烷烃电离能和生成焓的相关性

根据化合物形成过程中价电子能量变化与生成焓之间的关系, 推导出烷烃的生成焓和电离能之间的关系. 以21个烷烃化合物为模型将实验测定的电离能与标准生成焓进行直接关联, 证实了模型方程的适用性, 所得回归方程的相关系数达到0.9999, 估算值与实验值之间的标准偏差仅为0.03 eV. 同时还利用实验测定的标准生成焓对一系列烷烃的电离能作了预测.     

新型分子筛的生成焓计算

The enthalpies of formation of some compounds are not easy to be measured experimentally. This paper reports the calculated values of the heat of formation for some novel moleclar sieves by a method of consistant molecular mechanics force field. The enthalpies of formation of novel type molecular sieves: ZSM-48, ZSM-22, ZSM-23 and ZSM-18, have been calculated.     

Structural studies of cyclic ureas: 2. Enthalpy of formation of parabanic acid

Thermophysical and thermochemical studies have been carried out for crystalline parabanic acid. The thermophysical study was made by differential scanning calorimetry, DSC, over the temperature interval between T = (263 and 473) K. Two phase transitions were found: at T = (392.3 ± 1.6) K with the enthalpy of transition of (2.1 ± 0.4) kJ · mol⁻¹ and at T = (509.8 ± 1.5) K, when the compound was scanned to its fusion temperature. The standard (p = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, for crystalline parabanic acid was determined using static-bomb combustion calorimetry as −(590.2 ± 1.0) kJ · mol⁻¹. The standard molar enthalpy of sublimation, at T = 298.15 K, was derived from the variation of their vapour pressures, measured by the Knudsen-effusion method, with the temperature. These two thermochemical parameters yielded the standard molar enthalpy of formation in the gaseous phase, at T = 298.15 K, as −(470.8 ± 1.2) kJ · mol⁻¹.     

Interplay of thermochemistry and <Emphasis Type="Italic">Structural Chemistry</Emphasis>, the journal (volume 18, 2007) and the discipline

In this study, we relate the contents of the journal Structural Chemistry for the calendar year 2007 and thermochemistry. The year’s articles were briefly summarized and a thermochemical comment written to supplement them. Frequently questions were asked and future research was suggested.     

Structural studies of cyclic ureas: 3. Enthalpy of formation of barbital

A thermochemical and thermophysical study has been carried out for crystalline barbital [5,5′-diethylbarbituric acid]. The thermochemical study was made by static bomb combustion calorimetry, from which the standard () molar enthalpy of formation of the crystalline barbital, at T = 298.15 K, was derived as −(753.0 ± 1.8) kJ · mol⁻¹. The thermophysical study was made by differential scanning calorimetry over the temperature interval (265 to 470) K. A solid–solid phase transition was found at T = 413.3 K. The vapour pressures of the crystalline barbital were measured at several temperatures between T = (355 and 377) K, by the Knudsen mass-loss effusion technique, from which the standard molar enthalpy of sublimation, at T = 298.15 K was derived as (117.3 ± 0.6) kJ · mol⁻¹. The combination of the experimental results yielded the standard molar enthalpy of formation of barbital in the gaseous phase, at T = 298.15 K, as −(635.8 ± 1.9) kJ · mol⁻¹. This value is compared and discussed with our theoretical calculations by several methods (Gaussian-n theories G2 and G3, complete basis set CBS-QB3, density functional B3P86 and B3LYP) by means of atomization and isodesmic reaction schemes.     

Standard Enthalpy of Formation of Monoclinic Ammonium Paratungstate

Monoclinicammoniumparatlingstate,(NH.),,H,W,,O.,4H,O(s),isanessentialintermediatecompoundintheextractionoftungstenfromitsoresl.Theknowledgeofthepropertiesofammoniumparatungstateisdesirableforcontrollingitscrystallizationanditsthermaldecomposition.However,thestudyonthethermodynamicpropertieshasnotbeenreported.Inthepresentwork,theenthalpyofreactionforthethermaldecompositionofammoniumparatungstatewasmeasured,anditsstandardenthalpyofformationat298.15Kisobtained.Thesampleofmonoclinicanunoniumpa…     

L－苏糖酸钴的制备及标准生成焓

以L－苏糖酸钙与草酸的复分解反应得到的L－苏糖酸溶液，在80℃下与过量 CoO反应较长时间，滤液浓缩后加无水乙醇制得L－苏糖酸钴粉红色粉末。用化学分 析及元素分析确定其组成为Co(C4H7O5)·H2O,IR光谱分析结果表明新化合物中苏糖 酸以羧基氧原子与Co^+配位。TD－DTG结果说明，它在热分解中有一定稳定性，经 脱水生成Co-(C4H7O5)2,最后生成CoO。用转动弹热量计测得其恒容燃烧能ΔcE为（ －3504.47±1.64)kJ·mol^-1，计算得其标准燃烧焓和标准生成焓ΔfHm^θ分别为 （－3501．99±1．64）和（－2170．67±1.97)kJ·mol^-1。     

L-苏糖酸镁的制备及标准生成焓

以L-苏糖酸钙与草酸的复分解反应得到的L-苏糖酸溶液，在80 ℃下与过量MgO反应较长时间， 滤液浓缩后加无水乙醇制得L-苏糖酸镁白色粉末.用化学分析及元素分析确定其组成为Mg(C4H7O5)2•H2O. IR光谱分析表明,化合物中苏糖酸以羧基氧原子与Mg2＋配位，Mg2＋为sp3杂化态，配位数为4. TD－DTG结果说明，它在热分解中有一定稳定性，而经脱水和生成Mg(OAc)2，最后生成MgO.用转动弹热量计测得其恒容燃烧能ΔE为 (－10407.34±4.67) kJ•mol－1,计算其标准燃烧焓ΔcHm和标准生成焓ΔfHm分别为(－3 249.49±1.46) kJ•mol－1和(－2 786.23±1.84) kJ•mol－1.     

灵芝多糖的结构特征分析

采用沸水回流法从灵芝子实体中提取多糖,经Sevage法除蛋白,乙醇沉淀,离心、透析、膜分离,浓缩、冻干后得灵芝多糖。经HIO4氧化、Smith降解及甲基化反应,并利用多糖及刚果红混合液在碱性溶液中的波长的红移变化,通过UV-VIS,IR,GC,GC-MS,NMR对灵芝水提多糖的结构特征及三螺旋体结构进行分析研究。结果表明:灵芝多糖含有三螺旋体构型,GC-MS分析灵芝多糖的主要单糖组分为葡萄糖,还有少量的半乳糖、甘露糖、木糖和艾杜糖,IR及1HNMR分析多糖为β-构型,HIO4氧化、Smith降解和甲基化分析表明:多糖主要为(1→3)糖苷键连接构型,并伴有少量的1→6位支链键连接的结构,灵芝多糖是由D-葡萄糖单元通过β-(1→3)糖苷键连接葡聚多糖,其主要构型特征为(1→3)β-D-线性连接的骨架结构。     

溶解量热法测三氧化钼标准生成焓

用溶解量热法,以KIO_4和KOH组成的弱碱性溶液为量热溶剂,设计3个不同的热化学循环,用RD-1型热导式自动量热计测定了MoO_3的标准生成焓,并推荐其值为ΔH_(t(moO_3))~0(298.15K)=-765.0±6.8kJ·mol~(-1)。     

L-苏糖酸锰的制备及标准生成焓

The pink powder of manganese L-threonate was obtained by extracting with alcohol the concentrated solution derived from the reaction between L-threonic acid solution prepared by double decomposition reaction of calcium L-threonate with oxalic acid and superfluous manganese oxide at 80℃ for certain time. The composition of the new compound was determined by chemical and elemental analyses and its formula fits Mn(C₄H₇O₅)₂·H₂O, the IR spectra indicated that Mn²⁺ in the compound coordinates to oxygen atom of the carboxyl group, while the proton of the carboxyl group is dissociated, it was assumed that the coordination number of Mn²⁺ was 4. The results of TG-DTG showed that the compound have fairish stability, the intermediate and final product of the thermal de-composition of the compound are Mn(C₄H₇O₅)₂ and MnO₂, respectively. The constant volume combustion energy of the compound, Δ_cE, were determined by a precise rotating-bomb calorimeter at 298.15K, it was (-3384.30±1.21)kJ·mol^-1, its standard enthalpy of Combustion,Δ_cH_m^?,and standard enthalpy of formation,Δ_fH_m^? , were calculated. They are (-3383.07±1.21)kJ·mol^-1 and (-2 571.68±1.63)kJ·mol^-1, respectively.     

氯化烷基咪唑系列离子液体标准摩尔燃烧焓和生成焓

用精密氧弹热量计测定了4种离子液体: 氯化1-甲基-3-乙基咪唑(C2MIC), 氯化1-甲基-3-丁基咪唑(C4MIC), 氯化1-甲基-3-戊基咪唑(C5MIC)和氯化1-甲基-3-己基咪唑(C6MIC)的燃烧热, 计算了它们的标准摩尔燃烧焓 和标准摩尔生成焓 , 结合文献中的标准摩尔溶解焓, 估算了烷基咪唑阳离子在水溶液中的标准摩尔生成焓, 以及亚甲基对标准摩尔燃烧焓和标准摩尔生成焓的贡献.     

室温离子液体EMIES的标准生成焓

在(298.15 ±0.01) K下用转动弹热量计测定了离子液体硫酸乙酯-1-甲基-3-乙基咪唑(EMIES)及合成它的原料1-甲基咪唑的恒容燃烧热,通过计算得到它们的标准燃烧焓 分别为(－2671±2) 和(－286.3±0.5) kJ·mol－1;标准生成焓 分别为(－3060±3) kJ·mol－1和(－2145±4) kJ·mol－1.结合文献上硫酸二乙酯的标准生成焓数据,得到了合成离子液体EMIES的反应热(－102.3±1.0) kJ·mol－1,与合成实验中观察到的强烈放热现象是一致的.根据离子液体EMIES的热容数据,计算了不同温度下EMIES的标准生成焓.     

烟酸的低温热容和标准摩尔生成焓

利用精密自动绝热热量计测量了分析纯烟酸在78～400 K温区的低温热容. 用最小二乘法将实验摩尔热容对温度进行拟合, 得到了热容随温度变化的多项式方程. 用此方程进行数值积分, 得到在此温区每隔5 K的舒平热容值和相对于298.15 K时的热力学函数值. 利用精密静止氧弹燃烧热量计测定了烟酸在298.15 K时的恒体积燃烧能为 Δ_cU＝ －(24528.3±16.1) J•g^－1. 依据物质燃烧焓定义计算出烟酸的标准摩尔燃烧焓为: Δ_cH_m^o＝－(3019.05±1.98) kJ•mol^－1. 最后, 依据Hess定律计算出烟酸的标准摩尔生成焓为: Δ_fH_m^o＝－(56.76±2.13) kJ•mol^－1.     

Determination of Standard Molar Enthalpies of Formation for "White Powdery Tungstic Acid" and for Dodecatungstophosphoric Acid by Solution Calorimetry

"White powdery tungstic acid" has been used for preparing various types of tungsten-containing compounds due to its high reactivity. The present paper covers the standard molar enthalpies of formation, △H0/f of three tungsten- containing acids. The values found for "white powdery tungstic acid" WO3·1. 68H2O, "yellow tungstic acid" WO3·1. 20H2O and dodecatungstophosphoric acid H3(PW12O40)·25H2O at 298. 15 K were-(1312±1), - (1192±1) and -(18150±13) kJ mol-1, respectively.     

The Plausible Aromaticity of 1,8-Naphthalimides: The Enthalpy of Formation of N-Methyl-1,8-Naphthalimide

In order to understand the aromaticity of 1,8-naphthalimides, the enthalpies of combustion and sublimation of N-methyl-1,8-naphthalimide were determined. The numerical values are –6095.8 ± 3.5 and 109.7 ± 0.8 kJ · mol^–1. The enthalpies of formation of condensed and gas phase N-methyl-1,8-naphthalimide are accordingly –306.1 ± 3.9 and –196.4 ± 4.0 kJ · mol^–1. It is deduced that naphthalimides enjoy some 40 kJ · mol^–1 of aromatic stabilization over that of the maleimides, shown to be nominally destabilized and modestly antiaromatic in our recently published thermochemical study.     

八面体纳米钼酸钡的制备及标准摩尔生成焓的测定

根据热力学势函数法建立纳米钼酸钡与块体钼酸钡标准摩尔生成焓之间的关系, 利用原位微量热技术获取纳米钼酸钡与盐酸反应的反应热, 以已知的块体钼酸钡的标准摩尔生成焓－1507.5 kJ•mol^－1为参考标准, 求得由反相微乳液法制备的八面体纳米钼酸钡的标准摩尔生成焓为(－336.62±0.33) kJ•mol^－1, 两种材料标准摩尔生成焓数值的差异证明纳米结构比块体结构能态更高, 更加不稳定.     

Paradigms and Paradoxes: Thoughts on the Enthalpy of Formation of Guanidine and Its Monosubstituted Derivatives

Despite their seeming simplicity, substituted guanidines have not particularly caught the attention of the thermochemical community. The current paper compares the enthalpy of formation of solid substituted guanidines with correspondingly substituted benzenes, also as solids.     

过渡元素卤化物标准生成焓的连接性拓扑研究

基于邻接矩阵和成键原子的价环值（Ｖ１）,建立２个新连接性指数（＾０Ｈ,＾１Ｈ）。它们与３３种过渡元素卤化物标准生成焓的直线方程为：－△Θｍ＝－３８．３９＋２２８．０８＾０Ｈ,ｒ＝０．９９０３－△ｆＨΘｍ＝１２７．４５＋３１８．５０＾１Ｈ,ｒ＝０．９８４０与其它指数相比,新指数计算更为准确。结果表明,＾０Ｈ、＾１Ｈ具有良好的结构选择性和性质相关性,可用于预测其它过渡元素卤化物的标准生成焓。