ORGLIST: Answers to my query o Cryoscopic solvent mixtures

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From: Hormuzd Mulla (mulla$##$caribe.chem.uky.edu)
Date: Mon Sep 07 1998 - 19:12:20 EDT


The following are the replies I got for my query regarding a cryoscopic solvent
mixture with water as one of the components to freeze to -80 C. Thanx one and
all for the response.
Hormuzd R. Mulla




On Sep 4, 11:44am, jchubb$##$qci.com wrote:
> Subject: Re: ORGLIST: Cryoscopic solvent mixtures
> You are best getting away from water entirely. Mixing water with most
> solvents (with which it is miscible) results in raising the melting point
> towards water.
>
> A couple of common solvents that have freezing points where you are looking
> for are:
>
> acetone mp -93 oC
> methanol mp -98 oC
>
> With either of these you should be able to "dial in" the temp you want by
> adding slight amounts of water.
>
> Of course, measuring the temperature at such cold temperatures is
> difficult: most thermometers and thermocouples fail at temperatures much
> below -70 oC.
>
> You want colder, I would suggest the small alkanes.
>
> For example, hexane gives -95 oC, pentane gives -130 oC, butane gives -138
> oC
>
> And with the smaller alkanes water contamination will not raise the melting
> point, since water just falls out as "snow".
>
> Ethylene glycol freezes at -13 oC, and one can only drop that a tiny bit
> with water.
>
> To make these low-freezers freeze, one would have to use liquid nitrogen,
> of course. Be prepared to use lots of LN2.
>
> John Chubb
> QCI A ChemFirst Company
>
>-- End of excerpt from jchubb$##$qci.com
********************************************************************************



On Sep 4, 1:19pm, Electron wrote:
> Subject: Re: ORGLIST: Cryoscopic solvent mixtures
> Mulla, just look in the CRC, they have data on such mixtures
> Marlon
>

> Marlon D. Jones
> University of Kentucky
> Department of Chemistry
> 125 Chemistry / Physics Bldg.
> Lexington, Kentucky 40506
> (606)-257-4886
>-- End of excerpt from Electron
********************************************************************************


On Sep 4, 12:35pm, Mike Fralish wrote:
> I know it might be too simple...
> The first thing that pops into my mind is the godd old CRC Handbook
> Yes or no?
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> * Michael Fralish *
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On Sep 4, 2:29pm, Herb Hedgecock wrote:
> Subject: Re: ORGLIST: Cryoscopic solvent mixtures
> On Fri, 4 Sep 1998, Mike Fralish wrote:
>
> > >I'm looking for a eutectic mix of water with another solvent that could be
> > >taken to temperatures much below 0 C (about -80 to -100 C). Suggestions
like
>
> > >Hormuzd R. Mulla
> >
> > I know it might be too simple...
> > The first thing that pops into my mind is the godd old CRC Handbook
> > Yes or no?
>
> CRC does have some data. More to the point, -80 deg is a bit much for
> water. -55 deg using calcium chloride is about as low as you will get.
>
> You might also try 'The Chemist's Companion: A Handbook of Practical
> Data, Techniques, and References.' It's an old book, but useful.
>
> Herb Hedgecock, PhD |)runrun |)
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>-- End of excerpt from Herb Hedgecock



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