Question

Base strength of the following
(i) `H_(3)C CH_(2)^(-)` , (ii) `H_(2)C=CH^(-)`
(iii) `HC-=C^(-)`
A. `(iii) gt (ii) gt (i)`
B. `(i) gt (iii) gt (ii)`
C. `(i) gt (ii) gt (iii)`
D. `(ii) gt (i) gt (iii)`

Answer 1

Correct Answer - C
To find the base strength of carbanions, we consider the corresponding conjugate acids. The order of their acidic strength is
`C-=underset(sp)CHgtCH_(2)=underset(sp^(2))CH_(2)gtCH_(3)-underset(sp^(3))CH_(3)`
Thus, the order of base strength is just the reverse of it:
`CH_(3)barCH_(2)gt CH_(2)=barCH gt CH-=barC`