Determination of the enthalpy and reaction volume changes of organic photoreactions using photoacoustic calorimetry
Determination of the enthalpy and reaction volume changes of organic photoreactions using photoacoustic calorimetry
复制标题
使用光声量热法测定有机光反应的焓和反应体积变化
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
J. Goodman
中科院分区：
文献类型：
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作者：
M. S. Herman;J. Goodman
光声量热法（PAC）可用于测量光引发反应的热变化和反应体积变化。用PAC研究了2,3-重氮杂环（2.2.1）庚-2-烯（DBH）、二苯基环丙烯（DPC）和反式二苯乙烯（TS）的光反应。通过温度依赖法或二元溶剂混合法来解决这些实验体积变化。热体积变化产生溶液中的反应焓，可以与文献值进行比较。在两种情况下（DPH和DPC），其值比由气相生成热预测的值更吸热。这种差异可能是由于反应物和产物在极性溶剂中的不同溶剂化。得到了光反应的绝对反应体积变化。PAC是压力依赖性研究的一种有用的替代技术，可获得这一信息。这些体积变化可以进一步通过时间解析来提供光过程的动力学信息。
Photoacoustic calorimetry (PAC) can be used to measure both the thermal and reaction volume changes for photoinitiated reactions. The photoreactions of 2,3-diazabicyclo(2.2.1)hept-2-ene (DBH), diphenylcyclopropenone (DPC), and trans-stilbene (TS) are investigated by PAC. The resolution of these experimental volume changes is accomplished by either a temperature dependence or a binary solvent mixture method. The thermal volume changes yield the enthalpies of reaction in solution, which can be compared to literature values. In two cases (DPH and DPC), the values are more endothermic than those predicted from gas-phase heats of formation. The differences can possibly be attributed to differential solvation of the reactants and products in the polar solvents employed. Absolute reaction volume changes for the photoreactions are also obtained for the photoreactions. PAC is a useful alternative technique to pressure-dependence studies to obtain this information. These volume changes can further be time-resolved to provide kinetic information about the photoprocesses.