AMU Engineering 2017 solved paper Solved Paper

(i) H3C→−

C

sp

≡C−
More electronegative (50% s -character )
+I -effect of −CH3 group destabilises the carbanion.
(ii) H→−C≡

C

sp

More electronegative (50% s -character)
No +I -effect to destabilise the carbanion.
(ii) H3C−

CH

sp

Less electronegative (25% s -character )
More the s -character of charged carbons, greater will be the stability. Hence, the correct decreasing order of stability is (ii) >( i) > (iii).