2-二甲胺基苯甲酰叠氮及其衍生物热解机理的AM1研究

采用UHF/AM1方法对2-二甲胺基苯甲酰叠氮、2-二甲胺基-3-甲基苯甲酰叠氮和2-二甲胺基-3-硝基苯甲酰叠氮的热分解反应进行了研究.结果表明,这些反应物能沿着四条竞争的反应路径生成三种不同的产物.这三条路径中有协同过程,也有分步过程;有吸热过程,也有放热过程.不同的取代基,将选择不同的路径进行分解反应.     

1,6-二氢-S-四嗪催化重排及其反应的研究--Ⅱ. 与氯甲酸三氯甲酯反应

在4－二甲胺基吡啶的存在下，1，6－二氢－S－四嗪重排成3，6－二氢－S－四嗪，与双光气反应后再与不同的胺反应，合成了11种1，4－二取代产物，产物经元素分析、IR和^1H NMR确证。用UV和^1H NMR分析结果对反应机理进行了初步探讨。     

2,2'－联吡啶桥连的双－4,4'-联吡啶哑铃型化合物的合成

二甘醇2与对甲苯磺酰氯在CH_2Cl_2中，0 ℃～r.t.及Et_3N存在下反应得2－ （羟乙氧基）乙醇对甲苯磺酸酯（3），收率88％。化合物3与对叔丁基苯甲酰氯在 CH_2Cl_2中0～5 ℃及吡啶存在下反应得2－（对叔丁基苯甲酰氧基乙氧基）乙醇对 甲苯磺酸酯（4），收率96％。4与对羟苯甲醇在乙腈中及CsF/K_2CO_3存在下70 ℃ 反应得2－（对叔丁基苯甲酰氧基乙氧基）乙氧苄醇（5），收率98％。5与NBS及 PPh_3在THF中，室温下反应得化合物2－（对 丁基苯甲酰氧基乙氧基）乙氧苄溴 （6），收率95％。6与4,4'－联吡啶在乙腈中，60 ℃反应1h得N－[2－（对叔丁基 苯甲酰氧基乙氧基）乙氧苄基]－4,4'－联吡啶六氟磷酸盐（7），收率85％。7与 α,α－二（溴甲基）－2,2'－联吡啶在乙腈中，油浴60 ℃反应36h，得到标题化 合物，产率为45％。     

4-二甲胺苯酰甲酸乙酯的合成及反应副产物的分离鉴定

α-酮酸酯是重要的有机合成中间体。前文报道了以Grignard试剂与草酸二乙酯反应,合成一系列脂肪族α-酮酸酯的方法。为了进一步了解和掌握这一方法,我们研究了合成4-二甲胺基苯酰甲酸乙酯(1)的反应。1的收率随反应温度、溶剂及原料配比的不同而有显著差别。在本文报道的条件下,收率高达90％。此外,从反应混合物中还分得了2-羟基-2,2-双(对-二甲胺基苯基)乙酸乙酯(2),4,4’-双(二甲胺基)-二苯基乙二酮(3),2-羟基-1,2,2-三(对-二甲胺基苯基)乙酮(4)及4,4’-双(二甲胺基)联苯(5)等副产     

稠杂环化合物的研究（X）──3－芳基－6－苯甲酰氨基均三唑并［3，4－b］－1，3，4－噻二唑类化合物的合成及生物活性

本文利用３－芳基－４－氨基－５－巯基－１，２，４－均三唑和苯甲酰异硫氰酸酯在无水丙酮中反应，得到一系列３－芳基－６－苯甲酰氨基均三唑并［３，４－ｂ］－１，３，４－噻二唑，用元素分析、ＩＲ、１ＨＮＭＲ和ＭＳ确定了其结构，提出了可能的反应机制。并对其代表产物２ｈ进行了初步的抗菌和除草实验。     

稠杂环化合物的研究（Ⅹ）—3—芳基—6—苯甲酰氨基均三唑并[3…

本文利用３－芳基－４－氨基－５－巯基－１，２，４－均三唑和苯甲酰异硫氰酸酯在无水丙酮中反应，得到一系列３－芳基－６－苯甲酰氨基均三唑并［３，４－ｂ］－１，３，４－二噻二唑。用元素分析、ＩＲ、＾１Ｈ ＮＭＲ和ＭＳ确定了其结构，提出了可能的反应机制。并对其代表产物２ｈ进行了初步的抗菌和除草实验。     

钒离子与乙烷反应的理论研究

用量子化学方法在UB3LYP／6－311＋＋G（3df,3pd)水平上研究了一阶钒离子与乙烷的反应，找到了[VC2H6]^ 势能面上各驻点的结构，分析了反应过程中有关的电子转移性质，给出了CH4和H2的还原消队理。结果表明：CH4消除反应一般按加成－消除机理进行，在高能条件下也可按协同机理进行；H2分子消除反应，一般按1，2－H2分子消除机理进行，在高能条件下也可按1，1－H2分子消除机理进行。计算表明：能量最有利的反应通道是V^ C2H6→V(C2H4)^ H2，该反应放热11.82kJ/mol。     

合成聚芳酯树状分子的新方法

以３，５－二羟基 苯甲酸为起始原料，经甲醇酯化保护羧基，与苯甲酰氯反应，得到３，５－二苯甲酰氧基苯甲酸甲酯用ＡｌＣｌ３．ＮａＩ去掉保护基甲基，以高收率得到３，５－二苯甲酰氧基苯甲酸。其结构均是由ＩＲ，＾１ＨＮＭＲ，ＥＡ等方法证实。     

2-烯丙基-1,3-二苯基-1,3-丙二酮的合成及其稀土配合物光致发光性质研究

用相转移催化法合成了2－烯丙基－1，3－丙二酮（ADBM）及其稀土配合物，用元素分析，IR和1HNMR对化合物进行了表征，研究了烯丙基的引入对稀土配合物发光性能的影响。结果表明：烯丙基的引入降低了二苯甲酰甲烷（DBM）对Eu^3 的敏化作用，发光减弱，增强了二苯甲酰甲烷对Tb^3 的敏化作用，发光增强：ADBM是铽的优良配体，是电子效应，能量匹配原理对此现象进行了解释。     

吡啶气相光氯化反应理论研究：—加成反应机理的过渡态IRC解析

通过PM3方法研究氯自由基与吡啶分子加成反应的结果表明，生成不同产物2－氯吡啶、3－氯吡啶、4－氯吡啶的每一个反应通道存在两个过渡态，生成2－氯吡啶反应路径主过渡态的能量及活化能量低，分别为－110293．6和139.2kJ/mol。反应优生成2－氯吡啶，与实验结果一致，生成2－氯吡啶反应过程（IRC）相关的键长，，键级和原子净电荷变化表明，吡啶环反应部位C原子与Cl加成形成C－Cl键主要与共轭双键断裂同步，而C－H键的断裂主要与共轭双键的重新形成同步，反应进程中氯原子净电荷从增加到减少的变化是氯原子诱导效应吸引电子和p-π共轭电荷平均分布等相互作用的结果。     

苯并碲唑衍生的多次甲基苯乙烯菁染料的合成

本文首次报道了由苯并碲唑季铵碘盐合成多次甲基苯乙烯菁的方法. 上述季铵盐与对二甲氨基苯甲醛或对二甲氨基肉桂醛等摩尔比混合, 在正丁醇介质中回流反应,分别以较高产率得到相应的二次甲基或四次甲基苯乙烯菁染料. 该反应被醛自身催化. 对反应机理和染料的可见吸收光谱进行了讨论.     

Studies of the inner reorganization energies of the cation radicals of 1,4-bis(dimethylamino)benzene, 9,10-bis(dimethylamino)anthracene, and 3,6-bis(dimethylamino)durene by photoelectron spectroscopy and reinterpretation of the mechanism of the electrochemical oxidation of the parent diamines

The inner reorganization energy of the cation radical of 1,4-bis(dimethylamino)benzene, 1, has been determined to be 0.72 +/- 0.02 eV by means of gas-phase photoelectron spectroscopy (PES). PES studies of 9,10-bis(dimethylamino)anthracene, 2, and 3,6-bis(dimethylamino)durene, 3, demonstrate that their reorganization energies are smaller than that of 1. The effect of lowering the inner reorganization energy on the rate constant for an electrochemical electron-transfer reaction is to increase the electron-transfer rate constant, k(s). However, voltammetric studies of the two-electron oxidation of 2 and 3 indicate that the values of k(s) for each step are smaller than those for 1, in contradistinction to the measured differences in reorganization energies. The voltammetric studies of 2 and 3 were reinterpreted according to a mechanism in which each step of oxidation was written as a two-step process, electron transfer with a small inner reorganization energy plus a chemical step of structural change. The agreement of simulations according to this mechanism with the experimental data was excellent. The new reaction scheme eliminated some suspicious features previously obtained with an analysis where electron transfer and structural change were considered to be concerted. In particular, all electron-transfer coefficients (alpha) were close to one-half, whereas the earlier treatment produced values of alpha much larger or smaller than one-half.     

Preparation of chlorofluoromethylene olefins via phosphine dechlorination of dichlorofluoromethyltris?dimethylamino?phosphonium chloride

The reaction of dichlorofluoromethyltris?dimethylamino?phosphonium chloride with tertiary phosphines provides a convenient preparation of the chlorofluoromethylenetris?dimethylamino?phosphonium ylide. This ylide provides reasonable yields of chlorofluoroolefins from aldehydes, activated ketones, non-activated ketones, and activated esters. The mechanism of phosphonium salt formation was shown to involve positive chlorine abstraction from CFCl₃ by (Me₂N)₃P followed by recombination of the intermediate ion pair. Dechlorination of the resulting dichlorofluoromethyltris?dimethylamino?phosphonium chloride by triphenylphosphine gave an olefinating solution of reasonable stability. In contrast, the solution obtained by dechlorination of the phosphonium salt by tris?dimethylamino?-phosphine showed no stability.     

The role of pi sigma* state in intramolecular electron-transfer dynamics of 4-dimethylaminobenzonitrile and related molecules

Evidence is presented which indicates that the photoinduced intramolecular charge transfer (ICT) in 4-dimethylaminobenzonitrile proceeds by a new mechanism in which pi sigma(C triple bond N) (*) state is the intermediate of a consecutive process that takes the initially excited pi pi(*) state to the fully charge-separated ICT state. The absence of the ICT-state formation in 4-aminobenzonitrile is attributed to the smaller electron-donor strength of the amino group relative to the dimethylamino group, which hinders the pi sigma(*)-->ICT charge-shift reaction.     

k-Restoring processes at carbon depleted ultralow-k surfaces

In this study we investigate the silylation of OH groups with different silazanes. In particular we use density functional theory and the nudged elastic band method to study the different reaction mechanisms. For the silylation reaction of hexamethyldisilazane and trimethylaminosilane with silanol, the minimum energy paths as well as the activation and reaction energies are discussed in detail. From minimum energy reaction paths we found that all studied silazanes react exothermically. Bis(dimethylamino)dimethylsilane shows the most exothermic silylation reaction with the lowest activation energies. Therefore, it is a good candidate for the chemical repair of porous films in the semiconductor k-restoring process.     

Microwave-promoted catalyst- and solvent-free aza-Diels-Alder reaction of aldimines with 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil

A microwave-promoted aza-Diels-Alder reaction between 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil and aldimines has been developed for the construction of dihydropyrido[4,3-d]pyrimidines. Urea is effectively employed as an environmentally benign source of ammonia in the absence of any catalyst or solvent. The key step in the reaction is in situ generation and trapping of the reactive aldimine formed from urea and aldehyde by the diene system of the uracil. The reaction is clean, and excellent yields are obtained in a matter of a few minutes.     

Application of selective 1 : 2 addition of ketene N,N-acetal and isocyanates to novel polyamide syntheses

1,1-Bis(dimethylamino)ethylene (ketene N,N-acetal) (1) reacted with isocyanates to give either 1 : 1 adduct 3,3-bis(dimethylamino)acrylamides (3) or 1 : 2 adduct bis(dimethylamino)methylenemalonamides (4), depending on the amount of the charged isocyanate. 3 was obtained selectively in the case of isocyanate/1 = 1, while 4 was exclusively yielded in the case of isocyanate/1 = 2. Isothiocyanate showed similar reaction behavior as isocyanate. Polyaddition of 1 with diisocyanates afforded polyamides bearing a bis(dimethylamino)methylenemalonamide group with higher molecular weight. The obtained novel polyamides are soluble in various organic solvents, and reacted with diacid chloride to give crosslinked polymer quantitatively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3079–3086, 1999     

The reaction of thiourea with carbon disulfide

A new type of compound ($\text{7}$) was obtained from the reaction of a metallated thiourea with carbon disulfide followed by methylation. A reaction mechanism involving a rearrangement of dimethylamino group was suggested.     

The DMAP-catalyzed acetylation of alcohols--a mechanistic study (DMAP = 4-(dimethylamino)pyridine)

The acetylation of tert-butanol with acetic anhydride catalyzed by 4-(dimethylamino)pyridine (DMAP) has been studied at the Becke3 LYP/6-311 + G(d,p)//Becke3 LYP/6-31G(d) level of theory. Solvent effects have been estimated through single-point calculations with the PCM/UAHF solvation model. The energetically most favorable pathway proceeds through nucleophilic attack of DMAP at the anhydride carbonyl group and subsequent formation of the corresponding acetylpyridinium/acetate ion pair. Reaction of this ion pair with the alcohol substrate yields the final product, tert-butylacetate. The competing base-catalyzed reaction pathway can either proceed in a concerted or in a stepwise manner. In both cases the reaction barrier far exceeds that of the nucleophilic catalysis mechanism. The reaction mechanism has also been studied experimentally in dichloromethane through analysis of the reaction kinetics for the acetylation of cyclohexanol with acetic anhydride, in the presence of DMAP as catalyst and triethylamine as the auxiliary base. The reaction is found to be first-order with respect to acetic anhydride, cyclohexanol, and DMAP, and zero-order with respect to triethyl amine. Both the theoretical as well as the experimental studies strongly support the nucleophilic catalysis pathway.     

Conformational preferences of beta- and gamma-aminated proline analogues

Quantum mechanical calculations have been used to investigate how the incorporation of an amino group to the Cbeta- or Cgamma-positions of the pyrrolidine ring affects the intrinsic conformational properties of the proline. Specifically, a conformational study of the N-acetyl-N'-methylamide derivatives of four isomers of aminoproline, which differ not only in the beta- or gamma-position of the substituent but also in its cis or trans relative disposition, has been performed. To further understand the role of the intramolecular hydrogen bonds between the backbone carbonyl groups and the amino side group, a conformational study was also performed on the corresponding four analogues of (dimethylamino)proline. In addition, the effects of solvation on aminoproline and (dimethylamino)proline dipeptides have been evaluated using a self-consistent reaction field model, and considering four different solvents (carbon tetrachloride, chloroform, methanol and water). Results indicate that the incorporation of the amino substituent into the pyrrolidine ring affects the conformational properties, with backbone...side chain intramolecular hydrogen bonds detected when it is incorporated in a cis relative disposition. In general, the incorporation of the amino side group tends to stabilize those structures where the peptide bond involving the pyrrolidine nitrogen is arranged in cis. The aminoproline isomer with the substituent attached to the Cgamma-position with a cis relative disposition is the most stable in the gas phase and in chloroform, methanol and water solutions. Replacement of the amino side group by the dimethylamino substituent produces significant changes in the potential energy surfaces of the four investigated (dimethylamino)proline-containing dipeptides. Thus, these changes affect not only the number of minima, which increases considerably, but also the backbone and pseudorotational preferences. In spite of these effects, comparison of the conformational preferences, i.e., the more favored conformers, calculated for different isomers of aminoproline and (dimethylamino)proline dipeptides showed a high degree of consistency for the two families of compounds.