高效液相色谱法测定果酸

本文研究了反相高效液相色谱法同时分离和测定6种果酸的色谱条件,提出了有效提取果酸的方法,并对苹果梨、香水梨等样品进行了实际分析。结果表明,该法简更快速,具有较高的准确度和精密度。     

Eco-friendly synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles using alumina-sulfuric acid as a heterogeneous reusable catalyst

A cost-effective and eco-friendly synthesis of 2-aryl-1-arylmethyl-1H-benzimidazoles has been developed through the condensation of different aldehydes with o-phenylenediamine using alumina-sulfuric acid as a recyclable heterogeneous solid acid catalyst. Morphological properties of the catalyst have been investigated. Effect of different solvents and comparison of alumina-sulfuric acid with different acid catalysts have also been studied. A plausible mechanistic pathway has been proposed on the basis of the isotope labelling experiments where catalytic behaviour of alumina-sulfuric acid has been explained.     

Studies on Vinyl Polymerization: Polymerization of Methyl Methacrylate by Permanganate-Malonic Acid Initiator System

Aqueous polymerization of methyl methacrylate initiated by the permanganate-malonic acid redox pair has been studied under atmospheric conditions in the temperature range of 35 to 45°C. The effect of monomer, permanganate, and malonic acid concentrations and temperature on the rate of polymerization was studied. The effect of various water-soluble salts and solvents has been investigated. The rate of polymerization of the permanganate-malonic acid system was compared with the rates involved in various other systems consisting of oxalic acid, citric acid, and tartaric acid coupled with permanganate under similar conditions. The end-group of the polymer has been characterized by IR spectra. A suitable kinetic scheme has been proposed, and appropriate rate expressions have been derived on this basis and explained in the light of experimental findings.     

Polymers from 12-hydroxymethyltetrahydroabietic acid and its vinyl and acrylate esters

12-Hydroxymethyltetrahydroabietic acid has been homopolymerized by melt condensation and homopolyester has been obtained. Vinyl 12-hydroxymethyltetrahydroabietate has been prepared from 12-hydroxymethyltetrahydroabietic acid by vinyl interchange procedure with vinyl acetate, and has been homopolymerized, copolymerized with vinyl chloride, vinyl acetate, and terpolymerized with styrene and acrylonitrile. The acrylate ester of 12-hydroxymethyltetrahydroabietic acid also has been prepared from 12-hydroxymethyltetrahydroabietic acid and acrylyl chloride. The acrylate thus obtained has been homopolymerized and copolymerized with vinyl chloride and vinyl acetate. Polymers thus obtained have been characterized.     

Preparation and polymerization of a diisocyanate from the Diels-Alder adduct of levopimaric acid and acrylic acid

Starting from tetrahydroabietic acid the model compounds tetrahydroabietoyl chloride, 2-aminoethyltetrahydroabietate hydrochloride, and 2-isocyanatoethyltetrahydroabietate have been prepared. Carbamate and urea derivatives of the isocyanate have been prepared. A Diels-Alder adduct of levopimaric acid and acrylic acid has been prepared and converted to its diacid chloride. The β-aminoethyl ester hydrochloride has been synthesized and converted to a diisocyanate which has been polymerized with poly(tetramethylene glycol) and also with p-phenylenediamine. Dimerex resin, a technical polymerized rosin, has been similarly converted to a diisocyanate. This isocyanate has not proven to be useful as a polymer-forming intermediate.     

Studies on the Chemical Structure of llexolide A

A new tritcrpene glycoside,ilexolidc-A(Ⅰ),exhibiting cardiac activity,has been isolated from the root of ilex publcscens HorJk et Am.(Ⅰ) has been determined as a β-xyloside of iicxolic acid(Ⅱ),(Ⅱ) is also a new triterpenic acid,and its structure has been assigned as 18-dehydro-20-epi-ursolic acid by chemical reactions and physical methods.The stcreochcnrstry of iicxolic acid was mainly confirmed by X-ray single crystal diffraction method.     

Theoretical study of the interaction between C2H5OH and mordenite zeolite by periodic density functional theory method

The interaction of a single ethanol with pure‐silica and acid mordenite (MOR) has been investigated using density functional theory. Different interaction modes have been studied for three acid sites. All initial structures have been optimized by minimizing the total energy with respect to all lattice parameters and to the atomic coordinates. The nature of the ethanol–acid site complex has been discussed in detail. The strength of the adsorption is directly correlated to the local structural distortion of the MOR framework, especially of the acid site. By using partial density of states method, a detail in the distribution of density of states (orbital) has been obtained. An analysis of the differential charges has been performed, indicating substantial polarization effects for the acid site and for the ethanol molecule as well. Finally, the red‐shift of the harmonic OH stretching frequencies due to the interaction has been estimated. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Extraction of cations as salts of fatty acids : Analytical and chromatographic separation of beryllium from iron and aluminium

Quantitative extractions of aluminium and ferric ions are carried out in presence of butyric acid. A method has been given for quantitative extraction of beryllium from aluminium and ferric ion in presence of ethylenediaminetetra-acetic acid. Interference has been studied and interference due to phosphate has been avoided by addition of zirconium salt. The method has been applied to thc analysis of beryl.     

Uv-spectra of the copper chelate of quinoline-8-car-boxylic acid

A comparative study of the absorption spectra of an alcoholic solution of quinolinc-8-carboxylic acid, with and without NaOH and perchloric acid, and its copper chelates has been made and a probable electronic structure for the metal chelates of quinoline-8-carboxylic acid has been suggested.     

Analysis of the fatty acid from Bupleurum Chinense DC in China by GC-MS and GC-FID

Fatty acid of the root of the medicinal plant of Bupleurum Chinense DC in China has been investigated by gas chromatography combined with mass spectroscopy. After methyl-esterification, eight fatty acid compositions were identified by GC-MS. A simple and rapid determination of the fatty acid has been firstly developed by GC-FID. The derivatization condition was investigated in order to validate this method. Palmitic acid, palmitoleic acid, oleic acid and linoleic acid were analyzed simultaneously by internal standard method. The validity of method has been examined both experimentally with good recovery, intra-assay precisions and linearity. The quick and accurate method of capillary gas chromatography could be used for the analysis of the fatty acid from Bupleurum Chinense DC.     

Influence of Solvents on the Rate of Thermal Decomposition of Peroxydecanoic Acid

Thermal decomposition of peroxydecanoic acid has been investigated in various organic solvents. The reaction medium significantly affects the rate of peroxydecanoic acid thermal decomposition. It has been shown that primary homolytic decomposition of peroxy group is followed by induced radical chain decomposition reactions. The solvent nature influences both primary homolytic decomposition and secondary induced reactions. The correlation equations relating kinetic parameters of peroxydecanoic acid thermolysis and basic solvent properties have been derived.     

Iodometric determination of ascorbic acid by controlled potential coulometry

An iodometric method for the determination of ascorbic acid has been devised. The method is based on previously developed coulometric instrumentation. The stability of different ascorbic acid solutions has been studied and the best conditions have been established. Ascorbic acid has been determined in different kinds of samples but with the main interest on pharmaceutical preparations. Speqial regard has also been paid to the other constituents in such samples, with respect to possible interferences. The error of the coulometric method is about 0·1% and the time of an analysis is in the range 2–6 min.     

Exploratory analysis in thermodynamics of equilibria. Classification and prediction of benzoic acid strength in aqueous-organic solvents

Decisive rule for classification and prediction of benzoic acid strength from dielectric constant and Kamlet–Taft parameter of the mixed solvents (water–methanol, water–ethanol, and water–2-propanol) has been elaborated basing on the results of multivariate exploratory analysis. The rule has been verified using the independent experimental data on dissociation constant of benzoic acid in water–dioxane and water–dimethylsulfoxide mixtures. Two-parameter linear regression model of the Gibbs energy of benzoic acid dissociation as a function of the properties of aqueous-alcoholic solvents has been built, and the contributions of dielectric and cohesion medium properties to the decrease in the acid strength have been shown.     

Effects of solvation on partition and dimerization of benzoic acid in mixed solvent systems

The partition of benzoic acid between 0.1M perchloric acid solution and two kinds of mixed solvents has been carried out at 25 degrees C. The partition and dimerization constants of benzoic acid have been determined in the 1-octanol-benzene and 2-octanone-benzene systems. In both the mixed solvent systems, with increasing content of 1-octanol and 2-octanone in each mixed solvent, the partition constant of benzoic acid has been found to increase, and the dimerization constant of benzoic acid in each organic phase to decrease. These phenomena are attributable to solvation of monomeric benzoic acid by 1-octanol and 2-octanone molecules in each mixed solvent.     

Cerate oxidimetry: Oxidation of glycerol,glycol and other organic compounds

1. Oxidation ot tartronic acid has been studied and it has been shown that the oxidation of glycerol by ceric sulphate does not proceed via this acid by was presumed by earlier workers. 2. It has been shown that the oxidation of formic acid by pure ceric sulphate is negligible, but using chromium sulphate as catalyst, formic acid can be quantitatively oxidized. 3. Oxidation of glycol and glycerol can be carried out quantitatively either to the -formic acid stage or completely to carbon dioxide and water. A combination of the above provides a method for the estimation of the two compounds when present together in a mixture.     

荧光法快速测定邻苯二甲酸酯的总量

基于邻苯二甲酸酯在浓硫酸下荧光增强的原理构建了一种测定邻苯二甲酸酯总量的荧光分析新方法。 体系的荧光强度与邻苯二甲酸酯的浓度在5.00~600 μg/L的范围内呈线性关系,方法的检出限为0.57 μg/L,回收率在91.6%~105.1%之间。 该方法简单、快速、灵敏度高、线性范围宽。 用于塑料水杯和聚氯乙烯水管中邻苯二甲酸酯总量的测定,结果令人满意。     

Diterpenoids ofPulicaria salviifolia. III. The structure of salvicinin

The new diterpene acid salvicinin has been isolated from the epigeal part ofPulicaria salviifolia and its structure has been established as 15-acetoxy-6α-hydroxy-trans-cleroda-3,13-dien-19-oic acid. A capacity of salvicinin for undergoing lactonization in the presence of acetic anhydride has been revealed, and the lactone formed has been isolated and chracterized.     

8,10-二炔二十五碳酸LB膜的聚合

Langmuir-Blodgett膜(LB膜)具有特殊的功能和生物活性,在现代高技术中有广泛的应用^[1]。本文合成了一个长链炔酸-8,10-二炔二十五碳酸,并研究其LB膜的聚合。     

TLC separations of some metal ions with aqueous and aqueous-organic solvent systems containing formic acid

Summary The chromatographic behaviour of some metal ions on silica gel thin layers has been studied in aqueous formic acid and mixed aqueous-organic solvent systems containing formic acid. Many analytically important separations of cations have been achieved in varying concentrations of formic acid solution in DMSO, acetone, and methyl ethyl ketone. Semiquantitative determination of nine cations has also been attempted.The most suitable concentration range of acid for reliable and reproducible separations was found to be 0.1M to 1.0M.     

The role of 70-80% perchloric acid as oxygen donor and the oxidation potentials made available

A study has been made of the probable oxidation potentials provided by perchloric acid in the concentration range 70-80 %. The effect of acid concentration and temperature on the oxidation of chromium, vanadium, cerium, and manganese has been investigated. Available oxidation potentials appear to be 2.0-2.1 V or higher. The monohydrate of perchloric acid, HClO(4).H(2)O, containing 84.6% of perchloric acid, has been made commercially available and authorized for distribution by common carrier. It can be diluted to give acid concentrations from 73.6% (corresponding to HClO(4).2H(2)O) upwards. Perchloric acid mixed with sulphuric acid is equivalent to high concentrations of perchloric acid and can be used for dissolution of ores and destruction of organic matter.