Sciencemadness Discussion Board

Test for Tetrahydrofuran

Deathunter88 - 15-4-2017 at 04:57

Hello everybody, once again I have a solvent related question. This time it's a bottle of solvent marketed as nitrocellulose lacquer thinner and I would like to figure out what it is.

First off, some basic information:
It does not have an SDS, as I bought at a local hardware store and it was sold in an old intravenous sugar solution bottle with the label scratched off.

Because it is so cheap, the company (or most likely, a single person operation) probably didn't bother with mixing solvents and so it more or less is a pure solvent.

Next, some tests I have performed so far:
1. Dissolves in about twice its volume of water.
2. Boiling point between 64-68 degrees.
3. Softens PVC plastic after soaking (just the surface layer)
4. Burns with a clean, sootless flame
5. Denser than absolute ethanol (0.789g/ml), but is less dense than ethyl acetate (0.895g/ml)

My current hypothesis is that it is tetrahydrofuran (THF) because:
1. THF has a solubility of about 30% in water
2. THF has a boiling point of 66 degrees
3. THF is commonly used as a PVC welding solvent
4. THF should burn without smoke
5. THF has a density of 0.886g/ml

However, I would like to have more evidence before making this conclusion and using it as such. So my question is, are there any chemical reactions/tests specific to THF that I can use to pinpoint the identity of the solvent?

Thanks in advance!

Metacelsus - 15-4-2017 at 05:07

THF is completely miscible with water. Where did you get the 30% solubility figure?

THF has a characteristic smell (which I know but wouldn't do a good job describing; it's kind of like diethyl ether but not quite the same). Does it smell like THF?

[Edited on 4-15-2017 by Metacelsus]

Deathunter88 - 15-4-2017 at 05:17

Quote: Originally posted by Metacelsus  
THF is completely miscible with water. Where did you get the 30% solubility figure?

THF has a characteristic smell (which I know but wouldn't do a good job describing; it's kind of like diethyl ether but not quite the same). Does it smell like THF?

[Edited on 4-15-2017 by Metacelsus]


Hmmm, that's interesting. I got my figure of 30% from a solvent properties table (I've attached it to this post, THF is on the last page). As for smell, it has a strongish odor, with just a hint of sour. However, I wouldn't rely on smell simply because it's an industrial solvent and who knows what else is in there that could affect the scent.

Attachment: Solvent Properties.pdf (24kB)
This file has been downloaded 312 times

PirateDocBrown - 15-4-2017 at 07:26

You should be able to get a considerably more accurate read on your unknown's density and BP.

Your table is indeed in error about the miscibility of THF and water. They dissolve in each other at all proportions.

Do a nice slow fractional distill of a small sample, and get qnatitative numbers on the different components.

You might try a number of simple chemical tests, too. Does it decolorize a Br2 solution? A KMnO4 solution? Reaction with cold concentrated H2SO4? etc.

[Edited on 4/15/17 by PirateDocBrown]