Question

For reaction(I),why is the order of reactivity of haldies `ArFgt gt ArClgtArBrgtarl`,although`F^(ᶱ)`is a oor leaving group?Explain.

Answer 1

`En` order of halogens:`FgtClgtBrgtI`.
Due to the high`EN`stablishes the negative charge more than other halogens on the neighbouring`C`atoms in the transitiona nd intermediate states.

This also suggest that step `1` is slow and `R.D.`if step`2` would have been `R.D,`then the reactivity of`ArF` would have been the lowest ,Since`F^(ᶱ)`is the weakest leaving group of the halidic ions,step`2` is fast since (II)(non-aromatic)change to (III)(aromatic).