Dawson结构磷钨酸镧催化绿色合成己二酸

通过复分解法制备出Dawson结构磷钨酸镧(La H3P2W18O62·n H2O),采用FT IR、SEM对其进行了表征,并将其用于催化30%H2O2氧化环己酮合成己二酸。考察了其用量、30%H2O2用量、反应时间、反应温度及重复套用次数对己二酸收率的影响。结果表明,自制磷钨酸镧具有Dawson结构,呈椭球状。优化合成工艺条件为:n(环己酮)/n(30%H2O2)=100/500,w(磷钨酸镧)=6.4%(基于环己酮的质量),反应温度100℃,反应时间5.5h。优化反应条件下,己二酸的收率最高可达86.5%。磷钨酸镧重复套用5次,己二酸收率仍可保持为74.1%。     

内酰胺型离子液体催化环己酮氧化合成己二酸

以钨酸和己内酰胺为原料一步法合成了[CP]HWO4室温离子液体,将其用于催化环己酮氧化合成己二酸,考察了离子液体用量、配体种类、体系pH值等方面的影响.结果表明,该离子液体对于环己酮氧化合成己二酸具有良好的催化效果,在环己酮100mmol,30%双氧水44.5mL,[CP]HWO45mmol,反应初始液pH值为0.8,反应时间8h,水杨酸5mmol条件下,己二酸分离产率可达85.35%.且离子液体可重复使用.     

磷钨酸-有机酸性助剂催化氧化环己酮合成己二酸

以磷钨酸-有机酸性助剂为催化体系,催化30%H2O2氧化环己酮合成己二酸。环己酮100 mol,n(磷钨酸)∶n(有机酸性助剂)∶n(环己酮)∶n(H2O2)=1∶10∶400∶2 000时,使用有机酸性助剂调节磷钨酸催化活性,结果表明以磷钨酸-酒石酸钾钠氧化环己酮效果最优,反应8 h时己二酸分离产率达93.1%;单独以磷钨酸为催化剂时,产率62.5%。以4-氨基安替比林或酒石酸钾钠为有机酸性助剂时,随反应时间的延长,产率一般会升高。磷钨酸-酒石酸钾钠和磷钨酸-4-氨基安替比林催化体系重复使用5次后,产率仍分别达到87.1%和80.6%。     

用双氧水绿色氧化环己酮合成己二酸的研究

以30%的双氧水为氧化剂, 钨酸钠与含N或O的双齿有机配体(草酸)形成的络合物为催化剂, 在无有机溶剂、无相转移剂的条件下, 研究了环己酮氧化制己二酸的反应. 研究结果表明, 用廉价的草酸为配体, 最佳反应条件为钨酸钠∶草酸∶环己酮∶30%的双氧水的物质的量比为2.0∶3.3∶100∶350, 在92 ℃下反应12 h, 可制得80.6%的己二酸; 用GC-MS跟踪了氧化过程中三种主要物质环己酮、己内酯及己二酸含量随反应时间的变化关系, 提出了其主要氧化机理为环己酮首先经Beayer-Villiger氧化反应生成己内酯, 己内酯进一步氧化成己二酸.     

回收灯用钨丝在H_2O_2催化氧化环己酮合成己二酸中的应用

以回收灯用钨丝为催化剂前驱物,30%H2O2为氧源,催化氧化环己酮合成了己二酸,反应体系中无须使用有机溶剂、酸性助剂和相转移剂。IR和TG分析表明,钨丝与H2O2反应生成的新生态过氧钨酸是催化活性成分,合成己二酸后转化为钨酸。钨丝为催化剂前驱物合成己二酸适宜反应条件为:100mmol环己酮,50mL30%H2O2,钨丝的摩尔用量为环己酮摩尔数的1.5%,回流反应6h,己二酸收率63.7%。比相同反应条件下用钨酸和WO3为催化剂的收率高10%～18%。     

两种结构钼磷酸的催化氧化行为

考察了Dawson与Keggin结构钼磷酸的催化氧化行为,并与结构特性进行了关联,结果发现,Dawson结构的杂多酸对氧化脱氢及插入氧反应均有更高的活性。     

环己醇电解氧化制备己二酸

研究了在1 mol/L NaOH溶液中环己醇电解氧化为己二酸. 电解前,镍电极首先活化从而在其表面形成三价氢氧化镍(NiOOH),后者将环己醇氧化为环己酮,并进一步氧化为己二酸等产物. 正交实验结果表明,在电流密度6×10-3 A/cm2,反应温度60 ℃,反应时间16 F/mol(F为Faraday常数),NaOH浓度1.0 mol/L的条件下,己二酸产率为42.59%. 电解动力学实验表明,反应具有典型连串反应的特征,各步骤的反应速率常数表明,环己醇电解氧化到环己酮是快反应,而环己酮进一步电解氧化到己二酸和戊二酸等产物是慢反应,是整个电解过程的控制步骤.     

杂多酸催化环己烯氧化合成己二酸

催化氧化;过氧化氢杂多酸;杂多酸催化环己烯氧化合成己二酸     

催化氧化合成己二酸的清洁方法

己二酸是一种非常重要的有机合成中间体,由于传统生产工艺的局限性,其绿色合成方法备受研究者的关注。本文综述了近年来用H₂O₂、O₂或O₃作为清洁氧化剂,以环己烯、环己酮、环己醇或其混合物为原料,催化氧化合成己二酸清洁方法的研究进展,重点介绍了含钨化合物-双氧水体系的催化氧化法,也概述了几种新的己二酸合成方法,并从溶剂、产率、后处理等方面探讨了各种方法的优缺点。在这些方法中,负载催化剂-双氧水体系将是未来工业化的最佳选择之一。     

氯化铜催化邻二甲苯与环己酮的分子氧共氧化

以Cu(Ⅰ、Ⅱ)的氯化物为催化剂,在常压液相催化分子氧氧化环己酮的同时,邻二甲苯得到较高程度的共氧化.其中,当以CuC l2.2H2O为催化剂、乙酸正丁酯为溶剂时,90℃反应10 h,环己酮及邻二甲苯转化率分别可达96.8%和74.2%,己二酸、邻甲苯甲酸及邻甲苯甲醛的收率分别可达93.3%、42.0%和31.7%.探讨了催化剂、溶剂、反应温度及反应物用量等对共氧化行为的影响.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.