Abstract
(Chemical Equation Presented) Ketene-forming eliminations from ArCH 2CO2C6H3-2-X-4-NO2 (Ar = thienyl, 1) promoted by R2NH/ R2NH2 + in 70 mol % MeCN(aq) have been studied kinetically. When X = CF3 and NO2, the reactions exhibit second-order kinetics as well as β = 0.30-0.64 and |β1g| = 0.31-0.52 that decrease with a better leaving group. Hence, an E2 mechanism is evident. As the leaving group is made poorer (X = H, OCH3, and CI), E2 transition state becomes more skewed toward the proton transfer, as revealed by the increase in Brönsted β to 0.5-0.64, and the Elcb mechanism competes. The changes in the k1 and k-1/k2 values with the reactant structure variation provide additional support for the competing Elcb mechanism. By comparing with existing data for 4-YC6H4CH2CO 2C6H3-2-X-4-NO2, the effect of β-aryl group on ketene-forming elimination is assessed.
| Original language | English |
|---|---|
| Pages (from-to) | 1098-1103 |
| Number of pages | 6 |
| Journal | Journal of Organic Chemistry |
| Volume | 72 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 2007 Feb 16 |
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Ketene-forming elimination reactions from aryl thienylacetates promoted by R2NH/R2NH2 + in 70 mol % MeCN(aq). Effect of the β-aryl group. / Cho, Bong-Rae; Sang, Yong Pyun.
In: Journal of Organic Chemistry, Vol. 72, No. 4, 16.02.2007, p. 1098-1103.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Ketene-forming elimination reactions from aryl thienylacetates promoted by R2NH/R2NH2 + in 70 mol % MeCN(aq). Effect of the β-aryl group
AU - Cho, Bong-Rae
AU - Sang, Yong Pyun
PY - 2007/2/16
Y1 - 2007/2/16
N2 - (Chemical Equation Presented) Ketene-forming eliminations from ArCH 2CO2C6H3-2-X-4-NO2 (Ar = thienyl, 1) promoted by R2NH/ R2NH2 + in 70 mol % MeCN(aq) have been studied kinetically. When X = CF3 and NO2, the reactions exhibit second-order kinetics as well as β = 0.30-0.64 and |β1g| = 0.31-0.52 that decrease with a better leaving group. Hence, an E2 mechanism is evident. As the leaving group is made poorer (X = H, OCH3, and CI), E2 transition state becomes more skewed toward the proton transfer, as revealed by the increase in Brönsted β to 0.5-0.64, and the Elcb mechanism competes. The changes in the k1 and k-1/k2 values with the reactant structure variation provide additional support for the competing Elcb mechanism. By comparing with existing data for 4-YC6H4CH2CO 2C6H3-2-X-4-NO2, the effect of β-aryl group on ketene-forming elimination is assessed.
AB - (Chemical Equation Presented) Ketene-forming eliminations from ArCH 2CO2C6H3-2-X-4-NO2 (Ar = thienyl, 1) promoted by R2NH/ R2NH2 + in 70 mol % MeCN(aq) have been studied kinetically. When X = CF3 and NO2, the reactions exhibit second-order kinetics as well as β = 0.30-0.64 and |β1g| = 0.31-0.52 that decrease with a better leaving group. Hence, an E2 mechanism is evident. As the leaving group is made poorer (X = H, OCH3, and CI), E2 transition state becomes more skewed toward the proton transfer, as revealed by the increase in Brönsted β to 0.5-0.64, and the Elcb mechanism competes. The changes in the k1 and k-1/k2 values with the reactant structure variation provide additional support for the competing Elcb mechanism. By comparing with existing data for 4-YC6H4CH2CO 2C6H3-2-X-4-NO2, the effect of β-aryl group on ketene-forming elimination is assessed.
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U2 - 10.1021/jo0612978
DO - 10.1021/jo0612978
M3 - Article
VL - 72
SP - 1098
EP - 1103
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 4
ER -