二氯苯的蒸发焓和升华焓测定

在进行分子内非键合相互作用的热化学研究中,我们已用燃烧量热法测定了各种取代的氯代苯在凝聚态的标准生成焓。为了排除分子间的相互作用,以得到准确的气态生成焓,需要这些化合物的标准蒸发焓或升华焓。文献中这类数据不多,且相当一部分是用测量蒸气压随温度变化按Clapeyron-Clausius方程计算的,不如直接量热法准确。对高取代的氯代苯,由于蒸气压很低,实验困难,数据更缺。为此,我们用量热法测定了三个二氯苯异构体的蒸发焓和升华焓,并结合已有的文献数据,建立了氯代苯标准蒸发焓和升华焓与其沸点的线性关系,估算了其余未知的数据。     

多氯代菲分子结构和热力学性质的密度泛函理论研究

采用密度泛函理论方法在B3LYP/6-311G(d, p)水平上对527个多氯代菲分子的几何结构进行了全优化并计算得到它们的热力学性质(等容热容( )、熵(S$)、标准生成焓(ΔfH$)和标准生成Gibbs自由能(ΔfG$)), 研究了这些性质与取代的氯原子数目和位置的关系, 根据各异构体的相对标准生成Gibbs自由能(Δr,fG$)的大小, 得到它们的热力学稳定性顺序. 计算结果表明: 绝大多数多氯代菲分子具有非平面的几何构型, 在多氯代菲分子中存在三种类型的分子内弱相互作用(H…H、C—H…Cl和Cl…Cl相互作用), 随着分子中取代的氯原子数目的增加, 多氯代菲最稳定异构体的ΔfH$和ΔfG$开始时逐渐减小, 然后又快速增加. 具有相同数目氯原子的多氯代菲异构体的ΔfH$和ΔfG$与氯原子的取代位置有很大的关系. 多氯代菲异构体的相对热力学稳定性主要由分子内的离域π键和Cl…Cl核排斥作用的强弱决定.     

mezo-和d, l-2, 3-二氯丁烷气态生成焓的测定

本文用直接量热法测量了298.15K时meso-和d, l-2, 3-二氯丁烷的液态蒸发焓值以及其混合物的液态燃烧焓值, 得到了它们的标准气态生成焓值, 考察了二氯烷烃分子内氯原子间的相互影响和相互作用对其气态生成焓值的影响。     

二氯丁烷标准蒸发焓的测定

用直接量热法测量了五种二氯丁烷位置异构体的标准蒸发焓值,探讨了二氯代烷烃液态蒸发焓的影响规律.     

计算饱和醇异构体标准生成焓的新方法

基于极性叠加原理,在成功设计烷烃异构体和多氯代烷烃生成焓计算新方法的基础上,设计了一种计算多元醇异构体生成焓的新方法,并合理地假定任一异构体的原子化焓等于三种键(C-C、C-H和C-O-H键)的键能、极性叠加能项以及氢键能项的加和.用这一模型拟合24种原子化焓数据,得到了标准生成焓的估算公式.为了检验预测的精确性,又设计了一种预测方法,使用在排除被预测的化合物条件下回归得到的参数,预测该化合物的生成焓.按这种方法,预测了24种异构体的生成焓.通过该5参数预测的相对于实验值的各种误差(平均绝对误差、均方根误差和最大绝对误差)不仅比7参数的基团法预测的对应误差小得多,而且比相应实验数据的误差还要小.与键加和法比较,该方法的模型包含了极性叠加能和氢键能量,该两项代表了主要的非键相互作用能,表征了不同异构体的结构差异,并大大减少了参数.     

计算多氯代烷烃异构体生成焓的新方法

在我们提出诱导极性叠加原理并用以解释同分异构体稳定性及设计烷烃异构体标准生成焓计算新方法的基础上,进一步设计了含多个杂原子体系的取代烷烃——氯代烷烃异构体生成焓的五参数的新方法.与目前应用较广的九参数的基团加和法相比,计算精度高、预报性好,其预报的均方根误差、平均误差比实验数据的相应偏差还要小.而且,特别重要的是,由于所用的参数少,它在理论上可以推广到含各种杂原子或基团以及多种杂原子或基团共存的化合物生成焓的计算.     

前手性硅甲基的非等时性: 卤代烷烃溶剂对化学位移差值的影响

本文报导了卤代烷烃溶剂及溶液浓度与化学位移差值的关系, 揭示了溶剂分子与硅烷分子间的相互作用。     

烷烃的热力学性质与结构的关系

在分子图邻接矩阵的基础上提出了一个新的连接性指数mX,mX与烷烃的标准熵、原子化焓、标准生成焓、汽化焓、标准生成吉布斯自由能具有良好的线性关系,相关系数均在0·99以上。结果表明,该模型简单、实用、可靠,而且物理意义明确,对有机物有较高的结构区分能力。对157种烷烃的计算结果表明,热力学性质的计算值和实验值的平均相对误差不超过0·77%。     

多阶F指数对碳氢化合物的QSPR研究

根据分子中原子与原子的不同邻接情况,重新定义了关联矩阵的矩阵元,并在此基础上定义了矩阵形式的多阶F指数 pF.多阶F指数 pF考虑了分子中每一顶点原子的特性及顶点原子与其它原子的多种相互作用.采用系列指数 pF中的F, 0F′, 1F′和 2F′对烷烃、烯烃、烷基苯共144个碳氢化合物的标准生成焓进行相关研究,相关系数均大于0.98,与卤化钛化合物TiXn (n=1～4, X=F, Cl, Br, I)的标准生成焓的相关系数也在0.99以上.     

反气相色谱法对八异辛基倍半硅氧烷热力学性质的表征

采用反气相色谱技术,以23种溶剂为探针分子,表征了八异辛基倍半硅氧烷(octaisooctyl-POSS)的热力学性质,包括摩尔溶解焓、分子间相互作用参数、质量活度系数、Hansen溶度参数,并有效判断了溶剂探针分子与共聚物分子间的相互作用以及共聚物在这些溶剂中的溶解性.结果表明,在实验温度范围内(343 ～393 K),烷烃、芳香烃、卤代烃类、乙醚以及乙酸甲酯是octaisooctyl-POSS的良溶剂,乙酸乙酯、乙酸正丙酯、乙酸正丁酯与乙酸正戊酯是中等溶剂,醇类、丙酮以及四氢呋喃是不良溶剂;Hansen溶度参数表明,octaisooctyl-POSS与烷烃分子强烈的色散作用使其在烷烃溶剂中具有优良的溶解性能.     

Interaction of alkali metals with unsaturated heterocyclic compounds. The reductive metalation of 1,4-diphenylphthalazine

1,4-Diphenylphthalazine ( 1 ) was reduced in tetrahydrofuran by sodium metal to a monomeric dianion 2 . Chemical reactions of this new dianion were examined with various reagents. Generally, the protonation, acylation and alkylation products were 1,2-dihydrophthalazine derivatives. An annulation of the phthalazine ring system was accomplished by treating the dianion with 1,3-dichloropropane or 1,4-dichlorobutane. With 1,2-dichloroethane however, only 1,4-diphenylnaphthalene was detected.     

The reductive metalation of 9-phenylacridine

The reductive metalation of 9-phenylacridine by sodium to a dianion is described and the reactions of the dianion with electrophiles investigated. Reactions of the dianion with methanol, dimethyl sulfate, X(CH₂)_nX (n = 2,3,4, X = Cl, Br), and methyl chloroformate were studied. Reactions occurred exclusively at the 9 and 10 positions forming 9,10-dihydro-9-phenylacridine derivatives. Of particular interest was the fact that the dianion was dialkylated with 1,2-dichloroethane but monoalkylated at the 9-position with 1,3-dichloropropane and 1,4-dichlorobutane. These results are compared to those obtained with dianions derived from other heterocyclic systems and analyzed using Baldwin's Rules for Ring Closure.     

Refractive Indices Measurement and Correlation for Selected Binary Systems of Various Polarities at 25 °C

New refractive indices at 25 °C were measured and are reported here for 19 binary mixtures of pentan-3-one+1,2-dichloroethane, +1,3-dichloropropane, +1,4-dichlorobutane, +trichloromethane, +1,1,1-trichloroethane, +1,1,2,2-tetrachloroethane; cyclopentanone+1-chlorobutane, +1,1,2,2-tetrachloroethane; cyclohexanone+1,1,2,2-tetrachloroethane; 5-chloro-2-pentanone+n-hexane, +toluene, +ethylbenzene; nitromethane+trichloromethane; and nitromethane or nitroethane, +1,2-dichloroethane, +1,3-dichloropropane, +1,4-dichlorobutane. The experimental refractive index deviations from linear mixing behavior have been evaluated and correlated consistently with the 3-parameter Redlich–Kister equation with good results. The molar refraction was also examined for the systems including pentan-3-one, cyclopentanone, cyclohexanone and 5-chloro-2-pentanone for which densities and excess molar volumes are available from previous works. Different theoretical (n, ρ) mixing rules were tested for these systems. The excess Gibbs energy G ^E and excess enthalpy H ^E values were considered together with the excess molar volumes V ^E, excess refractive indexes $ n_{\text{D}}^{\text{E}} $ , molar refraction R and excess molar refractions R ^E on mixing in the discussion of the influence of the alkyl chain length or of the nature of the second component in the mixture in terms of molecular interactions.     

Vibrational analysis of 1,2-dichloroalkanes

IR and Raman spectra have been obtained for 1,2-dichlorobutane and 1,2-dichloro- pentane. The butane crystallizes in the P_XS_XH conformation, but the pentane could not be made to crystallize. Normal coordinate calculations were made for the P_XS_XH, P_CS_HH, and P_HS_HH conformers of these two compounds and for 1,2-dichloropropane. The ob- served spectra were interpreted with the aid of these calculations, and it was concluded that all three conformers exist for each of these compounds. The force field that was obtained should be applicable to other 1,2-dichloroalkanes.     

Synthesis of Bis(2-Pyridylphosphino)Alkanes in Superbasic Medium and Their Hydroxymethyl Derivatives

Abstract

Novel P-H-diphosphinoalkanes with pyridyl substituents at the phosphorus atoms have been obtained in good or moderate yields by the interaction of primary 2-pyridyl-phosphine with dichloroalkanes in superbasic medium. The formation of novel 1-(2-pyridyl)-1-phosphacyclopentane together with bis(2-pyridylphosphino)butane was observed as the result of the interaction of 2-pyridylphosphine and 1,4-dichlorobutane under the same reaction conditions. The reaction of the bis(2-pyridylphosphino)alkanes thus obtained with formaldehyde leads to the formation of the corresponding hydroxymethyl derivatives.     

Ion-transfer voltammetry at 1,6-dichlorohexane|water and 1,4-dichlorobutane|water interfaces

The usefulness of 1,6-dichlorohexane (1,6-DCH) and 1,4-dichlorobutane (1,4-DCB) as organic solvent (O) for ion-transfer voltammetry at O|water (W) interface has been examined, and the results are compared with those with 1,2-dichloroethane (1,2-DCE). The width of potential window of the 0.1 M tetraoctylammonium tetrakis(4-chlorophenyl)borate (O)|0.05 M Li₂SO₄ (W) interface increased in the sequence: O = 1,6-DCH > 1,4-DCB > 1,2-DCE. The voltammetric behavior of the transfer of various cations and anions at the 1,6-DCH|W and 1,4-DCB|W interfaces has been shown to be of reversible nature, and the midpoint potentials or the reversible half-wave potentials have been determined. The midpoint potentials of hydrophilic ions have also been determined by the analysis of anodic final rise or cathodic final decent of the voltammograms with the O|W interfaces, where the W contains a salt of the hydrophilic ion. Also, the effect of ion-pair formation in O on the midpoint potentials has also been discussed.     

Rotational isomerism in open-chain polychlorinated hydrocarbons: Problems in predicting conformations from carbon-chlorine stretching frequencies

Normal coordinate analysis calculations have been made to determine the carbon-chlorine stretching (v(C-Cl)) frequencies of model rotational isomers of 1,2-dichloroethane, 1,2-dichloropropane, 1,3-dichloropropane, 1,5-dichloropentane and 1,2,3-trichloropropane. The calculations were based on prior calculations on models of a number of primary and secondary monochlorohydrocarbons. The models were derived from the real isomers by ignoring the hydrogen atoms and considering only the heavy atom skeletal structure. The possible effect on v(C-Cl) frequencies of coupling between C-C1 stretching and adjacent CH₂ rocking modes in some isomers was taken into account where necessary. The results, and in some cases the frequency of the highest ∠CCC deformation mode, are used to establish the conformations of rotational isomers present in these molecules in the vapour, liquid and crystalline states. Conclusions are drawn concerning the applicability of known v(C-Cl) frequency structure correlations for monochlorohydrocarbons to polysubstituted chlorohydrocarbons. v(C-Cl) frequency correlations and assignments have also been made for several chloropropanes containing one CCl₃ group.     

Thionin derivatives in the extraction and direct photometric determination of boron

Thionin and nine commercially available thionin derivatives were studied for their applicability in the analytical solvent extraction and direct photometric determination of boron, Azure A, Azure B, Azure C, Methylene Blue, New Mcthylene Blue N, Méthyléne Green, Toluidine Blue O, Thionin and the cosinates of Azure A and B were investigated. Over thirty organic solvents, mostly chlorinated or brominated were tried with these dyes. 1,2-Dichloroethane, 1,2-dichloropropane, dichloromethane, I,I,2-trichlorocthane, cis-dichloroethylene, o-dichlorobenzene, 1,4-dichlorobutane and mixtures of these solvents proved applicable. Many good dye-solvent combinations were found which were very attractive for the separation and determination of various amounts of boron. Only thionin itself proved unsatisfactory.