BISMUTH (III) NITRATE SUPPORTED ONTO SILICA GEL,A NEW CATALYST FOR ACETYLATION OF ALCOHOLS AND PHENOLS UNDER MICROWAVE IRRADIATION

Bismuth (III) nitrate supported onto silica gel is found to be efficient catalyst for acetylation of alcohols, phenols and naphthals in the presence of acetic anhydride under microwave irradiation in solventless system.     

CHEMOSELECTIVE ACETYLATION OF ALCOHOLS,AMINES, AND THIOLS WITHOUT CATALYST AND SOLVENT

Microwave induced rapid and selective acetylation of alcohols, amines and thiols with acetic anhydride was carried out under non-catalytic and solvent free conditions.     

PHOSPHORUS PENTOXIDE AS AN EFFICIENT CATALYST FOR THE TETRAHYDROPYRANYLATION OF ALCOHOLS UNDER SOLVENT-FREE CONDITIONS

A facile and efficient method for the preparation of tetrahydropyranyl ethers from alcohols is improved in solvent-free media. These reactions are catalyzed by P₂O₅ and afford various tetrahydropyranyl ethers in shorter reaction time, with good to excellent yields (75–95%) at room temperature. This method is also compatible with substrates containing acid-sensitive functional groups.     

固体超酸POSA催化醇脱水制烯

固体超酸由于其优良的催化性能,近年来倍受重视。其中以全氟骨架的磺酸树脂Nafion H应用最广。POSA(全氟辛基磺酸,C_8F_(17)SO_3H)也是一种化学性质稳定、易回收的固体超酸,具有与Nafion H相似的氟碳链磺酸结构。     

Fe-Al络合催化苯乙烯-马来酸酐交替共聚

应用Ｆｅ（ａｃａｃ）３ Ａｌ（ｉ Ｂｕ）３（ａｃａｃ＝乙酰丙酮）催化苯乙烯 马来酸酐共聚,制得富于交替的白色粉末共聚物．共聚反应动力学研究表明,共聚反应与单体浓度呈一级关系,表观活化能为４８６ｋＪ／ｍｏｌ．     

THE USE OF NAFION-H® AS AN EFFICIENT CATALYST FOR THE DEPROTECTION OF TRIMETHYLSILYL ETHERS TO THEIR CORRESPONDING ALCOHOLS UNDER MILD AND HETEROGENEOUS CONDITIONS

Trimethylsilyl ethers were converted to their corresponding alcohols in the presence Nafion-H® and wet SiO ₂ with good-to-excellent yields under mild and heterogeneous conditions.     

MANGANESE(III) PORPHYRIN SUPPORTED ON POLYSTYRENE AS A HETEROGENEOUS ALKENE EPOXIDATION AND ALKANE HYDROXYLATION CATALYST

ABSTRACT

Carboxymethylated crosslinked polystyrene resin [poly(4-styrylmethylacylchloride) (PSA)] support have been used to covalently attach manganese(III) tetrakis(4-aminophenyl)porphyrin. This catalyst was found to be efficient for alkene epoxidation and alkane hydroxylation by sodium periodate. This new hydrogenised catalyst is of high stability and reusability.     

SURFACE ACIDITY OF ZEOLITE ZSM-5 AND ITS CATALYTIC PROPERTIES IN ESTERIFICATION OF ACETIC ACID WITH ALCOHOLS

IntroductionTheuseoflarge-PorezeolitessuchasXandYforcarelyzingtheesterificationhasbeenearlysuggestedbyBergklllandnorelationshipbetweentheactivityandsubdueaciditywasobserved.ItalianPatent[2]reportedthatdecationizedYzeolitesareveryactiveandselectivecatalyst…     

SILICA SULFURIC ACID; AN EFFICIENT AND REUSABLE CATALYST FOR REGIOSELECTIVE RING OPENING OF EPOXIDES BY ALCOHOLS AND WATER

The nucleophilic ring opening reactions of epoxides by aliphatic alcohols and water are achieved efficiently in the presence of catalytic amounts of silica sulfuric acid with high degree of regioselectivity. The catalyst is reusable and can be applied several times without any decrease in the yield of reactions.     

STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A BIDENTATE POLYMER BOUND CIS-DICARBONYLRHODIUM COMPLEX AS CATALYST

Copolymer of 2-vinylpyridine and vinylacetate coordinated with dicarbonylrhodiumused as a catalyst for carbonylation of methanol to acetic acid and anhydride has beenstudied. The structural characteristics of the copolymer ligand and complex, and the in-fluences of the reaction conditions on the carbonylation catalyzed by this polymer complexhave been investigated. In comparison with small molecule catalyst of Rh complex, thebidentate copolymer coordinated complex has better thermal stability. The reactionmechanism of the carbonylation reaction is also illustrated.     

以氨基酸酯为轴向配体的铁、锰卟啉配合物的合成及表征

The new six-coordinate complexes (TPP)Fe^Ⅱ(Gly-OMe)₂ C₅₀H₄₂FeN₆O₄ and (TPP)Fe^Ⅱ(β-Ala-OMe)₂ (C₅₂H₄₆FeN₆O₄) wbere TPP=meso-tetraphenyl porphyrinate, Gly-OMe=glycine methyl ester, β-Ala-OMe=β-alanine methyl ester and five-coordinte complex (TPP)Mn^(Ⅱ)(Gly-OMe) (C₄₇H₃₅MnN₅O₂) have been prepared by sodium borohydride method.These complexes were characterized by UV-Vis, IR, ESR, spectra and by elemental analysis. The synthesized divalent iron porphyrins are d⁶ low spin states and their UV-Vis spectra are Hypso type; while divalent manganese porphyrin is d⁵ high spin state and its UV-Vis spectrum is pseudo-Normal type.     

磷酸锡晶体去除海水中Pb(Ⅱ)研究

利用合成的磷酸锡晶体作为吸附剂,考察了pH值、吸附时间、初始浓度、温度等因素对吸附水溶液中Pb2+的影响,同时考察了在模拟海水中的吸附效果。结果表明,磷酸锡对Pb2+的吸附量随着pH(3~6)以及吸附时间的增大而增加。吸附动力学过程符合准二级动力学模型。等温吸附数据用Langmuir方程拟合效果最好,20℃时饱和吸附量达到110.50mg/g。Dubinin-Radushkevich(D-R)模型研究表明吸附机理属于化学离子交换。反应机理为磷酸锡中的H+与溶液中的Pb2+发生了离子交换反应。热力学研究表明磷酸锡对Pb2+的吸附是一个自发的、吸热的过程,升温有利于吸附。模拟海水中Pb2+的吸附实验结果表明,高盐度对磷酸锡吸附Pb2+有一定的不利影响,但幅度不大,可以用于去除养殖海水中的Pb2+。所吸附的Pb2+可以用HCl解吸,说明磷酸锡具有重复利用的潜能。     

POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] AS AN EFFICIENT REAGENT FOR OXIDATION OF ALCOHOLS

POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] is readily prepared. It is a stable, mild, and efficient oxidizing reagent that can be used for oxidation of different alcohols to their corresponding carbonyl compounds in approtic solvents. This polymer can be synthesized from the reaction between poly [N-(4-pyridyl)-p-styrene sulphonamide] and CrO ₃ in a minimum amount of water. The latter polymer was prepared by free radical polymerization of [N-(4-pyridyl)-p-styrene sulphonamide] by using azobis(isobutyronitrile) (AIBN) as an initiator. N-(4-pyridyl)-p-styrene sulphonamide was synthesized from commercial 4-vinyl benzene sulphonic acid sodium salt and 4-amino pyridine. POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] can oxidize both aliphatic and aromatic alcohols in good yields at a temperature of 38°C and in CH ₂ Cl ₂ as solvent. One advantage in using this reagent is the mild condition of the reaction system. The synthesized compounds including polymeric reagent and carbonyl compounds were identified by HNMR and IR spectroscopy.     

单茂钛/甲基铝氧烷催化剂乙烯/丙烯共聚合研究

改性甲基铝氧烷(mMAO)激活五甲基茂基三氯化钛(Cp TiCl3)催化乙烯 丙烯共聚合,控制两种单体的进料配比,得到单元序列分布不同的共聚物.混合单体中含有少量丙烯,共聚合活性高于相同聚合条件下乙烯均聚合的活性.用1 3C -NMR测定共聚物分子链的微观结构和单元序列分布,计算出单体的竞聚率;结果表明共聚物分子链中两种单体的序列分布均匀.混合单体中丙烯含量较大时,共聚物为完全无规共聚物;而当丙烯含量少时,丙烯链节或短的聚丙烯链段均匀分布于聚乙烯链段之间.共聚物经DSC分析,也证明不存在长序列的聚乙烯链段;因此,即便在进料气体中丙烯含量很少的情况下,共聚物仍然没有明显的熔融温度和结晶性.     

硫酸铜催化下乙烯酮、乙酐与环酮、戊二酮及乙酰乙酸乙酯的反应

烯醇酯是合成高分子化合物的单体,较早由快烃与羧酸反应得到,1944年Bedoukian用醋酸钾为催化剂由异丁醛与乙酐反应得到乙酸异丁烯酯,Gwynn等在硫酸、磷酸等催化下由乙烯酮与酮反应合成了乙酸烯醇酯。我们曾由环戊酮、环己酮在硫酸铁催化下合成了环烯醇酯。本文在合成反应中改用硫酸铜为催化剂时提高了烯醇酯的产率。     

STUDY OF THE MECHANISM FOR THE REARRANGEMENT OF THIOLSULFINATE WITH ACETIC ANHYDRIDE BY 13C AND 18O-TRACER EXPERIMENTS

Abstract

Recently, we found that benzyl phenylmethanethiolsulfinate (I) reacts with acetic anhydride at 60°C to afford the rearranged sulfoxide, i.e., an almost 1:1 mixture of both erythro and threo-1-(acetoxylthio)benzyl benzyl sulfoxides(II) in a substantial yield.     

以四价锰为引发剂纤维素与丙烯腈接枝共聚的研究

<正> 对天然高分子纤维素进行接枝改性可以获得一系列新型高分子材料。但是,在接枝共聚过程中往往产生大量的均聚物,阻碍了该法的工业应用。此外,对接枝共聚产物的结构尚缺乏深入的研究,因此寻找不形成或少形成均聚物的简便接枝共聚方法,及研究纤     

HEXAMETHYLDISILAZANE IN THE PRESENCE OF N,N′,N″,N‴-TETRAMETHYLTETRA-2,3-PYRIDINOPORPHYRAZINATO COPPER (II) IS A NEW,MILD AND HIGHLY EFFICIENT REAGENT FOR SILYLATION OF ALCOHOLS AND PHENOLS

Alcohols and phenols are protected with hexamethyldisilazane in the presence of N,N′,N′,N?-tetramethyletra-2,3-pyridinoporphyrazinato copper (II) in good-to-excellent yields at room temperature.     

WOBr_4催化聚苯乙炔的合成与表征

本文研究了苯乙炔在WOBr_4催化剂作用下的聚合行为,并对催化聚合机理进行了探讨。所得聚合物是可溶可熔的褐红色固体,其最高分子量为1830(M_n)。WOBr_4催化剂具有催化剂用量少(2/100),聚合反应时间短(10秒钟),产物收率高(80％以上)等特点。结构分析结果表明,WOBr_4催化聚苯乙炔具有顺-反式微观结构。