mr.crow
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Rubbing alcohol (sucks)
Today was such a nice day outside I decided to distill something. I got some weird results with "99% Isopropanol" from the drug store (Shoppers).
Most of the liquid came over at 78-80 degrees, too low for isopropanol and more like ethanol. When there was only ~100 mL left it shot up to 83
degrees.
Either my thermometer sucks or the supposed isopropanol really isn't! Has anyone used this product before?
Double, double toil and trouble; Fire burn, and caldron bubble
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smuv
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Does the distillate that came over between 78-80 degrees smell like isopropanol or ethanol? the two both have pretty characteristic smells
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mrjeffy321
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I cannot speak to the distillation results that you obtained, but I have had some strange results with rubbing alcohol too.
For my base bath (to clean glassware) I bought some 99% rubbing alcohol (intended for first aide use) to replace the much more expensive isopropanol I
was buying from a chemical supplier. The rubbing alcohol turned brown overnight in my base bath, when the 95% isopropanol from the chemical supplier
stayed clear much much longer.
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mr.crow
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It does smell like IPA and not of booze. Maybe its just masking the ethanol smell.
How about a test to identify primary and secondary alcohols?
I'm thinking of labeling it Cleaning Solvents >: (
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not_important
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Isopropanol has an azeotrope with water, 87.9% IPA and BP of 80.4C. As 100% IPA has a BP of 82.5C , unless your thermometer is calibrated in the
position you had it in for the distillation, you could well see a boiling range of high 70s to mid 80s for pure dry IPA. Try distilling just pure
water and see what readings you get.
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bbartlog
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If your drug store sold you 91% IPA mislabeled as 99%, you'd get results like that. First you'd get the 80C azeotrope (88% IPA), then after the water
was gone you'd get progressively more concentrated IPA remaining in the flask.
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mr.crow
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I heated some CuSO4 crystals until they turned gray, then added some of the distilled IPA. No color change was observed. Adding a drop of water turned
the CuSO4 powder blue.
I find it hard to believe my thermometer was that bad. I will check that next with some boiling water.
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Random
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You can dillute your alcohol to 5% and leave it in the air, bacteria should oxidize it if it's ethanol to acetic acid which you can recognize
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entropy51
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Quote: Originally posted by Random  | | You can dillute your alcohol to 5% and leave it in the air, bacteria should oxidize it if it's ethanol to acetic acid which you can recognize
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Yeah, I left a beer out while I went to the head and it turned to vinegar.
Uh, you think it might evaporate before magically becoming acetic acid?
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Random
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If it would evaporate, how vinegar could be made?
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mr.crow
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I've had beer turn into mold colonies after being left out for who knows how long.
Oh hey its new year's eve
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hkparker
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Was your thermometer calibrated?
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"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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mr.crow
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Ok I put the kettle on and the thermometer says 95-96 degrees. So there you go, crappy thermometer that cost a few bucks from the surplus store.
Science n00b 
Happy new years!
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Sedit
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Seperate your IpOH via the addition of NaCl which will give you two distinct layers, seperation followed with distillation should give the results
desired. I dont know if EtOH is in your product but serious Saturated NaCl washes should wash any other alcohols out of the mixture.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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hkparker
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An off thermometer isn't toally worthless, find the % that it is low, and correct the reading by that percent
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bfesser
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Also be sure it's partial immersion, and not total immersion.
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not_important
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| Quote: Originally posted by mr.crow | Ok I put the kettle on and the thermometer says 95-96 degrees. So there you go, crappy thermometer that cost a few bucks from the surplus store.
Science n00b
Happy new years! |
Ah, but one that is willing to admit to the mistake - an important quality. Making mistakes is a good way to learn, provided you avoid really
bad mistakes (please do not collapse tje eta-stable pseudo-vacuum, as destroying the universe is difficult to recover from).
The salting out does work, and for all simple alcohols; but remember that some alcohol will remain in the aqueous salt layer and some salt will be in
the organic layer. You can recover the remaining alcohol from the salt layer by distilling until the temperature rises towards the BP of water; when
distilling the organic layer do not attempt to take it to dryness but stop if bumping starts to occur and return the residue to the next batch of
rubbing alcohol.
Distilling alone works, but it really helps to have some fractionating going on, even some metallic scrubbing pads stuffed into the flask neck and
making sure there is reflux happening.
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