The correct order of stability for the following alkoxides is :
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A more stabilised alkoxide has a more delocalised or better-stabilised negative charge: resonance with a nitro group (-M) beats the -I effect alone, and an sp2 carbon stabilises more than an sp3 carbon.
Step 1: (A) is O- on an sp3 carbon that also carries NO2; only the -I effect of NO2 stabilises the negative charge. Step 2: (B) is O- on an sp2 carbon (C=CH2) that carries NO2. The sp2 carbon is more electronegative than sp3, giving extra stabilisation, so (B) is more stable than (A). Step 3: (C) is -O-CH=CH-NO2. Here the negative charge on oxygen is delocalised through the C=C onto the nitro group (a push-pull resonance O--CH=CH-NO2 to O=CH-CH=NO2-), the strongest stabilisation. Step 4: Order of stability: C greater than B greater than A. Answer: Option (A), i.e. (C) > (B) > (A)
