FloridaAlchemist - 9-9-2016 at 14:19
Is it possible to convert xylene solvent to toluene by controlled decarboxalation conditions?
Metacelsus - 9-9-2016 at 16:34
Decarboxylation? Xylene doesn't have any carboxylic acid groups (although it would if you oxidized it). You might be able to shuffle some methyl
groups around with a good Lewis acid (in effect "disproportionating" your xylenes into a statistical mixture of toluene, xylenes, and
trimethylbenzenes), but separating the mix would require an excellent column.
Anyway, toluene is as easy to buy as xylenes (at least for me), so I don't see the value of making xylenes into toluene.
clearly_not_atara - 10-9-2016 at 00:17
IIRC the thermodynamically preferred situation is a mixture of mesitylene and benzene. If you want to use toluene as a solvent, xylene is usually
fine. If you are interested in a derivative of toluene, you can probably find a source of benzyl alcohol somewhere, since it has tons of uses.
Fulmen - 10-9-2016 at 02:18
Wouldn't it be safe to assume that he asks because toluene isn't readily available? Around here toluene is quite hard to find while xylene is sold in
every paint shop.
Mesitylene boils at 165°C while toluene has a b.p. of 111°C, so separation should be possible.
myristicinaldehyde - 10-9-2016 at 04:30
Oxidize to toluic acid:
www.orgsyn.org/demo.aspx?prep=CV3P0820
Decarboxylation to toluene would be identical to benzene from benzoic acid, but it might need a catalyst.
This will yield toluene in high purity if the ring is not nitrated, and if all the xylene reacts. Over oxidation could make benzene from phthalic
acid, but this did not seem to be an issue in the paper.
Texium - 10-9-2016 at 07:41
Quick tear down of that procedure:
It calls for o-xylene. Commercial xylene is a mixture of isomers, and the other two may be more prone to double oxidation which could lead to benzene
being produced by the decarboxylation later on. Double oxidation of the o-xylene could lead to phthalic acid impurities as well, which rather than
decarboxylating, would dehydrate to phthalic anhydride and sublime, leading to another source of contamination in the product. The final question is
whether that procedure is actually worth it at all. It calls for double the volume of concentrated nitric acid for the amount of o-xylene used. Even
if I had no OTC source of toluene, I wouldn't consider that to be worth it.
Fulmen - 10-9-2016 at 12:08
Re: My earlier post. A section disappeared for some reason.
According to Wikipedia:
Mesitylene is prepared by equilibration of xylene over solid acid catalyst:[3]
2 C6H4(CH3)2 ⇌ C6H3(CH3)3 + C6H5CH3
new and not sure how this works but
JBSC - 31-5-2018 at 16:55
Man they got some BIG BRAINS in here. Some of these conversations/threads are unreal. So advanced i can not even follow some of
it..............OK....WHAT YOU NEED TO DO is get some mixed xylenes like maybe startex cause it is like 85% xylenes. Then take X mL of the mixed
xylenes and 2X that in concentrated nitric acid (68 to 70%) and then take 4X in water and mix them all together............So if you got 100 mL of
85% xylenes then you need 200 mL of concentrated nitric acid and 400 mL of water. NOTICE THE TREND. WHAT EVER YOU USE IN XYLENE JUST DOUBLE THE
AMOUNT OF NITRIC ACID. AND WHAT EVER YOU USE IN CONCENTRATED ACID THEN USE DOUBLE THAT IN WATER. Now reflux it for 7 to 8 hours. You will see the
the toluic acid precip out of solution as it is made. Toluic acid is just toluene with a carboxylic acid group on it. Or you can think of it as
benzoic acid with a methyl group on the ring.......Now add some water (1L) and chill it down and filter out the toluic acid. Now suspend the
filtered product in another L of water. And filter. Now take the wet product and put it in 1/2 L of 10% NaOH. This will make the salt of toluic
acid which is soluble. Now take a smidge of ether and throw it in to soak up any unreated xylene and use a seperation funnel to separate the layers.
To the aqueous layer add like 125 mL of concentrated HCl acid to get the toluic acid to precip out. It will precip out. Filter and wash with ice
cold water. Then use hot 95% ethanol to dissolve the toluic acid and as it cools down to room temp then add some water to the alcohol/toluic acid
mixture so that the toluic acid precips out. Should be needle like crystals like bezoic acid crystals. Since toluic acid is just benzoic acid with a
methyl group on the benzene ring you can do a soda lime decarboxylation with NaOH (and if you want CaO) and remove the carboxylic acid group. Just
like when you take benzoic acid and NaOH and heat it up to make benzene. The only difference is that toluic acid has a methyl group which will be
untouched by the decarboxylation. SO YOU WILL HAVE TOLUENE INSTEAD OF BENZENE. ................i am actually making a video where i do this. It
should be posted soon. Go to youtube and i am JOHN BLACK SUPER CHEMIST............And on BITchute i am JBSC.........So far i did the refluxing
.........I just need to purify it. Then i can post the video. I actually refluxed it for 7 1/2 hours and filtered and then refluxed it for another
55 hours on top of the 7 1/2 hours. I made probably 4 times as much the first 7 1/2 hours than i did the last 55 hours. I think i can do a lot
better job the next time i do this. I am thinking ........well it is to much to type but i will put my thoughts about a better method in the video
part 3..........................The reason the dilute nitric acid does not oxidize BOTH methyl groups on the xylene is because a carboxylic acid
group is an electron withdrawing group which deactivates the ring. So the second oxidation does not occur UNLESS YOU ADD A CATALYST........IF YOU ADD
A CATALYST THEN YOU WILL MAKE PHTHALIC ACID instead of toluic acid.............HEY I LOVE TALKING ABOUT CHEMISTRY SO IF YOU have any question just
let me know. I really hope i helped. I am new to this site though so i really do not know what i am doing or how i know someone replied to a post.
But if you contact me on youtube or bitchute i know what i am doing over there........HEY IF ANYONE READS THIS DO ME A FAVOR and post something back
to me. Just so i can see how i get messages on here. Something tells me i am going to have trouble figuring it out........LOOKING FOR FRIENDS TO
TALK TO ABOUT CHEMISTRY
diddi - 31-5-2018 at 17:29
agree with ZTS here. you would have to start with AR ortho xylene. way too dear. easier to just buy toluene
zed - 1-6-2018 at 12:46
Toluene has been harder to locate during the last few years. Still, use the search engine, it should tip you off to a few potential sources.
aga - 1-6-2018 at 13:02
Erm, did nobody notice that they're commenting on a 2 year old thread without reading the rest of it ?
Maybe now you see what JBSC did there.
Happens a lot.
JBSC - 4-6-2018 at 08:40
ok here is exact instructions but i really do not like them. I would start with less water and drip in the concentrated acid and try to keep the pot
as 30% concentration when it comes to the acid/water. BUT ANYWAYS GOTO GOOGLE AND copy and paste this............. "organic synthesis nitration of
xylene to make toluic acid org. syn. coll. vol. 3 , 820"..........then click on the option that says org. syn. coll. vol. 3 , 820 and there are EXACT
INSTRUCTIONS to take ortho xylene and make toluic acid out of it. I suspect you can just use mixed xylenes and then you would make mixed toluic acid
but who cares. Ortho , meta , or para does not matter cause you will do a soda lime decarboxylation next and all 3 isomers will turn into methyl
benzene
to aga
JBSC - 4-6-2018 at 08:53
aga........i thought i did read all the post but i re read them and see i missed one. The one saying what i just said. I am new to this site so a
bit confused.
Plus i am old and new to computers so you know how that goes. Just trying to post and see how things work. Did not realize it was such an old
thread but i just so happen to be in the middle of doing the experiment i was talking about so i clicked on the thread to give my 2 cents...lol.
More for me to just get some practice on this site. Some of the threads are to advanced for me and others are just stuff i am not doing right now. I
did figure out just now that if i want to be notified about replies i need to hit the "receive e-mail on reply" box. ANYWAYS HAVE A GREAT DAY
Old thread but still curious about this topic
FloridaAlchemist - 4-6-2018 at 10:11
Thanks JBSC.
So a thread is old it does not mean there is still no interest in it.
I'm looking forward to your results converting Xylene solvent to Toluene. Many chemicals I used to buy locally are no longer available. Just this week
Lowes methylene choride paint stripper was removed off the shelf.