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Previous by Date: Subject: Re: [DCHAS-L] Serious Explosion during Large-Scale Preparation of an Amine by Alane (AlH3) Reduction of a Nitrile Bearing a CF3 Group Date: Thursday, July 9, 2020 at 2:28:28 PM Author: ILPI Support <info**At_Symbol_Here**ILPI.COM>

Next by Date: Subject: [DCHAS-L] Chemical Safety headlines (11 articles) Date: Fri, 10 Jul 2020 07:41:27 -0400 Author: DCHAS Membership Chair

Also on a similar note, many people are not aware of how strong of a reducing gas/liquid the silanes (silane, disilane, trisilane, tetrasilane, etc) are.
"Unlike the alkanes, silanes have pronounced reducing properties and reactivity with even mildly oxidizing is much enhanced. The difference is electronegativity. While C-H bonds are polarized giving a positive charge on the hydrogen, the Si-H hydrogen is charged negatively. Hydrogen abstraction by materials such as halogens introduces the potential for hazardous reactions with halocarbons" (Britton, L. G., ‰??Combustion Hazards of Silane and Its Chlorides‰??, Paper 12b, Loss Prevention Symposium, AIChE Spring National Meeting and Petrochemical EXPO‰??89, Houston, TX April 6, 1989)
When mixed with the inert halocarbons such as hexafluoroethane or chlorodifluoromethane creates an explosive gas mixture. Even sulfur hexafluoride and carbon dioxide will react. I investigated a explosion a few years ago involving a silane compound and a fluorocarbon oil.

Eugene Ngai
Chemically Speaking LLC
www.chemicallyspeakingllc.com

-----Original Message-----
From: ACS Division of Chemical Health and Safety On Behalf Of davivid
Sent: Thursday, July 9, 2020 2:09 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Serious Explosion during Large-Scale Preparation of an Amine by Alane (AlH3) Reduction of a Nitrile Bearing a CF3 Group

On a similar note, I was once shown a high speed video of a shaped charge penetrating a crew vehicle bearing aluminum armor, followed immediately by discharge of halon. A few milliseconds after the halon discharge there was an explosion originating in the vehicle atmosphere.
The project manager was trying to figure out why.

Hot aluminum particles/vapor plus halon go boom!

Dave Lane
Principal
Clavis Technology Development

On 7/9/20 10:16 AM, Jack Reidy wrote:
> All,
>
> I forwarded this to our Chemistry Department and received an interesting reply from Prof. Bob Waymouth, chair of the department safety committee, about an alternative explanation for the explosion. In the original email he attached an article, which can be found at this link (http://pubsapp.acs.org.stanford.idm.oclc.org/cen/safety/19970317.html?). The text of the email he sent is below:
>
> Thanks for forwarding. The use of reducing metals (Li, Mg, Al) with fluorinated organic compounds is hazardous and as pointed out by authors, there are several examples of explosions. We had previous experience with Grignards of compounds containing trifluoromethyl groups. (See C&E News Letter from 1997). We had attributed the explosion hazard to be due to the high lattice energies of the metal fluorides. I think this a a more likely interpretation than that of the authors, but they do describe previous explosions with Al reducing agents and perflourinated compounds.
>
>>From my quick CRC look (you should check these numbers)
>
> MgF2. Lattice energy -2922 kJ/mol
> AlF3 Lattice energy - 5924 kJ/mol
>
> -----Original Message-----
> From: ACS Division of Chemical Health and Safety
> On Behalf Of DCHAS Membership Chair
> Sent: Thursday, July 9, 2020 4:49 AM
> To: DCHAS-L**At_Symbol_Here**Princeton.EDU
> Subject: [DCHAS-L] Serious Explosion during Large-Scale Preparation of
> an Amine by Alane (AlH3) Reduction of a Nitrile Bearing a CF3 Group
>
> Serious Explosion during Large-Scale Preparation of an Amine by Alane
> (AlH3) Reduction of a Nitrile Bearing a CF3 Group
>
> https://pubs.acs.org/doi/10.1021/acs.chas.0c00045
>
> Here, we wish to report a serious explosion during large-scale preparation of an amine by alane (AlH3) reduction of a nitrile bearing a CF3 group. The accident took place during the reduction of a 1 mol batch of 1-methyl-3-(trifluoromethyl)-1H-pyrazole-5-carbonitrile. At the stage of decomposition of the reaction mixture after reduction with MeOH, the reactor was destroyed by detonation; one researcher was seriously harmed by shatters and burnt by flames. This Case Study describes this incident in detail and discusses how we can prevent similar incidents.
>
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