mezo-和d,l-2,3-二氯丁烷气态生成焓的测定

Measurements of Enthalpies of Formation of 2, 3-Dichlorobutane in Gaseous State

本文用直接量热法测量了298.15K时m330-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。

Two samples of pure mezo-and d, l-2, 3-dichlorobutanes were obtained from their mixture by fractional distillation, and their enthalpies of vaporization at 25℃ were measured by using an LKB-8721-3 vaporization calorimeter, they are 38.41±0.07(mezo-) and 39.78±0.05(d, l-)kJ/mol, respectively. A mixture sample with(mezo-/d,l-)=1.34/1 was used for combustion experiments, its enthalpies of combustion at 25℃ were determined by using a rotating bomb combustion calorimeter with a tantanum lined bomb, as -2519.74±1.06kJ/mol. By using the literature's enthalpies of isomerizm between the liquid mezo- and d, l-2, 3-diehlorobutanes, -1.13±0.21kJ/mol, measured by the equilibrium method, enthalpies of combustion of mezo- and d, l-2, 3-dichlorobutanes were obtained. Then enthalpies of formation of both in gaseous state were derived as, -202.34+1.72(mezo-) and -202.15±1.72(d, l-)kJ/mol, respectively. According to the following equation: a,b-C_4H_8Cl_2(g)+n-C_4H_(10)(g)=a-C_4H_9Cl+b-C_4H_9Cl+△H_r the enthalpies of reaction are derived as +5.3(mezo-) and +5.5(d, l-)kJ/mol, which are closed with that of 1, 2-dichlorobutane. The determined enthalpies of formation of the mezo- and d, l-2, 3-dichlorobutanes also coincide witch the calculation results of our 'Electrostatic Bond Energy Scheme.'