From:
Craig Merlic <merlic**At_Symbol_Here**CHEM.UCLA.EDU>
Subject:
Re: [DCHAS-L] Lab Hydrogenation
Date:
Oct 3, 2024 02:07 UTC
Reply-To:
ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID:
<0D2002FB-599A-4ADB-88A3-7647D1C833B5**At_Symbol_Here**chem.ucla.edu>
In-Reply-To:
<901598FC-133B-4F0B-A0AF-B7877DCD8847**At_Symbol_Here**gmail.com>
There have been many fires due to the hydrogenation catalysts, but not as many concerning the questions Bill asked about. As Matt points out adding solvent to catalyst can start fires. Raney nickel is problematic as the catalyst already has hydrides on the metal as a reagent out of the can.
But far more fires started at the end of the reaction when people filtered off the catalyst from the product+solvent solution. The issue again is that the catalyst has reactive hydrides at the end of the reaction. The worst is palladium on carbon when using alcohol solvent. The most important safety reference on this is:
https://pubs.acs.org/doi/10.1021/acs.oprd.1c00190 DOI: 10.1021/acs.oprd.1c00190
Which focuses on Pd/C
A reference for Raney Nickel safety is:
https://pubs.acs.org/doi/10.1021/acs.oprd.0c00053 https://dx.doi.org/10.1021/acs.oprd.0c00053
And Tilak wrote a nice overall paper on hydrogenation safety, but it came out before the above two important papers on hydrogenation catalyst safety:
https://pubs.acs.org/doi/10.1016/j.jchas.2015.10.019 http://dx.doi.org/10.1016/j.jchas.2015.10.019
Craig
Craig A. Merlic
Professor of Chemistry, UCLA Department of Chemistry and Biochemistry
Executive Director , UC Center for Laboratory Safety
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of Matthew Meredith <matthewmeredith34**At_Symbol_Here**GMAIL.COM>
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Date: Wednesday, October 2, 2024 at 9:14 AM
To: <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: Re: [DCHAS-L] Lab Hydrogenation
It’s been a while but when I was a TA we did this with undergrads in an advanced synthesis course. One significant watch-out I only had to learn once is to make sure the catalyst and solvent fumes do not come into contact in the presence of oxygen.
We used methanol as the solvent and Pd/C catalyst and had a fire when a student poured the dry catalyst into an open flask containing the methanol and dissolved reactant. The catalyst exothermed when it came into contact with the solvent fumes above the liquid layer in the flask (due to heat of adsorption I think?) and ignited the fumes and solvent. A simple nitrogen headspace purge of the flask before adding the catalyst would have prevented this.
On Oct 1, 2024, at 6:13 PM, Galdenzi, Bill <bill.galdenzi**At_Symbol_Here**alexion.com> wrote:
Dear CHAS members
Wondered if anyone has some experience and specific guidance on lab hydrogenations specific to a Parr unit designed for lab scale hydrogenations:
- Scale limitations (pressure and volumes) for lab.
- Does it vary by floor?
- Special considerations – hydrogen monitor
- Limitations to cylinders
- Hood construction (hood sash considerations)
- Other??
Any procedures, SOP, slide decks….etc. would be greatly appreciated. Thank you
Bill Galdenzi
Environmental, Health and Safety
Cell = (475) 331-1698
email bill.galdenzi**At_Symbol_Here**alexion.com
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