Investigation of reaction products of sulphuric acid with ilmenite

The reaction of sulphuric acid with titanium raw materials runs violently with simultaneous emission of gases. Such run of reaction creates danger of explosion. This process is very complicated from the reason of complexity of reactions and variety of compounds in reaction mixture. To determine safe conditions of reaction with high efficiency, it is necessary to investigate phase composition products of reaction. Products of reaction were investigated by using X-ray diffraction. However reaction products show high amorphy and this is the reason of difficulties to determine all phases. For this reason also was used additional method — ‘drop’ calorimeter. This method is used for determination of average specific heat of liquid or solid samples. In this case, this method was used for verification of phase composition of products of reaction. On the basis of investigation the phase composition of reaction product is following: titanyl sulfate, iron(III) sulfate, monohydrated iron(II) sulfate, magnesium sulfate and unreacted remainders of ilmenite and magnesium silicate.     

混合多卤甲烷与金属镁反应产生溴氯卡宾及其反应机理的研究

应用CHBr3/CHCl3或CHBr3/CCl4和金属镁在一般的Grignard反应条件下与烯烃反应, 制备偕溴氯环丙烷衍生物。该反应原料易得, 反应条件温和, 产率良好, 后处理方便, 是制备偕溴氯环丙烷衍生物的一种简便的新方法。文中研究了上述反应的单电子转移和自由基链循环的复杂反应机理。     

苯甲醛肟与炔丙醇偶极环加成反应的理论研究

用密度泛函理论(DFT)方法在B3LYP/6-31G*水平上研究了苯甲醛肟与炔丙醇加成反应的微观机制和热力学、动力学行为. 结果表明, 在苯甲醛肟与炔丙醇加成反应过程中, 8个可能反应通道的过渡态中均形成非平面五元环结构, 其中苯甲醛肟的Z、E构型特征得到了部分保留, 但主要部分的键长、键角均发生了变化, 电荷也进行了重新分布. 苯甲醛肟以羟基型参与反应的4个反应通道均为吸热反应和热力学非自发过程, 它们均具有较高的反应势垒、较慢的反应速率和较小的平衡常数; 而以离子型参与反应的四个反应通道均为放热反应和热力学自发过程, 它们的反应势垒较低, 反应速度较快, 平衡常数也较大, 故苯甲醛肟应主要以离子型参与反应. 炔丙醇的两种取向对应着加成反应的两种产物, 反应达到平衡后, 3-羟甲基二氢异噁唑为主要产物.     

Simulation of differential pulse polarography of irreversible EC mechanism

A reversible electrode reaction that is followed by totally irreversible chemical reaction is investigated theoretically. The influence of chemical reaction on two components of the net response of differential pulse polarogram is analyzed. It is demonstrated that this EC mechanism depends on two kinetic parameters and that their critical values can be used for the measurement of the rate constant of chemical reaction.     

Kinetics of Phase Transfer Catalytic Preparation of Benzyl Phenyl Ether

Benzyl phenyl ether is prepared in a well-stirred batch reactor from phenol and benzyl chloride using tetrabutylammonium iodide as phase transfer catalyst. Phenol with sodium hydroxide is dissolved in water as the aqueous phase, and benzyl chloride is dissolved in toluene as the organic phase. Tetrabutylammonium iodide gives high reaction rate without the formation of micelles during the reaction. The reaction mechanism is verified by infrared spectrum study and other experimental observations. The kinetics of the reaction of benzyl chloride is modelled as a first-order chemical reaction. The cocatalytic effect of the iodide ion, and salting out effect on the overall reaction rate are discussed in detail using experimental data.     

The reduction ring-opening reaction of imidazoline

A new reduction ring-opening reaction of 2-imidazoline with sodium borohydride is reported, and the effect of reaction condition on the yield, reaction mechanism and the use of the new reaction in synthesis of ethylenediamine derivatives are discussed. A new method for the preparation of unsymmetrical substituted ethylenediamine via the reduction ring-opening reaction of imidazoline is provided.     

芴的9位羟甲基化反应产物的影响因素

以聚甲醛为羟甲基化试剂,研究了碱的种类、反应温度和反应时间等因素对芴与聚甲醛发生羟甲基化反应产物类型的影响。 结果表明,提高碱的强度有利于生成9,9-双羟甲基芴,升高温度和延长反应时间则有利于生成9,9′-亚甲基双芴。 通过控制反应条件,有可能优先生成9-芴甲醇或9,9-双羟甲基芴或联产这2个化合物。     

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.     

The use of polymer-bound triphenylphosphine in the stereochemical inversion of secondary alcohols

Polymer-bound triphenylphosphine can replace triphenylphosphine in the Mitsunobu reaction to generate stereochemically inverted secondary alcohols. This method is comparable with the standard Mitsunobu reaction in terms of inversion of stereochemistry, yield, and reaction time, even for sterically very hindered secondary alcohols. The special merit of this reaction is that the excess polymer-bound triphenylphosphine and its by-products are easily removed by filtration from the reaction products.     

Impact of water on the OH + HOCl reaction

The effect of a single water molecule on the OH + HOCl reaction has been investigated. The naked reaction, the reaction without water, has two elementary reaction paths, depending on how the hydroxyl radical approaches the HOCl molecule. In both cases, the reaction begins with the formation of prereactive hydrogen bond complexes before the abstraction of the hydrogen by the hydroxyl radical. When water is added, the products of the reaction do not change, and the reaction becomes quite complex yielding six different reaction paths. Interestingly, a geometrical rearrangement occurs in the prereactive hydrogen bonded region, which prepares the HOCl moiety to react with the hydroxyl radical. The rate constant for the reaction without water is computed to be 2.2 × 10(-13) cm(3) molecule(-1) s(-1) at room temperature, which is in good agreement with experimental values. The reaction between ClOH···H(2)O and OH is estimated to be slower than the naked reaction by 4-5 orders of magnitude. Although, the reaction between ClOH and the H(2)O···HO complex is also predicted to be slower, it is up to 2.2 times faster than the naked reaction at altitudes below 6 km. Another intriguing finding of this work is an interesting three-body interchange reaction that can occur, that is HOCl + HO···H(2)O → HOCl···H(2)O + OH.     

甘氨酸螯合钙的合成与性能研究

以甘氨酸和金属钙盐为原料,采用水体系合成法制备甘氨酸钙螯合物,探讨不同反应温度、反应时问、反应体系pH等对产品产率的影响,从而确定反应的最佳条件,并对甘氨酸钙螯合物采用傅里叶红外光谱FT-IR进行表征。实验结果表明,合成甘氨酸钙螯合物的最适反应条件是,反应体系pH为5～6,反应时间为2～3h,反应温度为70～80℃。     

Kinetics of phenol oxidation with ozone in a thin layer on a solid surface

Ozone has been reacted with phenol in thin supported layers, and the dynamics of this reaction has been investigated. The stoichiometry of this reaction coincides with the stoichiometry of the same reaction in solution. Specific reaction rate (β) has been determined for various phenol conversions. The effective rate constant of the reaction, estimated by extrapolating β to zero reaction time, is significantly higher than the rate constant of the reaction in solution. The reaction between ozone and phenol is diffusion-controlled. The reaction products form a barrier layer, which protects the deeper phenol layers against ozone. The barrier layer is as thick as 8–15 phenol monolayers.     

Theoretical Analysis of Structural Characteristics of Morin Rearrangement for Cephalosporins Prepared from Penicillin Sulfoxide

The structure of penicillin sulfoxide is rearranged to cephalosporins by the Morin rearrangement. It is a unit reaction for the preparation of various types of cephalosporins. In order to make better use of the reaction and in view of the shortage of the reaction theory, this study used m062x/6-311++G(d, p) to explore the possible ring-opening reaction of the penicillin sulfoxide. It is found that the isomer of(S)-sulfoxide is a necessary structure. At the same time, the intramolecular hydrogen bonding effect between the side-chain amide proton(-CONH-) and the sulfinyl oxygen(-SO) is the decisive structure factor for the formation of alkenyl in ring-opening reaction, and the best reaction path is S0- TS2- IN1 channel. The main effect of acid catalysis is to catalyze the dehydration reaction of sulfenic acid to form sulfur cations for subsequently ring closing reaction.     

用常温正丁烷异构化反应表征固体超强酸性

研究了室温下固体超强酸催化剂上正丁烷反应，发现转化率低于50％时，异构化选择性高于95％，正丁烷异构化反应动力学符合一级可逆反应规律，固体超强酸的酸强度与正丁烷异构化反应转化率和速率常数呈顺变关系，与反应表现活化能呈逆变关系．报出了一种新的表征固体超强酸性的实验方法．     

磷钨酸铝催化合成对甲氧基苯乙酮

以H3PW12O40和AlCl3·6H2O为原料合成AlPW12O40,以此为催化剂研究苯甲醚与乙酸酐的酰基化反应,其主要产物为对甲氧基苯乙酮.采用正交试验确定酰化反应的适宜条件为:苯甲醚0.1 mol,苯甲醚与乙酸酐物质的量比为1∶1.5,催化剂用量1 g,反应时间4h,反应温度100℃,在此条件下,产品收率达到69.80％.考察了不同反应底物及不同酰化试剂对反应的影响和不同磷钨酸盐的催化效果,比较了不同加热方式对催化反应的影响.结果表明,磷钨酸铝的催化活性最好,微波加热合成目标产物效果更好.     

Stoichiometry of the reaction of diphenylchlorophosphine with dimethylformamide in the presence of NaI

Stoichiometric relations of initial compounds and reaction products in the synthesis of N,N-dialkyl-(diphenylphosphinomethylene)iminium are established; the second reaction product is diphenylphosphinic iodide. Bringing triphenylphosphine into the reaction increases the N,N-dialkyl(diphenylphosphinomethylene)-iminium yield approximately twice. One of the reaction intermediates is shown to be iododiphenylphosphine. The reaction can be regarded as disproportionation.     

Chemoselective Schmidt reaction mediated by triflic acid: selective synthesis of nitriles from aldehydes

An excellent utility of Schmidt reaction of aldehydes to access corresponding nitriles in an instantaneous reaction is demonstrated. The reaction of aldehydes with NaN(3) and TfOH furnishes the corresponding nitriles in near quantitative yields and tolerates a variety of electron-withdrawing and electron-donating substituents on the substrates. Formanilides, a common side product in Schmidt reaction, is not observed in this reaction. Besides these advantages, the salient feature of this reaction is that it exhibits a remarkable chemoselectivity, as acid and ketone functionalities are well tolerated under the reaction conditions. The reaction is easily scalable, high yielding, and nearly instantaneous.     

A new ketone synthesis by palladium-catalyzed cross-coupling reactions of esters with organoboron compounds

[reaction: see text] The palladium-catalyzed coupling reaction of 2-pyridyl esters with organoboron compounds is described. The reaction is compatible with various functional groups and proceeds under mild reaction conditions. The coordination of the nitrogen atom to Pd is a key step for efficient reaction.     

H+NH3反应势能面的量子化学研究

本文采用UCCSD(T)/aug-cc-pVTZ方法研究了H NH3反应势能面,获得了夺氢反应和交换反应过渡态的的几何结构和振动频率。夺氢反应的过渡态具有Cs对称性,其能垒为61.92 kJ/mol。交换反应的过渡态具有C3v对称性,其能垒为39.69 kJ/mol。H NH3发生形成Td对称性的反应中间体NH4里德堡自由基。与夺氢反应相比,交换反应具有更低的反应能垒,并且NH4自由基在反应中可形成长寿命的共振态,和夺氢反应形成竞争关系,因此在H NH3反应的量子动力学研究中必须同时考虑这两类反应。本文还采用更大的基组aug-cc-pVQZ和aug-cc-pV5Z研究了势能面对基组的收敛行为。     

Pulse radiolysis study on the mechanisms of reactions of CCl_3OO radical with quercetin, rutin and epigallocatechin gallate

The mechanisms of reactions between CCI3OO radical and quercetin, rutin and epigal-locatechin gallate (EGCG) have been studied using pulse radiolytic technique. It is suggested that the electron transfer reaction is the main reaction between CCI3OO radical and rutin, EGCG, but there are two main pathways for the reaction of CCI3OO" radical with quercetin, one is the electron transfer reaction, the other is addition reaction. The reaction rate constants were determined. It is proved that quercetin and rutin are better CCI3OO radical scavengers than EGCG.