P2O2-V2O5-TiO2的表面结构

P_2O_5-V_2O_5-TiO_2(简写为P-V-Ti)对芳烃氧化有良好的催化效果.丁烷氧化催化剂P-V体系的体相和表面结构已有一些报道.但P_2O_5对V-Ti的影响文献较少报道.本文用XRD,IR,TPD和ESR考察了P-V-Ti体系. 1.试剂和催化剂:草酸、偏钒酸铵、二氧化钛均为化学纯.将V_2O_5:TiO_2=11:89(重量)样品分别按 P/V原子比为0.1,0.3,0.6,1.0,1.5和2.5制成编号为P-0.1,P-0.3,P-O.6,P-1.0,P-1.5和P-2.5的催化剂.     

PdC_2H_2和PtC_2H_2的键结构研究

关于过渡金属Pd,Pt对C_2H_2的吸附和氢化实验研究前人已作了不少工作,但有关Pd,Pt与C_2H_2之间成键问题的理论研究还尚不多见。为了了解Pd,Pt d轨道对炔键的活化行为和成键特性,本文以MC_2H_2(M=Pd,Pt)为模型,用赝势计算方法,对Pd,Pt与C_2H_2键的相互作用进行了研究。一、计算方法由于重原子的内层轨道对形成分子贡献很小,内层电子的相对论效应极为严重。本文采用Ps—HONDO程序,选取Hay的有效核芯势和价轨道Gaussian基组,对重原子Pd和Pt进行了价电子从头计算,对C和H进行了全电子从头算.部分地消除重原子内层电子相对论效应所引起的误差。     

[Mo2O2S2(S2)2][2-]的振动光谱研究

本文测定了原子簇化合物[Mo2O2S2(S2)2][2-]的红外和拉曼光谱,并在乙腈溶液中测得其共振拉曼光谱和退偏振比。利用X光晶体结构数据,对此阴离子的伸缩振动作了简化的正则坐标分析计算。所得结果可以帮助分析和归属一些Mo-Fe-S原子簇化合物的振动光谱。     

Cl_2 2HI=2HCl I_2反应机理的理论研究

分别在MP2/3-21G!!、CCSD(T)/3-21G!!//MP2/3-21G!!和B3LYP/3-21G!!3种水平上,计算研究了气相反应Cl2 2HI=2HCl I2的机理,求得一系列四中心和三中心的过渡态.通过比较六种反应通道的活化能大小,得到了相同的结论:双分子基元反应Cl2 HI"HCl ICl和ICl HI"I2 HCl的最小活化能小于Cl2、HI和ICl的解离能,从理论上证明了反应Cl2 2HI=2HCl I2将优先以分子与分子作用形式分两步完成.用内禀反应坐标(IRC)验证了MP2/3-21G!!方法计算得到的过渡态.     

对Na_2O_2与CO_2反应的验证

Na_2O_2与CO_2气体的反应在高师教材(见北师大等编《无机化学》下册652页)和(中学教材(见高中化学上册86页)都列出了反应方程式。但怎样验证这个反应不仅中学教材没有介绍,而且高师实验教材(如北师大等编《无机化学实验》)也未提及。由于这个反应能产生氧气,所以在防毒面具、高空飞行和潜水艇中用作二氧化碳的吸收和供氧。学生对这一     

F2＋2HI=2HF＋I2反应机理的研究

根据氯离子型层状复合氢氧化物(LDH-Cl)制备过程中溶液浓度变化的监测结果和不同反应进程时产物的EDS、IR、XRD、TEM、TG-DTA表征结果,研究了合成LDH-Cl的共沉淀反应动力学特征及机理.实验结果表明, LDH-Cl的生成符合多核层表面反应动力学模型;反应过程中LDH的晶胞参数c从2.421 nm变为2.399 nm,通道高度h由0.3321 nm减小为0.3228 nm,粒子直径Da由6.40 nm增大为15.16 nm, Dc由7.43 nm增大到10.93 nm,纵横比由0.86增大为1.39; IR和TG-DTA特征变化表明了层板对阴离子作用的强度和层板的结构稳定性随反应进程而提高.     

CHF_2CF_2CH_2OCHF_2与OH自由基反应机理的理论研究

采用从头算和密度泛函方法研究了多通道反应CHF2CF2CH2OCHF2+OH→产物的反应机理.首先在BMK/6-311+G(d,p)水平下优化了稳定点的几何构型并计算了振动频率;然后在BMC-CCSD水平下,对势能面进行高水平能量校正.结果表明,此反应存在提氢和取代两类反应通道,但是无论从动力学还是从热力学分析,提氢反应通道才是主要的反应通道,且从-CH2-基团上提取氢原子的提氢通道是主要的反应通道.     

H_2O_2氧化N_2生成N_2O和H_2O机理的研究

采用量子化学计算方法研究了Ｈ２Ｏ２ 氧化Ｎ２ 生成Ｎ２Ｏ 和Ｈ２Ｏ 的机理．结果发现, Ｈ２Ｏ２ 氧化Ｎ２ 先通过１ 个四元环过渡态形成中间体Ｈ２Ｎ２Ｏ２ 分子,Ｈ２Ｎ２Ｏ２ 再通过一个五元环过渡态形成Ｎ２Ｏ和Ｈ２Ｏ．根据计算得到的每步反应的活化能,得知Ｈ２Ｏ２ 氧化Ｎ２ 生成中间体Ｈ２Ｎ２Ｏ２ 分子是整个反应的控制步骤．     

Ni[S2 P(OCH2 CH2 Ph)2]2·2Py的制备及结构表征

O,O’-二烃基二硫代磷酸根及其过渡金属配合物能阻止烃类自动氧化,广泛地用作润滑油的抗氧剂、燃油的添加剂、高分子材料的稳定剂和人造橡胶的硫化促进剂;在生物学上具有杀虫、抗菌、抗癌和抑制酶水解等特性[1-3]。[(RO)2PS2]nM用作润滑油抗氧剂时,为了有效地缩减氧化作用,一般     

Syntheses of 2-hydroperoxy-and 2-hydroxy-2H-imidazoles

Oxidation of fully substituted imidazoles 1 by singlet oxygen gives in good yield fully substituted 2-hydroperoxy-2H-imidazoles 2 . Reduction of 2 by triphenylphosphine leads to 2-hydroxy-2H-irnidazoles 3 . Limitations of the methods are reported.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

Homopolymerization of 2-alkyl- and 2-aryl-2-oxazolines

2-Aryl- and 2-alkyl-2-oxazolines have been polymerized to poly-(N-aroyl)aziridines and poly(N-acyl)aziridines, respectively, in the presence of boron trifluoride. The polymers obtained were glassy, light yellow resins with molecular weights ranging from 3500 to 7500 (35–50 oxazoline units per chain). The polymerization rates have been determined for several of these monomers. A polymerization mechanism is proposed.     

Photocycloaddition of 2-Cyanocycloalk-2-Enones to 2, 3-Dimethylbut-2-Ene

Irradiation of 5,5-dimethyl-6-oxocyclohex- l-ene- l-carbonitrile ( 1 ) in the presence of 2,3-dimethylbut-2-ene afforded 3,3,4,4,7,7-hexamethyl-3,4,4a,5,6,7-hexahydroindeno[1,7-c,d]-],2-oxazole (3) in nearly quantitative yield. In contrast, 4,4-dimethyl-5-oxo-cyclopent-l-ene-l-carbonitrile ( 2 ) under the same conditions reacted not to a tricyclic isoxazole but to a 2:1 mixture of 3,3,6,6,7,7-hexamethyl-2-oxo-bicyclo[3.2.0]heptane-l-carbonitrile ( 4 ) and trans-3,3-dimethyl-2-oxo-5-(2,3-dimethylbut-3-en-2-yl)cyclopentane-l-carbonitrile ( 5 ), respectively.     

Stereoselective synthesis of 2-deoxy-beta-galactosides via 2-deoxy-2-bromo- and 2-deoxy-2-iodo-galactopyranosyl donors

[reaction: see text] A series of 2-bromo- and 2-iodo-galactopyranosyl acetates and trichloroacetimidates were evaluated as glycosyl donors for the synthesis of 2-deoxygalactopyranosides. The best selectivity for the beta-glycosidic linkage was achieved by using 6-deoxy-3,4-carbonate-protected galactosyl donors.