From: ILPI Support <info**At_Symbol_Here**ilpi.com>
Subject: Re: [DCHAS-L] Glassware inspection guide?
Date: Thu, 3 Sep 2015 16:19:22 -0400
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
It's all a matter of kinetics and mass/heat transfer. Unless you are doing something completely inappropriate - like trying to ignite thermite inside a dry vessel submurged in a dry ice/acetone bath, this is not normally a concern. Most lab reactions are exothermic, and many would qualify as "significantly" exothermic if done at room temperature - for example, quenching a Grignard reaction, nitrations etc.
I'll generalize more to say that it's really a matter of ensuring your have enough solvent to absorb any heat rise, a condenser, a properly selected bath to transfer the heat from the vessel, effective stirring etc. I have seen a number of reactions run away because the stirring stopped or became unobservable due to precipitation or other factors. Added reagent then causes a very localized and very hot spot --> up it goes.
If you have the specific procedure, I'd be happy to follow up on or off-list. Is this something that other folks might have an SOP for?
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Stuff that needs more careful attention is anything that will be subjected to vacuum or pressure.
Thanks for this information. The procedure I'm looking today at involves temperature considerations. Because the reaction in the glassware is significantly exothermic, so it will be contained in the ice bath. Are temperature stresses likely to be of concern for lab glassware without visible chips or cracks?
Ralph Stuart, CIH, CCHO
Chemical Hygiene Officer
Keene State College
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