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Unformatted text preview: At this point, we compare the structures of acid chlorides (a.k.a. acyl halides), esters and amides. Heteroatoms bound to the carbonyl perturb the structure of the carbonyl group in two ways: through resonance via pi-bonds and through electron withdrawing effects (inductive effects) via sigma bonds. comparisons of bond length, we were able to infer the extent of resonance effects for acyl halides, esters and amides: for acid chlorides resonance was not important, for esters resonance was somewhat important, and for amides resonance was very significant. These results agree with the barrier to rotation about the heteroatom-carbonyl carbon bond. For esters, this barrier to rotation is about 13 Kcal/mol and for amides this barrier to rotation was about 22 Kcal/mol. We compared this to the strength of a C=C pi-bond: 66 Kcal/mol. Hydrolysis of esters and other acyl derivatives was discussed....
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- Spring '08