Sciencemadness Discussion Board

Toluene from benzene, styrene, gasoline?

testimento - 10-6-2013 at 03:14

I have become aware that the availability of toluene in my country is limited and I need to find an alternative supply route. Is it possible to generate toluene from the listed items? The styrene should be first reduced to benzene, or are there other routes? Synthesizing toluene from benzene from the synthesis I've discovered is PITA so is my information limited or are there any feasible ways?

From gasoline, I mean primarily by fractional distillation separation by using fractionating column up to 2 meters in height. I have found that gasoline would contain 5-40% of toluene depending on the quality and producer of the fuel and it should, at least in theory, be possible to fractionate pure enough toluene from it?

simba - 10-6-2013 at 06:55

It is possible, but the question is 'is it worth it?'. You can make toluene from benzene via friedel crafts, from styrene by oxidizing it to benzaldehyde or benzoic acid and reducing it all the way into toluene. But none of these ways are an option just for getting toluene. My opinion is that you should just pick another solvent that is available to you (unless you need toluene for synthesis), can you get xylene or DCM?

bbartlog - 10-6-2013 at 07:03

I don't know where you get 5-40% (except that apparently the maximum total aromatic fraction allowed by law in Chinese gasoline is 40%).
Couple minutes on Google turns up the following document:
Look for table 3 on page 10. Apparently the toluene content varies widely depending on which gasoline you're talking about. I don't think you can achieve full separation by mere fractional distillation, even with a good column; there will be alkanes with almost the same boiling point, in this case iso-octanes would be very similar. Given their lower reactivity maybe this wouldn't matter for your purpose, though.

testimento - 11-6-2013 at 15:16

Thanks for your answers.

Is it possible to get benzene or toluene from styrene by any reliable way?

Few methods:

Styrene + ozone = benzaldehyde + oxidation = benzoic acid + calcium acetate = toluene
Styrene + alcl3 in reflux = benzene

Organikum - 11-6-2013 at 16:08

We have one comprehensive and several smaller threads covering the syntheisi of benzene. Just search only in the thread-headings for "benzene" and voila'!

I can tell you this though, that benzene from benzoic acid and NaOH by dry distillation is a nice reaction with decent yields of very pure benzene, and I wanted to recommend it to you anyways.

In almost all countries where toluene is taken from the public one can buy it without problems with a business license (no specific business necessary). I recommend to get a license for a "janitor service" which includes cleaning up graffity and a thousand little things. The expense to get the papers is usually very small and you can forever buy all solvents you ever wanted and more, even those you did not even know existed. DCM, Toluene, GBL, chloroform and thats the harmless section.
Suppliers will happily send you their catalogues which make your eyes bleed.


elementcollector1 - 20-6-2013 at 16:33

I have no access to toluene where I live, and the method described above (benzaldehyde + oxidation = benzoic acid + calcium acetate = toluene), where the beginning benzaldehyde is (possibly distilled? Depends on purity) from almond extract. But what oxidizing agent should I use? I have KMnO4, NH4NO3, and a few others in reasonable quantities.

simba - 21-6-2013 at 10:25

Its common to see people asking how to make benzaldehyde from toluene, but seeing people asking how to do the other way around sounds ridiculous to me. Toluene from benzaldehyde? That's a crime. If you're really willing to do that, just give me your benzaldehyde instead, and I will be happy to give all the toluene you need.

testimento - 25-6-2013 at 02:51

So, how would one turn styrene into toluene? Styrene is done by dehydrogenating ethylbenzene and toluene is methylbenzene, so would it be possible to hydrogenate styrene again into ethylbenzene and metatheze its ethyl group with some other methyl group? Or is it necessary to reduce it all the way to benzene and do the toluene with methyl chloride and aluminium chloride all way around?

PVC plastic produces benzene upon combustion. Could it be obtained by means of dry distillation, or is it necessary to induce burning? If so, I was thinking of installing a small air pump into steel reactor and induce propane burner under it and condense the combustion gases.

adamsium - 25-6-2013 at 04:35

Of course you can make toluene from styrene. If you want it as a reagent, it's going to be far more work (and expense) than just buying it.

You could oxidise the styrene to benzoic acid, convert to a benzoate and get benzene as discussed at length elsewhere on SM. You could then do a Friedel-Crafts to get toluene (along with, likely, a mixture of xylenes and perhaps even further methylation of the ring).

If this is for anything other than the experience, it's absolutely pointless and uneconomical, and probably not really for a beginner. You'd need a halomethane, which would probably mean messing around with thionyl chloride and other fun (and not-so-accessible-to-most) things. Reducing benzoic acid or benzaldehyde directly to toluene would, likewise, not really be a project to be undertaken lightly (or at all, really) by a beginner in a home lab and would also require reagents that are likely much more difficult to procure than toluene.