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Magpie
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Purification of Toluene
I am presently purifying ~100 mL of Ace brand toluene. The label on the can says that it is "100% pure." I have reason to believe that is a
reasonably correct statement.
My first step in purification was simple distillation. Wiki says that the azeotrope with water boils at 84.1C and that pure toluene boils at 110.6C.
In my distillation the temperature shot right up to 109.8C without any hesitating around 84.1C. The temperature soon read 110.0C. At this point I
discarded a foreun of ~20mL. The bp stayed at a steady 110.0C for the rest of the distillation. I left a few mLs in the pot.
My local weather station said the barometric pressure was 29.59"Hg, or 751.6mmHg. So, I thought that the lower barometric pressure vs the 760mmHg for
the normal bp accounted for this difference.
I checked this against the Sigma-Aldrich nomograph but it gave me an obviously way too low value for the barometric pressure of 27.6"Hg (700mmHg), the
upper limit of its scale.
So then I went to the Clausius-Clapeyron equation, which produced an expected bp of 110.24C. The Antoine equation produced a value of 110.23C.
So, even knowing that my thermometer is uncalibrated, I am satisfied with my bp and believe that it indicates toluene of high purity. It is also
obvious that the Sigma-Aldrich nomograph has its limitations.
My distilled toluene has been sitting overnight on CaCl2 (per Vogel). Today I will transfer it to a bottle with activated 4A mole sieves for storage.
The single most important condition for a successful synthesis is good mixing - Nicodem
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jamit
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I have done simple distillation of ace brand toluene and got the same result. After getTing rid of the early distillate, the temp remained at a
steady 110c for the rest. I also stopped the distillation before getting dry. The remaining liquid in the boiling flask was colorless like water. I
collected about 450ml of toluene. I also added cacl2 and next day filtered and poured the toluene into a 500ml bottle for storage. I believe my
toluene is very pure.
So I confirm your distillation of OTC toluene. Hope this helped.
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turd
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OK... You distilled toluene...?
No offense intended, but what is the point of this thread? I was somehow waiting for the punchline and it didn't come.
Unless your toluene is turbid or contains other solvents that increase water solubility (acetone?), no seizable water azeotrope is expected. All OTC
toluene I bought was always quite dry. Unless you're doing metal organics all that drying is probably not even necessary. Distill through a column
throw away a fem ml pre-run and it will be fine! Evidently: the larger the batch the less relative loss. 100 ml sounds a little bit on the low side.
And concerning the temperature: don't be more catholic than the pope! Distillation is an equilibrium thing - heat supply here, heat loss there,
vaporization, condensation, diffusion, convection, etc. I'm sure there is more than one official boiling point. Organic chemistry is about cooking,
not to act out your OCB. 
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Magpie
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Thanks Jamit I appreciate you sharing your experience.
Turd, there was no real point other than a sharing of my experience in a purification. You may think I'm quibbling over the boiling point but what
else do we home chemists have for establishing purity of toluene? If there would have been any water there it surely would have shown up at the
azeotrope temperature.
Mostly I'm concerned with obtaining anhydrous toluene. I know this is no great challenge, I just thought my data and calculation results would be of
interest to some. You even pitched in and gave some valuable opinions.
My next challenge is going to be preparing anhydrous ethanol from rectified spirit (95% ethanol, Everclear). I want to share my experience here also,
as I think this is going to be much more of a challenge. I know there are time tested techniques in Vogel and elsewhere but I still think sharing our
experiences as home chemists is both interesting and valuable.
Universities have sodium presses, Schlenk lines, glove boxes, Grubbs columns, and Karl Fischer analyzers. In fact a technician probably dries the
solvents. They also start with purchased "anhydrous" ethanol which is probably no more than 0.5% water. It's a much tougher challenge for the home
chemist who is likely starting with 5% water and has no fancy tools or grunts to do his work.
[Edited on 1-2-2012 by Magpie]
[Edited on 1-2-2012 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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jamit
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I think magpie just wanted to confirm his results. And I concur!. And it seems
like you concur too turd with most of magpie's results. 
The point is... It's hard to believe that you can get really pure toluene from OTC solvent. But you can now, at least with toluene. Usually there's
all kinds of junk... Ie denatured alcohol or 70% ethyl rubbing alcohol contains all kinds of mixed solvents.
I'm glad magpie posted his finding... Because I did my purification last year but didn't post my results...but I have been wondering about my results
and it's good to know that someone has also tried the same thing.
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S.C. Wack
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The source is likely BTX, and there is no point in separation and purification of this without separating and purifying; no surprise then.
BTW I've mentioned here before the correction necessary for altitude from altitude-calibrated barometers. The internet says the pressure in Denver is
currently higher than in Seattle.
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Lambda-Eyde
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I'd really recommend that you shake your toluene with conc. sulfuric acid before distilling next time - I didn't. (my image host is down right now, but when it comes back the pictures will speak for themselves...)
This just in: 95,5 % of the world population lives outside the USA
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Magpie
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Quote: Originally posted by S.C. Wack  |
BTW I've mentioned here before the correction necessary for altitude from altitude-calibrated barometers. The internet says the pressure in Denver is
currently higher than in Seattle. |
I am aware that airport weather stations report barometric pressure as "corrected to sea level." I was careful to ask about this and made sure the
pressure I got (not from an airport) was "uncorrected," ie, a raw pressure uncorrected for altitude. I then checked with the local airport, and sure
enough, their value was corrected 0.44" Hg higher (11 mmHg).
I've always been curious as to what effect my barometric pressure was having on the bp I would get during distillations, as compared to the normal bp.
So yesterday when distilling the toluene I called and got the pressure, then made the comparisons.
I first tried to reconcile the data with the Sigma-Aldrich nomograph, but it was not useful here. The Clasius-Clapeyron and Antoine equations, which
agreed to a remarkable degree, did give me reasonable results. Per these equations the lowering would be 0.36C from the normal bp. A 0.6C lowering
was the actual differential per my uncalibrated thermometer.
[Edited on 2-2-2012 by Magpie]
[Edited on 2-2-2012 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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benzylchloride1
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I use Ace Hardware toluene for all of my syntheses. I always distill about 25 mL of the solvent,the distillate is always milky due to a small amount
of water present which would cause problems with much of the chemistry I do. I then reflux the toluene over sodium metal for several hours and then
distill under helium. I have also run a sample of the purified toluene on a Gow-Mac 150 gas chromatograph of this purified toluene as an internal
standard for another experiment that I was running and there appeared to be no extraneous peaks that would be attributed to any impurities.
[Edited on 2-2-2012 by benzylchloride1]
Amateur NMR spectroscopist
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Magpie
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| Quote: Originally posted by benzylchloride1 | I have also run a sample of the purified toluene on a Gow-Mac 150 gas chromatograph of this purified toluene as an internal standard for another
experiment that I was running and there appeared to be no extraneous peaks that would be attributed to any impurities.
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I take it from this that your purified Ace Hardware toluene has no sulfur compounds such as methylthiophene. Is that correct?
FYI:
http://www.iupac.org/publications/pac/1989/pdf/6110x1823.pdf
[Edited on 2-2-2012 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Magpie
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My distilled Ace Hardware toluene has rested on activated 4A mole sieves overnight. Today I tested it for water using CaC2 and anhydrous CuSO4
(Brewster). Both tests were negative.
I also tested some 95% ethanol (rectified spirits), and some rectified spirit I had previously attempted to dry to <100ppm water using unactivated
3A mole sieves. Both tested positive for each test.
Edit: I just tested the toluene in the can: both tests were negative here also. This can is about 3/4's empty and is several years old.
[Edited on 2-2-2012 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Panache
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I find distilling toluene from cacl2, using the maximum possible vacuum available to you yeilds better results cf/ distillation at atmospheric
pressure. A couple of caveats herein though, firstly the commercial tolly here in australia still has the thio antioxidants added, they are neigh on
impossible to remove via std distillation, vogel uses multiple sulphuric washes to remove them, which is horrendously expensive and time consuming,
however i have reason to believe distillation under reduced pressure affects a separation, which forms the basis of the second caveat.
That being when an atmospherically dist. Toluene is treated with sodium a horrible orange gunky slop results, however with the vac dist. Toluene no
colouration and little bubbling upon the sodium surface is observed. It is known that an effective way to crudely dry etoh fom the azeotropic 96%
solution is under reduced pressure, this shifting the dynamics in favour of pure etoh, this was the basis for my trial regarding tolly and the
annoying codistilling thiophenes.
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starman
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@Panacche I am interested on the basis of this statement.Reochem - Diggers brand that I make use of has the msds stating 100% Toluene.Though using
atmospherically distilled tolly (went very smoothly at precise temp) has given me some unexpected problems in synthetic use (ie pTSA synthesis.)
I was going to repeat doing sulphuric washes but also have good vacuum capability now so may attempt to mirror your efforts.
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Panache
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Have you tried drying some wih sodium, post distillation?
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scientician
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After a few failed MPVO runs I tested my Ace brand toluene (which I had previously just dried over CaCl2.) While I don't have isatin to test with,
adding conc. H2SO4 resulted in a lot of "white shit" precipitating out, which is the same thing I observed in my redox that ruined everything. Trust
NO solvents, especially those made for purposes other than lab work.
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MyNameIsUnnecessarilyLong
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All the Ace Hardware stores in California where I live have permanently removed toluene, MEK, naptha, and xylene off the shelves a little less than 2
months ago. I really wish I had known ahead of time to stock up. So if anyone else here lives near the western United States or a state that has a
tendency to mimic California, you should check to see if there are any impending bills that aim to do the same where you live.
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kristofvagyok
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Bingo, abs. Toluene is distilled from metallic sodium or from calcium hydride. The CaCl2 will dry it mostly, but it won't be truly waterfree, CaCl2 is
not the best, because as we know CaCl2 pellets ar CaCl2.2H2O
But for the most reactions the CaCl2.2H2O, or MgSO4, Na2SO4, ect. dried toluene is good.
I use Sigma, but it's not that better than "Ace" brand.
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starman
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Unfortunately attempting tp procure sodium in W.A. invites unwarranted attention due to the the illicit drug trade.
(Seems to be running at about one explosion a week here in Perth,so I guess the authorities have a point.)
I've often looked at Len 1's set up for Na in a future project,time and money permitting...
So in short 'no'.
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Texium
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Sorry to dredge up this old thread, but I was curious: is the toluene that you have actually ACE brand, or just purchased from ACE? Because I bought
some toluene at ACE earlier today and was looking to find out how pure it was, but it is KleanStrip brand.
I suppose it really doesn't matter as I can try distilling it like you did and see what results I get, but I thought it would still be good to know.
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JJay
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KleanStrip seems to be very much hit or miss... some of their products are low quality and some are high quality. I imagine their toluene is pretty
good. Do we have any current ACS members who know what chemical tests to use to verify ACS quality? Maybe I should register....
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Texium
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I found another thread where gdflp mentions using isatin to test for thiophenes, which are the most frustrating and difficult to remove impurity (forms a
blue color with isatin). Unfortunately I don't have any, so I may just have to try reacting it with sulfuric acid in a container I wouldn't mind
mucking up with possible polymerization products. I want to use this toluene to make p-toluenesulfonic acid, so it can't have any thiophenes in it,
though water wouldn't be a problem since I'll be using a Dean-Stark trap.
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Oscilllator
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| Quote: Originally posted by zts16 | | I found another thread where gdflp mentions using isatin to test for thiophenes, which are the most frustrating and difficult to remove impurity (forms a
blue color with isatin). Unfortunately I don't have any, so I may just have to try reacting it with sulfuric acid in a container I wouldn't mind
mucking up with possible polymerization products. I want to use this toluene to make p-toluenesulfonic acid, so it can't have any thiophenes in it,
though water wouldn't be a problem since I'll be using a Dean-Stark trap. |
I'm not familiar with the ACE brand but I just looked it up and it seems like a hardware store. If that's the case then your toluene certainly
contains thiophenes.
With regards to cleaning it with sulfuric acid, don't worry about the container. I've done this exact procedure also with the aim of making
p-toluenesulfonic acid and although the sulfuric acid did get quite gunky on the first wash, it wasn't a problem to clean. I just added some water to
the sulfuric acid once I had separated the toluene to get it nice and hot and it washed right out. I think I washed my toluene 2 or 3 times and that
got out the vast majority of the thiophenes, but the resulting p-toluenesulfonic acid was an interesting pink colour.
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CharlieA
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http://www.kleanstrip.com/msds-cpsia I don't know how to make an attachment. On the link shown you can find the MSDS for Klean Strip Toluene; it
shows the composition on page 3, as 100 % toluene.
On a side note, MSDS's can be find relatively easily, so why all the speculation about possible additives that one "thinks" might be in something?
Magpie: You like the results of correcting the bp for atmospheric pressure, but then give the caviat that your thermometer is un-calibrated. Therefore
it is not correct to say your calculated bp was in good agreement with the observed bp. Why not just calibrate the thermometer? (please don't take
this as a knock on your posts. I just think if you calibrated the thermometer, then your comparison of the observed and calculated bp's would be more
meaningful.)
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Magpie
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Yes, I should have calibrated it. It has so often given expected results for mp's and azeotrope bp's that I have just assumed it to be sufficiently
accurate.
I have also noted that Ace is now stocking more KleanStrip brands than offering these solvents under their own label. When it comes to trace amounts,
like methylthiophene, I wouldn't trust an MSDS to list them.
[Edited on 9-11-2015 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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CharlieA
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I guess, really, there are probably few things that are 100% pure...there is always that next decimal place to be measured! I think it would do me
good to see just what the requirements are for listing components/additives in the MSDS.
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