Sciencemadness Discussion Board

Mystery Paint Thinner

Deathunter88 - 5-4-2016 at 10:20

I recently picked up a bottle of "Alkyd Paint Thinner" which I hope to get some useful solvent out of. I am currently trying to figure out what it contains since it is not marked anywhere on the bottle. (The bottle is a glass IV bottle and the label is written in permanent marker). The only other information on the bottle is "Highly flammable" and "Do no use indoors". Here are some things I have noted about the thinner.

Doing a crude boiling point test, I put about 3ml into a test tube and immersed it in some near boiling water. Then I stuck a thermometer into the vapour (not the liquid) and got a constant reading of 42˚C. The temperature of the vapour did not change the entire time until all of the liquid has boiled off. This leads me to believe it is not a mixture.

The liquid is indeed highly flammable, and when placed onto a concrete floor a match ignites the vapour 3cm before contacting the liquid.

The liquid has a strong ethereal smell, similar to that of diethyl ether, except less sweet. (keep in mind I have only smelled ether 2-3 times so I may not be familiar enough)

The liquid is less dense than water, when 2ml is put into a test tube containing 6ml of water, it floats. But when shaken, it appears to be completely miscible. It might just be forming an emulsion, I honestly am not sure. In either case, the resulting solution/mixture is still highly flammable.

What could it be? (further suggestions on tests I can do would be appreciated)

DutchChemistryBox - 5-4-2016 at 11:42

Check the MSDS

chemrox - 5-4-2016 at 12:09

The MSDS is shorthand for "material safety data sheet." Do the following search: "MSDS, (name of manufacturer), (name of product.) If you're using google you should get a boatload of hits and among the top three or four there should be a link for the MSDS. Welcome to the club. UTFSE and outside search engines.

ParadoxChem126 - 5-4-2016 at 14:11

It seems likely to be what is known as petroleum ether, or ligroin. It is essentially a mixture of low boiling hydrocarbons that are distilled from petroleum. Typically, it contains components with boiling points ranging from 40-60 degrees Celsius. It is fairly inert and quite useful.

It would be best to confirm its identity with an MSDS, however, if it was available.

Deathunter88 - 6-4-2016 at 00:18

Thanks for the help guys :D
A few things:
No MSDS is available because 1) It's China, and 2) This was bought from a mom and pop type hardware store and the label is written in permanent marker. The most likely candidate is petroleum ether, BUT:

It seems soluble in water. Upon further testing, 2.5ml will dissolve in 3ml of water. According to wikipedia, petroleum ether is insoluble in water.

Also, petroleum ether is said to smell like gasoline/diesel fuel, but this thinner smells more like ether/alcohol. Are there any other tests out there for petroleum ether?

Thanks!

Deathunter88 - 6-4-2016 at 01:51

I finally got around to distilling about 200ml of the thinner. The liquid began boiling and the temperature read 40˚C. The still head temperature began to gradually rise until at 45˚C I changed receiving flasks. At this point about 150ml of liquid had been distilled. Then I collected the remaining 50ml of liquid. The temperature read 50˚C when there was a little bit of liquid left and heating was stopped.

The two fractions look identical, but the one coming over between 40-45 seems to have a slightly sweeter smell, while the 45-50 seems to have a more hydrocarbon smell. The difference though is very slight.

DJF90 - 6-4-2016 at 02:32

Could it be methylal?
https://en.m.wikipedia.org/wiki/Dimethoxymethane

Boiling point fits
Solvent "power" fits
Odour fits
Water miscibility fits(?)

[Edited on 6-4-2016 by DJF90]

ParadoxChem126 - 6-4-2016 at 04:52

Sorry, I must have overlooked where you mentioned the miscibility. DJF90's prediction seems more likely.

According to Wikipedia:
Quote:
In aqueous acid, it is hydrolyzed back to formaldehyde and methanol.


Perhaps you can try hydrolyzing a small amount and performing a Tollens or Jones oxidation test for aldehydes?

[Edited on 4-6-2016 by ParadoxChem126]

Boffis - 6-4-2016 at 09:17

Other possibilities are formate esters, methyl formate is partly miscible with water, ethery smell and volatile. Try mixing with some conc ammonia solution in a tightly closed bottle and setting aside for a week then evaporate half. A solid residue of hexamine would indicate dimethoxymethane while methyl formate would produce liquid formamide which is volatile but a lot less so than the original ester. Several monochloro and monobromo-alkanes are also used as solvent but I am not sure about the miscibility of halo-propanes with water but I would expect that it is low.

testimento - 6-4-2016 at 10:02

Stuff sold here contains acetone, toluene and butyl acetate or something that boils at 130-140C in ratios of 30:55:15. Easiest way to process it is to get a bucket, pour in the solvent and generously add water and separate the organic layer and then distill the +90% toluene to high purity dry solvent.

DJF90 - 6-4-2016 at 11:08

Quote: Originally posted by Boffis  
Other possibilities are formate esters, methyl formate is partly miscible with water, ethery smell and volatile. Try mixing with some conc ammonia solution in a tightly closed bottle and setting aside for a week then evaporate half. A solid residue of hexamine would indicate dimethoxymethane while methyl formate would produce liquid formamide which is volatile but a lot less so than the original ester. Several monochloro and monobromo-alkanes are also used as solvent but I am not sure about the miscibility of halo-propanes with water but I would expect that it is low.


I don't think you've taken time to read the information that has been provided. Deathunter said that the bulk of the material boils between 40 and 45 *C, and the crude boiling point determination prior to that had indicated 42 *C. The boiling point of methyl formate is too low (32 *C), whilst that of ethyl formate is too high (54 *C), as is methyl acetate (57 *C), so ester species are eliminated on this basis. n-Chloropropane (bp = 47 *C is the only real haloalkane possibility, but is ruled out on its insolubility in water.