Organic Chemistry Some Basic Principles And Techniques Ques 55

55. The stability of carbanions in the following :

(a) $RC \equiv \overline{C}$

(b)

(c) $R_2 C=C \overline{H}$

(d) $R_3 C-CH_2$

is in the order of :

[2008]

(a) (a) $>$ (b) $>$ (c) $>$ (d)

(b) (b) $>$ (c) $>$ (d) $>$ (a)

(c) (d) $>$ (b) $>$ (c) $>$ (a)

(d) (a) $>$ (c) $>$ (b) $>$ (d)

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Answer:

Correct Answer: 55.(a)

Solution:

  1. (a) As ’ $s$ ’ character increases, stability of carbanion increases. Also, electron donating groups decreases the stability of carbanion. Hence, the correct stability, order:

$\underset{+1}{R_3} \to C \underset{s p^{3}}{\stackrel{\ominus}{C}} H_2$