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Subject: Re: [DCHAS-L] Letting employees leave during severe weather
Date: Tuesday, December 14, 2021 at 3:53:52 PM
Author: Jeffrey Lewin <jclewin**At_Symbol_Here**MTU.EDU> 		Next by Date:
Subject: Re: [DCHAS-L] Letting employees leave during severe weather
Date: Tue, 14 Dec 2021 16:08:41 -0500
Author: pzavon**At_Symbol_Here**ROCHESTER.RR.COM

From: TILAK CHANDRA <0000058f112ac338-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject: Re: [DCHAS-L] Chemistry World article: Mashed magnesium used to prepare Grignards without worrying about air
Date: Tue, 14 Dec 2021 21:07:34 +0000
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: SA1PR06MB79750BDF46EF884DC174F80588759**At_Symbol_Here**SA1PR06MB7975.namprd06.prod.outlook.com
In-Reply-To <3642010E-043E-489F-B838-A7D8730047C7**At_Symbol_Here**chem.ucla.edu>


Hi Craig, Thank you!

CF3 or F-substituted phenyl halides are also known to form the explosive intermediates during the Grignard preparation. I am not aware of the exact cause behind this chemistry; however, it is believed that Mg and fluorine-containing compounds can generate some unstable/explosive compounds during the process. There are numerous instances reported in the OPRD journal. Several explosions and runaway reactions have been reported involving 4-trifluoromethylphenyl magnesium chloride, an accident that happened during the preparation of 4-trifluoromethylphenyl magnesium chloride on a large scale resulted in the loss of life and destruction of a chemical plant. It was believed that the severe decomposition was initiated by highly active magnesium particles generated during reaction.

Ashby, E. C.; Al-Fekri, D. M. J. Organomet. Chem. 1990, 390, 275.
 Waymouth, R.; Moore, E. J. Chem. Eng. News 1997, 75, 6.
Appleby, I. C. Chem. Ind. 1971, 120.

Tilak
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of Craig Merlic <merlic**At_Symbol_Here**CHEM.UCLA.EDU>
Sent: Tuesday, December 14, 2021 2:10 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: Re: [DCHAS-L] Chemistry World article: Mashed magnesium used to prepare Grignards without worrying about air
 

All,

 

Ball mills can cause catastrophic accidents, even on small scale, when the wrong chemicals are used. A major explosion occurred at Iowa State University just a couple years ago.

https://www.scribd.com/document/355343467/Ball-Mill-Explosion-Ames-Laboratory-Write-Up-for-Ball-Mill-Event-Lesson-Learned-8-31-15-1

Only 3 grams of aluminum and 5 mL of Vertrel=AE XF (decafluoropentane) were at the root of the explosion.

 

The key is the Barbier reaction (Victor Grignard's mentor) which is the reaction of organic halides with metals.  The specific combination of aluminum and Teflon is actually a military explosive.   As often the case, chemistry is the key.

 

Craig

 

Craig A. Merlic

Professor of Chemistry, UCLA Department of Chemistry and Biochemistry

Executive Director, UC Center for Laboratory Safety

http://cls.ucla.edu

Los Angeles, CA  90095-1569

Voice:  310-825-5466

 

 

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of TILAK CHANDRA <0000058f112ac338-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Date: Tuesday, December 14, 2021 at 11:40 AM
To: <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: Re: [DCHAS-L] Chemistry World article: Mashed magnesium used to prepare Grignards without worrying about air

 

Thank you, Rob,


Using less solvent can be a green chemistry feature and the prep will be cost-effective at plat scale. However, I am not sure if the process is safer - what if that material caught fire? or water gets into it? Grignard reactions are highly exothermic, and I will be worried about using that much energy in a reaction with no media to transfer heat.

 

Tilak Chandra

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of Info <info**At_Symbol_Here**ILPI.COM>
Sent: Tuesday, December 14, 2021 12:18 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: Re: [DCHAS-L] Chemistry World article: Mashed magnesium used to prepare Grignards without worrying about air

 

No real need to worry about runway thermal reactions when you are prepping at most a 1.5 grams of a substrate inside a comparatively huge and sealed metal heat sink. If I reviewed this paper, I would have insisted that the authors at least address the potential unknown hazards of scaleup.

 

Nowhere in the paper or supplemental materials do I find the word "safety". The inevitable result of this procedure, however useful it may become, is that someday someone will say "we did this reaction a dozen times before and nothing ever happened until now."

 

Rob Toreki

 

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Safety Emporium - Laboratory and Safety Supplies 
https://www.SafetyEmporium.com
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Fax: (856) 553-6154, PO Box 1003, Blackwood, NJ 08012

 

On Dec 14, 2021, at 12:39 PM, CHAS membership <membership**At_Symbol_Here**DCHAS.ORG> wrote:

 

I'm used to the idea that there's no predicting which topics will catch the Internet's fancy, but the article I posted on the **At_Symbol_Here**acsdchas twitter steam yesterday has received 24,000 views and 800 click throughs over night. Both of these numbers tend to be in the single digits for most of the CHAS tweets. So I believe that the topic of the article is of interest to the chemistry community and I thought I would share it with the e-mail list as well…

The process is a ball-milling operation, an approach that is favored by Green Chemists as a more sustainable approach to synthesis.

- Ralph

Mashed magnesium used to prepare Grignards without worrying about air

https://www.chemistryworld.com/news/mashed-magnesium-used-to-prepare-grignards-without-worrying-about-air/4014897.article

Researchers at Hokkaido University, Japan, have discovered a new method to prepare Grignard reagents using mechanochemistry - and what's more these reagents aren't destroyed by air. 'It's easier and faster,' says Deborah Crawfordfrom the University of Bradford, UK, who was not involved in the study. 'I would now employ [this] method if I was to need a Grignard.'

...


Ralph Stuart, CIH, CCHO
Membership Chair
American Chemical Society Division of Chemical Health and Safety
membership**At_Symbol_Here**dchas.org

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