UnintentionalChaos
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Diethylene Glycol
I may feel like an idiot for asking later, but sometimes I overlook obvious things...
I have found a relatively cheap and clean source of diethylene glycol and was hoping it could stand in for regular ethylene glycol (only available to
me as antifreeze with dye, water, and methanol mixed in) as a solvent for example, the depolymerization of poly(ethylene terepthalate). Is there any
situation in which its use would be ill advised and is there anything interesting you can think of to do with it besides solvent use?
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Sauron
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Diethylene glycol is a glycol ether, right?
O(CH2CH2OH)2
Aka bis(2-hydroxyethyl) ether.
Never use it in any reaction where it might be halogenated. The corresponding bis(2-chloroethyl)ether is the oxygen analog of sulfur mustard and is a
potent vesicant and carcinogen, although less so than the S-compound.
You might want to compare its bp with that of ethylene glycol. But in general its solvent properties ought to be similar as it is both a glycol and an
ether.
The bromo compound is also quite nasty.
[Edited on 5-12-2007 by Sauron]
Sic gorgeamus a los subjectatus nunc.
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UnintentionalChaos
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Thank you Sauron. That's the kind of "avoiding stupid mistakes" information i was looking for. I'll keep hydrogen halides out of it altogether. The
boiling point is about 50C higher than regular ethylene glycol. I figured the solvent properties could be interesting.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Sauron
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50 C higher than ethylene glycol is quite high. Not a solvent you will rotavap off!
Ethylene glycol is hygroscopic as hell, diethylene glycol may also be and that may make your life miserable if you use either in reactions that you
want to keep dry. You may also want to look into azeotropes of these glycols and water.
In short you may end up with a very difficultly seperated mess.
HCl and HBr dry or aqueous need to be shunned as well as all of the usual chlorinating agents and brominating agents, anything that can replace -OH
with -X (X = Cl, Br) Do not exempt F and I from this. Same goes for pseudohalogens like -CN.
Sic gorgeamus a los subjectatus nunc.
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not_important
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Di- an tri- ethylene glycols, and their mono-ethers, have been used in solvents in several semi-micro org chem lab books; the high boiling points
leading to shorter reaction times.
The Huang-Minlon modification of the Wolff-Kishner reaction is often run in diethylene glycol. The N-ethylene glycohol are often useful for reactions
involving bases or neutral salts, the form weak complexes with metal ions and so function a bit like crown ethers.
Reagents and products soluble in alkanes can be extracted from DEG by petroleum ether, sometimes along with the addition of a small amount of water or
by first adding a water-ethanol mix to the DEG reaction mix. The petroleum ether extracts are washed with water to remove and DEG, and then
evaporated.
For some reactions the product is low enough boiling that it is distilled from the reaction as it is formed.
oxidation use NaOCl with DEG as the organic solvent:
http://www.mdpi.net/molecules/papers/80300318.pdf
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UnintentionalChaos
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Thank you again for your insight Sauron.
Very interesting material not_important.
Wild speculation here: Do you think diethylene glycol could be heated with conc. sulfuric acid (analagous to ether synthesis) to form a mixture of
1,4-dioxane, assorted crown ethers, and of course polymerized poly(ethylene glycol) crap. Since they are already double units, 12-crown-4 and
18-crown-6 would predominate. I think the boiling points are different enough to seperate the products somewhat easily, although vacuum distillation
might be necessary. The boiling points I found for the crown ethers were all for vacuum distillation and probably for good reason...Any reason to
pursue diglyme synthesis?
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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smuv
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Maybe of limited help but I'll post it anyways
| Quote: | | Even more markedly than was the case with monoethylene glycol, the chemistry of polyethylene glycols is the chemistry of isolated hydroxyl groups and
isolated ether groups. Even the simplest cyclic acetal involving both hydroxyl groups of diethylene glycol would require a ring containing eight
atoms. Understandably therefore, the formation of cyclic compounds is much less a part of the chemistry of the higher polyethylene glycols. In
general, review of the chemistry of these compounds here is unnecessary. |
| Quote: | | Commercially useful procedures for preparing dioxane include the dehydration of ethylene glycol, polyethylene glycols and the corresponding ethers
over acidic catalysts such as sulphuric acid, hydrochloric acid, zinc chloride, phosphoric acid, benzenesulphonic acid, and ferrous sulphate.
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From 'Ethylene and Industrial Derivatives' by Miller
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