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Analysis of LFER’s Combined with Activation Parameters Assigns a Concerted Mechanism to Alkaline Hydrolysis of X-Substituted Phenyl Diphenylphosphinates

등록일
2008년 2월 14일 13시 30분 39초
접수번호
1380
발표코드
32P238포 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
발표시간
금 <발표Ⅴ>
발표형식
포스터
발표분야
유기화학
저자 및
공동저자
한정윤, 엄익환
이화여자대학교 나노과학부,
A kinetic study is reported for alkaline hydrolysis of X-substituted phenyl diphenylphosphinates. The Brønsted-type plot is linear over 4.5 pKa units with a typical βlg value(–0.49) for a concerted mechanism. The Hammett plots correlated with σo and σ– constants are linear but exhibit scattered points, while the corresponding Y-T plot results in excellent linear correlation (ρ = 1.42, r = 0.35). A stepwise mechanism is excluded since HO– ion is much more basic and a poorer nucleofuge than the leaving aryloxide. A dissociative mechanism is ruled out on the basis of the small βlg value. As the substituent X changes from H to 4-NO2 and 3,4-(NO2)2, ΔH‡ decreases from 11.5 kcal/mol to 9.7 and 8.7 kcal/mol, respectively, while ΔS‡ varies from –20.7 cal mol–1 K–1 to –19.7 and –18.5cal mol–1 K–1, in turn. Analysis of LFER’s combined with the activation parameters assigns a concerted mechanism.

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