Sharif Digital Repository

A modified carbon-paste electrode (CPE) is prepared by incorporating thionine-nafion supported on multi-walled carbon nanotube (MWCNT). The electrochemical behavior of dopamine (DA) and ascorbic acid (AA) on the surface of the modified electrode is investigated by cyclic voltammetry (CV). The results show that thionine effectively immobilized in the matrix of the paste by using an appropriate mixture of nafion/MWCNT under the ultrasonic condition. On the other hand, presence of nafion enhances the stability of the thionine supported by MWCNT in the composite electrode and improves the reproducibility of the surface of the modified electrode under renewing process by polishing. The results of... 

ZnO nanopowder has been successfully synthesized by a microwave-assisted solution approach using Zn(CH3CO2)2·2H2O and NaOH. The results obtained from X-ray diffraction (XRD), scanning electron microscopy (SEM) and transition electron microscope (TEM) show that the mean particle size is 30 nm. SEM and TEM micrographs of ZnO nanopowder also reveal that nanoparticles have spherical shape. Catalytic activity of ZnO nanopowder for O-acylation of alcohol and phenol has been investigated. The results show that the reaction time by using ZnO nanopowder has been reduced by almost 24 times with higher yield than ZnO bulk. © 2007  

With modified measuring procedure and measuring cell design in the drop profile tensiometer PAT, it became possible to study the rate of water evaporation through adsorbed or spread surface layers. This method was employed to measure the rate of water evaporation from drops covered by adsorbed layers of some proteins and surfactants, in particular n-dodecanol. It was shown that the formation of dense (double or condensed) adsorbed layers of protein and the formation of 2D-condensed n-dodecanol layer decrease the water evaporation rate by 20-25% as compared with pure water. At the same time, the adsorbed layers of ordinary surfactants (sodium dodecyl sulfate and nonionic ethoxylated... 

Heteropoly acid was found to be an effective and efficient catalyst for the ring opening reaction of epoxides with various aromatic amines to produce the corresponding β-amino alcohols in moderate to excellent yields in water. This method provides a new and efficient protocol in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst, and simple work-up procedure. © 2006  

A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups. © 2005 Elsevier B.V. All rights reserved  

Oxidation of aromatic alcohols to corresponding aldehydes and ketones have been carried out using molecular oxygen and FeCl3 supported on kieselguhr as catalyst in good yields. © 2005 Bentham Science Publishers Ltd  

In this work, the group contribution approach has been used in combination with the linear isotherm regularity (LIR) equation of state to estimate pvT properties of primary, secondary and tertiary alcohols, ketones and 1-carboxylic acid. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. We assume each of these organic compounds as a hypothetical mixture of methyl, methylene and a functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state (EOS) has been extended to such a hypothetical mixture. Three basic compounds, namely propane,... 

A novel combination between N-hydroxy phthalimide (NHPI) and a silica based cobalt (II) interphase catalyst (1) efficiently catalyzes the aerobic oxidation of various types of alcohols to the corresponding carbonyl compounds. The catalyst 1 shows high thermal stability and also could be recovered and reused in combination with NHPI for at least five reaction cycles without considerable loss of reactivity. © 2005 Elsevier B.V. All rights reserved  

Iodic acid supported on wet silica gel and K10 clay are used for the efficient oxidation of benzylic alcohols under microwave irradiation and solvent free condition  

Lithium perchlorate catalyzed the ring opening of epoxides with amines to provide the corresponding β-aminoalcohols in excellent yields with high regioselectivity. The reaction proceeds rapidly under mild and neutral conditions and worked well with primary, secondary, aliphatic, aromatic, and hindered amines in short times at room temperature, in the absence of solvent. © 2005 NRC Canada  

In this work the Ghotbi-Vera mean spherical approximation (GV-MSA) model, coupled with two different expressions for the cation-hydrated diameters, was used in predicting the mean ionic activity coefficients (MIAC) of electrolytes for a number of the mixed-solvent and mixed-salt electrolyte solutions at 25 °C. In all cases the cation diameters in solutions changed with concentration of electrolyte while the anion diameters were considered to be constant and equal to the corresponding Pauling diameters. In application of the GV-MSA model to the electrolyte systems, two different expressions were used for concentration dependency of cation-hydrated diameters, i.e., the GV-MSA1 and GV-MSA2... 

Acyclic and cyclic acetates of various alcohols and phenols were obtained in excellent yields under mild reaction conditions in the presence of a catalytic amount of sodium hydroxide under solvent-free conditions and microwave irradiation. Selective deprotection of acetate group from the corresponding phenolic compounds was carried out in the presence of LiClO4· 2H2O. Copyright © Taylor & Francis, Inc  

The second-order rate coefficients for aromatic nucleophilic substitution reaction between 1-chloro-2,4-dinitrobenzene and aniline have been measured in aqueous solutions of ethanol and methanol at 25°C. The plots of rate constants versus mole fraction of water show a maximum in all-aqueous solutions. The effect of four empirical solvent parameters including hydrogen bond donor acidity (α), dipolarity/polarizability (π*). normalized polarity (ETN), and solvophobicity (Sp) has been investigated. This investigation has been carried out by means of simple and multiple regression models A dual-parameter equation of log k2 versus Sp and α was obtained in all-aqueous solutions (n = 41, r = 0.962,... 

Purpose. Variable-Temperature Kinetics has been used to obtain the rate constants of the reaction at various temperatures during one kinetic run. Methods. Pseudo-first-order rate constants for the transesterification of procaine with aliphatic alcohols ethanol, n-propanol and tert-butanol were obtained by the fluorescence spectroscopy using the variable-temperature kinetics (VTK) method. Results. The activation parameters of the reactions were calculated (24-28 kcal.mol-1). The half-life of the procaine decreases in the ethanol solution compared with the other alcoholic solutions in the presence of sodium ethoxide. Conclusions. The investigation time of the reactions is reduced to one-tenth... 

The polymer supported hypochlorite ion is a facile selective oxidizing agent for the oxidation of various alcohols to aldehydes and ketones. Similarly it successfully oxidizes various Hantzsch type 1,4 - dihydropyridines to corresponding pyridines  

Effects of formulation parameters on the fractional release profile of diclofenac sodium from matrices having the manufacturing formulation ingredients are studied. As a content of cetyl alcohol (rate controlling agent) in the matrix increases, the fractional release decreases. The fractional release increases either by increasing sucrose content outside the granule or by decreasing sucrose content inside the granule. Results presented here indicate that as PVP content outside the granule or aerosil fraction inside or outside the granule in the matrix increases, the fractional release increases. The fractional release profiles of diclofenac sodium from matrices, when each ingredient is... 

Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields  

A remarkably fast microwave assisted selective oxidation of benzylic alcohols with calcium hypochlorite under solvent-free conditions is described