Investigations into the mechanism of the liquid-phase hydrogenation of nitriles over Raney-Co catalysts

The co-hydrogenation of acetonitrile and butyronitrile over Raney-Co was investigated in order to obtain insight into the mechanism underlying the formation of secondary amines. Acetonitrile was reduced much faster to the corresponding primary amine due to stronger adsorption on the catalyst surface. In parallel, dialkylimines were formed and subsequently converted to secondary amines. It is suggested that the dialkylimines are formed by reaction of partially hydrogenated intermediate species on the cobalt surface with amines. In this respect, n-butylamine was found to react much faster than ethylamine. The stronger inductive effect of the butyl chain is thought to facilitate nucleophilic attack of the amine at the α-C-atom of the surface species. By comparing the C₂ and C₄ balance for dialkylimines and dialkylamines, it was found that direct hydrogenation of the dialkylimine cannot be the only way of dialkylamine formation. Instead, it is suggested that alkyl group transfer occurs by reaction of a monoalkylamine with a dialkylimine and cross-transfer between two dialkylimines.     

聚(异氰脲酸酯—噁唑烷酮)的增韧研究

本文对聚(异氰脲酸酯一噁唑烷酮)进行了增韧改性研究.端羟丁睛、端羧丁腈液体橡胶和端羟聚醚N220作为增韧剂均取得较好的增韧效果.本文还对其增韧规律以及增韧的主要耗能过程进行了探讨.     

丁腈-40增韧室温固化环氧结构胶

采用丁腈-40液体橡胶对环氧体系进行增韧,研究了丁腈-40液体橡胶含量、甲组分处理温度及时间对所制备环氧结构胶剪切强度的影响。结果显示:环氧树脂和橡胶的最佳质量比为10∶1;所得结构胶室温固化24h,室温剪切强度最高可达22.4 MPa,具有良好的力学性能。     

Tailoring Raney-catalysts for the selective hydrogenation of butyronitrile to n-butylamine

The influence of LiOH promotion on Co-based Raney-catalysts for the selective hydrogenation of butyronitrile to n-butylamine was explored. Doping with LiOH led to an increase in the fraction of metallic surface area and reduced concentration of Lewis acid sites resulting from alumina particles decorating the metal surface. Two factors were found to be crucial to achieving high selectivity to primary amines. These factors include a low adsorption constant of n-butylamine relative to butyronitrile (because adsorbed butylamine is necessary for byproduct formation) and a low concentration of Lewis acid sites catalyzing condensation reactions.     

High pressure phase behavior for the propionitrile and butyronitrile in supercritical carbon dioxide

Pressure-composition isotherms for the (carbon dioxide + propionitrile) and (carbon dioxide + butyronitrile) systems are measured in static-type high pressure apparatus at several temperatures of 313.2, 333.2, 353.2, 373.2 and 393.2 K and at pressures range from 3.5 to 16.7 MPa. The carbon dioxide + nitriles systems have continuous critical mixture (local) curves that exhibit maximums in pressure–temperature space between the critical point of carbon dioxide and monomers (propionitrile or butyronitrile). At a fixed pressure, the solubility of propionitrile or butyronitrile for the two binary systems increases as the temperature increases. The (carbon dioxide + propionitrile) and (carbon dioxide + butyronitrile) systems exhibit type-I phase behavior. The experimental results for the (carbon dioxide + propionitrile) and (carbon dioxide + butyronitrile) systems are correlated with Peng–Robinson equation of state using mixing rule including two adjustable parameters.     

催化合成2,2,6,6-四甲基-4-氨基哌啶

采用骨架钴催化剂替代Raney—Ni催化剂,由2,2,6,6-四甲基-4-哌啶酮经胺化氢化合成2,2,6,6-四甲基-4-哌啶胺,避免了副产2,2,6,6-四甲基-4-哌啶醇的生成,得到了胺化加氢过程中钴铝合金催化剂的适宜配比和反应工艺条件。在此工艺条件下,2,2,6,6-四甲基-4-哌啶胺产率达98％以上,催化剂具有较好的稳定性。     

2,4-二(邻溴苯基)-3-亚胺基丁腈的合成

报道以邻溴苯甲醇为原料，经溴代、氰化及α-负碳离子的亲核加成反应，合成出2,4-二(邻溴苯基)-3-亚胺基丁腈。3步反应收率分别为93％、95％、39％。各步产物结构经IR、MS、NMR分析数据得以确定。     

氨基模塑料耐电击穿和耐冲击性能研究

简要介绍了氨基模塑料的基本生产工艺流程,探索了玻璃纤维、纳米蒙脱土、丁腈橡胶粉、玉米淀粉等对氨基模塑料耐电击穿性能和缺口冲击强度的影响。实验结果表明,玻璃纤维作为增强剂对氨基模塑料的电气强度提高效果最为明显,而缺口冲击强度呈下降趋势;纳米蒙脱土的加入使氨基模塑料性能都有提高;玉米淀粉的加入对氨基模塑料的电气强度影响不明显,对缺口冲击强度略有提高;而丁腈橡胶的加入使氨基模塑料的电气强度明显下降,缺口冲击强度提高比较明显,但随丁腈橡胶加入量的增加影响不显著。改性后的氨基模塑料的电气强度能超过17 kV/mm,缺口冲击强度最高可以达到2.7 kJ/m2,最佳耐电压时间在100 s以上。     

乙烯-醋酸乙烯共聚物改性聚氯乙烯的研究

研究了乙烯醋酸乙烯共聚物(EVA)对聚氯乙烯(PVC)材料结构和性能的影响,主要考察了EVA及其用量对PVC复合材料力学性能的影响,并对复合材料的结构进行了表征。结果表明,与传统丁腈橡胶(NBR)复合PVC相比较,EVA可在大幅度提高PVC冲击强度的同时,还能避免NBR复合PVC时存在的低温环境下材料弹性模量过低、高温易变色的缺陷,且EVA在PVC基体中具有良好的分散性。     

硫化体系在丁腈手套制备中的应用

介绍了N-羟甲基丙烯酰胺（N-AM）硫化体系在丁腈手套制备中的应用。实验采用羧基丁腈胶乳（XNBRL）为原料,以N-AM为硫化剂、二丁基二硫代氨基甲酸锌（Bz）为促进剂、ZnO为硫化活性剂,经过预硫化、硫化、干燥等过程制得羧基丁腈胶膜。通过测试胶膜性能,研究了A（N-MA）、B（ZnO）、C（Bz）配比等因素对胶膜物理机械性能的影响,发现C（BZ）是影响胶膜物理性能的主要因素,其次是A（N-MA）和B（ZnO）。研究最终确定了最佳硫化体系配比A：B：C为3．5：2：1。     

PVG输送带覆盖胶性能的研究

用粉末丁腈P83来改性PVC研制PVG输送带覆盖胶,研究了P83对覆盖胶的拉伸强度、撕裂强度、表面电阻、热空气加速老化性能和阻燃性能的影响。实验结果表明,P83与PVC共混的性能较好,可达到性能互补的效果。综合考察,P83用量在30份时,PVG输送带覆盖胶的综合性能较佳。     

Quantitative analysis of synthetic mixtures of triacylglycerols with fatty acids from caprylic to stearic

Separation and quantitation of triacylglycerols tricaprylin to tristearin was achieved by high-performance liquid chromatography with refractive index detection and an eluent composed of propionitrile and butyronitrile (80:20, vol/vol). Peak identification was based on the logarithms of retention times, and quantitation was achieved by way of theoretical relative response factors. The validity of the response factor calculations was tested by analysis of primary standard mixtures of saturated triacylglycerols and of triacylglycerols obtained by interesterification of binary mixtures of monoacid triacylglycerols.     

高性能室温固化环氧结构胶的制备与研究

为了改善环氧固化物的韧性,又保持其热稳定性及提高其抗冲击性能,采用超细全硫化羧基丁腈橡胶粒子改性环氧树指技术,并辅以玻璃微珠,球型硅微粉,ACR丙烯酸酯橡胶微球等抗冲剂填充,制备出一款高性能室温固化环氧结构胶.实验中采用高速搅拌球磨法在环氧树脂中分散超细全硫化羧基丁腈橡胶粒子,辅以填充物,制备的环氧树脂结构胶剪切冲击强...     

Solvent Polarity Dependent Photophysics of a Fixed-Distance,Symmetric Chlorophyll Dimer. A Model of the Special Pair in Photosynthetic Reaction Centers

The synthesis and properties of a fixed-distance symmetric bis-pyrochlorophyllide-a molecule are described. The molecule, 1 , consists of two methyl pyrochlorophyllide-a (MePChlide-a) moieties which share a common vinyl group at the 2-position of each macrocycle. The two chlorophylls are trans to one another across the vinyl linkage. The dihedral angle between the plane of each macrocycle and the vinyl linkage is about 50°. The Q_y absorption band of this dimer occurs at 689 nm and is essentially independent of solvent. The band is red-shifted by about 27 run relative to that of MePChlide-a. The fluorescence maximum of 1 occurs at 722 nm. This is a red-shift of 49 nm relative to methyl MePChlide-a. The circular dichroism spectrum of 1 shows strong, nonconservative bands in the red region. The fluorescence quantum yield, fluorescence lifetimes, and picosecond transient absorbance kinetics all exhibit a very strong dependence on solvent polarity. The fluorescence quantum yields of 1 in toluene, butyronitrile, and N, N-dimethyl formamide (DMF) are 0.18, 0.008, and 0.002, respectively. The bleach of the 689 nm band (following excitation with a 1.5-ps, 610-nm laser pulse) recovers with single exponential time constants of 2.51 ns, 100 ps, and 64 ps in toluene, butyronitrile, and DMF, respectively. Possible mechanisms for the polarity-dependent increase of the nonradiative decay rate of 1 are considered.     

YAG掺铷——钇铝石榴石激光晶体胶粘剂

YAG掺铷——钇铝石榴石激光晶体胶粘剂以丁腈改性环氧树脂,酚醛变性胺为固化剂,用于掺铷——钇铝石榴石激光晶体与钢套粘接,安装在陕西省人民医院YAG激光医用治疗机,临床应用3年,效果很好。后中国电子科技集团第二十七研究所从1990年开始用YAG激光胶粘剂粘接各类激光产品至今,经高低温试验、振动试验、冲击试验等各项性能测试及15年来工程应用证明,在各类激光产品中从未出现开裂、脱胶现象,性能稳定可靠,其粘接强度、耐冲击、耐振动、耐高低温变化、耐水、耐化学介质、耐光、耐老化性能均好,能满足生产要求,用途广泛,符合激光及各种工程应用。文中详述了酚醛变性胺固化剂的选择及该胶粘剂的性能。     

硬质高聚合度PVC的改性

以硬质高聚合度ＰＶＣ为对象,采用ＤＯＰ、ＣＰＥ或ＳＡＮ进行增韧改性,研究了液体丁腈、ＡＣＲ及内、外润滑剂对加工流变性能的影响,结果表明,ＣＰＥ是高聚合度ＰＶＣ的优良增韧改性剂,对拉伸强度影响很小,ＳＡＮ对ＰＶＣ／ＣＰＥ＝１００／１０体系起到既增韧又增强效果,用量在３份以下,ＬＮＢＲ可降低熔体的表观粘度、缩短塑化时间,降低能耗,改善流变性,ＡＣＲ－２可明显改善熔体强度,促进熔融塑化,在高速剪切下,表面平整光滑,从力学性能、混炼状态、熔体流动和挤出物外观,选择ＥＳＯ、丁二烯、ＴＲＯ１６为润滑剂。硬质料的挤出性能及外观接近进口料水平。     

Impact of solvent on Co/SiO2 activity and selectivity for the synthesis of n-butylamine from butyronitrile hydrogenation

The impact of solvent on Co(9.8%)/SiO₂ activity and selectivity for the synthesis of n-butylamine from butyronitrile hydrogenation was investigated using methanol, benzene, toluene and cyclohexane as solvents. In non-polar solvents, the yield of n-butylamine increased from 60% to 79% following the order cyclohexane < toluene < benzene. Nevertheless, the highest n-butylamine yield (91%) was obtained in methanol, a protic solvent. The solvent effect on the catalyst performance was interpreted by considering: i) the solvent–catalyst interaction strength and ii) the solvent polarity and its ability for H-bond formation with n-butylamine.     

中腈基含量液体丁腈橡胶的合成

以丁二烯(Bd)和丙烯腈(AN)为聚合单体,以过硫酸盐为引发剂,以硫醇为相对分子质量调节剂,在10 L聚合釜上采用自由基乳液聚合法合成了AN质量分数为(25±2)%的中腈基含量液体丁腈橡胶。研究了聚合配方及后处理工艺对聚合物性能的影响。结果表明,在聚合反应温度为(30±1)℃;过硫酸盐B 1.5~2.5份,硫醇5~6份,复配阴离子乳化剂A 2~4份;洗涤剂为90℃以上热水,用量为胶浆的1.5倍;干燥温度为(120±5)℃的条件下,可以制得Mn为(1 400±200),AN质量分数为(25±2)%的中腈基含量液体丁腈橡胶。     

Effect of pressure on the rate of butyronitrile hydrolysis in high-temperature water

The reactions of butyronitrile were investigated in high-temperature water at 330 °C and various pressures ranging from 128 to 2600 bar. Residence times ranged from 5 to 180 min. The product spectrum included butanamide, butyric acid and ammonia; gas formation was negligible. A four-step autocatalytic rate model incorporating the product acid as the catalytic species fitted the data well. This allowed the estimation of apparent activation volumes for each of the reaction steps. These were in turn decomposed into electrostatic and non-electrostatic contributions. At the lowest pressure studied (128 bar), the electrostatic activation volume ΔV_es^≠ was twice as large as the hydrostatic activation volume ΔV_hs^≠. These activation volumes were comparable in value at all other pressures studied.     

Preparation of micron‐size monodispersed PS/P(St/MAA) microspheres by seeded dispersion polymerization

Uniform polystyrene (PSt) particles with the size of 1.9 μm were first prepared via dispersion polymerization, and then used as the seeds in a second‐stage dispersion copolymerization of styrene (St) and methacrylic acid (MAA) to produce carboxyl‐carrying microspheres. The PSt seed particles were swollen by monomer mixture of St and MAA, including an oil‐soluble initiator 2,2′‐azobisiso‐butyronitrile (AIBN), before polymerization. Finally, uniform PS/P(St/MAA) (polydispersity index, PDI = 1.02) microspheres with the size of 2.2 μm were obtained. The average particle size and size distribution of the final microspheres were investigated. MAA contents between 54 and 97 mg/g were detected from the PS/P(St/MAA) particles produced under different conditions. Dispersion medium has great influence on the kinetics of polymerization, due to its effect on the partitioning of monomers, solvents, and initiator in the particle phase, probably as well as on the conformation of the dispersion agent on the surface of the particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3586–3591, 2006