Comments on: Reactions of Grignard Reagents

By: James Ashenhurst

James Ashenhurst — Thu, 11 Jul 2024 13:48:56 +0000

In reply to michael. No. Molecular N2 does not interact with Grignard reagents, but there are other metallic compounds which do (molybdenum compounds come to mind).

By: michael

michael — Tue, 25 Jun 2024 18:03:34 +0000

Can a Grignard reagent interact with molecular nitrogen, as in N2 gas?

By: James Ashenhurst

James Ashenhurst — Sat, 24 Feb 2024 18:32:37 +0000

In reply to manushree. No, it's not practical to quench the reaction fast enough to get single addition in most cases. There are ways to do mono-addition to form ketones from esters (e.g. using a Weinreb amide) but a fast quench of a Grignard is not it.

By: manushree

manushree — Sat, 24 Feb 2024 04:53:45 +0000

If we were to do an acid work up right after the first step of reaction of Grignard reagent with an ester, could a hemiacetal be formed? If not, why?

By: James Ashenhurst

James Ashenhurst — Tue, 09 Jan 2024 20:44:53 +0000

In reply to Ak. It does not, Grignard reactions happen fine at room temperature and above.

By: James Ashenhurst

James Ashenhurst — Tue, 09 Jan 2024 20:44:38 +0000

In reply to Hina.

There is no good way to time the workup so that it is done after the first addition occurs but before the second does.

After the first addition happens, the subsequent breakdown to the ketone and second addition occur very quickly.

If a ketone is desired, there are species known as “Weinreb amides” that form a stable tetrahedral intermediate after the first addition. This tetrahedral intermediate can be quenched and a ketone obtained.

By: Hina

Hina — Sun, 07 Jan 2024 17:19:04 +0000

Why is acidic workup not done after the first step in case of reaction with ester?

By: Ak

Ak — Mon, 27 Nov 2023 07:24:15 +0000

Why grignard reaction need extremely cold conditions like -78°C

By: James Ashenhurst

James Ashenhurst — Mon, 14 Aug 2023 16:41:24 +0000

In reply to Aakash Pathak. You'll probably have reduction of the carbonyl. I would check out March's Advanced Organic Chemistry.

By: Aakash Pathak

Aakash Pathak — Thu, 10 Aug 2023 10:45:50 +0000

Hi James,
Thanks for creating this website. It has helped me a lot and I can’t thank you enough.
I have one doubt. Please if you can help me out. What happens when you take a very sterically hindered carbonyl or acid derivative substrate and equally sterically hindered grignard reagent? The mechanism in both case I believe is SN2 and SN(addition-elimination). Will the reaction proceed? Or not? Or if it does then how? And do you have any reference which I can go through? Actually back in the college, one of my professors had taught us about bulky G.R. giving out hydride , which attacks further on sterically hindered substrates. But since, I am not in college now, I can’t ask that professor. And I haven’t been able to find it in any standard textbooks. I checked clayden, klein and bruice.