JEE Main · 2020 · 09 Jan 2020 · Shift 1 · General Organic Chemistry

Basicity of these carbon-centred intermediates falls as the carbanion is better stabilised, and stabilisation grows both with the s-character of the charged carbon and with resonance delocalisation. The aryl-type anion (v) is the most stabilised and therefore the weakest base, followed by the higher-s-character anion (iii); the resonance-delocalised allylic anion (ii) comes next, then the plain $s{p}^3$ alkyl anion (iv), and finally (i) is the least stabilised and the strongest base. The increasing order of basicity is thus (v) less than (iii) less than (ii) less than (iv) less than (i).