Theoretical study on the reaction mechanism of(CH_3)_3CO+CO

The global environment pollution includes pho-tochemical smog, acid rain and stratospheric ozonedepletion. The short-lived species/radicals in atmos-phere are closely related to these phenomena. Theshort-lived species/radicals bring the photochemicalsmog,…     

Cu(I)-assisted carbon---carbon bond forming reactions of γ,γ-dialkoxyallylic zirconium species: a new versatile homoenolate equivalent of propionate

In the presence of CuCN, reaction of γ,γ-dialkoxyallylic zirconium species 1 with acyl chloride or allylic phosphates proceeded at the -position of 1 to give alkanoates 3 after aqueous work-up. The ketene dialkylacetal moiety in the coupling products 2 can be used for further bond forming reaction with electrophiles such as nitrosobenzene, nitrostyrene or trichloroacetylisocyanate.     

3-亚甲基异苯并呋喃-1(3H)-酮的合成

以邻甲基苯甲酸甲酯为原料,经过自由基溴代,Wittig反应,酯水解反应,得到邻乙烯基苯甲酸;随后发生环氧化反应,环合反应得到3-羟甲基异苯并呋喃-1(3H)-酮;再发生亲核取代和消除反应合成了3-亚甲基异苯并呋喃-1(3H)-酮。目标产物在空气中长期放置没有发生二聚。化合物结构用1H NMR、13C NMR和IR表征。     

Total Synthesis of Several 3, 3"-Biflavones

BiflavonesareamorecomPlicatedclass0fflavonoids.MostofthemareusefulcomPonentsoftraditionalmedicinetocurediseases.Sincechamaejasminel,anewtoeofbiflavonoidpossessingaC-3/C-3"linkage,wasisolatedfromSteUerachamaejasmaeL.byHuangetal',especiallyafterthebiologicalactivityofani-cancerwasdiscovered',thestUdyof3,3"-biflavonoidshasattfactCdmuchattention.3-5ButtherehasbeennoprogressmentionedonthesynthesisofthiskindofcomPoundsinrecentdecades.AsaresultofoursystematicresearchonthesynthesisofchamaejasInin…     

Kinetics of the Oxidative Dehydrogenation of Isobutance over Cr2o3／La2（CO3）3

The oxidative dehydrogenation (ODH) of isobutane over Cr2O3/La2(CO3)3 has been investi- gated in a low-pressure Knudsen cell reactor, under conditions where the kinetics of the primary reaction steps can be accurately determined. By heating the catalyst at a constant rate from 150-300oC, temper- ature uctuations due to non-equilibrium adsorption are minimized. The evolved gas profiles show that ODH to isobutene and water is a primary reaction pathway, while carbon dioxide, which forms from the catalyst during reaction, is the only other product. This CO2 evolution may enhance the activity of the catalyst. Isobutene formation proceeds with the participation of lattice oxygen from the Cr2O3/La2(CO3)3 catalyst. The small pre-exponential factor is expected for a concerted mechanism and for such a catalyst with a small surface area and limited porosity.     

Theoretical study on the reaction mechanism of (CH3)3CO(.) radical with NO

The reaction mechanism of (CH3)3CO(.) radical with NO is theoretically investigated at the B3LYP/6-31G* level. The results show that the reaction is multi-channel in the single state and triplet state. The potential energy surfaces of reaction paths in the single state are lower than that in the triple state. The balance reaction: (CH3)3CONO←→ (CH3)3CO(.)+NO, whose potential energy surface is the lowest in all the reaction paths, makes the probability of measuring (CH3)3CO(.) radical increase. So NO may be considered as a stabilizing reagent for the (CH3)3CO(.)radical.     

Iodine-promoted selective 3-selanylation and 3-sulfenylation of indoles with dichalcogenides under mild conditions

A simple method was developed for the synthesis of 3-chalcogen indoles via iodine-promoted direct 3-selanyl- and 3-sulfenylation of indoles with dichalcogenides. The reaction was carried out smoothly in EtOH under air at room temperature, selectively giving a series of 3-chalcogen indoles bearing different functional groups in good to excellent yields. The procedure has the merits of environmental friendliness, easy operation, wide substrate scope and mild reaction conditions.     

Controlled Growth of CH3NH3PbBr3 Perovskite Nanocrystals via a Water–Oil Interfacial Synthesis Method

Fundamental insights into the reaction kinetics of organic–inorganic lead halide perovskite nanocrystals (LHP NCs) are still limited due to their ultrafast formation rate. Herein, we develop a water–oil interfacial synthesis of MAPbBr₃ NCs (MA=CH₃NH₃⁺), which prolongs the reaction time to tens of minutes. This method makes it possible to monitor in situ the formation process of MAPbBr₃ NCs and observe successive spectral evolutions from 438 to 534 nm in a single reaction by extending reaction time. The implementation of this method depends on reducing the formation rate of PbBr₆^4? octahedra and the diffusion rate of MA. The formation of PbBr₆^4? is a rate‐determining step, and the biphasic system offers a favorable reaction condition to control the mass transfer of MA. The effects of temperature and concentration of precursor and ligand are investigated in detail.     

3,3-二氟环己基甲胺的简便合成

以环己烯酮和硝基乙酸乙酯为原料,经Michael加成、水解脱羧、亲核氟化和还原反应合成了3,3-二氟环己基甲胺(4),总收率55％,其结构经¹H NMR和MS确证。在最佳还原反应条件［1,1-二氟-3-硝甲基环己烷83.73 mmol, Raney Ni (80％)和NH₃·H₂O为共催化剂,EtOH为溶剂,于室温反应12 h］下,4的收率82%。     

CH_3自由基和O（~3P）反应机理的量子化学研究

用分子轨道从头计算MP2（full）方法和密度泛函理论（DFT）中的B3LYP方法 研究了CH_3自由基和三线态O原子反应的微观机理，优化得到了反应途径上的反应 物、过渡态、中间体和产物的几何构型，通过振动分析对过渡态和中间体构型进行 了确认，在G3不平上计算了能量，同时用经典过渡态理论对该反应的绝对速率常数 进行了理论计算。研究结果表明：CH_3自由基与O（~3P）反应有四条不同的放热反 应通道，主反应通道为IM1→TS1→CH_2O + H，同时反应可彻底裂解生成CO, H_2 及H。     

A simple one-pot synthesis of 3-alkoxy-3-cyanocarboxylic acids: a rapid entry to new GABA derivatives

A simple one-pot procedure to obtain a series of new 3-alkoxy-3-cyanocarboxylic acids from the reaction of 4-alkoxy-1,1,1-trichloro-but-3-en-2-ones with sodium cyanide is described.     

CF3CH2CH3+OH的反应机理及动力学性质的理论研究

采用密度泛函理论BB1K/6-31+G(d,p)计算了反应CF₃CH₂CH₃+OH各反应通道上驻点的稳定结构和振动频率, 并分别在BMC-CCSD, MC-QCISD和G3(MP2)水平上进行了单点能校正. 运用变分过渡态理论, 在BMC-CCSD//BB1K, MC-QCISD//BB1K, G3(MP2)//BB1K以及BB1K水平上计算了各反应通道的速率常数, 讨论了-CH₂和-CH₃基团上H提取通道对总反应的贡献, 并与已有实验和理论结果进行了对比. 计算结果表明, BMC-CCSD水平上的速率常数与实验测量值符合得很好, 进而给出了该水平上反应在200~1000 K温度范围内速率常数k(cm³?molecule^-1?s^-1)的三参数表达式: k=1.90×10^-21T^3.21exp(-292.62/T).     

C2H3与CH3F氢抽提反应机理与动力学性质

采用双水平直接动力学方法对C₂H₃与CH₃F氢抽提反应进行了研究. 在QCISD(T)/6-311++G(d, p)//B3LYP/6-311G(d, p)水平上, 计算的三个反应通道R1、R2和R3的能垒(ΔE^≠)分别为43.2、43.9和44.1 kJ·mol^-1, 反应热为-38.2 kJ·mol^-1. 此外, 利用传统过渡态理论(TST)、正则变分过渡态理论(CVT)和包含小曲率隧道效应(SCT)的CVT, 分别计算了200-3000 K温度范围内反应的速率常数k^TST、k^CVT和k^CVT/SCT. 结果表明: (1) 三个氢抽提反应通道的速率常数随温度的增加而增大, 其中变分效应的影响可以忽略, 隧道效应则在低温段影响显著; (2) R1反应是主反应通道, 但随着温度的升高, R2反应的竞争力增大, 而R3反应对总速率常数的影响很小.     

A convenient one-pot three component synthesis of 3-aminoalkylated indoles catalyzed by 3-chlorophenylboronic acid

An efficient protocol was developed for the synthesis of 3-aminoalkylated indoles using 3-chlorophenylboronic acid as a catalyst under ambient temperature conditions. The three-component reaction of indoles, aromatic aldehydes and N-methyl aniline offered corresponding 3-aminoalkylated indoles in excellent yields. This protocol presents some remarkable features such as mild reaction conditions, simple workup procedure and excellent yields.     

Ca_4GdO(BO_3)_3:Eu~(3 ),Sm~(3 )的发光及离子间的能量转移

Ca4 RO( BO3 ) 3 ( R=La,Ln,Y)三硼酸盐具有优良的非线性特征 . Khamaganova等[1] 以Pb O作助熔剂在合成 Ca4 Sm2 ( BO3 ) 4的过程中发现了一种新相 ,经过结构分析判定是一种新的化合物 .Norrestam等通过高温固相反应合成出此类三硼酸盐 .Iiykhuin[2 ] 对 Ca4 RO( BO3 ) 3( R=Lu,Tb,Gd)的结构进行了研究 .Dirkse等 [3 ]报道了 Ca4 Gd O( BO3 ) 3 粉末的发光特性 .1 996年 ,Aka[4 ] 采用提拉法 ( Czochralski)首次生长出较大尺寸的 Ca4 Gd O( BO3 ) 3 单晶 .孟宪林等 [5]报道了 Ca4 YO( BO3 ) 3 :Nd晶体的激光发射和自倍…     

Selective N-Alkylation of 2-Amino-4H-chromene-3-carbonitrile Derivatives with Alcohols Catalyzed by AlCl3 Under the Assistance of CH3COOH

A highly efficient and selective N-alkylation reaction of 2-amino-4H-chromene-3-carbonitrile derivatives using various alcohols as alkylation agent were developed in the presence of AlCl₃ as a catalyst as well as CH₃COOH as an additive, in which the cyano group kept inert and the amino group was alkylated in high yields. All the target products were characterized and determined by infrared(IR), ¹H NMR, ¹³C NMR, and HRMS. And the X-ray structure of product 3ab was obtained. A bimolecular reaction mechanism catalyzed by AlCl₃ was proposed under the assistance of CH₃COOH.     

BaLiF3:Ce 3+纳米粒子的制备及其光谱特性

BaLiF3属立方钙钛矿型复合氟化物, 作为高效闪烁晶体可用于热中子检测［1］. 由于其能带隙宽, 易于实现各种不同价态稀土离子掺杂, 可以获得许多可调谐性质, 因此它也是比较理想的光学功能材料的基质［2］. Ce3+激活的BaLiF3晶体作为紫外发射的短波固体激光材料和光放大材料的研究多有报道［3~5］     

3‐Formylpyrroles from 3‐Furfurylamines by Bromine Oxidation Reaction

Oxidation of 3‐furfurylamines 3a‐e with bromine in acetone‐water solution gave N‐substituted 3‐formylpyrroles 4a‐e in good yields. A reaction mechanism via the Clauson‐Kaas reaction followed by the cis‐trans isomerization of the 2‐ene‐1,4‐diones 13 and 14 was proposed to account for the formation of the pyrroles 4a‐e .     

La(NO3)3和Pr(NO3)3对高岭石脱羟基动力学的影响

采用热重和微商热重(TG/DTA)综合热分析技术在不同升温速率下研究了掺入La(NO₃)₃和Pr(NO₃)₃的高岭石的热分解过程, 利用Coats-Redfern积分法和Achar微分法对热分析实验数据进行动力学计算, 得到了高岭石脱羟基反应过程中的控制机理函数、 活化能和指前因子等动力学参数; 分析了2种稀土掺入对高岭石脱羟基过程动力学参数的影响, 并用Ozawa法对活化能进行了验证. 结果表明, 未掺稀土和掺入Pr(NO₃)₃的高岭石的脱羟基反应过程均受化学反应模型F₃控制, 反应的活化能分别为307.94和282.86 kJ/mol, 指前因子lnA的值分别为47.8980和44.1718; 掺入La(NO₃)₃的高岭石脱羟基反应过程控制机理函数发生改变, 受化学反应模型F₂控制, 反应活化能为196.02 kJ/mol, 指前因子lnA的值为29.5551. 与未掺稀土的高岭石对比, 掺入Pr(NO₃)₃后活化能和指前因子略有降低; 而掺入La(NO₃)₃后则显著降低, 分别降低了36.34%和38.30%. 采用Ozawa法验证得到的活化能与Coats-Redfern积分法和Achar微分法结果一致.     

Fe3O4@SiO2-CeCl3 Catalyzed Chemoselective Synthesis of Functionalized 3-Substituted-1,5-Benzodiazepines via One-pot Multicomponent and Domino Reactions

Fe₃O₄@SiO₂-CeCl₃ catalyzed chemoselective synthesis of functionalized 3-substituted-1,5-benzodiazepines via one-pot multicomponent and domino reactions has been developed. During the one-pot synthesis process, one new cycle and four new bonds (one C–C, two C–N and one C=C) were constructed by the nucleophilic addition and eliminate reaction (dehydration etc.) process, intramolecular proton transfer and cyclization process. The major advantages of the present method are good to excellent yields, shorter reaction time, simple experimental procedure, easy work up, mild reaction conditions, recyclability of the catalyst and ability to tolerate a variety of functional groups which gives economical as well as ecological rewards.