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大孔交联聚(对乙烯基苄基苯基醚)树脂对苯酚的吸附机理 总被引:1,自引:0,他引:1
由氯甲基化聚苯乙烯合成了大孔交联聚(对乙烯基苄基苯基醚)树脂(简称为苯基醚树脂), 测定了其对正己烷和水中苯酚的吸附等温线, 计算了吸附焓. 同时, 比较了聚(对乙烯基苄甲醚)、苯基醚树脂、聚(对乙烯基苄基对硝基苯基醚)和聚(对乙烯基苄基对甲基苯基醚)对正己烷中苯酚的吸附性能以及氯甲基化聚苯乙烯和苯基醚树脂对水中苯酚、2,3,5-三甲基苯酚和对硝基甲苯的吸附性能. 结果表明, 苯基醚树脂是通过氢键吸附正己烷溶液中苯酚的, 而其对水中苯酚的吸附是基于氢键和疏水作用的协同. 相似文献
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A Grignard reaction of reactantA and phenyl magnesium chloride is used to make a pharmaceutical intermediate at the production scale. The elimination of protecting groups onA was proposed as a means to reduce synthesis costs. This new synthesis route, however, had process efficiency and safety issues associated with it: (1) build-up of unreactedA in the reactor, (2) influence ofA's particle size on the reaction rate, (3) the sensitivity of the reaction rate to the reaction temperature and to the (changing) solvent composition, and (4) the highly exothermic nature of the reaction.The Mettler RC1 Reaction Calorimeter was used to quantify the influence of solvent composition, temperature, and particle size on the reaction rate. Results indicated a dramatic effect of solvent composition and reaction temperature on the reaction rate; for example, over a temperature range of just 30°C, the reaction time decreased from more than a day to just a few minutes. At such high reaction rates, the vessel jacket could not remove the reaction heat sufficiently and the internal temperature rose adiabatically.These results were used to make process design and operation recommendations for safe and efficient plant operation with this modified Grignard reaction system.The authors would like to thank the following for their assistance in this work: E. Daugs for preparing the Grignard reagents, K.L. Gonzales for her help in running the experiments and in the subsequent data work-up; P.M. Russell for his assistance in the design of the slurry addition assembly, and K. Chritz and J. Engel for performing the HPLC analyses of the samples. 相似文献
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Maxim E. Dmitriev 《Tetrahedron letters》2010,51(19):2613-269
A new and milder version of the procedure for the synthesis of N-protected α-aminoalkylphosphorylic compounds by reaction of alkyl carbamates, aldehydes and hydrophosphorylic compounds in acetic anhydride/acetyl chloride and a new mechanism for this type of reaction are described. The isolation, for the first time, of N,N′-benzylidene- and N,N′-alkylidenebiscarbamates as intermediates from the reaction medium and studies of the direct reaction of pre-obtained biscarbamates and hydrophosphorylic compounds in acetic anhydride are reported. A new version of the mechanism for this reaction which includes an Arbuzov-type reaction is proposed. 相似文献
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提出反应类等键方法并用于高温燃烧机理中一类重要反应——烷基自由基β位裂解反应的反应势垒和速率常数的精确校正计算. 通过10种不同从头算水平对类反应中5个代表反应的反应势垒的计算发现, 用反应类等键反应方法和直接从头算方法获得的5 个代表反应的反应势垒最大绝对偏差的平均值分别为5.32 和16.16 kJ·mol-1, 表明反应类等键反应方法计算的反应势垒对不同水平从头算方法的依赖性小, 可在较低从头算水平计算得到精确的反应势垒, 解决大分子体系反应势垒的精确计算问题. 此外应用反应类等键反应方法在BHandHLYP/cc-pVDZ 从头算水平计算了3 个代表反应的速率常数, 并与文献报道的实验值进行了比较, 其在500-2000 K温度区间内计算速率常数与实验速率常数中较大值与较小值的比值kmax/kmin的平均值为1.67, 最大值也仅有2.49. 表明应用反应类等键反应方法在较低从头算水平即可对同类反应的速率常数进行精确计算.最后在BHandHLYP/cc-pVDZ从头算水平用反应类等键反应方法计算了13个烷基自由基β位裂解反应的速率常数. 相似文献
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Jianing Huang Jean-Pierre Leblanc H. K. Hall 《Journal of polymer science. Part A, Polymer chemistry》1992,30(3):345-354
Model reactions were carried out to simulate the acidolysis process for polyarylate synthesis by using p-tert-butylphenyl acetate (ptBuPhOAc) and benzoic acid in diphenyl ether. p-tert-Butylphenol was formed in the reaction mixture and its concentration stayed constant throughout the reaction. Acetic benzoic anhydride and benzoic anhydride were detected by NMR. Based on this experimental evidence, a mechanism for the acidolysis was proposed involving the mixed anhydride. The kinetics of the acidolysis reaction was studied for this model reaction. The overall reaction order is two and the reaction order with respect to each reactant is one. Second-order reaction rate constants were measured at different reaction conditions (200–250°C). The activation energy (Ea), activation enthalpy (ΔH≠), and activation entropy (ΔS≠) were calculated from these data. The thermodynamic parameters of the acidolysis reaction were also measured for the analogous reaction of p-tert-butylphenyl pivalate (ptBuPhOPiv) and benzoic acid. The kinetics of two other elementary reactions involved in the acidolysis reaction were also studied: p-tert-butylphenol with acetic anhydride or benzoic anhydride, and p-tert-butylphenyl pivalate with benzoic acid. 相似文献
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脯氨酸催化的不对称有机反应 总被引:1,自引:0,他引:1
脯氨酸作为一种结构简单、商品化的、廉价小分子手性催化剂,在多种不对称催化反应中表现出非常好的催化性能,本文综述了近年来脯氨酸直接催化的不对称有机反应涉及Aldol反应,Mannich反应,Michael反应,Diels-Alder反应,直接α-胺化反应,α-氧胺化反应,Baylis-Hillman反应,还原反应和氧化反应的进展并展望了其应用前景。 相似文献
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《The Chemical Engineering Journal》1993,51(3):167-176
The calculation of temperature vs. time sequences to palliate catalyst deactivation in an integral reactor has been studied either by maintaining constant the conversion at the reactor outlet in a simple reaction or by maintaining constant the concentration of a given component at the outlet in a complex reaction system. The experimental systems studied, which are a simple one (dehydration of 2-ethylhexanol) and a complex one (isomerization of cis-butene), have kinetic models of the Langmuir-Hinshelwood-Hougen-Watson type for the main reaction and deactivation, with deactivation by coke dependent on the concentration of the reaction components. In the reaction of dehydration of 2-ethylhexanol deactivation occurs in parallel with the main reaction and in the isomerization of cis-butene deactivation occurs in series-parallel with the main reaction. A parametric study has been carried out for both reaction systems. The sequences calculated have been experimentally proven in an automated reaction apparatus. 相似文献
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Microwave irradiation does not accelerate the rate of the Perkin reaction carried out under normal atmospheric pressure. Water is an essential yet catalytic reactant for the Perkin reaction to occur. Containment of the Perkin reaction in a sealed vessel improves the yield. Two pressure increases are observed during a 4 h reaction time. An induction period is seen in the Perkin reaction when sodium acetate is used as a base. A re-appraisal of the reaction mechanism is proposed on the basis of these observations. The use of PFA® reaction vessels enables the Perkin reaction to occur under aqueous conditions for around 80 reactions/vessel. 相似文献
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湿法脱硫中亚硫酸盐非催化氧化本征动力学 总被引:1,自引:0,他引:1
亚硫酸盐的氧化是湿法烟气脱硫工艺中的重要过程. 利用间歇式反应装置, 研究了亚硫酸盐非催化氧化的本征反应动力学. 结果表明, 该反应分为两个阶段进行, 即富氧区的快速反应和贫氧区的慢速反应. 在富氧区, 亚硫酸盐和溶解氧的分级数分别为1.0和1.0, 反应的表观活化能为49.3 kJ•mol-1; 在贫氧区, 亚硫酸盐和溶解氧的分级数分别为2.0和0, 反应的表观活化能为122.6 kJ•mol-1. 对反应的机理进行了预测, 结果与实验现象有较好的吻合. 相似文献
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We present nonadiabatic quantum dynamical calculations on the two coupled potential en-ergy surfaces (12A′ and 22A′) [J. Theor. Comput. Chem. 8, 849 (2009)] for the reaction. Initial state-resolved reaction probabilities and cross sections for the N+ND→N2+D reaction and N′+ND→N′D+N reaction for collision energies of 5 meV to 1.0 eV are determined, re-spectively. It is found that the N+ND→N2+D reaction is dominated in the N+ND reaction.In addition, we obtained the rate constants for the N+ND→N2+D reaction which demand further experimental investigations. 相似文献
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Study of the reaction between 1,5-naphtalene diisocyanate and polycaprolactone in different solvents
Meta Lesar Majda
igon Tatjana Malavai
《Journal of polymer science. Part A, Polymer chemistry》1995,33(10):1573-1580
The reaction between polycaprolactone and 1,5-naphtalene diisocyanate has been investigated in solvents with different dielectric constants and hydrogen bonding powers (toluene, ethyl acetate, ethyl methyl ketone), and in the same solvents with the addition of a catalytic amount of dimethyl sulfoxide (DMSO). The reaction was considered to proceed over two steps, the reaction of the first NCO group being faster. The course of the reaction was measured by titration of the unreacted NCO groups, 1H- and 13C-NMR spectroscopy, and size exclusion chromatography. By titration only the overall reaction order and reaction rate constants could be determined. DMSO accelerated the reaction in all three solvents, which was explained by the stabilization of the activation complex by DMSO. Both steps of the reaction could be specified by NMR spectroscopy. The ratio between the reaction rate constants for the first and the second step decreased with the increased hydrogen bonding strength of the solvent and with DMSO. By SEC only the reaction of the first NCO group could be determined due to the low resolution for higher molar mass reaction products with a broad distribution. The values obtained for the first step reaction rate constants were in good agreement with NMR values. © 1995 John Wiley & Sons, Inc. 相似文献