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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 27, Number 3
JKCSEZ 27(3)
June 20, 1983 

 
Title
Chemical Reaction of Solvated Electrons in Binary Mixture

이성분계 (THF-H2O)에서 용매화전자의 화학반응속도
Author
Yu-Chul Park

박유철
Keywords
Abstract
테트라히드로퓨란-물 이성분계에서 용매화전자와 벤젠간의 반응속도 상수를 광분해법으로 측정하였으며, 이때 온도 범위는 -18℃∼+51℃이였다. 속도 상수를 Arrhenius식에 따라 도시하여 얻은 활성화 에너지는 테트라히드로퓨란 함량이 증가할 수록 감소하였다. 물의 함량이 증가하면 이성분계의 점성도는 감소하고, 또 반응속도 상수도 감소하였으므로 용매화전자의 반응은 확산지배가 아니다. 활성화엔탈피 변화와 이차반응속도 상수는 테트라히드로퓨란의 함량이 39, 49, 75M%일 때 각각 4.90, 2.80 및 -0.3kcalM-1과 8.86×108, 5.14×108 및 1.43×108M-1sec-1이었다. 활성화반응 파엔탈피변화, 활성화엔트로피 변화에서 얻은 등속도 온도는 본 실험온도보다 낮은 244˚K로 이것은 라메터가 활성화엔트로피 변화라는 것을 의미한다. 활성화 에너지에 대한 용매효과로부터 용매화전자(es-)와 벤젠(B)간의 반응과정 중에 es- + B ↔ B- 단계는 테트라히드로퓨란 함량이 증가할수록 더욱 더 발열반응성으로 진행되었다.

The rate constants for solvated electrons with benzene in the binary mixture (tetrahydrofuran-water) were measured at a various temperatures(-18℃∼+51℃) by photolysis. From Arrhenius plots of rate constants it was observed that the activation energies were decreased with increasing tetrahydrofuran(THF) content. Decreasing the viscosity of solvent mixtures by adding water, the rate constants were also decreased. It indicates that the reaction of solvated electrons are not controlled by diffusion. The change of activation enthalpy in kcal M-1and the rate constants in M-1sec-1 were 4.90 and 8.80×108 for 30M% of THF, 2.80 and 5.14×108 for 49M% of THF, and -0.30 and 1.43×108 for 75M% of THF, respectively. The slope of the linear plot of activation enthalpies against activation entropies was 244oK, which supports the reaction parameter is the change of activation entropy in the range of the experimental temperature. From the solvent effect on the activation energy, it was found that the step of the reaction, es- + B ↔ B- shifted to the exothermic reaction with increasing THF content.

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201 - 207
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