The stability of carbanions in the following (1) $\mathrm{RC} \equiv \stackrel{\ominus}{\mathrm{C}}$ (2)…

The stability of carbanions in the following (1) $\mathrm{RC} \equiv \stackrel{\ominus}{\mathrm{C}}$ (2) (3)\(\mathrm{R}_2 \mathrm{C}=\stackrel{\ominus}{\mathrm{C}}\mathrm{H}\) (4) $\mathrm{R}_3 \mathrm{C}-\stackrel{\ominus}{\mathrm{C}} \mathrm{H}_2$ is in the order of
  1. (1) $>$ (2) $>$ (3) $>$ (4)
  2. $(2) > (3) > (4) > (1)$
  3. (4) $>$ (2) $>$ (3) $>$ (1)
  4. (1) $>$ (3) $>$ (2) $>$ (4)

Solution

Key Idea : When s-character increases, then electrons becomes more closer to the nucleus and structure is of lower energy and is more stable. The stability order of carbanions is as : $\mathrm{RC} \equiv \mathrm{C}^{\ominus} > \mathrm{C}_6 \mathrm{H}_5^{\ominus} > \mathrm{R}_2 \mathrm{C}=\stackrel{\ominus}{\mathrm{C}} \mathrm{H} > \mathrm{R}_3 \mathrm{C}-\stackrel{\ominus}{\mathrm{C}} \mathrm{H}_2$

Asked in: NEET 2008 (Screening)

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