Li^+ extraction/insertion reaction with Mg_2Mn_(0.5)Ti_(0.5)O_4 inverse spinel in the aqueous phase

An inverse spinel-type metal oxide, magnesium-manganese-titanium oxide （Mg2Mn0.5Ti0.5O4）, were prepared using the coprecipitation/thermal crystallization method. The extraction/insertion reaction with this material was investigated by X-ray, saturation capacity of exchange, pH titration, and distribution coefficient （Kd） measurement. The acid treatments of Mg2Mn0.5Ti0.5O4 caused Mg^2＋ extractions of more than 81%, whereas the dissolutions of Mn^4＋ and Ti^4＋ were less than 10%. The experimental results proved that the acid-treated sample has a capacity of exchange 56 mg·g^-1 for Li^＋ in the solution. The chemical analysis showed that the Li^＋ extraction/insertion progressed mainly by ion-exchange mechanism and surface adsorption.

Theoretical studies of insertion reactions of singlet germylene into aryl C-C1 bond of 1-chlorobenzene

The insertion reactions of germylene into C-Cl bond of 1-chorobenzene have been explored using density functional theory. Five germylene species have been chosen for systematically studying. All the stationary points were determined at the B3LYP/ 6-311＋G （d, p） level of the theory. The results show that, the smaller the AEsT of germylene, the lower the barrier height, and the electropositive substituents on the germylene can increase the reaction activity and exothermicity of insertion into C-Cl bond of 1- chorobenzene.

Mechanism of Insertion Reactions between Silylenoid H_2SiLiF and GeH_3R(R=F,OH,NH_2):a Theoretical Study

Theoretical investigations on the insertion reaction mechanisms of three- membered-ring silylenoid H2 Si Li F with GeH 3R（R = F, OH, NH2） have been systematically carried out by combined density functional theory（DFT） and ab initio quantum chemical calculations. The geometries of all stationary points for these reactions were optimized using the B3 LYP method and then the QCISD method was used to calculate the single-point energies. The calculated results indicate that, there are one precursor complex（Q）, one transition state（TS）, and one intermediate（IM） which connect the reactants and the products along the potential energy surface. The insertion reactions of three-membered-ring silylenoid with Ge H3 R proceed in a concerted manner, forming H2RSi-Ge H3 and Li F. The calculated potential energy barriers of the three reactions are 29.17, 30.90, and 54.07 k J/mol, and the reaction energies for the three reactions are –127.05, –116.91, and –103.31 k J/mol, respectively. The insertion reactions in solvents are similar to those in vacuum. Under the same situation, the insertion reactions should occur easily in the following order： GeH 3-F GeH 3-OH GeH 3-NH2. The elucidations of the mechanism of these insertion reactions provided a new mode of silicon-germanium bond formation.

Application of Fast Radical Rearrangement in the Mechanistic Investigation of Intramolecular C-H Insertion by Rh(Ⅱ)-Mediated Carbenoids

In order to investigate the reaction mechanism of intramolecular C-H insertion by Rh(II)-mediated carbenoids with trans-(2-phenylcyclopropyl) carbinal radical as the mechanistic probe, diazo compounds 2-(2-phenylcyclopropyl)ethyl diazoacetoacetate 8a and methyl 2-diazo-3oxo-6-(2-phenylcyclopropyl) hexanoate 8b have been synthesized. Preliminary investigation of the intramolecular C-H insertion with Rh2(OAc)4 as catalyst supports a concerted insertion process.

Insertion of Selenium into Zinc Carbon Bond and Application in Synthesis of Arylselenoester

Selenium was inserted into the zinc carbon bond of aryl zinc halides to form corresponding zinc selenoates. They reacted in THF-HMPA with acylhalides to afford the selenoesters in high yields.

The facile insertion of β-keto sulfones to arynes:The direct preparation of polysubstituted ortho-keto benzyl sulfones

One novel carbon-carbon bond insertion reaction of arynes has been developed. By this reaction β-keto sulfones can insert the triple bond of arynes to prepare polysubstituted ortho-keto benzyl sulfones.

Competition between C-C and C-H Activation in Reactions of Neutral Nickel Atom with Cycloalkanes （n = 3-7）

A theoretical investigation of the reaction mechanisms for C-H and C-C bond activation processes in the reaction of Ni with cycloalkanes C,,H2. （n = 3-7） is carried out. For the Ni ＋ CnH2, （n = 3, 4） reactions, the major and minor reaction channels involve C-C and C-H bond activations, respectively, whereas Ni atom prefers the attacking of C-H bond over the C-C bond in CnH2n （n = 5=7）. The results are in good agreement with the experimental study. In all cases, intermediates and transition states along the reaction paths of interest are characterized, It is found that both the C-H and C-C bond activation processes are proposed to proceed in a one-step manner via one transition state. The overall C-H and C-C bond activation processes are exothermic and involve low energy barriers, thus transition metal atom Ni is a good mediator for the activity of cycloalkanes CnH2n （n = 3 -7）.

CX_2(X=H,F,Cl)与甲基异丙基醚C-H键插入反应的理论研究

用从头计算方法在MP2 /6 31G(d)水平上研究了CX2 (X =H ,F ,Cl)与甲基异丙基醚的C -H键插入反应。CCl2 与甲基异丙基醚两个不同的α C的C -H键插入势垒分别为 117.2kJ/mol (甲基 )和 2 0 .6kJ/mol (异丙基 )。CF2 与异丙基α C的C -H键上插入势垒为 12 0 .0kJ/mol,在插入甲基上C -H键时会引起C -O键的断裂。CH2 的插入反应则不需要势垒。对CX2 与二甲醚、甲乙醚、甲基异丙基醚、甲基苄基醚上各种不同的C -H键插入势垒进行了比较 ,甲基和苯基都促使其毗邻的C -H键更容易被CX2

Oxidative co-dehydrogenation of ethane and propane over h-BN as an effective means for C-H bond activation and mechanistic investigations

Hexagonal boron nitride(h-BN)is a highly selective catalyst for oxidative dehydrogenation of light alkanes to produce the corresponding alkenes.Despite intense recent research effort,many aspects of the reaction mechanism,such as the observed supra-linear reaction order of alkanes,remain unresolved.In this work,we show that the introduction of a low concentration of propane in the feed of ethane oxidative dehydrogenation is able to enhance the C_(2)H_(6) conversion by 47%,indicating a shared reaction intermediate in the activation of ethane and propane.The higher activity of propane makes it the dominant radical generator in the oxidative co-dehydrogenation of ethane and propane(ODEP).This unique feature of the ODEP renders propane an effective probe molecule to deconvolute the two roles of alkanes in the dehydrogenation chemistry,i.e.,radical generator and substrate.Kinetic studies indicate that both the radical generation and the dehydrogenation pathways exhibit a first order kinetics toward the alkane partial pressure,leading to the observed second order kinetics of the overall oxidative dehydrogenation rate.With the steady-state approximation,a radical chain reaction mechanism capable of rationalizing observed reaction behaviors is proposed based on these insights.This work demonstrates the potential of ODEP as a strategy of both activating light alkanes in oxidative dehydrogenation on BN and mechanistic investigations.

Reaction of Bis(Methylcyclopentadienyl) Lanthanide Amido Complex with n-Hexyl isocyanate-Synthesis and Characterization of {(MeC_5H_4)_2YbOC(NPh_2)N(n-hexyl)}_2

Bis （methylcyclopentadienyl） lanthanide amido complex （MeCp） 2YbNPh2 （THF） reacted with n-hexyl isocyanate （n-nexylNCO） in 1：1 molar ratio to give {（MeC5H4）2Yb[OC（NPh2）N（n-hexyl）] }2（1）. Complex 1 was characterized by elemental analyses and X-ray diffraction. The title complex belongs to trigonal system and R-3 space group. Its unit cell parameters are a =2.9533（11） nm, b =2.9533（11） nm, c = 1.5873（6） nm, V= 11.9896（80） nm^3, Z =9, Dc= 1.562 mg·m^-3, μ = 3.536 mm^-1（Mo Kα）, F（000） =5670, R =0.034, Rw =0.064. It is a dimeric structure with two symmetrical bridged oxygen atoms. Nitrogen atom is coordinated to the ytterbium atom to form a tricyclic backbone. The coordination number of ytterbium is 9. The whole molecule shows central symmetry.

Theoretical Study on the Mechanism of CF_2 Reaction with CH_2O

The insertion reaction mechanism of CF2 with CH2O was investigated at the B3LYP/6-311G（d）//MP2/6-311G（d） level. The geometric conformations at each stationary point in reaction potential surface were fully optimized and the transition states were verified by intrinsic reaction coordinate （IRC） and frequency analysis. The energies of all reactants were calculated with CCSD（T）/6-311G（d）//G2MP2 methods. Results indicated that the P1 reaction route with difuoroaldehyde as product is the dominant reaction pathway, which exhibits nucleophilic character. According to NBO analysis, the starting point of insertion reaction is the interaction between carbene LP（C3） and formaldehyde π（Cl-O2）. Besides, the thermodynamic and dynamic properties of dominated reaction （1） at different temperature were studied with statistic thermodynamic method and Eyring transition state theory adjusted by Wigner means, from which the proper temperature （500- 1200 K） of reaction （1） could be estimated. Finally, the thermo- dynamic and dynamic properties of insertion reaction mechanisms （CF2, CX2 （X = Cl, Br） with CH2O） were compared and discussed.

Thermodynamic and Kinetic Studies on the SiH + XH_3 (X=N, P) Reactions

Based on the quantum chemical study of the silylidyne insertion reaction with NH3 or PH3, the general statistical thermodynamics and Eyring transition state theory with Wigner correction are used to compute the changes of thermodynamic functions, equilibrium constants, A factors and rate constants of the two reactions in the temperature range 200-2000K. The results show that both of these reactions are thermodynamically dominant at low temperatures and kinetically favored at higher temperatures. The comparison between these two reactions shows that the SiH reaction with NH3 is more exothermic than SiH with PH3, while the rate constant of SiH reaction with NH3 is lower than that of SiH with PH3 at the same temperature.

Measuring compliance of package inserts in the Emirate of Abu Dhabi—UAE

Purpose: The aim of this study was to examine if package inserts (PIs) supplied with prescribed medications in the Emirate of Abu Dhabi contain all relevant information to the safe and appropriate use of these medications. Methods: Sixty seven PIs for prescription—only medications were evaluated against a set of safety criteria published from the Ministry of Health. Results: Analyzed PIs showed many deficiencies with regard to the Ministry of Health (MOH) Investigation New Drug Application (INDA) requirements. Particularly of concern were side effects, warnings, use in pregnancy, lactation, and the storage conditions for the product. Conclusions: This study indicated that information relevant to the safe and appropriate use of medications was not uniformly mentioned in the PIs analyzed. To avoid medication errors due to deficits in the current PIs, we recommend regulatory oversight and regulator audits from pharmaceutical company, followed by enhancement of regulations requiring companies to also create patient information leaflets.

蓝光诱导苯基重氮乙酸酯与1,3-二酮的C-C键插入反应

卡宾是有机合成中的一类重要的活性中间体,可发生丰富的化学转化,在C-C键、C-H键、C-N键、C-O键和C-S键等构建中有重要应用。采用重氮化合物为卡宾前驱原料,在蓝光诱导下与1,3-二羰基化合物进行反应,合成了全碳季碳中心的1,4-二羰基产物。该方法的特点是不使用金属催化剂、有良好的产率和选择性、操作简单、绿色环保无污染。

Quantum chemical study on insertion and abstraction reaction of dichlorocarbene with methyl alcohol and methyl mercaptan

The insertion and abstraction reaction mechanisms of singlet and triplet CCl2 with CH3MH (M=O, S) have been studied by using the DFT, NBO and AIM methods. The geometries of reactions, the transition state and products were completely optimized by B3LYP/6–311G(d, p). All the energy of the species was obtained at the CCSD(T)/6–311G(d, p) level. The calculated results indicated that the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CCl2 can not only trigger the insertion reaction with C-H and M-H in four pathways, by which the products P1 [CH3OCHCl2, reaction I(1)], P3[Cl2HCCH2OH, reaction I(2)], P5[CH3SCHCl2, reaction II(1)] and P7[Cl2HCCH2SH, reaction II(2)] are produced respectively, but also abstract M-H, resulting P4 [CH2O+CH2Cl2, reaction I(3)] and P8[CH2S+CH2Cl2, reaction II(3)]. In addition, the important geometries in domain pathways have been studied by AIM and NBO theories.

Density functional theory study on the insertion reaction mechanism of dibromocarbene with formaldehyde

The insertion reaction mechanism of CBr2 with CH3CH2O has been studied by using the B3LYP/6-311G(d) and CCSD(T)/6-311G(d) at single point. The geometries of reactions,transition state and products were completely optimized. All the transition state is verified by the vibrational analysis and the internal re-action coordinate (IRC) calculations. The results show that reaction (1) is the dominant reaction path,which proceeds via two steps: i) two reactants form an intermediate (IM1),which is an exothermal re-action of 8.62 kJ·mol?1 without energy barrier; ii) P1 is obtained via the TS1 and the H-shift,in which the energy barrier is 44.53 kJ·mol?1. The statistical thermodynamics and Eyring transition state theory with Wigner correction are used to study the thermodynamic and kinetic characters of this reaction in temperature range from 100 to 2200 K. The results show that the appropriate reaction temperature ranges from 200 to 1900 K at 1.0 atm,in which the reaction has a bigger spontaneity capability,equi-librium constant (K) and higher rate constant (k).

Density functional theory calculation on the C―H bond insertion reaction of dibromocarbene with acetaldehyde

The insertion reaction mechanism of CBr_2 with CH_3CH_O has been studied by using the B3LYP/6-31G(d) method. The geometries of reactions, transition state and products were completely optimized. All the energy of the species was obtained at the CCSD(T)/6-31G(d) level. All the transition state is verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The results show that the propionaldehyde (~HP1) is the main product of CH_2 insertion with CH_3CH_O. The calculated results indicated that all the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CBr_2 not only can insert the C_α-H [reaction I(1)]) but also can react with C_β-H [reaction II(1)]. The statistical thermodynamics and Eyring transition state theory with Wigner correc- tion are used to study the thermodynamic and kinetic characters of I(1) and II(1) in temperature range from 100 to 2200 K. The results show that the appropriate reaction temperature rang is 250 to 1750 K and 250 to 1600 K at 1.0 atm for I(1) and II(1) respectively. The rate constant and equilibrium constant are distinct in the range from 250 to 1000 K so that I(1) more easily occurs, while the reactions are not selected in the temperature range of 1000-1600

Quantum chemical and topological study on the insertion reaction of dichlorcarbene with acetaldehyde

The insertion reaction mechanisms of siglet and striglet CCl2 with CH3CHO have been studied by using the DFT, NBO, CCSD(T) and AIM method. The geometries of reactions, transition state and products were completely optimized by B3LYP/6-31G(d). All the energy of the species was obtained at the CCSD(T)/6-31G(d,p) level. The calculated results indicated that all the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CCl2 can not only insert the Cα—H (reaction I) but also can react with Cβ—H (reaction Ⅱ). There are three main existing pathways and the products are P1 (CH3COHCCl2), P2 (CH2COHCHCl2) and P4[CHCl2CHCHOH] respectively. Reaction Ⅱ happens more easily according to the energy changes and the barrier in rate-controlling step. In addi-tion, the important geometries in domain pathways have been studied by AIM theory. And also, the en-ergy changes of H in the inserted C—H bond have been investigated.