Hi Michael Schmidt

You could do the conversion with BBr3, but I wouldn't recommend it. BBr3 and BCl3 are terrific water-getters so you'll most likely end up with oxyhalide contamination.

I would rather use anhydrous HBr gas. If you have the right work environment, get yourself an HBr lecture bottle, a fritted-glass-bottom vessel to put your SbCl3 in, and pass the HBr through the frit. The conversion should be essentially complete if you use some excess HBr and give it time. (You will of course have to pay attention to all the relevant safety issues, such as where the spent gas is going, what happens if a connection leaks, etc. - BUT the same is true with BBr3/BCl3!)

You'll still need to keep water out, for instance by passing the exiting gas through a dehydrating trap so accidental backflow doesn't bring ambient air into the system.

Adding to my previous reply:

You assume that BCl3 will graciously evaporate from the system, but that may well not happen. BCl3 and BBr3 are very strong Lewis acids, while SbCl3 and SbBr3 are weak Lewis bases (as well as moderate Lewis acids, but that's not relevant here). So chances are that if you go by the BBr3 route you'll "discover" in your vessel 1:1 compounds of B halides with Sb halides, possibly new to science. I haven't found literature references to those, but 1:1 compounds between BCl3 and PCl3 (CAS # 17496-58-1) and between BBr3 and PBr3 (CAS # 15194-82-8) are known.

Thank you very much Emanuel for your answer, may it could help. I have a larger amount of SbCl and I need the SbBr. I will try and check it with HBr. Best greetings. Michael