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JEE Main levelOne or more correct optionsDifficulty 2 of 3o3180

1-Fluoro-2,4-dinitrobenzene reacts with sodium methoxide in methanol. Which statements are correct?

  1. AIn the sigma complex the negative charge is delocalised onto the oxygens of both nitro groups
  2. BThe corresponding 1-chloro compound would react faster because the C-Cl bond is weaker than the C-F bond
  3. CThe slow step is the formation of the anionic sigma complex
  4. DReplacing the 4-nitro group by hydrogen would lower the rate

Answer: A, C, D

The first (addition) step is rate determining, so a group that stabilises the complex speeds up the reaction. Both the ortho and para nitro groups can accept the charge, and removing the para group removes one of the stabilisations. The chloro compound is slower because bond strength is not rate determining.
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