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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 32, Number 6
BKCSDE 32(6)
June 20, 2011 

Elimination Reactions of (E)-2,4,6-Trinitrobenzaldehyde O-Aryloximes Promoted by R3N/R3NH+ in 70 mol% MeCN(aq). Effect of β-Aryl Group the Nitrile-Forming Transition-State
Sang Yong Pyun*, Woong Sub Byun, Bong Rae Cho*,
Elimination, E2 and Elcb-like, β-Aryl group effect
Nitrile-forming eliminations from (E)-2,4,6-(NO2)3C6H2CH=NOC6H4-2-X-4-NO2 (1) promoted by R3NH/ R3NH+ in 70 mol % MeCN(aq) have been studied kinetically. When X = NO2, the reactions exhibited secondorder kinetics as well as Brönsted β = 0.63 and |βlg| = 0.34-0.46, and an E2 mechanism is evident. As the leaving group was made poorer (X = H, Cl, and CF3), Brönsted β value increased from 0.63 to 0.85-0.89 without much change in the |βlg| value E2, indicating that structure of the transition state changed to an E1cb-like with extensive Cβ-H bond cleavage, significant negative charge development at the β-carbon, and limited Cα-OAr bond cleavage.
1921 - 1924
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