nitric acid +ethylene glycol = ?
David Punsalan
I am working on a project and am trying to follow a recipe which
prescribes to add ~10cc HNO3 to ~40cc ethylene glycol then heat it for
72h till viscosity gets to ~90cP.
They propose that this simple set of reagents leads to a polymer which
looks a lot like something I would call polyetheylene oxalate:
[- C - C - O-CH2-CH2-O-]_n
|| ||
O O
is the formation of this "polymer" possible? likely?
I know that the viscosity increases as I heat/stir the mix, but I am
not sure that I buy that the proposed polymer actually forms. With a
viscosity of 90cp - I suspect that the n=5-7.
Any comments on this?
Regards,
David
--
Paul J. Franklin(moderator - sci.chem.organic.synthesis)
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Atlanta, GA
Uncle Al
>
> Hi,
>
> I am working on a project and am trying to follow a recipe which
> prescribes to add ~10cc HNO3 to ~40cc ethylene glycol then heat it for
> 72h till viscosity gets to ~90cP.
> They propose that this simple set of reagents leads to a polymer which
> looks a lot like something I would call polyetheylene oxalate:
> [- C - C - O-CH2-CH2-O-]_n
> || ||
> O O
> is the formation of this "polymer" possible? likely?
> I know that the viscosity increases as I heat/stir the mix, but I am
> not sure that I buy that the proposed polymer actually forms. With a
> viscosity of 90cp - I suspect that the n=5-7.
> Any comments on this?
Clean out the acid, dry the product, IR. TLC maybe, too. Elemental
analysis. Base hydrolysis pr ammonolysis and isolation of products
Poly(ethylene oxalate) would not be my first guess.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Gabriel Tojo
> David Punsalan wrote:
> >
> > Hi,
> > I am working on a project and am trying to follow a recipe which
> > prescribes to add ~10cc HNO3 to ~40cc ethylene glycol then heat it for
> > 72h till viscosity gets to ~90cP.
> > They propose that this simple set of reagents leads to a polymer which
> > looks a lot like something I would call polyetheylene oxalate:
> > [- C - C - O-CH2-CH2-O-]_n
> > || ||
> > O O
> > is the formation of this "polymer" possible? likely?
> > I know that the viscosity increases as I heat/stir the mix, but I am
> > not sure that I buy that the proposed polymer actually forms. With a
> > viscosity of 90cp - I suspect that the n=5-7.
> > Any comments on this?
Nitric acid is a known oxydant to transform primary alcohols into
carboxylic acids. Its use in organic synthesis is limited because of
the need of a water soluble alcohol, the tendency of nitric acid to
produce nitration, and the many side reactions. Nevertheless,
sometimes-for instance with some sugars-it works fine.
This means that the reaction looks reasonable. On the other hand many
side reactions are possible, and I would anticipate the formation of a
very unpure polymer, perhaps just a mixture of small oligomers with
plenty of rubish.
The following mechanism could work:
1- nitric acid plus alcohol gives alkyl nitrate (explosive)
2- alkyl nitrate decomposes to aldehyde plus nitrous acid.
3- nitric acid oxydizes aldehyde to carboxylic acid, probably via
hydrate.
4- the carboxylic acid is esterified by starting alcohol under acidic
catalysis.
The following side compounds are likely: aldehydes, alkyl nitrates,
nitrogen oxides, dioxolanes....
The real thing could be a mess.
Best regards.
Gabriel Tojo
Scientific Consultant
Galchimia, S.L.
www.galchimia.com