苄基咪唑氯镍酸盐的合成、结构及催化醛醇酯化反应活性研究

合成了三种苄基咪唑氯镍酸盐,通过红外光谱、元素分析、1H NMR以及X-射线单晶衍射对其进行结构表征,并研究了其在醛醇酯化反应中的催化活性。结果表明,在优化条件下,苄基咪唑氯镍酸盐对醛醇酯化反应有着较好的催化活性,以1,3-二(4-甲基苄基)咪唑鎓氯镍酸盐为催化剂,通过一步氧化酯化路线可以有效地催化氧化苯甲醛进行酯化反应,产率为80%。     

硫酸亚铈催化的芳香化合物与苄基醇、烯丙醇类化合物以及苄基氯的傅-克烷基化反应研究

硫酸亚铈作为一种便宜的和有效的催化剂催化芳香化合物与苄基醇、烯丙醇类化合物和苄基氯的傅-克烷基化反应. 在1～10 mol%的硫酸亚铈存在下, 芳香化合物分别与苄基醇、烯丙醇类化合物和苄基氯能够顺利有效地进行傅-克烷基化反应. 此外, 催化剂能回收, 再次使用三次也没有明显地失去催化活性.     

聚苯乙烯支载N—烷基—N—苄基氨基吡啶的合成及催化活性研究

本文以聚苯乙烯氯球为原料，通过与4-氨基吡啶及烷基化试剂反应，制成聚苯乙烯支载N-烷基-N-苄基氨基吡啶催化剂。通过醇的酰化反应，对其催化活性进行了研究。     

侧链PEG基聚合物的制备及其催化酯化反应性能

聚乙二醇单(乙烯基苄基)醚(PEG-VBE)和聚乙二醇二(乙烯基苄基)醚(PEG-DVBE)是重要的可聚合聚乙二醇衍生物,可用于催化剂载体及功能高分子的合成。本文以氢氧化钾为碱,乙烯基苄基氯(VBC)与乙二醇、一缩二乙二醇、二缩三乙二醇、PEG400、PEG600和PEG1500反应,高效合成了一系列乙烯基苄基聚乙二醇衍生物,乙烯基苄基氯的转化率可达96%以上,PEG-VBE的分离收率为32 ~ 93%。乙烯基衍生物在过硫酸钾引发下聚合得到水溶性高分子,产物经1H NMR、ESI-HRMS及FT-IR分析表征。以制备的水溶性PEG基聚合物为微反应器,研究了苯甲酸与甲醇的酯化反应,PEG基聚合物与硫酸的体系对酯化反应具有很好地催化活性。在优化的条件下,苯甲酸的转化率可达99%以上,催化体系循环5次后,催化活性几乎没有下降     

氮杂环卡宾的合成及在氢转移反应中的应用

利用氯甲基吡啶与咪唑反应制备了一系列含吡啶取代咪唑L1～L5,考察了所得咪唑衍生物与钌化合物在碱性条件下原位形成的氮杂卡宾钌络合物对苯胺与醇氢转移反应的催化活性.研究了碱的种类、钌前体、温度等对反应的影响,结果表明RuCl3 H2O/1-(2-吡啶甲基)-3-甲基碘化咪唑(L3)/KOH催化体系在185℃时对苯胺与乙二醇反应的催化活性较高,选择性生成N-羟乙基苯胺,TON(单位活性转化的底物分数)可达2130.此外,还考察了RuCl3 H2O/L3/KOH催化体系对苯胺与丁醇、环己醇、异丙醇、苯甲醇反应的催化性能.在催化剂作用下,醇与苯胺可形成亚胺及仲胺,伯醇可以自氢转移反应形成酯,反应产物的结构及选择性取决于醇的结构及反应条件.     

Oxone/CaCl_2/TEMPO体系在温和条件下对醇的氧化反应

Oxone/TEMPO/CaCl_2(TEMPO=2,2,6,6-Tetramethyl-1-piperidinyloxy)是一种稳定安全和易得的氧化催化体系,在室温条件下,可以氧化苄基或烷基醇生成醛或酮.苄基伯醇很容易被氧化成相应的醛,有较高的反应收率(90%～96%),仲醇氧化成相应的酮,收率在81%～85%之间,1,4-丁二醇环氧化生成γ-丁内酯得到了94%的收率.     

用于催化氧气氧化苄醇到醛的新型且简单的催化体系（溴化铜/TEMPO/哌啶）

构建了一个可用于催化氧气氧化苄醇类醇到醛的新型催化体系(溴化铜/四甲基哌啶氧化物/哌啶).该体系以乙腈为溶剂,可以在50℃下高活性和选择性地催化氧气将含不同取代基的苄醇氧化为相应的醛.然而,该体系对于仲醇、脂肪族伯醇以及烯丙醇类型醇的氧化没有催化活性.     

双核烷基咪唑过氧磷钨酸盐相转移催化剂合成及催化烯烃环氧化性能

合成并表征了一类双核长链烷基咪唑阳离子修饰的过氧磷钨杂多酸盐催化剂[Dnmin]1.5PW4O24,考察了催化剂在过氧化氢为氧源的烯烃环氧化反应中的催化活性.研究表明,这类催化剂在反应过程中表现出相转移催化现象,并具有较高的催化活性和选择性.其中,双核十二烷基咪唑杂多酸盐催化剂[D12min]1.5PW4O24的活性最佳,其环己烯转化率和环氧环己烷选择性分别达到97.7%和96.3%.催化剂在经过简单离心分离后可重复使用,重复使用4次后环己烯转化率和环氧环己烷选择性仍可分别达到72.4%和97.2%.催化剂[D12min]1.5PW4O24在其它几种烯烃的环氧化反应中均表现出相转移催化特性,且具有较高的催化活性.     

环钯化苯基咪唑啉-卡宾络合物的合成及催化Suzuki反应研究

以间硝基苯甲酸或苯甲酸和(S)-缬氨醇为起始原料,室温反应制得酰氨基醇1a和1b,在亚硫酰氯存在下,酰胺基醇与对甲苯胺关环反应得到苯基咪唑啉化合物2a和2b.通过对苯基咪唑啉配体2进行钯化反应、1,3-二苄基苯并咪唑盐解聚,得目标产物环钯化苯基咪唑啉-卡宾络合物3a和3b.通过1H NMR,13C NMR,IR,MS和元素分析等手段对新化合物3a和3b进行了表征.进一步通过单晶X射线衍射对3a进行了结构确证,络合物3a晶体结构表明该化合物通过分子间氢键形成一维链状结构.催化性能考察发现,络合物3a在萘硼酸和碘代甲氧基萘的Suzuki偶联反应中表现出较好的催化活性.     

室温下以水为溶剂的双氧水氧化苯甲醇制备醛的绿色化反应设计

通过环境友好、价格便宜的铁配合物,在室温下催化以水为溶剂的双氧水氧化苯甲醇制备醛的反应,是典型的绿色醇氧化法。同时,原位制备的催化剂不仅具有高效催化活性,而且选择性强,有效地避免苯甲醛的过度氧化产生苯甲酸。     

A facile and efficient [bmim]N3 catalyzed direct oxidative esterification of arylaldehydes with alcohols

Task-specific ionic liquid, [bmim]N₃ was used as an effective catalyst and reaction medium for the direct oxidative esterification of arylaldehydes with alcohols. The oxidative esterification reaction of a variety of arylaldehydes took place smoothly with some primary and secondary alcohols in [bmim]N₃. Satisfactory results were obtained with arylaldehydes containing electron withdrawing groups. Tertiary alcohols did not react under these conditions.     

乙醇在双功能Pd－Cu／分子筛催化剂上气相氧化酯化一步合成乙酸乙酯

研究了乙醇在双功能Ｐｄ－Ｃｕ／分子筛催化剂上一步合成乙酸乙酯的反应，发现Ｐｄ是氧化活性中心的主组分，ＣＵ主要对Ｐｄ的氧化功能起调变作用，以减少乙醇深度氧化副反应，提高酯化选择性．分子筛的酸性强弱对活性，特别是对酯化选择性有明显的影响，酯化要求在较强的酸中心上进行．探讨了氧化活性中心和酸中心的匹配关系以及ＣＵ对Ｐｄ的调变作用，提出了乙醇氧化酯化机理．     

1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions

Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α, β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.     

[IrCl(cod)]2-catalyzed direct oxidative esterification of aldehydes with alcohols

[IrCl(cod)]₂ catalyzed the oxidative esterification of a variety of aldehydes with methanol as a solvent in combination with K₂CO₃ under mild conditions (rt, 12 h). The oxidative esterification reaction of aliphatic aldehydes also took place with olefinic alcohols as reagents in toluene under similar conditions.     

Highly stereoselective oxidative esterification of aldehydes with beta-dicarbonyl compounds

Copper-catalyzed oxidative esterification of aldehydes with beta-dicarbonyl compounds was developed using tert-butyl hydroperoxide as an oxidant. In general, the enol esters were synthesized in good yields (up to 87%) and high stereoselectivity under the optimized reaction conditions.     

Recyclable CuMgAl hydrotalcite for oxidative esterification of aldehydes with alkylbenzenes

A series of hydrotalcite-like compounds with various Cu:Mg:Al molar ratios were prepared by the co-precipitation method. The catalytic performance for oxidative esterification of aldehydes was investigated. X-ray diffraction, N₂ adsorption–desorption (BET), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy, the scanning electron microscope (SEM), the transmission electron microscope and atomic absorption spectrometry were used to characterize the catalysts. The results showed that the benzyl benzoate product was obtained in good to excellent yield using tert-butyl peroxybenzoate as oxidant at 90°C under air atmosphere over Cu₂Mg₁Al₁-LDH catalyst. The catalyst can be recovered and used with 45% conversion after recycling five times. The oxidative esterification reaction in the heterogeneous system is environmentally friendly.

The Cu₂Mg₁Al₁-LDH catalyst prepared by co-precipitation method showed high catalytic activity for oxidative esterification of aldehydes. 81.0% yield of benzyl benzoate with benzaldehyde and toluene as reactants was obtained using tert-butyl peroxybenzoate as oxidant at 90°C under air atmosphere over Cu₂Mg₁Al₁-LDH catalyst. The catalyst can be recovered and used with 45% conversion after recycling five runs. The oxidative esterification reaction in the heterogeneous system is environmentally friendly.     

Highly Efficient Direct Aerobic Oxidative Esterification of Cinnamyl Alcohol with Alkyl Alcohols Catalysed by Gold Nanoparticles Incarcerated in a Nanoporous Polymer Matrix: A Tool for Investigating the Role of the Polymer Host

The selective aerobic oxidation of cinnamyl alcohol to cinnamaldehyde, as well as direct oxidative esterification of this alcohol with primary and secondary aliphatic alcohols, were achieved with high chemoselectivity by using gold nanoparticles supported in a nanoporous semicrystalline multi‐block copolymer matrix, which consisted of syndiotactic polystyrene‐co‐cis‐1,4‐polybutadiene. The cascade reaction that leads to the alkyl cinnamates occurs through two oxidation steps: the selective oxidation of cinnamyl alcohol to cinnamaldehyde, followed by oxidation of the hemiacetal that results from the base‐catalysed reaction of cinnamaldehyde with an aliphatic alcohol. The rate constants for the two steps were evaluated in the temperature range 10–45 °C. The cinnamyl alcohol oxidation is faster than the oxidative esterification of cinnamaldehyde with methanol, ethanol, 2‐propanol, 1‐butanol, 1‐hexanol or 1‐octanol. The rate constants of the latter reaction are pseudo‐zero order with respect to the aliphatic alcohol and decrease as the bulkiness of the alcohol is increased. The activation energy (E_a) for the two oxidation steps was calculated for esterification of cinnamyl alcohol with 1‐butanol (E_a=57.8±11.5 and 62.7±16.7 kJ mol^?1 for the first and second step, respectively). The oxidative esterification of cinnamyl alcohol with 2‐phenylethanol follows pseudo‐first‐order kinetics with respect to 2‐phenylethanol and is faster than observed for other alcohols because of fast diffusion of the aromatic alcohol in the crystalline phase of the support. The kinetic investigation allowed us to assess the role of the polymer support in the determination of both high activity and selectivity in the title reaction.     

异维A酸新木脂素酯的合成与表征

以香草醛(或对羟基苯甲醛)和丙二酸为原料,经Knoevenagel反应、酯化、氧化银为氧化剂的自由基仿生氧化偶联反应合成了新木脂素3a,3b。3a,3b分别与异维A酸酯化,合成了两种新型的异维A酸新木脂素酯4a和4b。用1H NMR,IR和MS对它们的结构进行了表征。研究了异维A酸酯的反应机理。     

1D iron vanadate-reduced graphene oxide nanorod composite for efficient oxidative esterification of aldehydes

In this paper, we report a facile and one-pot hydrothermal synthesis of FeVO₄-rGO nanorod composite and its application as a heterogeneous catalyst in the oxidative esterification reaction of aldehydes using hydrogen peroxide oxidant. The nanomaterial is thoroughly characterized by different techniques, namely, XPS, FESEM, elemental mapping, XRD, Raman, HRTEM, etc. The as-prepared nanocatalyst shows good activity for the controlled base-free oxidative esterification of various aromatic aldehydes in alcohol solvents under refluxing conditions, achieving good yields of the desired esters. Furthermore, the substrate scope was explored over a wide array of substituted aromatic aldehydes with diverse electron-withdrawing and electron-donating groups in the phenyl ring. The presence of heterogeneous interfaces-induced properties in the nanorod composite results in synergistic effects to provide good catalytic performance. Thus, binary transition metal oxide-reduced graphene oxide-based nanocomposite as a nanocatalyst can open doors for efficient and sustainable esterification of aromatic aldehydes and aliphatic alcohols under oxidative conditions.     

Palladium/NHC-catalyzed oxidative esterification of aldehydes with phenols

A palladium-catalyzed oxidative esterification of aldehydes with phenols is described, using air as the clean oxidant. This reaction tolerates many functional groups, providing esters with yields ranging from moderate to excellent.