Sciencemadness Discussion Board

Toluene to benzene conversion??!!

bluamine - 13-1-2022 at 05:12

Hi everyone!!
I read something on Wikipedia about reacting (directly instead of Friedel craft alkylation) methanol with benzene to produce toluene in presence of a solid acid... and may be I read somewhere else that it can be done in presence of a strong base. Did someone here try it ever? And what acid/base would be the most appropriate for this reaction?

Texium - 13-1-2022 at 09:49

Your subject is toluene to benzene conversion but the body of the post suggests the opposite…

Bedlasky - 13-1-2022 at 10:15

Quote: Originally posted by bluamine  
Hi everyone!!
I read something on Wikipedia about reacting (directly instead of Friedel craft alkylation) methanol with benzene to produce toluene in presence of a solid acid... and may be I read somewhere else that it can be done in presence of a strong base. Did someone here try it ever? And what acid/base would be the most appropriate for this reaction?


I guess some polyoxometalic acid. But I doubt that this can be used in home setting. This reaction occurs in gas phase, probably at high temperature.

bluamine - 13-1-2022 at 10:28

Quote: Originally posted by Bedlasky  
Quote: Originally posted by bluamine  
Hi everyone!!
I read something on Wikipedia about reacting (directly instead of Friedel craft alkylation) methanol with benzene to produce toluene in presence of a solid acid... and may be I read somewhere else that it can be done in presence of a strong base. Did someone here try it ever? And what acid/base would be the most appropriate for this reaction?


I guess some polyoxometalic acid. But I doubt that this can be used in home setting. This reaction occurs in gas phase, probably at high temperature.


I'm wondering if it could be done easily why do we have to do it through Friedel craft alkylation which would be much more complicated?!
We have to keep in mind that the yield of this last is still not good enough

[Edited on 13-1-2022 by bluamine]

Bedlasky - 13-1-2022 at 11:00

Not everything which is done industrialy can be easily done in laboratory. And honestly, making toluene from benzene isn't economical.

bluamine - 13-1-2022 at 11:06

Quote: Originally posted by Bedlasky  
Not everything which is done industrialy can be easily done in laboratory. And honestly, making toluene from benzene isn't economical.

Well that's the rule!!
Of course it isn't economical at all.

crow6283 - 13-1-2022 at 11:24

I was always under the impression that Friedel-Krafts isn’t really effective in this case. Gatterman-Koch, Reimer-Tiemann, or Vilsmeier followed by Clemmensen reduction is what I would assume.

Gosh that’s a lot of German names I hope I didn’t spell too many wrong.

SWIM - 13-1-2022 at 11:37

The reference in Wikipedia for this reaction is a book of industrial chemistry.
Many industrial reactions involve conditions that are difficult if not impossible for a home lab, like high temperatures/pressures/etc.

I think Bedlasky is right about this reaction being impractical or at least extremely difficult for a home lab.

Maybe with a tube furnace, but even if that could work it sounds like a lot more effort than the wet processes mentioned by Crow6283

BTW: You want to make toluene from benzene??
In my part of the world benzene is much harder to get than toluene.

It's also pretty hard on the old bone marrow, so be careful to limit your exposure as much as possible.

I have multiple myeloma, a form of bone marrow cancer which can be caused by benzene exposure.
It is slowly killing me and there is no cure.
I'll probably live another 8 to 10 years, if I'm lucky.

This kind of situation can have serious ramifications on any long-term plans you might have.
It can also be devastating to your sex life as it is nearly i possible to get an erection when you're dead.

https://youtu.be/Hm0cAbK-ays




bluamine - 13-1-2022 at 11:53

Quote: Originally posted by SWIM  

I'll probably live another 8 to 10 years, if I'm lucky.

This kind of situation can have serious ramifications on any long-term plans you might have.
It can also be devastating to your sex life as it is nearly i possible to get an erection when you're dead.

https://youtu.be/Hm0cAbK-ays



OMG I wish you live longer and in a better health

bluamine - 13-1-2022 at 12:03

I read about a catalyst used to realize that reaction but I think what's on Wikipedia isn't all right (at least I don't know if there can be a silicon dioxide solution since this last isn't soluble in water!!)

It's mentioned here:

https://pubs.acs.org/doi/10.1021/ie00044a002

And this is Wikipedia link:
https://en.m.wikipedia.org/wiki/ZSM-5

ZSM-5 is a synthetic zeolite, closely related to ZSM-11.[citation needed] There are many ways to synthesize ZSM-5; a common method is as follows:[8]

an aqueous solution of silica, sodium aluminate, sodium hydroxide, and tetrapropylammonium bromide are combined in appropriate ratios
SiO2 + NaAlO2 + NaOH + N(CH2CH2CH3)4Br + H2O → ZSM-5 + analcime + alpha-quartz
ZSM-5 is typically prepared at high temperature and high pressure in a Teflon-coated autoclave and can be prepared using varying ratios of SiO2 and Al containing compounds.


What do you think guys?

[Edited on 14-1-2022 by bluamine]

Bedlasky - 14-1-2022 at 08:30

Quote: Originally posted by bluamine  
Quote: Originally posted by Bedlasky  
Not everything which is done industrialy can be easily done in laboratory. And honestly, making toluene from benzene isn't economical.

Well that's the rule!!
Of course it isn't economical at all.


I work in factory which synthesise amines. For example N-ethylaniline is made by ethylation of aniline by ethanol on copper catalyst at temperature 170-240 °C and pressure of 4-10 MPa. Than separation by distillation. Can you do this in lab scale (and if yes, can you do it safely?). Still don't believe that industrial synthesis is often very hard to replicate in laboratory?

bluamine - 14-1-2022 at 08:38

Quote: Originally posted by Bedlasky  

I work in factory which synthesise amines. For example N-ethylaniline is made by ethylation of aniline by ethanol on copper catalyst at temperature 170-240 °C and pressure of 4-10 MPa. Than separation by distillation. Can you do this in lab scale (and if yes, can you do it safely?). Still don't believe that industrial synthesis is often very hard to replicate in laboratory?


I think it's not hard to it at such a temperature but when it comes to pressure you must have a special equipment to reach a relatively high pressure (may be higher than three or four ATM)

Texium - 14-1-2022 at 11:42

Yeah, you need special equipment to handle the high pressures, and another factor that people often neglect when looking at industrial procedures is that the catalyst is often more complicated than it sounds. The copper catalyst in Bedlasky’s example is probably not just a copper wire or plate that’s tossed into the reactor. In your case, preparing that zeolite catalyst is obviously a huge technical undertaking in its own right… high temperature and pressure in a Teflon coated autoclave. The exact ratios of reagents used are probably also a trade secret and varying them could give you an ineffective catalyst. As to your question about the silica not dissolving, some of it should go into solution as sodium silicate since there’s sodium hydroxide in the solution, but it’s in equilibrium and likely would be a slurry. I bet their fancy autoclaves have built in mechanical stirring to keep everything suspended.

Amos - 14-1-2022 at 15:00

You're using Wikipedia! Brilliant! That means that every time you, or any other user here, comes across a synthesis there, you already have an easily accessible source cited right there, a single click away. Now read the source. Every last post asking "What catalyst, what temperature, what pressure, what yield" could be avoided for the rest of time with a tiny amount of forethought. That's exactly what we, the responders, are going to do anyway; go google your reaction for you and find the research paper it came from. If the source is a book, you might not be able to find the answer on your own, but it gives you something to cite when you make a forum post.

[Edited on 1-14-2022 by Amos]