ExamsMy practice
How many compounds among the following compounds show inductive, mesomeric as well as hyperconjugation effects? [figure]
Answer
4
Solution
All three effects need: a polar group (inductive), a group conjugated with a π-system (mesomeric) and an α-H on a carbon attached to an sp2 carbon (hyperconjugation).
Anisole: −I and +M of -OCH3, but no α-H (the CH3 is on O), so no.
The enone: −I/−M of C=O conjugated with C=C, α-H on -CH(CH3)2 and -COCH3, so yes.
Benzene: no group; chlorocyclohexane: only −I (no π-system), so no.
Both nitro compounds: −I/−M of -NO2 and a benzylic C–H for hyperconjugation, so yes (2).
m-Xylene: +I and hyperconjugation of CH3, but no mesomeric group, so no.
Last compound: -COCH3 conjugated with C=C (−I, −M) and CH3/ring C–H next to C=C, so yes.
Hence 4.
Answer: 4