Sciencemadness Discussion Board

Ortho Nitration

Geomancer - 5-1-2004 at 07:56

Does anyone know of a highly regioselective (ortho) means of nitrating toluene (or benzaldehyde)? Most research seems directed towards para selective nitration. I recall reading a mention that one of the clay supported nitrates (Clayfen?) gave 98% selectivity, but it was in a journal volume I couldn't get, so I don't know the conditions involved.

Al Koholic - 5-1-2004 at 08:05

What journal volume? I have access to basically every major one there is.

Geomancer - 5-1-2004 at 18:08

I really can't say. It was a while ago that I saw this. Probably not one of the usual suspects--Clays and Clay Minerals perhaps. I'll get back to you once I get a chance to go to that library.

Al Koholic - 5-1-2004 at 21:45

You know what else I can do actually...
In a week or two, I'll be able to get over to the library as well and I can just search for reactions producing o-nitrotoluene on bielstein. This will definetly lead to a journal article that I can get...it might be some other language but we can work that out.

Marvin - 5-1-2004 at 23:14

Why are you after such a high yeild of the ortho product?

In most apps the 2:1 yeild is less trouble and expense than going to a higher yeilding process...

Nitration of toulene

Acid Test - 6-1-2004 at 11:55

Toulene can be simmered on low heat and have
nitrogen bubbled through it.The toulene can
be refluxed back into the flask while the
procedure is taking place.The same with
benzaldehyde.
Nitrogen gas is generated from an unwanted
sub-procedure from synthesizing
hydrazine from 2NH3 and 3NaClO.
You get 3NaCl,3H2O and Nitrogen.
This is generated with H2SO4.
This will start the reaction.There will be
a 1 part of sulfhur left over probably in
the salt and/or water.
At best,to be efficient with your lab
procedures when making hydrazine sulfate
make a double yield(one for boiling to make
hydrazine crystals-and the other for the
generation of nitrogen)
Whenever you make a batch of hydrazine you
do your nitration at the same time since
Nitrogen gas is not explosive or flammable

???

Polverone - 6-1-2004 at 13:16

What the hell are you saying? Are you suggesting that toluene can be nitrated with nitrogen gas?

Acid Test - 6-1-2004 at 16:14

Quote:
Originally posted by Polverone
What the hell are you saying? Are you suggesting that toluene can be nitrated with nitrogen gas?


Well you could do it the traditional way or with nitric oxide or nitric acid.
Maybe it would even be possible with ammonia if you can release the hydrogen

Al Koholic - 6-1-2004 at 18:42

Dude....chill out man. You can't just stick any old nitrogen compound in and expect nitration to occur. What the hell? The oxidation state of the nitrogen is what matters. I think you might need to get some time off and read a bit...

Acid Test - 7-1-2004 at 11:15

I was only suggesting a simple way to dissolve
nitrogen into toulane.It is possable and it
will react.It may not have the same effect
as adding a nitrogen compound to it,but it
will do something

Geomancer - 7-1-2004 at 14:17

Marvin: I'm looking at making indigo via the Baeyer-Drewson reaction and I was hoping that I could get away with modest yield without a separation. Additionally, I simply find it inelegant to use such unselective reactions. Most of the the times I wish I had some nitrotoluene, it's the ortho isomer I want.

Acid Test: You could do almost as well by putting a small amount of toluene in a bottle and shaking vigorously. Creating a solution of N2 is not what is meant by nitration. In this case I was refering to replacing one of the H's on the aromatic ring with an NO2.
N2 is safe precisely because it is so unreactive. You have to go to great lengths to get it to do anything at all; unless you're a legume.

Acid Test - 7-1-2004 at 14:23

I know what nitration is.It is when you add a chemical which contains a nitrate or nitrite,or nitric acid or nitric oxide to another chemical to alter the chemical structure by adding a Nitrogen element within the chemical structure.

I would propose that you could take meperidine and nitrate it to form a fentanyl type narcotic

guaguanco - 7-1-2004 at 14:29

Quote:
Originally posted by Acid Test
I was only suggesting a simple way to dissolve
nitrogen into toulane.It is possable and it
will react.It may not have the same effect
as adding a nitrogen compound to it,but it
will do something

You would be well served by taking a chemistry class.

Acid Test - 7-1-2004 at 14:31

I have taken chemistry.I have lost my periodical table.I need a new one.Do you know where i can get one?

guaguanco - 7-1-2004 at 14:44

Quote:
Originally posted by Geomancer
Does anyone know of a highly regioselective (ortho) means of nitrating toluene (or benzaldehyde)? Most research seems directed towards para selective nitration. I recall reading a mention that one of the clay supported nitrates (Clayfen?) gave 98% selectivity, but it was in a journal volume I couldn't get, so I don't know the conditions involved.

Here's an example, using CH2Cl2 as a solvent. I don't know how generally applicable this is.
one example

guaguanco - 12-1-2004 at 11:29

Apperently, Acetyl Nitrate also preferentially nitrates at the ortho position. This is generated In Situ from Ac2O and HNO3, since the pure chemical is too explosive.

Geomancer - 16-1-2004 at 16:00

Thanks. I went to the library, but couldn't find the book I had originally looked at. My memory looks to be faulty, though--all the clay assisted nitrations I saw were para selective.
Perhaps acetyl nitrate in DCM will have even higher selectivity?

Rattata2 - 15-7-2009 at 01:59

From what I have read, the mono-nitration of toluene leads mostly to the ortho- isomer. Both http://www.thecatalyst.org/experiments/AndersonS/AndersonS.h... and http://pubs.acs.org/doi/abs/10.1021/ie50413a020 state the yield of ortho- to be 56-59% compared to 4% meta- and 37-40% para-.

Nitration of benzaldehyde on the other hand yields mostly meta-, http://chemistry2.csudh.edu/rpendarvis/ElAromSubst.html states the average yield as 19% ortho, 72% meta, and 9% para. This is problematic if one wants ortho-substitution on benzaldehyde.

Here, this may be worth your time. According to http://www.orgsyn.org/orgsyn/prep.asp?rxntypeid=181&prep... - Cinnamaldehyde will yield almost purely ortho-nitrocinnamaldehyde upon nitration with HNO3 in acetic anhydride/acetic acid, and will also yield a large amount of the ortho-compound (with para- being the other major impurity) upon nitration via H2SO4 acidification of NO3-. This can be oxidatively cleaved with KMnO4 or the like to yield ortho-nitrobenzaldehyde.

However since mono-nitration of toluene yields mostly ortho- it may be more cost-effective to perhaps nitrate toluene and oxidize the o-nitrotoluene to o-nitrobenzaldehyde. In either case, proper workup should lead to 30-50% yield.

Perhaps look into the mechanism behind the use of Ac2O/AcOH in the cinnamaldehyde nitration and see if a similar technique can be used upon toluene, however it might be specific to cinnamaldehyde.

Ftw: That o-nitrobenzaldehyde is a direct precursor to indigo ;) React it with acetone in aqueous (maybe basic, I forget...) conditions and you should yield a blue dye.

[Edited on 15-7-2009 by Rattata2]

manimal - 16-7-2009 at 11:07

In "Trinitrotoluenes and Mono- and Dinitrotoluenes" it says:
Quote:
A possibly better method of separating the isomeric mononitrotoluenes is one used by the firm Meister, Lucius and Bruning. This consists in cooling the mixed nitrotoluenes to -4C to -10C, and removing the liquid portion after about one-half the mixture has crystallized. The separation may be affected by a centrifuge. The liquid obtained by one crystallization is practically pure ortho-nitrotoluene. The resulting mixture of meta and para nitrotoluenes may be separated by steam distillation. The para is very volatile with steam, while the meta is but slightly so.

Rattata2 - 18-7-2009 at 23:51

Since you're after the ortho-nitro compound, nitrate the toluene slowly to achieve a fairly high yield of mono-nitrotoluenes. Continue until all of the reagents (KNO3) is used up. Once the reaction completes, stick the whole thing in the fridge or freezer and cool between ~-8 and 15C, filter out any solids (as these will be meta and para-substituted nitrotoluenes, dinitrotoluene or even trinitrotoluene.) Afterwards evaporate/distill off any remaining toluene to obtain the 2-nitrotoluene in around 58% theoretical yield. Should be fairly pure if done right.

I plan to try this when I can, want to try synthesizing indigo :)

Wondering currently what would be the best at-home way to oxidize the 2-nitrotoluene into 2-nitrobenzaldehyde.

Grandma - 22-2-2017 at 12:35

Has anyone ever tried the method published in "Prussian Blue as an Eco-Friendly Catalyst for Selective Nitration of Organic Compounds Under Conventional and Nonconventional Conditions"?

They use nitric acid with the complex Prussian blue refluxed in methanol for the nitration of toluene and claim to get 87% of the ortho Product. I recooked it several times, got something but was not able to isolate and characterize a product besides seeing it on a tlc plate.

They are very short handed with the description of the work up in the paper, so I was wondering if I maybe loose the product during my work up. So far, after the reaction, I filtered the Prussian Blue with celite, evaporated the methanol and added H2O. I extracted the H2O phase with ether several times and washed the organic layer with H2O till it was neutral (only two times).
Then I evaporated the ether and got something yellowish, but apparently not enough....
Next step would be a flash column.

Can anyone comment if my workup procedure seems to be all right? Or if anyone has experience with this reaction if it worked for him/her?

Thanks

BuzzKillerOfFire - 24-2-2017 at 05:00

Chemplayer on youtube published this video a while back: https://www.youtube.com/watch?v=QKFETtEE-CQ

Sadly, the source material is behind a paywall. A commenter stated that after synthesis using this procedure he/she ran a GC and found no p-nitrotoluene, and <5% m-nitrotoluene, though it is the youtube comments so take it with a grain of salt.

[Edited on 24-2-2017 by BuzzKillerOfFire]

Texium - 24-2-2017 at 07:07

Quote: Originally posted by BuzzKillerOfFire  
A commenter stated that after synthesis using this procedure he/she ran a GC and found no p-nitrotoluene, and <5% m-nitrotoluene, though it is the youtube comments so take it with a grain of salt.
That YouTube commenter is our own Amos, and he's certainly trustworthy.

Amos - 24-2-2017 at 08:06

Oh hey, look, it's me! I carried out more or less the same procedure as Chem Player did in their video, but to increase the yield I left the solids from the nitric acid preparation in the DCM, and physically ground the mixture periodically as I added the toluene.

Like Chem Player, I tried freezing my product after all of the toluene had been stripped off. It froze at -15 C but no solids could be seen at -2 C (I have two different freezers at home.) I did indeed encounter those results on our GC-MS at work but I accidentally overwrote the chromatogram with the toluidine I made from the nitrotoluene. The toluidines were 92% ortho and 8% meta according to the readout (a small portion of the ortho isomers were singly chlorinated but that's due to my error in the reduction), but this particular GC tends to inflate the impurities; a more accurate instrument like a GC-FID would likely give a ratio around 94:6, just from experience.

I will however caution that the ortho selectivity seems very dependent on anhydrous conditions; I tried to scale it up using 91% sulfuric acid instead of 98 and got around 60% para; a complete failure. So if you attempt this, use only very dry reagents.

Grandma - 24-2-2017 at 13:16

This method looks nice, but with an overall yield between 50-70% it yields not enough ortho product for my purpose, even though the selectivity is very nice. In the paper I mentioned above they claim to get 87 % ortho product which would be perfect for me :D

Today I cooked toluene with prussian blue in methanol using more HNO3 (65%) than last time. It was 13 ml methanol, about 1 ml toluene and 2 ml HNO3. Result:
-I got strong absorption on the TLC plate under the UV light
-after filtration of the prussian blue I saw that I got a yellow colored liquid
-when I evaporated the methanol the residue was a thick gel which was kind of strange

It was possible to solve some of the yellow colored substance in ethyl acetate, but the gel was stable and not soluble in H2O, EtOAc nor Et2O.

after evaporating of the Ethyl acetate I got a yellow residue, UV active on tlc but again no aromatic signals in NMR spectra...

Has anyone any Ideas what the gel could be? I cannot imagine any polymerization reactions going on with the substances I used...

Liebig - 7-10-2017 at 06:12

I wonder why Chemplayer’s procedure should produce selectively o-nitrotoluene, because I could find no publication that says so. The paper that Chemplayer refers to only demonstrates that it is possible to nitrate aromatics with the Nitrate/H2SO4/DCM-Method. Toluene was not even among the compounds that were tested by the authors. And the other compounds in the paper were not nitrated very selectively.
In Mellor, JM, et al., Tetrahedron 2001 it is reported that nitrating toluene with metal nitrate /sulfuric acid systems in DCM produces a similar isomeric ratio as the conventional mixed acid nitration.
Therefor I wonder if there is any publication that demonstrates that the nitration of toluene in DCM is indeed regioselective.