Selectivity in the Phase Transfer Catalytic Hydrogenation of Nitrobenzene by Transition VIII Metals

The phase transfer hydrogenation of nitrobenzene to p-aminophenol has been investigated for the catalysts Pt, Pd, Rh and Ru. The influence of factors such as surfactant concentration, sulfuric acid concentration, hydrogen pressure and temperature on the reaction was determined. It was found that the rate-determining step for the catalytic hydrogenation of nitrobenzene is the catalytic process by which the hydrogen atom is absorbed on the metal surface. A reaction model is suggested which accounts for the observed hydrogenation selectivity and explains how these factors affect product composition and yield. It is shown that Pt favors p-aminophenol production, while Pd favors aniline production.     

相转移催化合成N,N′-二(3,5-二甲基吡唑)烷

近年来,多齿含氮配体在金属有机配合物的合成和研究中日益受到重视,不仅用在高氧化态、缺电子中心的高价过渡金属有机配合物上,而且已开始在低氧化态、富电子中心的低价过渡金属有机配合物上应用,其中一个重要原因是自然界里许多的金属酶普遍含有以氮为配位原子的配体。因此,本文试图研究N,N′-二(3,5-二甲基吡唑)烷的合成。70年代初,Trofimenko 用3,5-二甲基     

Stereoselective Synthesis of Some Dialkyl (E)-2-Bromomethylene Glutarates

Reaction of 2-bromo-2-bromomethyl glutaric acid esters with tetraalkylammonium fluoride in HMPA, conveniently provides the corresponding dialkyl (E)-2-bromomethylene derivatives in good yields.     

Vinyltriphenylphosphonium Salt Mediated One-Pot Stereoselective Synthesis of Dialkyl ( E )-2-(2-methyl-5-oxo-1-cyclopentenyl)-2-butenedioates

Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 2-hydroxy-3-methyl-2-cyclopenten-1-one leads to vinyltriphenylphosphonium salts, which undergo an intramolecular Wittig reaction to produce the corresponding cyclobutene derivatives. The cyclobutene derivatives are not isolable and undergo electrocyclic ring-opening reactions in CH 2 Cl 2 at room temperature to produce dialkyl ( E )-2-(2-methyl-5-oxo-1-cyclopentenyl)-2-butenedioates in moderate yields.     

液—液相转移催化反应合成N—取代吩噻嗪

本文叙述以四正丁基溴化铵为相转移催化剂,液一液相转移催化合成了六个 N-取代吩噻嗪化合物。由于在方法上作了改进,所以产率均优于文献报导。     

Synthesis and Characterization of Polysulfide Rubber Using Phase Transfer Catalyst

Summary : Poly(alkyltetrasulfide) is prepared via reaction of ethylene dichloride with sodium tetrasulfide (Na₂S₄) in the presence of methyl tributyl ammonium chloride as phase transfer catalyst (PTC). The polysulfide polymer is characterized by CHN analysis, FT-IR, TGA, DTA and DSC techniques.     

Facile Stereoselective Synthesis of (E)-1-Arylseleno-Substituted 1,3-Enynes and Their Applications in Synthesis of (E)-Enediynes

(E)-1-Iodo-2-arylselenoethylenes 1 underwent the Sonogashira coupling reactions with terminal alkynes 2 to afford (E)-1-arylseleno-substituted 1,3-enynes 3 in high yields. (E)-1-Arylseleno-substituted 1,3-enynes 3 were coupled with alkynylmagnesium bromides 4 in the presence of a catalytic amount of NiCl₂(PPh₃)₂ to give stereoselectively (E)-enediynes 5 in good yields.     

Regio- and Stereoselective Synthesis of (E)-2-Bromo-1-(phenoxymethyl)vinyltellanes

Russian Journal of General Chemistry - Regio- and stereoselective synthesis of tribromo[(E)-2-bromo-1-(phenoxymethyl)vinyl]tellane based on the reaction of tellurium tetrabromide with propargyl...     

超声波辐射下固-液相转移催化法合成N-(α -萘乙酰基)-N'- 芳基硫脲化合物

利用超声波辐射固－液相转移催化法合成了十三种未见文献报道的N(α-萘乙酰基)-N'-芳基硫脲新化合物,并经IR,1^HNMR,13^CNMR和元素分析确定了它们的结构。初步考查它们对玉米生长的促进作用,初步生物活性实验结果表明所有合成的化合物在(0.1～10)×10^-6的浓度内对玉米的根部生长具有显著的促进作用,部分化合物对玉米的幼苗具有促生长作用。     

相转移催化法合成反式-3，4，5-三甲氧基-4′-硝基二苯乙烯

以3,4,5-三甲氧基苯甲醛和对硝基甲苯为原料,利用相转移催化法经缩合脱水合成了反式-3,4,5-三甲氧基-4′-硝基二苯乙烯。其结构经1H NMR,13C NMR,IR和元素分析确定。以苄基三乙基氯化铵为相转移催化剂时,在室温下反应12 h,产率89%。     

相转移催化法合成反式-3,4,5-三甲氧基-4''''-硝基二苯乙烯

以3,4,5-三甲氧基苯甲醛和对硝基甲苯为原料,利用相转移催化法经缩合脱水合成了反式-3,4,5-三甲氧基-4'-硝基二苯乙烯.其结构经1H NMR,13C NMR,IR和元素分析确定.以苄基三乙基氯化铵为相转移催化剂时,在室温下反应12 h,产率89%.     

A Novel Approach to the Stereoselective Synthesis of (E)-1-(1-Alkenyl)Benzotriazoles

The Horner-Wadsworth-Emmons olefination of diethyl-(1-benzotri-azolmethyl)phosphonate by means of aldehydes was found to be a convenient method for the stereoselective preparation of (E)-1-(1-Alkenyl)benzotriazoles.     

Stereoselective Synthesis of (2E)-,(2E,4E)-Unsaturated Carboxamides via Tellurium Ylides

Reaction of dibutyl(alkylcarbamoylmethyl) tellurium halides with aldehydes in presence of potassium carbonate gave α, β-unsaturated carboxamidee with high E-selectivity and good yields.     

钼矿石物相分析及催化极谱法测定钼

为测定钼矿中钼的总量,将矿样与盐酸加热后加硝酸-硫酸(8+2)混合酸蒸发冒烟至干。用150 g.L-1氢氧化钠溶液溶解残渣取代了常用的碱融熔法,在所得上清液中测定总钼量。为溶解钼矿中不同相态,另取一份矿样先用氨水处理以溶解钼华矿(MoO3),在每次分相溶解中所得的残渣先后用40 g.L-1酒石酸溶液和150 g.L-1碳酸钠溶液处理依次溶解出钼钨钙矿[Ca(W,Mo)O4]和钼酸铅矿(PbMnO4),在溶解分去钼酸铅矿后的残渣中存在有辉钼矿(MoS2)。将其在580℃灼烧后按测定总钼的溶解方法处理,在所得溶液中测定辉钼矿的钼量。采用催化极谱法测定上述各溶液中的钼量,所用底液为含有氯酸钾、二苯羟乙酸、二苯胍及硫酸的混合液。按所提方法分析了3个钼矿标准样品,所测得每一试样中各物相中钼量之和与该样品的总钼量测定值一致,其相对标准偏差(n=5)均小于3.5%。     

Synthesis and resolution of 2-(diphenylphosphino)heptahelicene

Palladium catalysed Heck couplings have been applied to the two-step synthesis of a stilbene derivative bearing a diphenylphosphine oxide function which represents a suitable precursor for the photochemical generation of the corresponding [7]-helicene. After reduction of the phosphine oxide, resolution of the monodentate helical phosphine has been performed by means of the ortho-metallated (R)-1-(naphthyl)ethylamine-palladium complex. A ruthenium complex of (heptahelicen-2-yl)diphenylphosphine has also been prepared and fully characterized.     

High-Yield Synthesis of the Novel E,E-2,5-Dimethoxy-1,4-bis[2-(4-ethylcarboxylatestyril)]benzene by the Heck Reaction

The novel E,E-2,5-dimethoxy-1,4-bis[2-(4-ethylcarboxylatestyril)]benzene, 4, was obtained in good yield (92%), by the Heck cross-coupling reaction using Pd(dba)₂ and P(OPh)₃ like catalytic system. The high trans specificity of the product produced by the Heck reaction was confirmed by Fourier Transform–infrared and NMR. The methodology reported can be used as synthetic route for precursors to phenylenevinylene target systems with highly desired functional groups in their molecular structure, such as carboxylic, to build metal–organic frameworks and other applications within the supramolecular chemistry.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

A Highly Stereoselective Synthesis of (E,E)-1,5-Dienes

Several representative 1,5-dienes were synthesized, with a high degree of regioselectivity, by a series of nitrone cycloadditions and subsequent deamination of the adducts.     

聚γ-(β-氰乙硫基)丙基硅氧烷钯(0)配合物的合成与催化性能

γ-(β-氰乙硫基)丙基三乙氧基硅烷依次用气相法二氧化硅固载,与氯化钯反应,然后用水合肼还原,合成了二氧化硅负载的聚γ-(β-氰乙硫基)丙基硅氧烷钯(0)配合物。研究了其催化共轭烯烃Heck芳基化反应的性能。     

(E)-1-氯-6,6-二甲基-2-庚烯-4-炔的立体选择性合成

(E)-1-氯-6,6-二甲基-2-庚烯-4-炔是合成盐酸特比萘芬的关键中间体,N-氯代二异丙胺/三苯基膦与6,6-二甲基-1-庚烯-4-炔-3-醇反应,可以立体选择性地得到反式的该化合物,其反式/顺式异构体的比例达9/1,为特比萘芬提供了可工业放大生产的立体选择性合成方法。