和CH分子之间发生的氢转移反应机理是在反应剖面的反应物一边 生成一个较稳定的分子复合物HNJ（CH）CO,而后,在生成物一边又生成一个既有 热力学又有动力学稳定的复合物H_2CNCO。     

新型尼龙214,414,614,814,1014和1214的合成与表征

用熔融缩聚法基于十四碳二酸合成了一系列偶偶尼龙，包括尼龙2 14，4 14， 6 14，8 14，10 14，12 14。用红外光谱、元素分析、核磁共振、差示扫描热分析 、热失重分析、热机械分析、粘度法对合成尼龙的结构与性能进行了表征。同时还 初步研究了尼龙12 14的物理性能，发现其物理性能介于尼龙66和聚乙烯之间。     

Cyclodehydration of 1,4-butanediol catalyzed by metal(IV) phosphates

Metal(IV) phosphates of tin, zirconium and titanium in different morphological forms, viz. amorphous, calcined and crystalline, have been used as catalysts for selective cyclodehydration of 1,4-butanediol to tetrahydrofuran. A comparative study of the three catalysts for the above reaction has been carried out to understand the effect of their composition and morphology on the catalytic activity.     

Culture conditions dictate protease and tannase production in submerged and solid-state cultures of Aspergillus niger Aa-20

Undesirable protease production by Aspergillus niger Aa-20 in submerged culture and solid-state culture was evaluated using different concentrations of tannic acid as sole carbon source in a model system designed for tannase production. Protease production was found to be dependent on the culture system used (submerged culture or solid-state culture) and on the initial tannic acid concentration. Expression of protease activity in submerged culture was higher (up to 10 times) than activity obtained in solid-state culture, using identical culture medium composition. In submerged culture, the lowest final protease activity (0.13 IU) was obtained with the highest tannic acid concentration, while in solid-state culture protease activity was not affected by changes in initial substrate concentration. Absence of detectable proteolytic activity in solid-state culture is related to high production of tannase enzyme. Hence, the use of solid-state culture for fungal enzyme production may allow for higher and more stable enzyme titers present in culture extracts.     

Synthesis of Cholesteryl Esters of Heterocyclic Analogs of Cinnamic Acid and Hetaroyloxycinnamic Acids by the Wittig Reaction

The reaction of cholesteryl triphenylphosphonioacetate chloride with heterocyclic aldehydes and hetaroyloxyarenecarbaldehydes in the presence of base gave the corresponding cholesteryl esters of substituted propenoic acids possessing liquid crystal properties.     

Synthesis and properties of organosoluble poly(amide imide imide)s based on tetraimide dicarboxylic acid condensed from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline,and trimellitic anhydride and various aromatic diamines

A novel tetraimide dicarboxylic acid was synthesized with the ring‐opening addition of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline, and trimellitic anhydride in a 1/2/2 molar ratio in N‐methyl‐2‐pyrrolidone followed by azeotropic condensation to tetraimide dicarboxylic acid. A series of poly(amide imide imide)s (PAIIs) with inherent viscosities of 0.8–1.1 dL/g were prepared from tetraimide dicarboxylic acid with various aromatic diamines by direct polycondensation. Most of the PAIIs were readily soluble in a variety of amide polar solvents and even in less polar m‐cresol and pyridine. Solvent‐cast films had tensile strengths ranging from 99 to 106 MPa, elongations at break ranging from 8 to 13%, and initial moduli ranging from 2.0 to 2.3 GPa. The glass‐transition temperatures of these PAIIs were recorded at 244–276 °C. They had 10% weight losses at temperatures above 520 °C in air or nitrogen atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1092–1102, 2002     

Cationic copolymerization of indene with styrene derivatives: Synthesis of random copolymers of indene with high molecular weight

Random copolymers with high molecular weights of indene and p‐methylstyrene (pMeSt) were synthesized by cationic polymerization with trichloroacetic acid/tin tetrachloride in CH₂Cl₂ at low temperatures. When indene and pMeSt (1:1 v/v), for example, were polymerized at ?40 °C, both monomers were consumed at very similar rates to give a copolymer with high molecular weight [number‐average molecular weight (M_n): 8–9 × 10⁴]. This is indeed quite unexpected behavior for the combination of these two monomers because pMeSt polymerized over 1000 times faster than indene in the homopolymerization under the reaction conditions previously described. The product copolymer of indene and pMeSt had a random monomer sequence in it that was confirmed by NMR analyses and thermal‐property measurements. In sharp contrast with pMeSt, styrene and p‐chlorostyrene, which have no electron‐donating groups on the phenyl ring, led to low molecular weight polymers (M_n < 10,000) in the copolymerization with indene (1:1 v/v). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2449–2457, 2002     

A convenient one-pot synthesis of N-fused 1,2,4-triazoles via oxidative cyclization using chromium (VI) oxide

A facile one-pot synthesis of N-fused 1,2,4-triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by chromium (VI) oxide to afford the desired products mostly in high yields and in relatively short time. The high yield of the products and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.     

Novel two step synthesis of bis/Mono 1-aryl-1H-tetrazole-5-carboxylic acid

Some novel compounds of bis/mono 1-aryl-1H-tetrazole-5-carboxylic acid are synthesized by the hydrolysis of two different synthesized esters, they are ethyl-1-aryl-1H-tetrazole-5-carboxylate and ethyloxo(1-aryl-1H-tetrazol-5-yl)acetate. The ethyl-1-aryl-1H-tetrazole-5-carboxylate is resistant to get hydrolyzed, whereas the ethyloxo(1-aryl-1H-tetrazol-5-yl) acetate undergoes hydrolysis process and converts the ester to title compound. All the synthesized compounds are characterized by IR, ¹H and ¹³C NMR, mass and elemental analysis.The ethyl-1-aryl-1H-tetrazole-5-carboxylateis optimized by DFT B3LYP method and the HOMO and LUMO energy is 5.14?eV and also there is a formation of a weak bond between O₁₈ and C₈ as observed from the AIM analysis result.