Sciencemadness Discussion Board

Acylation with acyl bromide

biomechem - 3-3-2017 at 13:50

In the wiki I can read:
Quote:

Acid anhydrides tend to be less electrophilic than acyl chlorides, and only one acyl group is transferred per molecule of acid anhydride, which leads to a lower atom efficiency. The low cost, however, of acetic anhydride makes it a common choice for acetylation reactions.

What about acyl bromides? Acyl bromides react slower than chlorides, but somewhere I read that thanks to this fact reaction is more controllable and also less byproducts are formed. Is that true? Also what is a better catalyst for bromides AlCl3 or AlBr3?

Please move my post if it's in an inappropriate place.

clearly_not_atara - 3-3-2017 at 19:17

Acyl bromides are cool but usually you have to use excess bromine to make them and it's kinda expensive so it's not done. Also, the higher boiling point of acyl bromides is pretty much only an advantage for acetyl bromide, otherwise you want the lower bp.