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  • 02월 22일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

Combined dual substituent constant and activation parameter analysis assigns a concerted mechanism to alkaline ethanolysis at phosphorus of Y-substituted phenyl diphenylphosphinates

등록일
2008년 2월 14일 13시 29분 50초
접수번호
1378
발표코드
32P237포 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
발표시간
금 <발표Ⅴ>
발표형식
포스터
발표분야
유기화학
저자 및
공동저자
박지은, 엄익환
이화여자대학교 나노과학부,
Second-order rate constants have been measured for reactions of Y-substituted-phenyl diphenylphosphinates with EtO–K+ in anhydrous ethanol. A linear Brønsted-type plot is obtained with βLg = –0.54, a typical βLg value for reactions which proceed through a concerted mechanism. The Hammett plots correlated with σo and σ– constants are linear but exhibit many scattered points, while the corresponding Y-T plot results in excellent linear correlation (r = 0.41), indicating that the leaving group departs at the rate-determining step. However, a stepwise mechanism is excluded since the incoming EtO– ion is much more basic and a poorer leaving group than the leaving aryloxide. The ΔH‡ values are strongly dependent on the nature of the substituent Y, while the ΔS‡ values remain constant on changing the substituent Y in the leaving group. These ΔH‡ and ΔS‡ trends support also a concerted mechanism.

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