This set of Organic Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Reaction Intermediates”.
Explanation: This is stabilized by extended conjugation. The more adjacent methyl groups there are, the larger hyperconjugation stabilization is because of the increased number of adjacent C–H bonds.
Explanation: Higher the stability of cation more will be its half-life. As, in the carbocation, p orbital overlap with the compound, will be more stabilizing factor than aromaticity.
3. The order of decreasing stability of the following cations is:
(I) CH3C+HCH3 (II) CH3C+HOCH3 (III) CH3C+HCOCH3
a) III > II > I
b) I > II > III
c) II > I > III
d) I > III > II
Explanation: (II) Here, Mesomeric effect stabilizes carbocation. So, it is highly stabilized.
(I) It is stabilized by hyperconjugation.
(III) It is destabilized as because of carbonyl group; more electronegative Oxygen is present it will decrease electron density of C+.
Explanation: Stabilized by +M effect of OH and hyperconjugation effect (5αH).
Explanation: The positive charge of carbon will be stabalised by mesomeric effect of -NH2 group.
Explanation: Mesomeric effect will stabilize carbocation is highly stable.
+M effect of –NH2 > –OH
(I) It is destabilized by –M and high –I effect.
Sanfoundry Global Education & Learning Series – Organic Chemistry.
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