From: Slawomir Janicki <slawomir.janicki**At_Symbol_Here**COMCAST.NET>
Subject: Re: [DCHAS-L] Dichloromethane storage?
Date: Sat, 12 Apr 2014 12:07:53 -0400
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: 001b01cf5669$5cf245d0$16d6d170$**At_Symbol_Here**
In-Reply-To <8D12455F7063BB1-9B8-6B61**At_Symbol_Here**>

Dichloromethane can react with air moisture and oxygen and produce some nasty impurities like phosgene, hydrogen chloride, chloroform and 1,1,2,2-tetrachloroethane. DCM is more stable than chloroform, but not stable enough to leave it without inerting for storage.


If you google “dichloromethane decomposition” you will get many references with more details.


Slawomir Janicki, Ph.D.


From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Monona Rossol
Sent: Saturday, April 12, 2014 7:03 AM
Subject: Re: [DCHAS-L] Dichloromethane storage?


Whether the gases above the liquid are air or inert gases, the evaporation rate should be the same at the same temperatures and pressures. So that's not the reason.

Monona Rossol, M.S., M.F.A., Industrial Hygienist

President:  Arts, Crafts & Theater Safety, Inc.

Safety Officer: Local USA829, IATSE

181 Thompson St., #23

New York, NY 10012     212-777-0062



-----Original Message-----
From: Jim O'Connor <oconnor.jim77**At_Symbol_Here**GMAIL.COM>
Sent: Sat, Apr 12, 2014 6:06 am
Subject: Re: [DCHAS-L] Dichloromethane storage?

Sigma Aldrich has a SDS that says, "Heat sensitive. Store under inert gas" I 
don't agree with that statement but thought you should know about the ref. My 
experience says the inert gas recommendation is to prevent it from evaporating 
while storing. A liquid seal cap should negate the need for the inert gas too I 
Sent from my iPhone
> On Apr 11, 2014, at 12:39 PM, "Ralph B. Stuart" <ralph.stuart**At_Symbol_Here**CORNELL.EDU> 
> A lab tech noticed a statement on a Dichloromethane bottle that said "store 
under an inert gas". He would like to know if this is a safety recommendation or 
designed to maintain the quality of the chemical by avoiding exposure to 
environmental gases. From what I can find, it appears to be the latter, but I 
thought I would ask DCHAS-L to see if anyone knows of a safety reason for this 
> Thanks for any help with this.
> - Ralph
> Ralph Stuart CIH
> Chemical Hygiene Officer
> Department of Environmental Health and Safety
> Cornell University
> rstuart**At_Symbol_Here**

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