woelen
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Chlorinated hydrocarbon, boiling over at 80 C. What could this be?
I have two very old bottles, both of them labelled as trichloroethylene, CHCl=CCl2.
These bottles look ugly and dirty with swollen caps. One of them contains around 800 ml liter of a light green liquid, the other contains 300 ml of a
colorless liquid with a lof of dust in the liquid. Both liquids have a heavy sweetish smell.
I wanted to distill all of it, so I first put the green liquid in my distillation setup and distilled approximately 600 ml of this in two batches of
300 ml. Temperature readout of the vapor is 86 C, which is quite close to the boiling point, mentioned in literature. I now have 600 ml of a clear
liquid and 40 ml of a fairly dark green liquid, remaining (I did not boil away all of the liquid, just to asure purity of my distilled product).
I distilled in batches, and in the last batch, I took the last appr. 150 ml of the light green liquid and added around 150 ml of the colorless liquid.
Again this mix boils over, but this time, the liquid boils over at just below 80 C. Even after collecting 100 ml the readout still was 80 C. I
continued distilling until only 20 ml or so of a green liquid was left. At that point, the readout was 85 C. I stopped the distillation process and
did not add this 300 ml batch to my 600 ml of trichloroethylene. Although my setup is not that accurate, I find this difference too large and I do not
trust the label on my second bottle.
So, now I am left with 600 ml of a colorless liquid, boiling over at 86 C, 300 ml of a colorless liquid, which boils over at 80 ... 85 C and I have
150 ml remaining of the old undistilled 'dusty' liquid. All liquids have a strong sweetish smell.
So, I suspect that the second bottle with the 'dusty' liquid is not trichloroethylene, but some other chlorinated hydrocarbon. Its boiling point is
near 80 C.
What other common chlorinated hydrocarbon exists, which boils near 80 C?
Does any one of you know of a simple test for trichloroethylene?
I am not happy with this at all. Now I have lost 300 ml of these hard to obtain chemicals. The mix of these two liquids is very hard to separate and I
must consider that 300 as being lost. The only use remaining is as a solvent and as degreasing agent, but use as reagent is not possible anymore 
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garage chemist
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Do you have a rectification column?
You could try rectification to see how many components are actually in the mix.
Also, make sure that your thermometer bulb inserts deep enough into the vapor stream of the substance- many errors have been caused by too short
thermometers.
Trichloroethylene forms lower boiling azeotropes with some substances. Maybe it contains some alcohol (stabilizer!)?
Also, technical trichloroethylene for the degreasing of light metals contains substantial additions of dioxane (up to 10%) to inhibit reactions with
aluminium. Maybe you have some of this inhibited trichloroethylene? Dioxane has a weak smell (I have smelled the pure substance), you would most
likely not smell it at 10% in trichloroethylene.
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unionised
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Could it be carbon tet which boils at 77C?
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Justin
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^i was thinking the same thing, if it is your lucky!
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Jor
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If it's a very old bottle, it could be carbon tetrachloride. I think this was used untill the 70s for degreasing, after it was replaced by either
trichloroethane or trichloroethylene (I am never sure wich one), but I can imagine that these still contained significant amounts of CCl4.
I also have a old bottle with a pink turbid liquid in it, wich smells sweet (but also I hate the smell as it reminds me of the fact breathing a
carcinogen  ). It boils at around 80-90C (I did a very rough test 3 months ago)
and is not flammable. However, i am not going to distill it, as I have no interest in trichloroethylene. Where I need an inert chlorinated solvent I
always use DCM (of wich I have used about 200-250mLs the last year), I don't see why I would need trichloroethylene wich is much more toxic and is a
carcinogen. The only advantages I see are the use as a reagent, and a higher boiling chlorinated hydrocarbon.
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woelen
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I also have been thinking of carbon tetrachloride. But my liquid boils at 80 C and the thermometer seems to show one degree too low and then the
boiling point would be 81 C. Of course, it could be that CCl4 and CHClCCl2 form an azeotrope, boiling somewhere between 77 C and 87 C. I'll have to
distill the liquid without being mixed with trichloroethylene and see what boiling point it has. Maybe I'll do that next week, but it is VERY cold in
my lab now and not a pleasure at all to be there for a long time (I never leave distillations unattended, but babysitting such a distillation in a
room at less than 5 C is not very pleasant either).
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unionised
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When the weather picks up will you be able to measure the density and refractive index?
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