共查询到19条相似文献,搜索用时 140 毫秒
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用中国计量科学院提供的量热基准苯甲酸标定了本实验室建立的精密静弹燃烧热量计,测定了四邻甲氧基苯基卟啉(T_(o—OCH_3)PP)和四对二甲氨基苯基卟啉(T_(p—N(CH_3)_2)PP)的标准燃烧能,并计算出标准生成焓。实验仪器等温环境潜水式静弹燃烧热量计,量热环境主要包括恒温水槽和量热筒外套两部分,水槽中的两个泵式搅拌器能使水槽中的水充分搅动。量热体系包括量热筒、筒内定量的水、氧弹、内加热器、内搅拌器、热敏电阻测温探头以及一支辅助检测温度计。量热 相似文献
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我们曾报道2-溴间苯二酚在BF_3催化下酰化时的脱溴现象。本文在以下述反应制备6-溴代异黄酮时发现4-溴间苯二酚脱溴现象更为显著。 相似文献
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多溴吩噻嗪系列化合物的稳定性和热力学性质的密度泛函理论研究 总被引:1,自引:0,他引:1
用Gaussian 03程序, 在B3LYP/6-31G*水平上全优化计算了吩噻嗪和135个多溴吩噻嗪系列化合物(PBPTHs)在298.15 K和101.3 kPa状态时的热力学参数. 设计等键反应, 计算了PBPTHs系列化合物的标准生成热( )和标准生成自由能( ). 同时研究了这些参数与溴原子的取代位置及取代数目(NPBS)之间的关系. 结果表明: 多溴吩噻嗪的热能校正值(Eth)、恒容热容( )、标准熵( )、标准焓( )以及标准自由能( )与NPBS之间有很强的相关性(r2≥0.998). 在相关方程中, 溴原子的取代个数对多溴代吩噻嗪热力学数值的大小有很大影响. 根据 的相对大小, 从理论上求得异构体的相对稳定性顺序. 相似文献
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Using a precision static oxygen-bomb calorimeter, the standard energies of combustion at 298.15K of tetra-(p-nitrophenyl)-porphyrin, tetra-(3-pyridinyl)porphyrin were determined to be -27.412±0.012, -32.749±0.011 kJg~(-1), and the corresponding standard enthalpies of formation at 298.15 K were calculated to be 751.0±11.0, 811.8±8.6 kJ mol~(-1), respectively. The uncertainties of the results are given as twice of the final over-all standard deviation of the main. 相似文献
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用自行安装的精密静弹燃烧量热计测定了四苯基卟啉(TPP)、四甲苯基卟啉(T_((PCH)_3)PP)、四对甲氧苯基卟啉(T_((P-OCH)_3)PP)和四邻氨苯基卟啉(T_((O-NH)_2)PP)的标准燃烧能,并计算出标准生成焓。样品 1.将苯甲醛加入沸腾的丙酸中迥流30分钟后冷至50~60℃,加入乙醇,冷却,过滤,紫色产物用甲醇洗,干燥后得TPP粗品。将粗品溶于迥流的二氯甲烷,加入溶于苯的DDQ迥流30分钟,蒸除溶剂,残渣溶于氯仿,氧化铝-氯仿柱层析,氯仿-甲醇重结晶制得纯TPP. 相似文献
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Roux MV Notario R Foces-Foces C Temprado M Ros F Emel'yanenko VN Verevkin SP 《The journal of physical chemistry. A》2011,115(14):3167-3173
This paper reports an experimental and computational thermochemical study on 1,3-dimethylbarbituric acid. The value of the standard (p° = 0.1 MPa) molar enthalpy of formation in the gas phase at T = 298.15 K has been determined. The energy of combustion was measured by static bomb combustion calorimetry, and from the result obtained, the standard molar enthalpy of formation in the crystalline state at T = 298.15 K was calculated as -639.6 ± 1.9 kJ·mol(-1). The enthalpy of sublimation was determined using a transference (transpiration) method in a saturated N(2) stream and a value of the enthalpy of sublimation at T = 298.15 K was derived as 92.3 ± 0.6 kJ·mol(-1). From these results a value of -547.3 ± 2.0 kJ·mol(-1) for the gas-phase enthalpy of formation at T = 298.15 K was determined. Theoretical calculations at the G3 and G4 levels were performed, and a study on molecular and electronic structure of the compound has been carried out. Calculated enthalpies of formation are in very good agreement with the experimental value. 相似文献
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Matos MA Miranda MS Monte MJ Santos LM Morais VM Chickos JS Umnahanant P Liebman JF 《The journal of physical chemistry. A》2007,111(43):11153-11159
Condensed phase standard (p degrees = 0.1 MPa) molar enthalpies of formation for 1-indanone, 2-indanone, and 1,3-indandione were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of sublimation for 1-indanone and 2-indanone, at T = 298.15 K, were measured both by correlation-gas chromatography and by Calvet microcalorimetry leading to a mean value for each compound. For 1,3-indandione, the standard molar enthalpy of sublimation was derived from the vapor pressure dependence on temperature. The following enthalpies of formation in gas phase, at T = 298.15 K, were then derived: 1-indanone, -64.0 +/- 3.8 kJ mol(-1); 2-indanone, -56.6 +/- 4.8 kJ mol(-1); 1,3-indandione, -165.0 +/- 2.6 kJ mol(-1). The vaporization and fusion enthalpies of the indanones studied are also reported. In addition, theoretical calculations using the density functional theory with the B3LYP and MPW1B95 energy functionals and the 6-311G** and cc-pVTZ basis sets have been performed for these molecules and the corresponding one-ring species to obtain the most stable geometries and to access their energetic stabilities. 相似文献
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Roux MV Notario R Zaitsau DH Emel'yanenko VN Verevkin SP 《The journal of physical chemistry. A》2012,116(18):4639-4645
This paper reports an experimental and computational thermochemical study on 2-thiobarbituric acid (2-thioxodihydropyrimidine-4,6(1H,5H)-dione), [CAS 504-17-6]. The value of the standard (p(0) = 0.1 MPa) molar enthalpy of formation in the gas phase at T = 298.15 K has been determined. The energy of combustion was measured by bomb combustion calorimetry, using a rotatory bomb, and from the result obtained, the standard molar enthalpy of formation in the crystalline state at T = 298.15 K was calculated as -(396.8 ± 0.9) kJ·mol(-1). The enthalpy of sublimation was determined using a transference (transpiration) method in a saturated N(2) stream and a value of the enthalpy of sublimation at T = 298.15 K was derived as (118.3 ± 2.2) kJ·mol(-1). From these results a value of -(278.5 ± 2.4) kJ·mol(-1) for the gas-phase enthalpy of formation at T = 298.15 K was determined. Theoretical calculations at the G3 and G4 levels were performed, and a study of the molecular and electronic structure of the compound has been carried out. Calculated enthalpies of formation are in very good agreement with the experimental value. 相似文献
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Ribeiro da Silva MA Gomes JR Ferreira AI 《The journal of physical chemistry. B》2005,109(27):13356-13362
The standard (p degrees = 0.1 MPa) molar enthalpies of formation of 2-, 3-, and 4-chloroaniline were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by rotating bomb combustion calorimetry. The Calvet high-temperature vacuum sublimation technique was used to measure the enthalpies of vaporization or sublimation of the three isomers. These two thermodynamic parameters yielded the standard molar enthalpies of formation of the three isomers of chloroaniline, in the gaseous phase, at T = 298.15 K, as 53.4 +/- 3.1 kJ.mol(-1) for 2-chloroaniline, 53.0 +/- 2.8 kJ.mol(-1) for 3-chloroaniline, and 59.7 +/- 2.3 kJ.mol(-1) for 4-chloroaniline. These values, which correct previously published data, were used to test the computational methodologies used. Therewith, gas-phase acidities, proton affinities, electron donor capacities, and N-H bond dissociation enthalpies were calculated and found to compare well with available experimental data for these parameters. 相似文献
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用苯胺、氨基氰、乙酰丙酮三种物质合成了杀菌剂嘧霉胺(C12N3H13).并用溶解量热法在常压、298.15K下,分别测定了苯胺、氨基氰、乙酰丙酮和嘧霉胺在混合溶剂(VDMF:VDMSO=2:1)中的溶解焓:ΔsHmΘ(C6NH7(l),298.15K)=-(12.48±0.16)kJmol-1、ΔsHmΘ(NH2CN(s),298.15K)=-(8.06±0.42)kJmol-1、ΔsHmΘ(CH3COCH2COCH3(l),298.15K)=(1.26±0.03)kJmol-1和ΔsHmΘ[C12N3H13(s),298.15K]=(13.84±0.12)kJmol-1.根据热化学原理求出了298.15K时,合成反应的标准反应热ΔrHmΘ=-(35.65±0.47)kJmol-1,以及嘧霉胺(C12N3H13(s))的标准摩尔生成焓ΔfHmΘ(C12N3H13(s),298.15K)=(198.5±1.5)kJmol-1;用TAMair微量热仪测定了嘧霉胺(C12N3H13(s))在301.15K时对灰葡萄孢菌作用的产热曲线,根据产热曲线求算了在嘧霉胺作用下,灰葡萄孢菌生长代谢的最大发热功率Pmax、最大产热功率的时间tmax、速率常数k和抑制率I等热动力学参数.结果表明:嘧霉胺在低浓度下对灰葡萄孢菌有刺激作用,高浓度下为抑制作用,即嘧霉胺对微生物的生长具有双向生物效应,也称为Hormsis效应. 相似文献
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The standard (p(o) = 0.1 MPa) molar energies of combustion in oxygen, at T = 298.15 K, of four liquids: 2-ethylpyridine, 4-ethylpyridine, ethylpyrazine and 2,3-diethylpyrazine were measured by static bomb calorimetry in an oxygen atmosphere. The values of the standard molar enthalpies of vaporization, at T = 298.15 K, were obtained by Calvet microcalorimetry, allowing the calculation of the standard molar enthalpies of formation of the compounds, in the gas phase, at T= 298.15 K: 2-ethylpyridine (79.4 +/- 2.6) kJ mol(-1); 4-ethylpyridine (81.0 +/- 3.4) kJ mol(-1); ethylpyrazine (146.9 +/- 2.8) kJ mol(-1); and 2,3-diethylpyrazine (80.2 +/- 2.9) kJ mol(-1). The most stable geometries of all ethylpyridine and ethylpyrazine isomers were obtained using the density functional theory with the B3LYP functional and two basis sets: 6-31G* and 6-311G**. These calculations were then used to obtain estimates of the enthalpies of formation of all isomers, including those not experimentally studied, through the use of isodesmic reactions. A discussion of the relationship between structure and energetics of the isomers is also presented. 相似文献