硼氢化反应机理Ⅲ:HCN+BH_3反应过渡态的微扰分子轨道理论分析

在ＲＨＦ／４３１Ｇ基础上对氢氰酸硼氢化反应做了量子化学从头计算，借助微扰分子轨道理论，分析了该反应过渡态中前线分子轨道的性质．计算及分析表明：在过渡态形成过程中，仅仅考虑反应物分子间的ＨＯＭＯ－ＬＵＭＯ是不够的，ＨＯＭＯ－ＨＯＭＯ相互作用也起重要的作用．     

硼氢化反应机理(Ⅱ):HCN+BH_3反应的电荷行为及过渡态的性质

利用量子化学从头计算法ＲＨＦ／４３１Ｇ基组对氢氰酸硼氢化反应中的电子行为和轨道对称性进行了讨论．结果表明：在氢氰酸硼氢化反应中，从表面上看是对称性禁阻的“类四中心”过渡态，实质上是对称性允许的两组四中心三轨道相互作用．     

硼氢化反应机理Ⅳ——甲基腈硼氢化反应的反应途径解析(英文)

利用量子化学从头计算法ＲＨＦ／４－３１Ｇ基组对ＣＨ３ＣＮ＋ＢＨ３反应进行了理论研究．ＩＲＣ分析表明：甲基腈与甲硼烷通过“类四中心”过渡态，直接加成生成产物．计算的活化能是３４６２６８ｋＪ／ｍｏｌ．计算发现在反应途径中，ＢＨ３分子片随着与ＣＨ３ＣＮ分子片的接近经历一个由电子受体到电子授体的变化，并用前线轨道理论作了解释．     

2—甲基—3—芳基烯丙基三苯基溴化Lin的合成

取代苯甲本钱经醇醛缩合，硼氢化还原，溴化反应和成盐反应合成了２－甲基－３－间硝基苯基烯丙基三苯基溴化Ｌｉｎ和２－甲基－３０对硝基苯基烯丙基三苯基溴化Ｌｉｎ两个化合物，收率分别达８６．４％和６９．０％。结构经ＩＲ，＾１Ｈ ＮＭＲ确诊。     

二烯烃的硼氢化反应

单烯烃与硼烷的硼氢化反应及相关反应 ,已经研究得很多 ,各教学参考书中均有讨论。然而二烯烃尤其是共轭二烯烃的硼氢化反应并不常见。在高等教育出版社出版的高等师范专科学校教材《有机化学》[1] 中有一道习题 :　　　　 ＣＨ212 (ＢＨ3 ) 2 　 ?　 Ｈ2 Ｏ2ＯＨ-　 ?这是一道关于共轭二烯烃与硼烷反应的题目。反应怎样进行 ?是发生 1 ,4 加成还是只与其中一个双键加成或者与两个双键同时加成 ?历届学生都对此感到困惑。笔者为此查阅了一些相关书籍和文献 ,对二烯烃硼氢化反应的机理、影响因素及规律进行了较详细的论述 ,并据此给出习题的…     

碳－碳不饱和键的硼氢化反应在有机合成中的应用新进展

综述了近年来碳－碳不饱和键的硼氢化反应在有机合成中的应用，包括醇、酮、酸、胺、卤代烃、腈化物和烯的合成。参考文献３５篇。     

1,4—双（氯甲基）—2—甲氧基—5—壬氧基苯的均聚和共聚研究

以１，４－双（氯甲基）－２，５一二甲基苯（ＢＣＭＤＭＢ）和１，４－双氯甲基－２－甲氧基－５－壬氧基苯（ＢＣＭＭＯＮＯＢ）为单体，采用脱氯化氢法，合成了聚（２，５－二甲基）对亚苯基亚乙烯（ＰＤＭＰＶ）和聚（２－甲氧基－５－壬氧基）对亚苯基亚乙烯（ＰＭＯＮＯＰＶ）；并对ＢＣＭＤＭＢ和ＢＣＭＭＯＮＯＢ的共聚进行了研究。结果表明，适宜的反应条件为：碱与单体的摩尔比为２０∶１，在室温下聚合时间为３０ｈ，碱的ｐＨ＝１４时产率最高。用ＩＲ、１Ｈ－ＮＭＲ、ＵＶ—Ｖｉｓ对聚合物进行了表征。     

金属卟啉－甲基紫精二连体配合物的合成及其光化学行为

本文合成了四（对－氯代甲基）苯基－甲基紫精卟啉及其Ｚｎ、Ｃｏ、Ｍｎ配合物，用元素分析、红外光谱和紫外可见光谱进行了表征．研究了它们的光化学性质．结果表明．在ＴＥＯＡ中光照使Ｍ·ＴＣＭＰＰ—ｍｖ￣２＋发生了分子内从卟啉到甲基紫精的电子迁移反应．在ＺｎＴＣＭＰＰ－ｍｖ￣２＋／ＴＥＯＡ／ＤＭＳＯ—Ｈ２Ｏ体系中可发生光敏化还原ｍｖ２＋反应，生成较稳定的ｍｖ＋．在Ｍｎ（Ⅲ）ＴＣＭＰＰ－ｍｖ２＋／ＣＨ３ＯＨ／Ｈ２Ｏ体系中可发生光助氧化甲醇反应，并检出了氧化产物甲醛．     

MgO—MgCl2—H2O溶液热化学研究

用精密量热仪对模拟合成的ＭｇＯ－２７．５６％ＭｇＣｌ－Ｈ２Ｏ浓盐溶液进行恒沸盐酸－△Ｈ滴定。发现活性ＭｇＯ在２７．５６％ＭｇＣｌ－Ｈ２Ｏ溶液中不同浓度时表现出不同的结果。结合该浓盐溶液的恒混盐酸－ＰＨ滴定结果对反应机制进行了初步探讨。     

反式—2—（4—（2—（4—取代苯基）乙烯基）苯基）—5—（4—联苯基）恶唑的合成,？…

通过４－ＲＣ６ＨＣＨＯ与２－（４－甲基苯基）－５－（４－联苯基）恶唑（Ｒ＝Ｈ，Ｍｅ，Ｅｔ，ｉ－Ｐｒ，ｉ－Ｂｕ，Ｐｈ，ＯＭｅ，Ｆ，Ｃｌ，Ｂｒ）在碱催化下的缩合反应合成了１０个新的反式－２－（２－（４－取代苯基）乙烯基）苯基）－５－（４－联苯基）恶唑类化合物，经元素分析，ＩＲ，ＵＶ及ＭＳ确定了它们的结构，并测定了荧光发射光谱，荧光量子产率和激光转换效率。     

MNDO study of reaction paths: Hydroboration of methyl cyanide

The hydroboration reaction of methyl cyanide has been investigated by the MNDO method. It has been shown that the reaction requires an activation energy of 25.3 kcal/mol and involves a four-center-like transition state in the rate-determining step. This reaction has been compared with the corresponding reaction of hydrogen cyanide, and the effect of methyl substitution on the reaction has been discussed. The charge-transfer effects accompanying the reaction have also been studied.     

乙炔与氢化锂单体和二聚体加成反应中的HOMO-HOMO相互作用

用前线分子轨道分析乙炔与氢化锂单体和二聚体加成反应的过渡态.结果表明,在其反应过渡态形成过程中,反应物间的HOMO-LUMO和HOMO-HOMO相互作用均起重要作用.较强烈的HOMO-HOMO相互作用与过渡态附近反应由亲电性加成向亲核性加成转变相关,该反应特性的转变又与LiH中的氢原子在反应中的电荷转移相关.     

Hydroboration of Nitriles,Esters, and Carbonates Catalyzed by Simple Earth-Abundant Metal Triflate Salts

During the past decade earth-abundant metals have become increasingly important in homogeneous catalysis. One of the reactions in which earth-abundant metals have found important applications is the hydroboration of unsaturated C−C and C−X bonds (X=O or N). Within these set of transformations, the hydroboration of challenging substrates such as nitriles, carbonates and esters still remain difficult and often relies on elaborate ligand designs and highly reactive catalysts (e. g., metal alkyls/hydrides). Here we report an effective methodology for the hydroboration of challenging C≡N and C=O bonds that is simple and applicable to a wide set of substrates. The methodology is based on using a manganese(II) triflate salt that, in combination with commercially available potassium tert-butoxide and pinacolborane, catalyzes the hydroboration of nitriles, carbonates, and esters at room temperature and with near quantitative yields in less than three hours. Additional studies demonstrated that other earth-abundant metal triflate salts can facilitate this reaction as well, which is further discussed in this report.     

MNDO study of reaction paths: Hydroboration of carbonyl systems

The hydroboration reactions of acetaldehyde and acetone have been investigated by the MNDO method. The reactions have been shown to be twostep reactions involving an intermediate adduct. This adduct subsequently undergoes hydrogen rearrangement. The hydroboration reactions of acetaldehyde and acetone have been compared with the corresponding reaction of formaldehyde. The charge transfer effects accompanying these reactions have also been discussed.     

Mechanistic Insight into Hydroboration of Imines from Combined Computational and Experimental Studies

Boron Lewis acid-catalyzed and catalyst-free hydroboration reactions of imines are attractive due to the mild reaction conditions. In this work, the mechanistic details of the hydroboration reactions of two different kinds of imines with pinacolborane (HBpin) are investigated by combining density functional theory calculations and some experimental studies. For the hydroboration reaction of N-(α-methylbenzylidene)aniline catalyzed by tris[3,5-bis(trifluoromethyl)phenyl]borane (BAr^F₃), our calculations show that the reaction proceeds through a boron Lewis acid-promoted hydride transfer mechanism rather than the classical Lewis acid activation mechanism. For the catalyst- and solvent-free hydroboration reaction of imine, N-benzylideneaniline, our calculations and experimental studies indicate that this reaction is difficult to occur under the reaction conditions reported previously. With a combination of computational and experimental studies, we have established that the commercially available BH₃ ⋅ SMe₂ can serve as an efficient catalyst for the hydroboration reactions of N-benzylideneaniline and similar imines. The hydroboration reactions catalyzed by BH₃ ⋅ SMe₂ are most likely to proceed through a hydroboration/B−H/B−N σ-bond metathesis pathway, which is very different from that of the reaction catalyzed by BAr^F₃.     

The IRC method in chemical reactions: Reaction ergodography for the addition of LiH to acetylene

The ab initio calculation have been performed on the addition of LiH to acetylene at RHF/3-21G basis set. The geometries and energies of the isolated reactant, molecular complex, transition state and product have been determined on the singlet potential energy surface of the ground state. Our results indicate that there is a meta stable molecular complex near the isolated reactant in the reaction pathway. The process from isolated reactant to molecular complex is a non-bonding-exchanging reaction process, and the process from molecular complex to product is the rate-controlling step of the reaction. We also estimate the activated entropy and the frequency factor of the rate-controlling step by using the RRKM theory. The FMO analysis for the transition state reveals the HOMO of transition state to be formed from both HOMO-LUMO and HOMO-HOMO interactions.     

Reaction ergodography for the additions of HLi and its dimer to acetylene

The ab initio calculation has been performed with the addition pathways of HLi and its dimer to acetylene at the RHF/3-21G basis set. It shows that the reaction mechanisms of these two reactions are rather similar. In either of two reaction pathways, there is a meta-stable molecular complex near the isolated reactant state. This kind of addition can be treated approximately as the unimolecular reaction in which the molecular complex rearranges into the product. We have estimated the activation entropies and the statistical A factors of these two reactions by the use of RRKM theory. Frontier molecular orbital analysis of these two transition states reveals their HOMOS to be formed from both HOMO-LUMO and HOMO-HOMO interactions.     

Chemoselective Boron–Carbon Bond Cleavage by Hydroboration of Borirenes

We report on the hydroboration of 1‐[bis(trimethylsilyl)amino]‐2,3‐diethylborirene ( 3 ) with 9‐borabicyclo[3.3.1]nonane (9‐BBN), which led through ring‐opening to an amino(vinyl)borane. The viscous borane was subsequently converted into a crystalline borate on treatment with MeLi. Both compounds were fully characterized by multinuclear NMR spectroscopy and in case of the latter by single‐crystal X‐ray diffraction analysis. To elucidate the reaction mechanism of the unexpected boron‐carbon bond cleavage, DFT calculations of energy minima and transition states for the hydroboration were carried out.     

RhCl3-catalyzed hydroboration of alkenyl nitriles

RhCl₃-promoted hydroboration-oxidation reactions of representative alkenyl nitriles have been carried out. Carbanion of acetonitrile is formed from the carboncarbon heterolytic bond breaking in allyl cyanide during hydroboration. An unexpected process-trimerization of carbanion of acetonitrile has lead to the formation of 4-amino-2,6-dimethylpyrimidine.