Why in Nucleophilic addition-elimination reactions,does the #C=O# bond break when the nucleophile is added and not the#C-CL# bond ?

1 Answer
anor277
Nov 21, 2016

I take it you refer to nucleophilic attack on an #"acyl halide"#?

Explanation:

#"Reaction: " Nu^(-) + Cl(O=)CRrarr(Nu)(""^(-)O)(Cl)CRrarr Nu(O=)CR +Cl^-#

The carbonyl is presumed to stabilize the negative charge of the nucleophile, presumably by resonance. The ipso carbon is thus 4-coordinate, and we could trap such an intermediate by quenching with, say, #Me_3SiCl# to give #(Nu)(Me_3SiO)(Cl)CR#.

Does this address your query?

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