SOLVENT EFFECT ON THE RATE CONSTANT OF ROTETIONAL ISOMERISM IN SOLUTIONS

本工作的目的是用超声和拉曼光谱方法研究溶液中旋转异构体的速率常数。在5 MHz到800 MHz的频率范围内，测量了仲丁基溴在正己烷和邻苯二甲酸二异丁酯中的超声弛豫谱。考察了速率常数的松弛频率对粘度的依赖关系。根据与旋转异构体对应的拉曼光谱的温度和压力关系，估算了伴随旋转异构体的热焓(DELTAH)和体积(DELTAV)的变化从超声频率与温度的关系估计约为18kJ/摩尔。仲丁基溴化物的速率常数与粘度的关系不能用Kramers理论解释。在高粘度区域，偏离理论的现象被发现。超声波和拉曼光谱的结果表明，旋转异构体的势能曲线被溶液粘度的变化所修正。这是溶质与溶液之间的相互作用。这是可取的发展新的速率常数理论，它预测了粘度的依赖关系。

THE PURPOSE OF THIS WORK IS TO ELUCIDATE THE RATE CONSTANT OF ROTATIONAL ISOMERISM IN SOLUTIONS BY ULTRASONIC AND RAMAN SPECTROSCOPIC METHODS.THE ULTRASONIC RELAXATION SPECTRA OF SEC-BUTYLBROMID IN N-HEXANE AND DIISOBUTYLPHTHALATE WERE MEASURED IN THE FREQUENCY RANGE FROM 5 MHZ TO 800MHZ.THE VISCOSITY DEPENDENCE OF THE RELAXATION FREQUENCY OF THE RATE CONSTANT WERE OBSERVED.THE CHANGES IN THE ENTHALPY (DELTAH) AND VOLUME (DELTAV) ACCOMPANYING THE ROTATIONAL ISOMERISM WERE ESTIMATED FROM THE TEMPERATURE AND PRESSURE DEPENDENCE OF THE RAMAN SPECTRA CORRESPONDING THE ROTATIONAL ISOMERS.THE VALUES OF DELTAH AND DELTA1V DECREASED WITH INCREASING THE VISCOSITY IN SOLUTIONS.ON THE OTHER HANDS,THE ACTIVATION ENTHALPY,WHICH IS ESTIMATED FROM THE TEMPERATURE DEPENDENCE OF THE ULTRASONIC FREQUENCY ARE AROUND 18 KJ/MOL.THE VISCOSITY DEPENDENCE OF THE RATE CONSTANT OF SEC-BUTYLBROMID IS NOT INTERPRETED IN TERMS OF THE KRAMERS THEORY.THE DEVIATION FROM THE THEORY WAS RECOGNIZED IN THE HIGH VISCOSITY REGION.THE RESULTS OBTAINED FROM THE ULTRASONIC AND RAMAN SPECTROSCOPY INDICATED THAT THE POTENTIAL CURVES OF THE ROTATIONAL ISOMERISM IS MODIFIED BY THE CHANGE IN THE VISCOSITY IN SOLUTION.THAT IS THE INTERACTION BETWEEN SOLUTE AND SOLVENTS.IT IS DESIRABLE TO DEVELOP THE NEW THEORY OF THE RATE CONSTANT,WHICH PREDICTS THE VISCOSITY DEPENDENCE.