三芳胺合成的研究进展

三芳胺化合物的合成方法主要有3种:(1)非金属催化的胺化反应;(2)铜催化的Ullnann反应,包括使用过量铜粉为催化剂的传统的Ullmann反应、使用相转移催化剂的Ullmann反应以及使用配体的post-Ullmann反应;(3)钯催化的Buchwald-Hartwig反应.该类反应活性的关键是配体的选择,根据配体结构的不同可分为双膦螯合型配体、单膦配体和非膦配体.对该类化合物的这几种合成方法的研究进展进行了总结.     

Theoretical study on the alkaline hydrolysis of methyl thioacetate in aqueous solution

A base-catalyzed hydrolysis reaction of thiolester has been studied in both gas and solution phases using two ab initio quantum mechanics calculations such as Gaussian09 and CPMD. The free-energy surface along the reaction path is also constructed using a configuration sampling technique, namely, the metadynamics method. While there are two different reaction paths obtained for the potential profile of the base-catalyzed hydrolysis reaction for thiolester in the gas phase, a triple-well reaction path is computed for the reaction in the solution phase by two quantum mechanics calculations. Unlike the S(N)2 mechanism (a concerted mechanism) found for the gas-phase reaction, a nucleophilic attack from the hydroxide ion on the carbonyl carbon to yield a tetrahedral intermediate (a stepwise mechanism) is observed for the solution-phase reaction. Moreover, the energy profiles computed by these two theoretical calculations are found to be very comparable with those determined experimentally.     

Design and synthesis of two triazonine-carbaldehyde derivatives using several chemical tools

Several triazonine-carbaldehyde derivatives have been prepared using different protocols; however, some require special reagents and conditions. The aim of study involved the synthesis of two triazonine-carbaldehyde derivative using testosterone or OTBS-testosterone as chemical tool. Triazonine-carbaldehyde derivatives were prepared by a series of reactions that involve the following: (1) synthesis of two nitrobenzamide derivatives by reaction of testosterone or OTBS-testosterone with p-nitrobenzoyl azide using Copper(II) as catalyst; (2) reaction of the nitrobenzamides with ethylenediamine to form two triazonine derivatives using boric acid as catalyst; (3) preparation of hexynyl-triazonine derivatives by the reaction of two triazonines 6-chlorohex-1-yne in basic medium; (4) reaction of hexynyl-triazonine derivatives with benzaldehyde to form two triazoninol analogs; (5) preparation of triazoninynal derivatives through oxidation of triazoninol analogs with dimethyl sulfoxide; and (6) synthesis of triazonine-carbaldehyde derivatives by the reaction of triazoninynal derivatives with hexyne-1 using Copper(II) as catalyst. The chemical structure of compounds was determined by spectroscopic and spectrometric methods. In conclusion, in this work were prepared two triazoninone derivatives using several chemical techniques, which are simple procedures and easy to handle.     

Silylation of OH‐polymers by reactive extrusion

Silylation of poly(vinyl alcohol) and cellulose with hexamethyldisilazane (HMDS) in a twin screw extruder using ammonia as reaction medium has been studied. As the starting materials are powders which do not melt without decomposition both polymers were blended with the corresponding trimethylsilyl polymer and a reaction compartment was created using appropriate restrictor elements. Reaction profiles with temperatures below 100°C in the reaction zone and lower temperature in the restrictor zones enabled silylation of both polymers. Residence times were as low as 15 min.     

反应类等键反应方法及类反应热动力学参数计算

本文提出了反应类等键反应方法,将通常用于热力学性质计算的等键反应方法推广用于类反应中反应势垒和反应焓变的计算. 对碳氢燃料低温燃烧反应机理中的一类重要反应类：?烷基自由基过氧化氢裂解生成烯烃和HO2自由基的反应势垒和反应焓变进行了计算. 通过对该类16个反应中的5个代表反应分别在不同计算水平HF、DFT、MP2、CCSD(T)的比较计算发现,采用等键反应方法可在较低从头算级别计算得到类反应较高精度的反应势垒,提高了计算的效率和精度. 本文采用反应类等键反应方法在B3LYP/6-311G(d,p)计算水平对该类16个反应进行了反应势垒和反应焓变的计算,并建立了反应势垒和反应能的线性自由能关系：delta V=71.02+0.41?delta E.     

Catalytic Aerobic Phenol Homo- and Cross-Coupling Reactions with Copper Complexes Bearing Redox-Active Guanidine Ligands

Due to their large importance in synthetic chemistry, catalytic C−C coupling reactions of phenols are currently intensively studied. Herein, new copper catalysts for the C−C coupling reaction of phenols using dioxygen as a green oxidizing reagent are reported. By using redox-active guanidine ligands, the activity as well as chemoselectivity in the cross-coupling reaction of non-complementary phenols (between an electron-rich phenol and a less nucleophilic second phenol) is significantly improved. Based on the collected data for several test reactions, a reaction mechanism is proposed.     

Rapid and amenable suzuki coupling reaction in water using microwave and conventional heating

It is possible to prepare biaryls in good yield very rapidy (5-10 min) on small (1 mmol) and larger (10-20 mmol) scales from aryl halides and phenylboronic acid using water as a solvent and palladium acetate as catalyst. The reaction can be performed equally well using microwave and conventional heating, showing that using these conditions probably no nonthermal microwave effects are associated with the impressive speed of the reaction.     

Quantum calculations of the O(3P)+H2-->OH+H reaction

Quantum scattering calculations are reported for the O(3P)+H2(v=0,1) reaction using chemically accurate potential energy surfaces of 3A' and 3A" symmetry. We present state-to-state reaction cross sections and rate coefficients as well as thermal rate coefficients for the title reaction using accurate quantum calculations. Our calculations yield reaction cross sections that are in quantitative accord with results of recent crossed molecular beam experiments. Comparisons with results obtained using the J-shifting calculations show that the J-shifting approximation is quite reliable for this system. Thermal rate coefficients from the exact calculations and the J-shifting approximation agree remarkably well with experimental results. Our calculations also reproduce the markedly different OH(v'=0)/OH(v'=1) branching in O(3P)+H2(v=1) reaction, observed in experiments that use different O(3P) atom sources. In particular, we show that the branching ratio is a strong function of the kinetic energy of the O(3P) atom.     

A synthetic approach toward nitiol: construction of two 1,22-dihydroxynitianes

Synthetic work toward the total synthesis of nitiol has culminated in the construction of two epimeric hydroxylated derivatives, the 1,22-dihydroxynitianes. Key stereodefining steps in the construction of the A-ring fragment (13) were the use of a siloxy-epoxide rearrangement reaction, a Pauson-Khand reaction, a Norrish 1 photochemical cleavage reaction, and a highly regio- and stereoselective hydrostannylation reaction of an ynoate. The stereochemistry of the synthetically challenging C-ring fragment (20) was established using an Ireland-Claisen reaction and a Grubbs ring-closing metathesis process as key steps. The 12-membered B-ring of the nitiane skeleton was constructed using a copper-promoted Stille cross-coupling and a Kishi-Hiyama-Nozaki carbonyl addition reaction. Unfortunately, the carbonyl addition reaction produced hydroxyl functionality that could not be selectively removed. Consequently, a synthesis of epimeric 1,22-dihydroxynitianes, which are compounds that are structural hybrids of two natural products, nitiol and variculanol, was completed.     

氢原子共线交换反应的动力学计算I.Cl与HCl反应几率的振荡现象研究

我们利用超球坐标对共线Cl+HCl(V-3)→ClH(V'≤3)+Cl作了一维精确量子计算,计算所用势能面是LEPS型,Et=-3.23KJ/mol, 得到了态态反应几率等动力学信息, 通过分析结果发现, 反应是振动绝热的, 即以对角(V'-V')反应几率为主,非对角(V' V')反应几率小于0.1, 反应几率随总能量表现出强裂地振荡, 在有阱的势能面上动力学共振增强。     

Three component,one-pot synthesis of amidoalkyl naphthols using polyphosphate ester under solvent-free conditions

Amidoalkyl naphthols are synthesized via a simple, one-pot, three-component reaction between aldehydes, 2-naphthol and amides or ureas using polyphosphate ester (PPE) as a reaction mediator under solvent-free conditions in good to excellent yields. High yields, short reaction time, easy work-up, elimination of solvents and toxic catalysts are the advantages of this procedure.     

A RuH(2)(CO)(PPh(3))(3)-catalyzed regioselective arylation of aromatic ketones with arylboronates via carbon-hydrogen bond cleavage

When the reaction of aromatic ketones with arylboronates (arylboronic acid esters) using RuH(2)(CO)(PPh(3))(3) (3) as a catalyst was conducted in toluene, the corresponding arylation product was obtained in moderate yields. In this case, a nearly equivalent amount of a benzyl alcohol derived from a reduction of an aromatic ketone was also formed. The use of aliphatic ketones, such as pinacolone and acetone, as an additive or a solvent dramatically suppressed the reduction of the aromatic ketones and, as a result, ortho-arylation products were obtained in high yield based on the aromatic ketones. In these reactions, the aliphatic ketone functioned as a scavenger of ortho-hydrogens of the aromatic ketones and the B(OR)(2) moiety of the arylboron compound (HB species). A variety of aromatic ketones, such as acetophenones, acetonaphthones, tetralones, and benzosuberone, could also be used in this coupling reaction. Several arylboronates containing electron-donating (NMe(2), OMe, and Me) and -withdrawing (CF(3) and F) groups were also applicable to this coupling reaction. Intermolecular competitive reaction using pivalophenone-d(0)() and -d(5) and intramolecular competitive reaction using pivalophenone-d(1) were carried out using 3 as a catalyst. The k(H)/k(D) value for the intermolecular competitive reaction was substantially different, compared with intramolecular competitive reaction. This strongly suggests the production of an intermediate where the ketone carbonyl is coordinated to the ruthenium involved in this catalytic reaction. (1)H and (11)B NMR studies using 2'-methylacetophenone, phenylboronate (2), and pinacolone (6) indicate that 6 functions effectively as a scavenger of the HB species.     

Heterogeneous interactions of calcite aerosol with sulfur dioxide and sulfur dioxide-nitric acid mixtures

The heterogeneous chemistry of sulfur dioxide with CaCO(3) (calcite) aerosol as a function of relative humidity (RH) has been studied under isolated particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reaction of SO(2) with calcite produced gas phase CO(2) as a product in addition to the conversion of the particulate carbonate to sulfite. The reaction extent was found to increase with elevated RH, as has been observed for the similar reaction with HNO(3), but much higher relative humidities were needed to significantly enhance the reaction. Mixed experiments in which calcite aerosol was exposed to both HNO(3) and SO(2) were also performed. The overall reaction extent at a given relative humidity did not appear to be increased by having both reactant gases present. The role of carbonate aerosol as an atmospheric sink for sulfur dioxide and particulate nitrogen and sulfur correlations are discussed.     

A study of the alkene-ozone reactions, 2,3-dimethyl 2-butene + O3 and 2-methyl propene + O3, with photoelectron spectroscopy: measurement of product branching ratios and atmospheric implications

The reactions of ozone with the alkenes 2,3-dimethyl 2-butene (DMB) and 2-methyl propene (2MP) have been investigated using a flow-tube interfaced to a u.v. photoelectron spectrometer. These reactions were studied at low pressure at different reagent partial pressures, both with the alkene in excess and ozone in excess. In each case, photoelectron spectra recorded as a function of time have been used to estimate partial pressures of the reagents and products as a function of time using photoionization cross-sections of selected photoelectron bands of the reagents and products, which were measured separately. The yields of all the main products have been determined, some of which have been measured in previous studies. For each reaction, oxygen was observed as a product for the first time and its yield was measured. Kinetics simulations were performed using reaction schemes which were developed for these reactions, which are consistent with that used earlier for the ozone-ethene reaction, in order to determine the main reactions for production of the products. The experimental product yields have been used in a global model to estimate their global annual emissions in the atmosphere. For example, for the reaction of O(3) with 2MP the formaldehyde, formic acid and acetone global annual emissions are calculated as 0.4 Tg, 25.0 Gg and 0.16 Tg respectively, which are estimated as 0.02, 0.3 and 0.2% of the total annual emission respectively. For the reaction of O(3) with DMB, the acetone yield is higher at 0.9 Tg which is approximately 1% of the total annual estimated emission.     

Challenge toward structural complexity using asymmetric catalysis: target-oriented development of catalytic enantioselective Diels-Alder reaction

A new method for the catalytic enantioselective Diels-Alder reaction using polysubstituted silyl enol ethers as dienes is described. High enantioselectivity (up to 92% ee) was produced using a catalyst generated from FeBr(3) and AgSbF(6) in a 1:2 ratio and aryl-pybox (aryl = Ph or p-ethoxyphenyl). This reaction should facilitate the enantioselective synthesis of polycyclic acylphloroglucinols such as hyperforin or garsubellin A, which are currently of interest from synthetic and medicinal points of view.     

Multistep solution-mediated formation of AuCuSn2: mechanistic insights for the guided design of intermetallic solid-state materials and complex multimetal nanocrystals

Understanding how solids form is a challenging task, and few strategies allow for the elucidation of reaction pathways that are useful for designing new solids. Here, we describe an unusual multistep reaction pathway that leads to the formation of AuCuSn(2), a new ternary intermetallic compound that was discovered as nanocrystals using a low-temperature solution route. The formation of AuCuSn(2) using a modified polyol process occurs through a multistep pathway that was elucidated by taking aliquots throughout the course of the reaction and studying the products using a variety of techniques. The reaction proceeds through four distinct steps: (a) formation of Au nanoparticles at or near room temperature, mediated by a galvanic reaction between Au(3+) and Sn(2+) (forming Au(0) and Sn(4+), precipitated as SnO(2) that forms a shell around the nanoparticles), (b) formation of NiAs-type AuSn nanoparticles, along with Cu and Sn, upon addition of NaBH(4), (c) aggregation and thermal interdiffusion to form AuCu(x)Sn(y) alloy nanoparticles, and (d) nucleation of intermetallic AuCuSn(2), which has an ordered NiAs-derived structure. The proposed mechanism was tested by starting the reaction with the AuSn intermediate. AuSn nanoparticles were synthesized separately and reacted with Cu and Sn nanoparticles, and ordered AuCuSn(2) formed as expected. Elucidation of this reaction pathway has important implications for guiding the design of new intermetallic solids, as well as for controlling the synthesis of complex multimetal nanocrystals.     

Dimethyl carbonate as an ambident electrophile

[reaction: see text] The features of various anions having different soft/hard character (aliphatic and aromatic amines, alcohoxydes, phenoxides, thiolates) are compared with regard to nucleophilic substitutions on dimethyl carbonate (DMC), using different reaction conditions. Results are well in agreement with the Hard-Soft Acid-Base (HSAB) theory. Accordingly, the high selectivity of monomethylation of CH(2) acidic compounds and primary aromatic amines with DMC can be explained by two different subsequent reactions, which are due to the double electrophilic character of DMC. The first step consists of a hard-hard reaction and selectively produces a soft anion, which, in the second phase, selectively transforms into the final monomethylated product, via a soft-soft nucleophilic displacement (yield >99% at complete conversion, using DMC as solvent).     

循环连续流动分析法测定辣根过氧化物酶的活性

基于H2O2-辣根过氧化物酶(HRP)-邻苯二胺(OPDA)催化反应体系,建立了测定游离及固定化HRP酶活性的循环连续流动分析法(CCFA).CCFA实现了反应液、反应过程的循环连续检测.用CCFA法对酶催化反应条件进行研究,得到的最佳反应条件是:pH 5.0,反应温度27 ℃, 66.0 μmol/L H2O2 , 2 mg/L OPDA,缓冲液为0.1 mol/L柠檬酸-柠檬酸钠缓冲液; 测定游离HRP的线性范围为0～10 U/L,检出限为0.21 U/L,RSD＜1.03%.使用CCFA法测定了固定化HRP的活性,并对HRP酶促动力学进行了研究,得到的游离HRP的米氏常数为0.078 mmol/L,最大反应速度为0.26 mmol/(L min),催化常数为5.2 × 104 min-1.CCFA法操作简便、准确度高、节省试剂、易于实现自动化.     

An efficient and recoverable palladium organocatalyst for Suzuki reaction in aqueous media

Meso‐tetrakis[4‐(methoxycarbonyl)phenyl]porphyrinatopalladium(II) as a palladium organocatalyst was synthesized and then used in aqueous media as a heterogeneous organocatalyst in Suzuki reaction. The prepared organocatalyst was characterized using UV–visible, infrared and NMR spectroscopies. It was found to be an efficient catalyst for Suzuki coupling reaction between phenylboronic acid and a broad range of aryl halides. Mild reaction conditions, water solvent as green media, and easy catalyst separation and reusability are the advantages of the presented method.     

Transition-metal-free Suzuki-type coupling reactions: scope and limitations of the methodology

The scope and limitations of the transition-metal-free Suzuki-type coupling of aryl halides and arylboronic acids to form biaryls are presented. Confirmation that the reaction is indeed metal-free is presented. The effects of changing base, solvent, reaction temperature, phase-transfer catalyst, and substrate are shown and the implications of these results discussed in terms of their impact on the synthetic versatility of the methodology. The main findings are that the reaction works well for aryl bromides, water is necessary as a solvent for the reaction, the optimum temperature for the reaction is 150 degrees C, the reaction is best performed by using microwave promotion with the exception of an electron-poor aryl bromide example where conventional heating may be used, only limited boronic acids can be used as coupling partners, sodium carbonate is the best base for the reaction, tetrabutylammonium bromide proves to be the best phase-transfer catalyst for the reaction, the reaction is limited to couplings between aryl halides and aryl boronic acids with sp(2)-sp(3) couplings proving ineffective, and NaBPh(4) can be used in the place of phenylboronic acid as a phenylating agent.