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Author: Subject: Oxidation of THF with nitric acid
garage chemist
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[*] posted on 10-2-2007 at 13:38
Oxidation of THF with nitric acid


I did a little experiment today: I put a few ml of 65% HNO3 into a flask and added ca. ten drops of Tetrahydrofuran and swirled.

First, nothing happened, but then the air over the mix slowly became yellow, then brown, and then the mix suddenly boiled violently and spewed some of its contents and released huge brown NOx clouds. The reaction calmed down quickly again.

What could be the products of this reaction? Succinic acid seems likely. After cooling, nothing crystallized, but that may be due to its quite high solubility. Butyrolactone would also be possible.
Both are interesting products: first one is a precursor to N-bromosuccinimide, second one is for removing graffiti (of course).

At the moment, I do not have time to find out what has been produced. I also poured the mix away, if I do investigate the reaction further I will first repeat it under controlled conditions and without overboiling (Nitric acid warmed in a rbf, THF very slowly dropped in under stirring and not faster than it does react).

If someone happens to have spare time for experimentation at the moment, it would be interesting to investigate what this reaction produces.

It very much reminds me of the oxidation of cyclohexanone with HNO3, this also produces lots of NOx and yields adipic acid.
But here, the substrate is an ether, not a ketone.
This has to be investigated further.

[Edited on 10-2-2007 by garage chemist]




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[*] posted on 10-2-2007 at 14:50


Succinic acid seems more likely. It sounds as though the nitric acid chewed up THF pretty well.

I think you had best do this with cooling and under reflux (dry ice/acetone) to avoid losing THF

Much milder conditions/reagents would favor the lactone or succinic anhydride I would think. But I am not the reseident GBL guru. ask @Orgie.

Succinic acid and succinimide are cheap.
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[*] posted on 11-2-2007 at 06:29


Oxidation of Tetrahydrofuran and 1,4-Butanediol with Nitric Acid
- this was found on Springer

[Edited on 11-2-2007 by kmno4]

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[*] posted on 11-2-2007 at 07:18


Hah! I love it when I call it right. :)

But is succinic acid hard to get anywhere?

I'd suppose many of us were hoping for a milder rxn that did not rupture the C-O bond.

Mild, to succinic anhydride, or milder, to GBL.

How about hydrolyzing the 1,4-butanediol nitrate ester in the cold with sodium carbonate to obtain the butanediol?

THF -> BDO is still useful as BDO can be made into the lactone.
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[*] posted on 11-2-2007 at 12:53


Yes, if you can convert THF into BDO then you've won. Dehydrogenation to GBL is very simple to do in the liquid phase using copper chromite.
But the dinitrate is without a doubt unstable and explosive.

From THF, 1,4- dibromobutane can be obtained by boiling with HBr (ether cleavage with subsequent esterification).
But I think upon treating this with an alkali, one would probably get THF back (williamson ether formation- like with 2-chloroethanol which gives ethylene oxide and not glycol upon treatment with alkali).
Maybe at least some BDO is produced as well, so if one is recycling the bromide ions and the THF byproduct one could achieve reasonable conversion.
Making 1,4-dichlorobutane instead would lower the cost because HCl is so much cheaper than HBr.
But I don't know what conditions are necessary to cleave THF using HCl.

Back to the topic: So it is certain that succinic acid is the only product of the THF/HNO3 reaction.
I will try this out as a preparation method for succinic acid, just to have made it myself (I could buy it cheap, but making it is more fun).
I'll probably make a documented synthesis out of it, since THF is easy to get for most members here (distillation of PVC pipe cement).




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[*] posted on 11-2-2007 at 13:26


Isn't THF in an acidic environment (esp an oxidizing acid like HNO3) going to just love to form peroxides?

A German Ph.D. friend who used to be an energetics specialist at Dynamit Nobel told me a horrific tale of an accident. A colleague was working alone late night, and was rotavaping off some ether (maybe THF) from a product in a 1L Buchi flask. Apparently some peroxides were present, when he went to remove the flask from the rotavap, the flask exploded violently, severing his fingers. He tried to telephone for help but couldn't use the phone for lack of digits, and almost bled to death before someone finally found him on the lab floor.

The moral of this story was: don't forget when there is a chance for peroxides to form, always destroy them with base before concentrating the soln. Better still, don't create conditions that favor their formation. OK, end of spiel, I'm sure you know this.

Also, wasn't there a report of CC (TCT) cleaving THF to the 4-chloro-1-butanol or maybe it was 1,4-dichlorobutane? Similar to the HBr ring cleavage. Yeah, sorry, you have trouble buying that.

[Edited on 11-2-2007 by Sauron]
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[*] posted on 11-2-2007 at 19:56
peroxides


Quote:

Apparently some peroxides were present, when he went to remove the flask from the rotavap, the flask exploded violently, severing his fingers.



when its time for safety i always gear up, but as Karma would have it, i might be dealing with peroxide intermediates quite soon. It seems that the explosion is a shock initiated???, i.e when he moved the flask.

the temperatures ill be dealing with should be cold, but i think ill try not to jar the apparatus...huh, fingers are good..
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[*] posted on 11-2-2007 at 20:24


Apparently no one told the peroxides in the flask they weren't supposed to go off just then.

Timing is everything.
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[*] posted on 13-2-2007 at 12:43


If basic hydrolysis of butyl-1,4-dinitrate would indeed yield epoxybutane (tetrahydrofurane) a la 2-chloroethanol -> oxirane (which I strongly doubt, by the way), it would, supposedly, easily be converted to GBL by means of the Bayer-Villiger oxidation.


- Furch

EDIT: Upon further investigation of the issue, I realize that the product of a Bayer-Villiger rearrangement of said substrate would yield not gamma-butyrolactone, but rather the six-membered ditto... My apolagies! I still think basic hydrolysis of butyl-1,4-dinitrate would yield 1,4-butanediol, though.

[Edited on 13-2-2007 by Furch]




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[*] posted on 13-2-2007 at 16:37


OK, this is now completely offtopic, but I found a very simple method to cleave the ether linkage of THF without oxidation and with only the cheapest of reagents:

http://www.orgsyn.org/orgsyn/pdfs/CV2P0571.pdf

4-chloro-1-butanol is obtained by passing anhydrous HCl gas into refluxing THF. Very simple, and capable of upscaling.
Only drawback: Vacuum distillation is required to obtain a pure product.

Now, how does one convert this into 1,4-B without getting too much THF as the side product?




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[*] posted on 13-2-2007 at 19:20


Quote:
Originally posted by garage chemist
Now, how does one convert this into 1,4-B without getting too much THF as the side product?


Conversion of Alkyl Halides into Alcohols via Formyloxylation Reaction with DMF Catalyzed by Silver Salts. — A process for the conversion of primary and secondary alkyl halides to the corresponding alcohols is described. The transformation is based on a two-step reaction via Ag(I)-catalyzed formyloxylation reaction followed by hydrolysis of the resulting formates.

[Edited on 14-2-2007 by XxDaTxX]

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[*] posted on 15-2-2007 at 12:12


Quote:
Originally posted by garage chemist
OK, this is now completely offtopic, but I found a very simple method to cleave the ether linkage of THF without oxidation and with only the cheapest of reagents:

http://www.orgsyn.org/orgsyn/pdfs/CV2P0571.pdf

Nice, but there are also literature examples in using aqueous HCl. So you might want considering skipping the production of gaseous HCl.
Quote:
Only drawback: Vacuum distillation is required to obtain a pure product.

Yes, you can not do without it. But buying/making an aspirator is not prohibitively expensive/difficult.
Quote:
Now, how does one convert this into 1,4-B without getting too much THF as the side product?

Indeed, using any hydroxide would result in quantitative cyclization. However the acetate anion is similarly nucleophylic but nearly not as basic (for example, the amines which are more basic than the acetate anion do a normal SN2 substitution on 4-chlorobutanol with Et3N or K2CO3 as acid scavenger). Therefore mostly the 1,4-butandiol monoacetate should form with NaOAc in an appropriate solvent system. This can be hydrolyzed to 1,4-butandiol by basic hydrolysis. The biggest problem might just be the isolation of the highly water soluble 1,4-butandiol.
Another possibility might be an SN2 reaction with water in the suspension of NaHCO3 as HCl scavenger. The reaction would proceed quite slowly even at reflux temperature given that H2O is such a terrible nucleophile. The minimum necessary amount of acetone can be used as cosolvent. However given that there is little difference in the nuclephilicity of alcohols and H2O, I fear the intramolecular cyclization would be a major competition reaction (THF might actually be the major product).

If you have acetanhydride to waste, you can also transform THF directly to 1,4-butandiol diacetate as is described in:
Chinese Chemical Letters, 16 (2005) 747-750. (AcOH, Ac2O, H2NSO3H)
or
Journal of Heterocyclic Chemistry, 37 (2000) 1351-1353. (Ac2O, H2SO4)
Then you can hydrolyze it to 1,4-butandiol.




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[*] posted on 8-8-2007 at 13:08


Is it possible to react THF with sulfuric acid, to make 4-hydroxybutyl hydrogen
sulfate? If it is, I guess this ester should react with base to form butanediol easily.

I`m trying to imagine reaction conditions, and all I can think about is THF mixed with
diluted sulfuric acid (maybe 20%, molar ratio 1:1,2 , THF:acid) in flask with mixing
and cooling, for about 1 hour. Then mixing with litlle exces of NaOH, and boiling out
any remaining THF. Isolation of diol by salting out with Na2CO3 or NaCl, or extraction with
ethyl ether, or both.

Could someone with experience say if this is possible?
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[*] posted on 13-10-2007 at 15:13


I have stumbled across a use for 4-aminobutyraldehyde diethylacetal and the stuff is commercial but bloody expensive. Seems to me that it can be prepared from tetramethylene chlorohydrin which is the product of cleavage of THF with dry HCl or possibly (per Nicodem's post above) conc HCl.

However my memory nags me, I seem to recall that TCCA also cleaves THF in high yield to the same product Cl-(CH2)4-OH.

Anyone also recall this and hopefully, have references?

The target is 4-amino-1,1-diethoxybutane.




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[*] posted on 14-10-2007 at 00:14


TCCA alone only oxidizes THF. The product(s) depends on the presence/absence of water or other protic solvents, but it can never be 4-chlorobutanol as it has the same oxidation state as THF.

Alkylation of amines with 4-chlorobutanol is possible though unless carried in optimal conditions the cyclization to THF is a major side reaction. Alkylation of ammonia would however result in a mixture of mono-, di- and tri(butan-4-ol)amines with low yield of the monosubstituted. Using potassium phthalimide to obtain the N-protected 4-aminobutanol might be more rational (if at all possible to use phthalimide as nucleophile without causing recyclisation to THF).




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[*] posted on 14-10-2007 at 00:34


4-aminobutyraldehyde diethylacetal is $4 per gram in 100 g packing, and that would be $8 a gram by the time it got from Europe to me. For $8 a gram I will figure out how to make the damned stuff.
How about decarboxylation of glutamic acid (from MSG) to GABA then a nice soft reduction to the aldehyde and transformation to the acetal? I've always been good at acetals.




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