Phase transfer catalyzed reactions on polymers

Linear high-molecular weight polyepichlorohydrin elastomer (PECH) was reacted with potassium Superoxide in benzene and benzene-dimethylsulfoxide solutions in the presence of 18-crown-6 as a phase-transfer catalyst. Elemental analysis, spectroscopic studies, and viscosity measurements showed that Superoxide ion attacks both the chloromethyl group leading to the formation of various oxygen-containing groups, and main chain, causing its rapid degradation. A reaction mechanism has been proposed which appears to be dependent on the solvent.Part 4: A.S. Gód, Polymer Bull. 5, 591 (1981)     

相转移催化法合成取代苯甲酸乳糖酯

采用相转移催化法合成了7个取代苯甲酸乳糖酯,通过IR、^1HNMR、元素分析确证了糖酯的结构,通过对糖酯化合物的^1HNMR图谱中糖环碳1位质子的化学位移及偶合常数,并结合红外图谱中糖环C-H的弯曲振动吸收,确证糖酯化合物均为β型异构体。     

Phase transfer catalyzed reactions of crosslinked chloromethylated polystyrene with vanillin

Chloromethylated polystyrene was reacted with vanillin under phase transfer catalyzed conditions. This reaction was performed under different conditions, including variations of the phase transfer catalysts, the reaction solvent, the type of base, the reaction time and temperature. In addition, the effect of the reaction technique (i.e., solid–liquid–liquid and solid–liquid–solid systems) on the reaction conversion was studied. Polymer-supported vanillin was evaluated for its utilization in polymer analogue conversions by performing condensation reactions of the aldehyde functionality with malononitrile, ethyl cyanoacetate, cyanoacetamide, cyanothioacetamide, 2-aminophenol, hydrazine hydrate and hydroxylamine hydrochloride. In all cases, the reactions were followed up by means of FTIR spectroscopic analysis.     

相转移催化法合成二芳基对苯双氧乙酰基二硫脲类衍生物

以苯二氧乙酸为原料，用相转移催化法合成了8个1，4－对苯双氧乙酰基双硫脲类化合物，用IR、^1HNMR及元素分析及其结构进行了表征，经初步生物活性测试发现其中大多数化合具有良好的植物生长调节活性。     

相转移催化D-甘露醇合成1,2-甘油二酯

以D-甘露醇为原料,经丙叉基保护、氧化还原、苄基保护、脱丙叉保护、醇的酰化、苄基的脱保护合成了1,2-甘油二酯,中间体和目标产物结构经过了IR和元素分析鉴定。考察了不同的萃取溶剂和相转移催化剂对重要中间体甘油醇缩丙酮合成的影响。最终采用价廉的、环境友好的乙酸乙酯作为萃取溶剂,相转移催化剂季铵盐四丁基硫酸氢铵的质量分数为0.1%时效果最佳,并选择了一锅法合成的路线。考察了缚酸剂对中间体3-氧-苄基甘油合成的影响。在最优条件下,实验选择有机碱三乙胺作为3-氧-苄基甘油合成的缚酸剂。最终1,2-甘油二酯产率达到49.3%。     

Cadmium in alkaline solution

This review is intended to up-date the literature which has appeared since the previous article by Armstronget al. [1] concerning the behaviour of the cadmium electrode in alkaline solution. In general the early literature will not be discussed since this is adequately covered elsewhere [2–7]. The wider aspects of the electrochemical behaviour of cadmium in various electrolytes can be found in the extensive review by Hampson and Latham [6].     

相转移催化D-甘露醇合成镇咳药左旋羟苯哌嗪

采用新路线新工艺,以廉价易得的D－甘露醇为原料、用相转移催化合成（＋）－甘油醛缩丙酮、（＋）－甘油醇缩丙酮。在7种相转移催化剂（PEG和季铵盐系列）中,PEG－400催化效果最好。     

Effects of solution viscosity on heterogeneous electron transfer across a liquid/liquid interface

Scanning electrochemical microscopy (SECM) is employed to investigate the effect of solution viscosity on the rate constants of electron transfer (ET) reaction between potassium ferricyanide in water and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in 1,2-dichloroethane. Either tetrabutylammonium (TBA⁺) or ClO₄⁻ is chosen as the common ion in both phases to control the interfacial potential drop. The rate constant of heterogeneous ET reaction between TCNQ and ferrocyanide produced in-situ, k₁₂, is evaluated by SECM and is inversely proportional to the viscosity of the aqueous solution and directly proportional to the diffusion coefficient of K₄Fe(CN)₆ in water when the concentration of TCNQ in the DCE phase is in excess. The k₁₂ dependence on viscosity is explained in terms of the longitudinal relaxation time of the solution. The rate constant of the heterogeneous ET reaction between TCNQ⁻ and ferricyanide, k₂₁, is also obtained by SECM and these results cannot be explained by the same manner.     

磷钨酸铋非均相催化合成乙酸环己酯

以乙酸酐与环己醇为原料,磷钨酸铋为催化剂,合成乙酸环己酯,考察了催化剂用量、反应时间、醇酐摩尔比对乙酸环己酯产率的影响。结果表明,磷钨酸铋催化活性良好,当乙酸酐的加入量为0.1 mol,醇酐摩尔比为1.2时,使用0.9 g催化剂,反应30 min后,乙酸环己酯收率可达到93.8%,且催化剂重复使用5次仍保持良好活性。产品经折光率和红外光谱进行了表征。     

Phase transfer catalysis of alkaline hydrolysis of n-butyl acetate: Comparison of performance of batch and micro-reactors

The hydrolysis of n-butyl acetate with aqueous sodium hydroxide was studied in the batch mode as well as in the continuous mode in a micro-reactor. The progress of the reaction was analyzed both with and without a phase transfer catalyst. The concentration of the unreacted sodium hydroxide in the aqueous phase was determined by titration with hydrochloric acid to monitor the progress of the reaction. The performance of the two systems is studied for different operating conditions, i.e. concentrations of reactants, stirring speeds (in batch mode) and flow rates (in continuous mode). Conditions are identified when the performance of the micro-reactor system is superior to that of the batch system. To understand this better the performance of a 1 mm channel and a 0.4 mm channel are compared with that of the batch reactor.     

Anodic oxide on silver in alkaline solution

Ag₂O and AgO formed by potentiostatic oxidation of silver in 0·1N KOH have been chemically analysed for the mean valency of silver ion. The anodic oxide formation proceeds in two stages and the silver ion in the oxide changes from Ag⁺ to Ag²⁺ at a transition potential. The reduction of AgO at constant cathodic current occurs via two potential arrests. The transition from the first to the second potential arrest, however, does not correspond to the complete reduction of AgO to Ag₂O.     

Electro-oxidation of methanol on copper in alkaline solution

The electro-oxidation of methanol on copper in alkaline solutions has been studied by the methods of cyclic voltammetry, quasi-steady state polarization and chronoamperometry. It has been found that in the course of an anodic potential sweep the electro-oxidation of methanol follows the formation of Cu^III and is catalysed by this species through a mediated electron transfer mechanism. The reaction also continues in the early stages of the reversed cycle until it is stopped by the prohibitively negative potentials. The process is diffusion controlled and the current-time responses follow Cottrellian behavior. The rate constants, turnover frequency, anodic transfer coefficient and the apparent activation energy of the electro-oxidation reaction are reported.     

The anodic oxidation of nickel in alkaline solution

The anodic oxidation of nickel in alkaline solution was studied by cyclovoltammetric and optical techniques. The range of the scanning potential effects the resulting voltammograms. A constant I-E diagram with anodic peaks at 130 and 270 mV (at scan rate 10 mV · s^?1) is obtained after multiple scanning from ?800 to + 1200mV. The layer of Ni(OH)₂ that is formed in the anodic cycle, is only partially reduced by cathodic polarisation. Growth of the Ni(OH)₂ film on Ni occurs by repeated oxidation and reduction. This occurs via oxidation of Ni to α Ni(OH)₂ and conversion of α Ni(OH)₂ to β Ni(OH)₂.     

The surface oxidation of pyrite in alkaline solution

The collector-less flotation of pyrite has been studied by conventional techniques and is correlated to the electrochemical behaviour of pyrite in alkaline solution (1m NaClO₄, pH 11). It was concluded that the initial oxidation of pyrite produces a hydrophobic sulphur rich surface together with hydrophilic iron hydroxide species. Also upon grinding, the surface is covered by hydrophilic species and therefore no significant flotation was obtained in the absence of a collector. However, collectorless flotation was readily obtained in an iron complexing solution like EDTA. This indicates that the remaining sulphur-rich layer is responsible for the floatability of pyrite under these conditions.     

Cellulose/chitin films blended in NaOH/urea aqueous solution

Regenerated cellulose/chitin blend films (RCCH) were satisfactorily prepared in 6 wt % NaOH/4 wt % urea aqueous solution by coagulating with 5 wt % CaCl₂ aqueous solution then treating with 1 wt % HCl. The structure, miscibility, and mechanical properties of the RCCH films were investigated by infrared, scanning electron microscopy, ultraviolet spectroscopies, X‐ray diffraction, tensile test, and differential scanning analysis. The results indicated that the blends were miscible when the content of chitin was lower than 40 wt %. Moreover, the RCCH blend film achieved the maximum tensile strength in both dry and wet states of 89.1 and 43.7 MPa, respectively, indicating that the tensile strength and water resistivity of the RCCH film containing 10–20 wt % chitin was slightly higher than that of the RC film unblended with chitin. Structural analysis indicated that strong interaction occurred between cellulose and chitin molecules caused by intermolecular hydrogen bonding. Compared to the mechanical properties of chitin film, those of the blend films containing 10–50 wt % chitin were significantly improved. This work provided a novel way to obtain directly chitin material blended in the aqueous solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1679–1683, 2002     

Hydrogen sorption in Pd monolayers in alkaline solution

Hydrogen adsorption/absorption at palladium monolayers (ML) deposited on monocrystalline Au(1 1 1) electrode was studied in 0.1 M NaOH solution. H charge isotherms demonstrated that adsorption started at potentials more positive than at thicker nanometric Pd/Au(polycrystal) deposits. Due to 3-dimensional deposit growth, absorption could be seen at all deposits thicker than 1 ML. Besides, H sorption at Pd/Au(1 1 1) monolayers was more reversible than at nanometric Pd/Au(polycrystal) deposits. Strong geometric and electronic effects due to the Au substrate were observed up to 5 Pd ML. Influence of benzotriazole (BTA) on H sorption was also investigated. BTA blocked H adsorption above 250 mV vs. RHE. At less positive potentials adsorbed BTA layer seemed to undergo a reorientation allowing H adsorption. Stationary and dynamic electrochemical impedance spectroscopy was used to obtain double layer capacitance and charge transfer resistance. BTA also promoted kinetically H sorption into Pd/Au(1 1 1) monolayer and Pd/Au(polycrystal) nanometric deposits.