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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 39, Number 5
JKCSEZ 39(5)
October 20, 1995 

 
Title
The Effect of Pressure on the Iododestannylation between Tetramethyltin and Iodine
Author
Oh Cheun Kwun*, Young Hoon Lee, In Seung Jeun
Keywords
Abstract
요오드와 테트라메틸주석간의 전하이동에 따른 상호작용을 사염화탄소 용매내에서 분광학적방법으로 연구하였다. 이들의 결과로부터 일시적인 전하이동 착물의 흡수 스펙트럼(λmax=270nm)이 관찰되었으며, 흡수 스펙트럼의 후속적인 감소현상으로 요오드에 의한 테트라 메틸주석의 분해반응임을 알았다.(iododestannylation). 따라서 iododestannylation에 대한 속도상수를 온도 10,25 및 35℃, 압력을 1200bar 까지 변화시켜 가면서 측정하였으며, 이때의 반응속도상수는 온도와 압력에 따라 증가함을 알았다. 이 반응속도 상수로부터 ΔV≠, Δβ≠, ΔH≠ 및 ΔS≠의 값을 구했으며 이들 값으로부터 전이상태의 용매구조 변화 및 매카니즘을 규명하였다. 이러한 사실로부터 본 반응은 SF2 메카니즘이 지배적이며 압력이 증가함에 따라 SF2의 성격이 약화됨을 알았다.

UV spectrophotometric investigation has been carried out on the system of charge-transfer (CT) complex with iodine and tetramethyltin in carbon tetrachloride solvent. The transient CT absorption spectrum can be observed in λmax=270nm and the subsequent disappearance of CT absorption spectrum was accompained by the cleavage of tetramethyltin with iodine (iododestannylation). From there, the rate constants for the iododestannylation were determined at 10, 20 and 35℃ up to 1200bar and the reaction rates were increased with increasing temperature and pressure. From these rate constants, the values of the activation parameters (ΔV≠, Δβ≠, ΔH≠ and ΔS≠) were obtained and from these values discussed in terms of solvent structure variation of transition state and mechanism. From these results, it was found that the reaction is followed with SF2 mechanism and weakened SF2 mechanism nature by increasing pressure.

Page
350 - 355
Full Text
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