Comments on: Reagent Friday: NBS (N-Bromo Succinimide)

By: James Ashenhurst

James Ashenhurst — Tue, 06 Aug 2024 15:19:45 +0000

In reply to Schminit.

I’m not precisely sure what you’re asking. Could you be more specific – perhaps give an example?

By: Schminit

Schminit — Mon, 05 Aug 2024 19:06:51 +0000

For NBS substitution over allylic and benzylic substitution, is the rearrangement of free radical allowed or not???

By: James Ashenhurst

James Ashenhurst — Tue, 18 Apr 2023 19:07:10 +0000

In reply to RAJ. Which specific reaction with NBS?

By: RAJ

RAJ — Tue, 18 Apr 2023 18:57:34 +0000

Do stearic hinderance also comes to concern while reaction with NBS.

By: James Ashenhurst

James Ashenhurst — Thu, 22 Sep 2022 15:42:07 +0000

In reply to Dinesh Debnath.

Probably. Especially if acid catalysis is used. https://pubs.acs.org/doi/10.1021/ol006952r

By: Dinesh Debnath

Dinesh Debnath — Thu, 22 Sep 2022 02:58:28 +0000

Can we carry out mono bromination of quinone species using NBS as reagent?

Please answer

By: Samantha Richardson

Samantha Richardson — Thu, 24 Oct 2019 05:29:49 +0000

Toluene reacted with NBS yields p-bromotoluene, o-bromotoluene, and small amounts of m-bromotoluene…in your example you show it yields the bromine bonded to the methyl in the allylic position. I conducted this reaction in lab last week and FTIR and NMR confirmed the products I listed above. Confused as to how you came to that product?

By: James Ashenhurst

James Ashenhurst — Wed, 18 Sep 2019 18:16:37 +0000

In reply to Nm.

Yes, it will oxidize primary alcohols to aldehydes in polar solvents through forming a hypobromite intermediate. Interestingly, NBS is more selective for secondary over primary alcohols, and also very selective for oxidation of axial (vs equatorial) groups in steroid systems. See Chem. Rev. 1963, vol 63 page 21. https://pubs.acs.org/doi/10.1021/cr60221a002

By: James Ashenhurst

James Ashenhurst — Fri, 13 Sep 2019 17:03:28 +0000

In reply to Greig.

Possibly. I’m aware of N-chloro dialkylamines doing bridgehead chlorinations, see J. Am. Chem. Soc.1974 96 134307-4311 . https://pubs.acs.org/doi/10.1021/ja00820a042

By: James Ashenhurst

James Ashenhurst — Thu, 05 Sep 2019 19:02:26 +0000

In reply to Olivia. That will likely be an allylic bromination.