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Subject: Re: [DCHAS-L] first aid for HF
Date: Thursday, June 5, 2014 2:02:14 PM
Author: "Bencivengo, Juli M (GE, Appl & Light)" <juli.bencivengo**At_Symbol_Here**GE.COM> 		Next by Date:
Subject: Re: [DCHAS-L] Lab Safety training for Undergrads
Date: Thu, 5 Jun 2014 11:25:42 -0700
Author: Jyllian Kemsley

From: Dan Kuespert <dkuespert**At_Symbol_Here**JHU.EDU>
Subject: Re: [DCHAS-L] Perchloric acid-organic mixtures
Date: Thu, 5 Jun 2014 18:02:20 +0000
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: 55DD8411-CBF8-4D21-BE6E-1AEA9F68F114**At_Symbol_Here**jhu.edu
In-Reply-To <01b101cf80dc$2e9c0110$8bd40330$**At_Symbol_Here**chemical-safety.com>


Thanks, I've got a copy of Schilt on my desk, as well as the Schumacher book. Good for generalities, but I was hoping someone had come across something along the lines of "10-12% perchloric in EtOH is stable until you heat it past 130C." I did in the past find similar data for the ethanol-nitric system. I've asked our reference librarian to look as well, but neither he nor I have been coming up with anything.


Not quite as good (from several standpoints) would be any incident or near-miss stories involving perchloric and organic solvents.

The DSC idea had occurred to me. I may have to go to that length. The owner of our DSC has been reluctant to let me use it for stability tests in the past=97he's afraid I'll damage his instrument. If I do have to do that, I'll do a short composition study and publish it somewhere so that the next guy can find it.

Trifluoroacetic or trifluoromethanesulfonic acids may also be adequate substitutes. The investigator tells me that it's the acid strength that's really needed, not the oxidizing power.

regards,
dan

=============================
Dr. Daniel R. Kuespert
Homewood Laboratory Safety Advocate
Krieger School of Arts & Sciences/Whiting School of Engineering
The Johns Hopkins University
103G Shaffer Hall
3400 North Charles St.
Baltimore, MD 21218
(410) 516-5525

On Jun 5, 2014, at 12:35 PM, NEAL LANGERMAN <neal**At_Symbol_Here**CHEMICAL-SAFETY.COM> wrote:

You want to get a copy of the book "Perchloric Acid and Perchlorates" by Alfred A Schilt.  I obtained my copy from GFS Chemicals, Inc.  Page 140 ff has a discussion of the issues related to electropolishing with many literature references.
 
In the absence of specific data, I urge you to have a DSC analysis of the specific mixtures to determine their stability.  The thermal data will provide you with the boundaries for safe work.
 
nl
 
 
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From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Dan Kuespert
Sent: Thursday, June 05, 2014 7:21 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: [DCHAS-L] Perchloric acid-organic mixtures
 
I was wondering if anyone knows of any actual data about the stability of various perchloric acid-organic solvent mixtures. The mixtures in question are relatively (<10-15%) dilute solutions of perchloric in ethanol, ethylene glycol, butyl Cellosolve, etc. used for electropolishing. I'm having trouble finding literature reports.. Of course, there's plenty of reports (Bretherick's, et.al.) about hazards, but no actual information on how much is too much.
 
Normally, I would recoil from such mixtures, but perchloric-organic mixtures are pretty extensively used in the metallurgy literature. Just because something has been successfully used without incident, though, does not mean that it was used "safely." It may mean that the lab was lucky.
 
I've had some problems in the past with other witch's brews used for electropolishing, after which I determined that the literature-reported composition was beyond the actual stability limit for the particular (ethanol-nitric acid) system, so that's kind of sensitized me to this application.
 
regards,
dan
 
=============================
Dr. Daniel R. Kuespert
Homewood Laboratory Safety Advocate
Krieger School of Arts & Sciences/Whiting School of Engineering
The Johns Hopkins University
103G Shaffer Hall
3400 North Charles St.
Baltimore, MD 21218
(410) 516-5525

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