N-烯基硝酮分子内环加成反应区域选择性的理论研究I. N-3-丁烯基硝酮分子内环加成反应的区域专一性

n-烯基硝酮的分子内环加成反应可能得到氧桥和碳桥的两种产物, 但N-3-丁烯基硝酮却只有单一的氧桥产物, 已被用来合成一系列新的区域专一性人化合物。弄清此反应机理是很有意义的。本文用过渡状理论和AM1方法进行研究, 结果表明,虽然存在得到两种产物的平行反应, 但由于这两个反应的速率常数之比很大, 基本上只得到单一的氧桥产物。生成氧桥产物的反应活化焓比较小, 活化熵比较大。活化熵对反应速率常数比值的贡献是不可忽略的。     

Modified Ceria-Zirconia Fluorite-Like Catalysts for the Combustion of Methane

For dispersed ceria-zirconia-based solid solutions prepared via the polymerized complex method and annealed at 700℃, effects of bulk doping by Ca, Mn, Co, Bi or Nb cations and surface modification by Mn and Pt on their structural features, surface/bulk oxygen reactivity and catalytic activity in methane combustion are considered. With up to 20 mol% doping, a structural type of homogeneous solid solutions of anion-deficient fluorite with disordered anion vacancies is formed. Doping by transition metal cations or Pt increases the mobility and reactivity of the surface/bulk oxygen. A broad variation in specific rates of methane combustion for the studied systems was observed, suggesting structural sensitivity of this reaction. In general, there is no universal relationship between the oxygen mobility, the reactivity and the catalytic activity in methane combustion, which is explained by the factor of specific methane activation on surface active sites. For the Pt-promoted samples, Pt efficiency in methane activation depends on the Pt-support interaction, and the most favorable ones being mixed Pt/MnOx and Pt/NbOx clusters on the surface of the supports that exhibit high lattice oxygen mobilities.     

脱羧氯雷他定的合成

脱羧氯雷他定 (ＤＣＬ)是一种有效的非镇定性抗组织胺 ,对过敏性鼻炎 ,糖尿病、咳嗽、普通感冒、流行性感冒、关节痛及其它不适症状都有很好的疗效[1～2 ] 。它克服了氯雷他定、酮康唑、红霉素、伊曲康唑等易引发黑色素瘤、纤维肉瘤、胃刺激、肥胖症、心律失调、传导紊乱等症状的缺点。且它的使用剂量只有氯雷他定的十分之一 ,有很好的市场前景和实际应用价值。ＭａｒｋＷ .Ｈｏｌｌａｄａｙｅｔａｌ[3] 在水溶液中由酸、碱催化得到了脱羧氯雷他定 ,但无具体操作和反应结果报道。Ａ .Ｋ .ＧｕｎｎａｒＡｂｅｒｇ[1] 直接用ＫＯＨ在绝对无水…     

Mo、W金属氧化物对CH4/CO2重整Ni基催化剂性能的影响

用XRD、XPS、元素分析、TEM和活性评价等方法研究过渡金属氧化物MoO3和WO3对SiO2负载的Ni基催化剂物理化学性质和CH4/CO2重整制合成气催化性能的影响.结果表明,在负载型的镍催化剂中,MoO3和WO3的添加一方面提高了Ni的核外电子密度,减弱了对CH4深度裂解积炭;另一方面使催化剂表面镍的相对浓度降低,结构上起到了隔离、分散金属颗粒的作用,氧的相对浓度升高,有效提高了催化剂的抗烧结和抗积炭能力,显示出较好的催化稳定性.     

DFT Study on the （S）-Proline-catalyzed Direct Aldol Reaction between Acetone and 4-Nitrobenzaldehyde

1 INTRODUCTION Aldol reaction, one of the most important C–C bond-formation reactions, is widely utilized in orga- nic synthesis[1]. Extensive efforts have been donated to the development of catalytic stereo-selective va- riants of this reaction[2]. However, the direct aldol reaction between unmodified carbonyles would be the most attractive synthetic alternative. Proline-catalyzed intermolecular direct aldol reac- tion between acetone and 4-nitrobenzaldehyde was first reported by List…     

H4TPP^2＋吸附在Ag溶胶表面的吸收光谱

本文研究了５，１０，１５，２０－四苯基中啉二酸吸附在Ａｇ溶胶表面的吸收光谱。发现Ｈ４ＴＰＰ＾２＋吸附在Ａｇ溶胶表面的去质子化现象，生成游离碱卟啉Ｈ２ＴＰＰ，随样品放置时间延长，卟啉分子进一步发生络合反应，生成Ａｇ（Ⅱ）ＴＰＰ。对络合反应的过程和机理进行了讨论。     

洋葱色素的提取及抗氧化活性的测定

分别用芬顿（Fenton）反应法和1，1-二苯-2-苦肼基（DPPH）法测定了洋葱色素的抗氧化作用。结果表明，洋葱色素对羟自由基和DPPH自由基均有一定的清除作用，其清除率大小依次为42．4％，58．2％。洋葱色素是十分具有开发利用价值的天然色素。