Effect of traces of water in the solvent on the heat of solution of terephthaloyl chloride in the amide-salt system

Conclusions The dependence of the heat of solution of terephthaloyl chloride in a mixture of dimethylacetamide and 3% lithium chloride on small amounts of water in the solvent (0.01–0.5% by wt.) has been determined, using a Calvet microcalorimeter. It has been shown that hydrolysis of the acid chloride takes place in the amide-salt system in the presence of water.A calorimetric method of determining small amounts of water in the solvent with high accuracy by use of a calorimetric method has been described.Translated from Khimicheskie Volokna, No. 6, pp. 16–17, November–December, 1983.     

Viscosity properties of cellulose solutions in dimethylacetamide containing lithium chloride

Conclusions The effect of solvent composition and temperature on the properties of dilute and concentrated solutions of cellulose in dimethylacetamide containing lithium chloride has been examined.Increasing the lithium chloride content of the solution leads to the appearance of an inflection on the reduced viscosity-concentration dependence in the region of low cellulose concentrations (0.3 g/dl), which disappears on the addition of 1% water (by wt.) to the solution.Translated from Khimicheskie Volokna, No. 4, pp. 26–28, July–August, 1986.     

Quantitative determination of the low-molecular fraction content of spinning solutions of poly-meta-phenyleneisophthalamide

Conclusions A method for the quantitative determination of low-molecular fraction content in spinning solutions of poly-meta-phenyleneisophthalamide in dimethylacetamide has been established and developed using UV-spectroscopy; this is a basic procedure.The effect of the composition of the reaction mixture on the LMF content of the spinning solution has been shown.VNIISV, Tver'. Translated from Khimicheskie Volokna, No. 2, pp. 17–19, March–April, 1992.     

Heterogeneity of the supermolecular structure of fibre based on polyamidobenzimidazole

Conclusions A study of the reaction of fibre based on polyamidobenzimidazole with a solution of triethylenediamine in dimethylacetamide using x-ray diffraction and acoustic methods has made it possible to reveal a heterogeneity in the supermolecular structure of the fibre.It has been found that reaction in the indicated system takes place in two stages, whose rates are different.Translated from Khimicheskie Volokna, No. 1, pp. 9–10, January–February, 1989.     

Kinetic characteristics of side reactions of isophthaloyl chloride during synthesis of poly-m-phenyleneisophthalamide

The kinetic characteristics of reactions of isophthaloyl chloride with water, N,N—dimethylacetamide, and isophthalic acid were investigated and the rate constants of these reactions were determined.All-Russian Scientific-Research Institute of Synthetic Fibers (Tver'). Translated from Khimicheskie Volokna, Vol. 25, No. 1, pp. 11–12, January–February, 1993.     

Investigation of the properties of a mixture based on the rigid-chain polyamidobenzimidazole and a flexible-chain thermoplastic polymer in dimethylacetamide by the sedimentation method

Conclusions -- The sedimentation character of PABI-S—thermoplastic polymer mixtures has been studied where these differ in molecular weight and in the thermodynamic stiffness of the chain; studies were in dimethylacetamide containing 3% by wt. lithium chloride.-- The character of the gradient curve shows that the stiff chain PABI-S fills the role of a matrix in change in polydispersity of the mixed system at PABI-S—thermoplastic ratios of 99:1, 95:5; 90:10; or 80:20%.-- The bimodality on the sedimentation curve for a PABI-S—thermoplastic mixture at a weight ratio of 50:50 indicates compositional nonuniformity.Translated from Khimicheskie Volokna, No. 4, pp. 16–17, July–August, 1991.     

Corrosion of stainless steels in the dimethylformamide media of polyvinyl chloride fibre manufacturing

Conclusions The effect of individual components, temperature, and the gas medium on the corrosion properties of dimethylformamide media in the manufacture of polyvinyl chloride fibre has been investigated. It has been shown that the corrosive activity is caused by the joint action of chlorides and the acid components of the technological media. The corrosive activity of the media rises with increase in temperature and depends on the conditions of existence of the gas phase.In the case of the stillpot liquid, the mechanism of DMF hydrolysis in closed and open systems has been studied. It has been found that in a closed system hydrolysis of DMF is inhibited by the dimethylamine released. In an open system, inhibition of the hydrolysis does not occur. A specific effect of sulfuric acid on the hydrolysis of DMF in an open system has been found.The corrosive activity of media in the most corrosive-hazardous sections of the technological scheme in operating manufacture is considerably reduced by the introduction of measures to reduce the acid and chloride content of the technological media.Translated from Khimicheskie Volokna, No. 4, pp. 47–49, July–August, 1986.     

Characterization of hydrogen evolution on cobalt electrodeposits in water electrolysis

The hydrogen evolution reaction (HER) on cobalt electrodes has been investigated in both alkaline (30 wt% KOH) and acid (1m H₂SO₄) media at 25°C. The electrocatalytic cobalt materials were produced under different electrodeposition conditions, namely deposition in the absence or presence of bubbling oxygen or nitrogen gas with two gas flow rates (80 and 230 ml min^–1) and at different current densities (50–800 A m^–2) and deposition in a cobalt powder-containing bath. It has been shown that the electrocatalytic behaviour of the cobalt deposits can be significantly affected by deposition current density via a change of surface area of the cobalt deposits. A considerable HER overpotential decrease (up to 150mV) has been achieved on the highly porous and active cobalt electrodes deposited in the presence of bubbling oxygen and chloride ions in deposition solution. However, the HER overpotential was increased on the cobalt electrodes deposited with bubbling nitrogen in the bath.     

Electroreduction of hexachlorobenzene in protic solvent at Hg cathodes

The electrochemical reduction of hexachlorobenzene (HCB) to lower chlorinated benzenes has been studied in methanol solution. Differential pulse voltammetry at a sessile mercury drop cathode showed four reduction waves at E=–1.13, –1.33, –1.57 and –1.84V vs the standard hydrogen electrode, corresponding to sequential reduction to penta-, tetra-, tri- and dichlorobenzenes, respectively. The formation of these products was followed with time using a recirculating flow-through cell; the isomer distributions of the lower chlorinated benzenes were as predicted from a mechanism involving chloride elimination from radical anion intermediates. A maximum current efficiency of 60% was achieved in single-pass experiments in which the potential was controlled near the peak of the first reduction peak (–1.2V) and the initial concentration of HCB was 1mm.     

Effect of sulfuric acid concentration in the precipitation bath on the efficiency of modifier action in the preparation of viscose fibres

Conclusions The modifying power of polyethylene glycols (PEG-35 and PEG-115), an ethoxylated amine, dimethylamine, and sodium carbamate has been investigated under conditions which model the spinning of viscose fibres.It has been shown that the maximum modifying power is observed at a sulfuric acid content of 40–60 g/liter in the precipitation bath.On the basis of an analysis of diffusion kinetics, the suggestion has been made that the weak modifying ability at a sulfuric acid concentration below 40 g/liter in the precipitation bath is explained by an alkaline medium; and the weak modifying power at a concentration above 60 g/liter, by a strongly acid medium on the surface of the forming fibre.Translated from Khimicheskie Volokna, No. 3, pp. 48–49, May–June, 1989.     

Production of hydrogen-rich gas via reforming of iso-octane over Ni–Mn and Rh–Ce bimetallic catalysts using spray pulsed reactor

The conversion of hydrocarbon fuels such as gasoline and diesel is a potential source for hydrogen production towards various fuel cell systems. A novel spray pulsed mode reactor to create alternate wet and dry conditions on the catalyst surface has been used in this study to enhance the rates of hydrogen production compared with the solid-gas phase reaction due to the improvement of the catalyst reactant contact. The production of hydrogen-rich gas by reforming of iso-octane (2,2,4-trimethylepentane) in the presence of steam and air has been studied at 600 and 700 °C over Ni–Mn and Rh–Ce bimetallic catalysts supported on alumina mesh. The feed rate of iso-octane was varied from 0.553 to 5.53 m mol min^–1 by controlling pulse injection in terms of the width and frequency of injection of iso-octane. Based on the product analysis optimized condition for higher hydrogen production and high H₂/CO ratio has been deduced.     

Side-reactions in the synthesis of poly-m-phenyleneisophthalamide

Conclusions -- The side reactions which occur during the process of poly-m-phenyleneisophthalamide synthesis have been investigated qualitatively and quantitatively by the liquid-chromatography method.-- It has been found that the main side reactions are hydrolysis of isophthaloyl chloride in the N,N-dimethyl acetamide medium, reaction of isophthaloyl chloride with N,N-dimethyl acetamide, and also condensation of the isophthaloyl chloride with isophthalic acid.Translated from Khimicheskie Volokna, No. 4, pp. 12–13, July–August, 1991.     

Reaction of triethylenediamine solutions with aramide fibres

Conclusions An extremal character for solubility and change in supermolecular structure of polyamidobenzimidazole fibres as a function of the concentration of a solution of triethylenediamine in dimethylacetamide has been established, while fibres based on poly-p-phenyleneterephthalamide remain inert to the action of these solutions.The suggestion has been offered that the differences in behavior of the indicated fibres are caused by the presence of the benzimidazole groups in the polyamidobenzimidazole molecules.Translated from Khimicheskie Volokna, No. 5, pp. 43–45, September–October, 1988.     

Kinetic modelling of methylcyclohexane ring-opening over a HZSM-5 zeolite catalyst

A kinetic model is proposed in order to quantify product distribution in the ring-opening (using high hydrogen concentration in the reaction medium) of methylcyclohexane (MCH) over a catalyst based on HZSM-5 zeolite. The model is based on a reaction scheme proposed by Cerqueira et al. for methylcyclohexane cracking at atmospheric pressure, which has been modified in order to include the effect of hydrogen over the individual reaction steps. The experimental results used for estimating the kinetic constant were obtained in a fixed bed isothermal reactor in a wide range of conditions, i.e. 250–450 °C; WHSV = 0.5–10.5 h⁻¹ (τ = 0.095–2 g_cat h g_MCH⁻¹); pressure = 5–80 bar; H₂/MCH molar flow ratio = 4–79; conversion = 0–100%. The kinetic model proposed can be regarded as a basis for the proposal of models for ring-opening reactions of more complex naphthenic feedstock from a prior hydrogenation step involving aromatic refinery streams of secondary interest.     

Mass-transfer processes in sorption of gases by VION AN-1 and VION AS-1 fibres

Conclusions Coefficients of internal diffusion and of mass-transfer have been measured in the sorption of hydrogen chloride, nitrogen dioxide, and iodine by weakly basic and strongly basic chemisorptive fibres.A large effect of moisture content and basicity of the chemisorptive fibres on mass-transfer processes in the sorption of gases has been demonstrated.Translated from Khimicheskie Volokna, No. 6, pp. 9–10, November–December, 1988.     

Kinetic relationships in acylation of thermal amino groups in reaction solutions of poly-m-phenyleneisophthalamide

Conclusions The kinetics of acylation of amino groups in acid reaction solutions of poly-m-phenylene-isophthalamide oligomers (or polymer) has been examined. The course of the process is described by zero order with respect to amino group concentration. The rate of acylation is determined by the acylating properties of the dimethylacetamide-hydrogen chloride system.Similar kinetic relationships were found for m-phenylenediamine. The reactivity of the terminal amino groups hardly changes on transition from m-phenylenediamine to PMPI oligomer (polymer), apparently due to the fact that the course of the process is limited by the properties of the acylating system.It has been shown that reduction in acidity or in medium temperature reduces the contribution of this reaction to termination of the PMPI polymer chain and correspondingly raises the quality of the reaction solutions.Translated from Khimicheskie Volokna, No. 6, pp. 15–17, November–December, 1989.     

A facile and efficient method for preparation of chiral supported poly(styrene–divinylbenzene) copolymers

A new and efficient method for preparation of optically active poly(styrene–divinylbenzene) copolymers (PS-DVB) is presented here. This is carried out by Friedel–Crafts acylation reaction of chiral N-phthaloyl -leucine acid chloride with PS-DVB beads in the presence of aluminum chloride as Lewis acid catalyst and 1,2-dichloroethane as the solvent at ambient temperature. Reagents’ amounts and reaction conditions are mentioned and four samples with different amounts of functionality have been prepared. Final products were characterized by FT-IR and elemental analysis. The results obtained confirm that the above modification in preparation of chiral supported PS-DVB has been achieved well and in moderate yield.     

高纯度二甲基二烯丙基氯化铵的制备

以二甲胺和烯丙基氯为原料,制备高纯度二甲基二烯丙基氯化铵(DMDAAC).将第一阶段(叔胺化反应)分两步投料:第一步是二甲胺与烯丙基氯按物质的量的比为1∶0.5投料;第二步是继续滴加烯丙基氯和氢氧化钠,投料比为n(二甲胺)∶n(烯丙基氯)∶n(氢氧化钠)=1∶0.5∶1.采用气相色谱和pH酸度计监控传统一步法与该合成方法,并以聚合产物聚二甲基二烯丙基氯化铵(PDMDAAC)的特征粘度衡量DMDAAC聚合性能.结果表明,第一阶段体系维持pH≤l1,该合成方法所得DMDAAC中各杂质的含量均下降了60％ ～ 70％,季胺化反应控制在6h为宜,PDMDAAC特征粘度稳定在1.6 ～2.2 dL/g,DMDAAC聚合性能较好.     

The electrochemical hypochlorination of allyl chloride in dilute HCl solution

The electrochemical hypochlorination of allyl chloride has been studied. It was found that the reaction is best effected using 1 to 1.5 N HCl as the electrolyte, introducing allyl chloride as an emulsion and working at low current density (< 150 mA cm^–2).     

Determination of dimethylacetamide content of aqueous-organic solutions from manufacturing man-made fibres

Conclusions It is possible to determine the dimethylacetamide (DMAc) content in aqueous and aqueous-organic solutions by the potentiometric titration method after completely tying up water with acetic anhydride.The procedure developed permits one to determine DMAc in the concentration range 10–80% with a high accuracy and reproducibility. The procedure can also be used to determine dimethylformamide in aqueous or aqueous-organic solutions.Translated from Khimicheskie Volokna, No. 3, pp. 55–56, May–June, 1988.