YRVN13A
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Basifying isopropanol
This is probably a very elementary question, but I thought I would ask anyways. I need to raise the PH of isopropanol. Can this be achieved by simply
dissolving NaOH in it, or will the NaOH actually react with the iso? If it does react, what would it form? And if this is not the best way, what would
be a better chemical to use?
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Ozone
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Mostly nothing...and a small amount of Na isopropoxide. We use it as a base bath for cleaning glass. It still smells like iPrOH. Anyway, pH is
undefined in non-aqueous solvents.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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chemrox
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How does it work on organic residues? How is it on the glassware? Is it easier than strong NaOH solutions? The isopropoxide is only about 0.2% at
any time right?
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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smuv
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Base baths work great, we use KOH in IPA, and use it to clean all of our glassware (spatulas, septum stoppers, stirbars and stopcocks too). Even
after leaving stuff in it for a few days, the glass does not seem adversely affected. Probably over time, the glass ends up loosing its nice shiny
appearance more quickly, but for all practical purposes it is unaffected. Needless to say, it removes just about anything very well. I have
contemplated setting one up form my home lab, but I have decided having a concentrated solution of KOH in IPA would be a long term safety liability
that I don't want to deal with.
BTW The reason it works for removing just about any stain, is that It doesn't necessarily need to dissolve whats on the flask, it just loosens
everything up by ever so slightly etching the glass.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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Ozone
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It's pretty easy on the glass (it will remove gradation or labeling patches much more quickly), so don't forget it in there for weeks...It will kill
scinter, so that's a no-no.
KOH seems to be easier on the glass. The amount of iPrOK, at equilibrium, should be very small.
It does a great job on glass, super shiny after a subsequent rinse with DI.
Again though, YRVN is asking about raising the pH of iPrOH--this is impossible b/c pH is defined specifically for solutions containing water. Convert
some to iPrOK maybe, raise its pH, no.
Iv'e never found it to be a large hazard. I make mine in a 5 gal bucket filled 1/3 with the standard top (which is left slightly loose). Except for
the occasional top-off with alcohol, not too much to worry about. Just avoid fire and have some gloves, tongs and safety glasses in case you drop
something and get a splash.
CHeers,
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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smuv
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@Ozone, do you have any experience with it killing sintered glass or is this just something you heard? In our lab we use it to clean all glassware
including sintered glass funnels; we have had no problems that I know of.
P.S. Ozone has your base bath turned red over time? I am wondering if this color in our bath is due to aldol condensations, or just the compounds we
work with.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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Sauron
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The drawback to any alcohol/KOH bath is that you will never remove all traces of the KOH from ground joints, and some compounds and reactions are very
sensitive to base. Using such glassware later, can screw up such reactions. Unless you keep this in mind you will have a hard time identifying the
reason for failure.
Sic gorgeamus a los subjectatus nunc.
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Arrhenius
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smuv: yup they turn orange/red.
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Ebao-lu
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I've prepared once NaOH in ethanol to store in a glass jar. After 3-5 days it became yellowish, and then reddish. That's due to air oxidation to
acetaldehyde, and its condensation. Now, i never try to store any alcohol-alkaline solution. For cleaning stored solutions should be fine, but for
other purposes - not sure. Maybe t-BuOH is not oxydizable then?
[Edited on 28-2-2009 by Ebao-lu]
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