TADBIW在丙酸和正丁酸中的氢解脱苄

四乙酰基二苄基六氮杂异伍兹烷(TADBIW)是六苄基六氮杂异伍兹烷(HBIW)的氢解脱苄产物。在不同．酸性体系中氢解TADBIW将得到不同的脱苄产物。以丙酸和正丁酸为氢解介质,采用自制的Pd系催化剂氢解TADBIW制得了四乙酰基六氮杂异伍兹烷(TAIW),并对其反应过程做了初步的探讨。     

TADB氢解脱苄合成TADF的反应动力学

采用Pd(OH)2/C催化剂,研究了常压下四乙酰基二苄基六氮杂异伍兹烷(TADB)在甲酸介质中氢解脱苄合成四乙酰基二甲酰基六氮杂异伍兹烷(TADF)的反应动力学。通过空白实验消除催化剂及溶剂对吸氢量的影响,以吸氢量来表征反应程度。通过积分反应速率方程,对不同温度下该反应的实验数据进行了动力学计算。实验结果表明,在实验条件下,TADB的氢解脱苄对于TADB是一级反应,反应表观活化能为50.41kJ/mol,指前因子为4.5326×106min-1。而用Pd/C催化剂时,该溶液放出氢气且反应不完全。     

PNAM氢解脱苄合成NAM的反应动力学

采用湿Pd(OH)2/C催化剂在排除扩散影响的条件下,研究了常压下N-乙酰保护胞壁酸(PNAM)在w(乙酸)=80%的溶剂中氢解脱苄合成N-乙酰胞壁酸(NAM)的反应动力学。通过空白实验消除湿Pd(OH)2/C及溶剂对吸氢量的影响,以吸氢量来表征反应程度。通过积分反应速率方程,对不同温度下该反应的实验数据进行了动力学计算。实验结果表明,在实验条件下,PNAM加氢脱苄反应合成NAM反应表现为一级,反应表观活化能Ea为76.496 kJ.mol-1,指前因子A为4.868×1010min-1。用IR、1HNMR、13CNMR、LC-MS和元素分析对产物进行了表征,证实了该化合物即是目标产物NAM。     

声共振强化HBIW氢解脱苄合成TADB

为提高六苄基六氮杂异伍兹烷(HBIW)氢解脱苄反应的“气-液-固”多相间传质效率,以HBIW和H₂为原料、Pd(OH)₂/C为催化剂,在声共振强化反应器作用下,经氢解脱苄反应合成四乙酰基二苄基六氮杂异伍兹烷(TADB);利用核磁共振谱(¹H-NMR,¹³C-NMR)和高分辨质谱(HRMS)对产物结构进行了表征;通过单因素实验和正交实验研究了反应温度、反应时间、加速度和反应压力对收率的影响,并与传统的釜式反应进行了对比,分析了声共振技术强化反应过程的机理。结果表明,在反应原料为1.5g HBIW、0.15g质量分数10%的Pd(OH)₂/C催化剂、5mL Ac₂O、7mL DMF和0.1g PhBr的条件下,反应加速度为392m/s²,反应压力0.2MPa, 18℃反应30min, 45℃反应60min,产物TADB收率83%。在以上反应条件下,声共振强化技术与传统釜式工艺相比,产物TADB收率没有变化,但反应时间由18h缩短至90mi...     

水处理工艺中甾体雌激素的去除及控制研究进展

综述了甾体雌激素( SEs)在水处理工艺中的去除及其控制研究进展.文献表明,现有水处理工艺对SEs处理效果不佳,其在水处理工艺中会进一步发生迁移转化.根据SEs的研究进展,目前亟需进行SEs去除条件下的毒性削减技术研究,为确保水质安全提供科学依据和技术指导.     

甾体钠盐类化合物的合成研究进展

按照甾体钠盐结构特点进行分类,对国内外近年来有关甾体钠盐类化合物及其衍生物的合成、生理活性研究进展进行了综述,并对其发展趋势及应用前景作了展望。     

Pd基双金属催化剂催化HBIW氢解脱苄反应

为了降低六苄基六氮杂异伍兹烷(HBIW)氢解脱苄反应中钯催化剂的用量,提出沉淀-还原法合成钯基双金属催化剂的方法。对不同载体负载的催化剂进行筛选和优化,研究不同载体、金属助剂、催化剂中钯的质量分数、催化剂与原料HBIW的质量比对产物收率的影响。结果表明,在0.5 g HBIW、0.4 MPa H₂、15℃反应8 h,随后升温至45℃,继续反应24 h的条件下,以Pd质量分数为5%的催化剂(记为5%Pd-Ni/γ-Al₂O₃)为最优催化剂、催化剂的质量为0.037 5 g时,催化HBIW的氢解脱苄反应,产物获得85%收率,此时催化剂中钯与原料HBIW的质量比为0.375%。在声共振强化下进行氢解脱苄反应,在加速度为392 m·s^-2、0.5 g HBIW、0.4 MPa H₂的条件下,反应时间缩短至100 min,产物仍保持了85%收率。     

淡水环境中水生生物对甾体雌激素的物种敏感度分布

针对淡水环境中甾体雌激素对水生生物的毒理学影响,文中以雌二醇(E2)和乙炔基雌二醇(EE2)为研究对象,利用其对淡水生物系统中各营养级物种的慢性毒性效应浓度,建立基于对数-累积正态分布的物种敏感度分布模型.获得E2和EE2的5％危害质量浓度(HC5)分别为0.1137μg/L和0.0010μg/L,并推导出E2和EE2...     

甾体化合物1(2)位脱氢的化学法研究

在甾体化合物中引入1(2)位双键能提高其活性。本文综述了甾体化合物中1(2)位脱氢的化学方法,包括硒化合物脱氢法,上卤脱卤脱氢法,DDQ脱氢法。目前应用较为广泛的是DDQ脱氢法,特别是在BSTFA作用下的DDQ脱氢法,其收率高,生成的杂质较少。     

7-去氢胆甾乙酸酯的合成研究

研究7-去氢胆甾乙酸酯的合成方法,以胆甾乙酸酯为原料,经过上溴和脱溴反应制得7-去氢胆甾乙酸酯,用气相色谱法检测7-去氢胆甾乙酸酯的含量,通过7-去氢胆甾乙酸酯的质量变化以及计算从胆甾乙酸酯至7-去氢胆甾乙酸酯的收率来考察上、脱溴反应的选择性。对偶氮化合物和过氧化物化合物自由基引发剂进行选择,最终确定最合适的ABV引发剂,使上、脱溴反应的选择性得到提高。此外．还对上溴反应温度、上溴反应时间以及上溴引发剂的用量进行探讨,确定最佳反应条件。结果表明,脱溴物中7-去氢胆甾乙睃酯的含量由60％提高至70％,从胆甾乙酸酯至7-去氢胆甾乙酸酯的收率由56％提高至69％以上。     

催化氢解脱苄基Pd/C催化剂的研究和应用

评述了催化氢解脱苄基反应的类型、工艺和催化剂,并进一步对制备脱苄基蛋壳型Pd/C催化剂的因素进行了综述,为脱苄基Pd/C催化剂的设计、开发和应用指明了方向.     

High temperature hydrogenolysis of bibenzyl

Bibenzyl was pyrolysed in the gas phase, in the presence of a large excess of hydrogen at 600–850 °C. Products formed were benzene, toluene, ethylbenzene and styrene; no stilbene or phenanthrene were formed. The yield of toluene decreased with increasing temperature, that of benzene increased, that of ethylbenzene dropped to zero and that of styrene slowly decreased. The decrease in toluene plus ethylbenzene yield was roughly equal to the increase in benzene yield. The apparent pseudo first order ‘activation energy’ for loss of bibenzyl under these conditions is 10.2 ± 0.8 kcal mol^?1. The nature of products formed, their variation with increasing temperature and the low activation energy can be interpreted in terms of a radical chain mechanism in which the chain carrier is the hydrogen atom.     

Kinetics of hydrogenolysis of methylamine on a rhodium catalyst

The kinetics of hydrogenolysis of methylamine to methane and ammonia were investigated over a catalyst consisting of small clusters of rhodium dispersed on silica. Data obtained in the temperature range 353–408 K exhibit a characteristic pattern in which the rate passes through a maximum as the hydrogen partial pressure is increased by two orders of magnitude from 0.01 to 1.0 atm. At a given temperature, the position of the maximum shifts slightly in the direction of higher hydrogen partial pressure when the methylamine partial pressure increases by one to two orders of magnitude. Of particular interest is the finding that the rate increases with decreasing methylamine partial pressure over a broad range of hydrogen partial pressures covered in the investigation. As the hydrogen pressure increases, the inverse dependence of the rate on methylamine pressure becomes less pronounced and eventually disappears at a sufficiently high hydrogen pressure. At hydrogen partial pressures somewhat higher than those at which the rate maxima are observed, there is some indication that the inverse dependence changes to a positive dependence, especially at the lowest temperatures investigated. It seems likely that the rate limiting step of the reaction changes when the hydrogen pressure varies over a wide range. At the highest hydrogen pressures studied, it is suggested that the limiting step is one in which the scission of the carbon-nitrogen bond occurs in a hydrogen deficient surface intermediate formed in the chemisorption of methylamine, with no direct participation of hydrogen as a reactant in the step. On the other hand, at the lowest hydrogen pressures investigated, it is proposed that the rate is limited by a step in which chemisorbed hydrogen does participate directly as a reactant.     

甘油催化氢解制备丙二醇催化剂研究进展

简要概括了近些年生物柴油副产物甘油催化氢解制备丙二醇催化剂研究新进展,对甘油氢解分别采用贵金属催化体系和过渡金属催化体系的催化活性和选择性以及可能的机理进行了解释说明。采用贵金属Pt/WO3负载型催化剂、ReO x改性的Rh/SiO2、Ir/SiO2催化剂、贵金属催化体系中加入有机溶剂以及采用Cu-STA(硅钨酸)/SiO2的气相催化工艺等方式都能得到相对较多的1,3-丙二醇(收率最高为38%)。高分散的纳米铜基催化剂对甘油氢解有着较高的活性、选择性和稳定性,具有工业应用前景。纳米钴催化剂具有特定的形态和良好的催化效果颇受关注。     

生物质多元醇选择性催化氢解制小分子二元醇研究进展

乙二醇、1,2-/1,3-丙二醇等小分子二元醇在精细和有机化工、生物医药等领域应用广泛。与石化路径相比,以可再生的生物质多元醇（丙三醇、山梨醇/木糖醇）为原料选择性催化氢解制取上述小分子二元醇具有过程简单、绿色高效等显著优势,已成为生物质催化转化的研究热点。本文综述了典型生物质多元醇山梨醇/木糖醇和丙三醇选择性催化氢解为乙二醇、1,2-/1,3-丙二醇等小分子二元醇,重点阐述了丙三醇选择性氢解制1,2-丙二醇、1,3-丙二醇和山梨醇/木糖醇选择性氢解制小分子二元醇的催化剂体系和反应机理,并对该领域的发展前景作了展望,提出开发高效稳定的催化剂体系和工艺是未来的研究重点。     

糖醇催化氢解制低级多元醇研究进展

利用糖醇生产低级多元醇可以减少对石油资源的依赖,是可再生资源利用的一个重要研究方向。本文综述了利用糖醇为原料催化氢解制备低级多元醇的研究成果,氢解糖醇可以高选择性得到乙二醇、丙三醇和1,2-丙二醇的混合物。重点介绍了糖醇催化氢解的Retro-aldol、 Retro-Michael反应机理和铜系、镍系、贵金属催化剂,并对糖醇催化氢解的发展前景做了展望,提出开发更为高效稳定的催化体系、降低催化剂制备成本和优化工艺条件将是未来研究工作的重点。     

Methylamine hydrogenolysis on a rhodium catalyst: kinetics at high hydrogen partial pressures

The kinetics of hydrogenolysis of methylamine to methane and ammonia on a rhodium catalyst were investigated at hydrogen partial pressures in the range of 2–10 atm at temperatures of 368, 383, and 408 K. At a fixed methylamine partial pressure, the rate decreased with increasing hydrogen partial pressure. When the hydrogen pressure was held constant, the rate increased with increasing methylamine pressure. Results of a previous investigation by our group at lower hydrogen partial pressures (0.01–1 atm) indicated that the hydrogenolysis rate passed through a maximum with increasing hydrogen pressure. Moreover, at the lower hydrogen pressures, there was an inverse rather than positive dependence of the rate on methylamine partial pressure. With the aid of the present results, there is a much clearer definition of the maximum in the experimental data relating the reaction rate to hydrogen partial pressure. The inversion of the effect of methylamine pressure on the rate as the hydrogen pressure is varied over a sufficiently wide range is also firmly established. With regard to the interpretation of the many interesting features of the kinetics, we retain the suggestion from our earlier work that the rate limiting step at the highest hydrogen pressures is the scission of the carbon-nitrogen bond in a partially dehydrogenated methylamine intermediate chemisorbed on the rhodium, with no direct participation of hydrogen as a reactant in this step. At the lowest hydrogen pressures, however, there is a different rate limiting step in which hydrogen does participate directly as a reactant.     

制备条件对山梨醇氢解CuO-ZnO催化剂的影响

研究了并流共沉淀法制备的CuO-ZnO催化剂在山梨醇催化氢解反应中的催化性能,考察了催化剂制备时不同沉淀温度和不同pH对催化剂性能的影响。采用XRD、H₂-TPR和SEM等手段对催化剂及其前驱体的分散状态、还原性能和表面形貌进行了表征。结果表明,沉淀pH显著影响催化剂的分散程度和表面形貌,而沉淀温度则影响催化剂及其前驱体中CuO、ZnO的分散状态和分子组成形式;当 pH=8.0和沉淀温度为70 ℃时,催化剂的活性最佳。