Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: ethylene glycol -> oxalic acid?
Intergalactic_Captain
Hazard to Others
***




Posts: 228
Registered: 4-9-2004
Location: somewhere where i don\'t know where i am
Member Is Offline

Mood: frabjous

[*] posted on 23-9-2004 at 14:09
ethylene glycol -> oxalic acid?


This is my first post, and i apologize if it is against forum ethics. From what i've seen lurking around here, you guys are quite welcoming to newbies.

Here's my question - I've been trying to find a (relatively) simple synthesis for oxalic acid for a few weeks, but have come up with nothing. Yesterday, i had myself a good old brainfart...I was looking at the structures of etylene glycol and oxalic acid on chemfinder, and realized that they are quite similar in structure. Is there any simple way to oxidize (forgive me if it's the wrong term...i'm still an amateur in organic chem) the two carbon atoms in ethylene glycol insomuch as to replace the two existing hydrogens with one oxygen, without destroying the carbon skeleton or replacing the existing hydroxyl groups? Semi complicated proceses are no problem, it's just that my exotic precursor collection is borderline nonexistant as of yet.

Any and all help would be greatly appreciated.




If you see me running, try to keep up.
View user's profile View All Posts By User
Mephisto
Chemicus Diabolicus
****




Posts: 294
Registered: 24-8-2002
Location: Germany
Member Is Offline

Mood: swinging

[*] posted on 23-9-2004 at 14:57


Straight from Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 2002:
[color=darkblue]The oxidation of ethylene glycol with nitric acid is a one-step process. ... . An oxidizing mixture of 30 - 40 % sulfuric acid and 20 - 25 % nitric acid is used. The oxidation is carried out in the presence of vanadium pentoxide and iron (III) salts, at 50 - 70 °C and atmospheric pressure. Only CO2 is formed as a byproduct. This original process has been improved by the Mitsubishi Gas Company and in Japan most of the oxalic acid is produced this way (Mitsubishi Gas, US 3691232, 1972). The improved process operates at about 10 bar in a pressure reactor, in which ca. 60 % nitric acid and possibly also sulfuric acid at 80 °C, is pressurized with oxygen at 3 - 10 bar. Ethylene glycol is then continually pumped in and the temperature and pressure are maintained by addition of oxygen. The exothermic reaction must be held at a temperature of 50 - 70 °C by effective cooling. The yield of oxalic acid, based on ethylene glycol, is 90 - 94 % of the theoretical value. The nitric acid used can be recovered almost completely. This indicates that the nitrogen oxides and nitric acid only act as catalysts and the actual oxidation has been effected by oxygen.[/color]

Maybe the following methods are more efficient in your case.
Rhodium: Oxalic Acid from Household Cleaners
Rhodium: Oxalic Acid from Household Cleaners (Improved Method)




Visit the German synthesis collection LambdaSyn and our new LambdaForum!
View user's profile Visit user's homepage View All Posts By User
BromicAcid
International Hazard
*****




Posts: 3112
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline

Mood: Legitimate

[*] posted on 23-9-2004 at 17:28


Don't worry about loosing your OH group. Only weak oxidizing agents would oxidize to the aldehyde but stop there. It's a pain to stop there usually. Many oxidizing agents should facilitate this reaction. Then due to the low solubility of oxalate it should start to crystallize out as it is formed.

The trick with most things is finding the correct conditions that have the highest yield and work at the best rate. For this it is best to find a reference work. However you could just start from square one and just start experimenting with different mixtures.

Somewhat on topic, what oxidizing agents do you have at your disposal to possibly facilitate this oxidation?




Shamelessly plugging my attempts at writing fiction: http://www.robvincent.org
View user's profile Visit user's homepage View All Posts By User
Intergalactic_Captain
Hazard to Others
***




Posts: 228
Registered: 4-9-2004
Location: somewhere where i don\'t know where i am
Member Is Offline

Mood: frabjous

[*] posted on 23-9-2004 at 18:38


As of now, the only oxidizer i have access to is KNO3. Within the next few weeks, however, i will have access to HNO3 (need to make it), NaClO3, and KMnO4. The KMnO4 is a bit touchy, however. My method comes from Nemsen's "Inorganic Chemistry", 4th ed. It claims the synthesis by "fusing" KOH and MnO2 in the presence of oxygen. If it works, i will be a very happy man...if not, i won't have access to KMnO4 for quite some time.



If you see me running, try to keep up.
View user's profile View All Posts By User
S.C. Wack
bibliomaster
*****




Posts: 2419
Registered: 7-5-2004
Location: Cornworld, Central USA
Member Is Offline

Mood: Enhanced

[*] posted on 23-9-2004 at 21:18


HNO3 oxidation: US3691232 looks interesting, however - the pressure mentioned in Ullmann is not mentioned here. wtf?

Rhodium links: ning may be mistaken about the 50%. The MSDS says 5-10%. The MSDS of the other product says 10%, as the dihydrate.

Homemade KMnO4: I'd think that there is a thread on this here, didn't look though. Maybe your book is leaving a bit out. The product is manganate, on boiling in water or on dilution this gives permanganate + MnO2. I recommend boiling the manganate/unreacted crap in a small amount of water, much easier to crystallize out. Chlorate would be helpful, I think.

KMnO4 here: Well, there must be a patent...which one? There are other oxidation possibilities - glycollic acid, glyoxalic acid, CO2...the yield? In any case, this has to take place with alkali, or else the permanganate will react with the acid.

But you say that you're looking for simple oxalic acid syntheses, not just from the glycol. Well - sugar, starch, and sawdust have all been explored. I have some good info on sawdust but not where I can find it. It has already been covered here anyways. From sugar:
"Required: Cane sugar, 20 g.; nitric acid, 100 ml.
Owing to the copious evolution of nitrous fumes, this prepara-
tion must be carried out in a fume-cupboard having an efficient
draught. Place 20 g. of coarsely powdered cane sugar (sucrose)
in a 750 ml. flat-bottomed flask, add 100 ml. of concentrated
nitric acid and heat the flask on a boiling water-bath. As the
mixture becomes warm, the greater part of the sugar dissolves
and a vigorous but harmless reaction, accompanied by a tremen-
dous evolution of nitrous fumes, takes place. Immediately the
evolution of gas starts, remove the flask from the water-bath and
place it on a wooden block or some similar non-conducting
surface. When the reaction subsides (after about 15 minutes)
pour the hot solution into an evaporating-basin, wash out the flask
with about 20 ml of concentrated nitric acid, and then evaporate
the acid solution on the water-bath until it has a volume of about
20 ml. Some oxidation continues in the solution during the
evaporation, which is comparatively rapid. Now add about 40 ml.
of water to the solution, and again evaporate to about 20 ml.
Cool the solution thoroughly in ice-water; oxalic acid rapidly
crystallises. When crystallisation is complete, filter at the pump,
and then recrystallise from a small quantity of hot water. Dry
by pressing between pads of drying-paper, or in an atmospheric
desiccator, but not in an oven where partial loss of water of
crystallisation may occur. Yield, 7 g. The hydrated acid
has m.p. 101°; the anhydrous acid decomposes on heating.
Oxalic acid is poisonous." - Mann and Saunders.
View user's profile Visit user's homepage View All Posts By User
Geomancer
Hazard to Others
***




Posts: 228
Registered: 21-12-2003
Member Is Offline

Mood: No Mood

[*] posted on 24-9-2004 at 19:55


Not usefull preparatively, but you could drink it. Oxidation to oxalic acid, followed by precipitation of needlelike crystals of calcium oxalate in the blood, is the primary mechanism for EG toxicity.
View user's profile View All Posts By User
Theoretic
International Hazard
*****




Posts: 770
Registered: 17-6-2003
Location: London, the Land of Sun, Summer and Snow
Member Is Offline

Mood: eating the souls of dust mites

[*] posted on 24-10-2004 at 10:37


So its actual toxic mechanism is, on end, MECHANIC (CaC2O4 crystals)? The crystals actually damage something so hard it can kill you? That's... really freaky. :o
The sugar oxidation is quite inefficient. If you calculate what percentage of the C atoms from the sugar are converted into oxalic acid, you'll find it has actually a very low yield.
An alternative method is to catalytically dehydrogenate EG and then air-oxidize the resulting aldehyde.




View user's profile View All Posts By User
neutrino
International Hazard
*****




Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline

Mood: oscillating

[*] posted on 25-10-2004 at 08:23


This sounds like HF's toxicology: the F- binds to the calcium to the blood as an insoluble salt. This causes a decrease in the blood calcium level, leading to a cardiac arrest.
View user's profile View All Posts By User
BromicAcid
International Hazard
*****




Posts: 3112
Registered: 13-7-2003
Location: Wisconsin
Member Is Offline

Mood: Legitimate

[*] posted on 25-10-2004 at 09:47


Quote:
So its actual toxic mechanism is, on end, MECHANIC (CaC2O4 crystals)? The crystals actually damage something so hard it can kill you?


Partially, calcium is an essential ion in your muscles, if it precipitates your muscles cease to function, for example, your heat is a muscle. (Just like neutrino said) That is the main knockdown power of oxalates and fluorides. The actual abradtion (from abrade, to grind) power of oxalates and fluorides is weak, except in areas where they precipitate in mass, such as the liver, they will tear up a liver quite readily, especially if they are formed there, as is the case from metabolic oxidation of ethylene glycol.

Substances that cause their destructive damage strictly though abrading are somewhat uncommon (among substances taken orally, inhalation is a somewhat common mode of taking on substances that cause this kind of damage), however one good example is diamond dust.

[Edited on 10/25/2004 by BromicAcid]




Shamelessly plugging my attempts at writing fiction: http://www.robvincent.org
View user's profile Visit user's homepage View All Posts By User
Theoretic
International Hazard
*****




Posts: 770
Registered: 17-6-2003
Location: London, the Land of Sun, Summer and Snow
Member Is Offline

Mood: eating the souls of dust mites

[*] posted on 26-10-2004 at 13:32


Sorry about that, I myself thought it was improbable the crystals would do mechanical harm, just that I saw the word "needlelike" and thought oh, so it COULD actually be doing mechanical
damage :o.

[Edited on 26-10-2004 by Theoretic]




View user's profile View All Posts By User
macckone
International Hazard
*****




Posts: 2126
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline

Mood: Electrical

[*] posted on 13-9-2018 at 19:13


In ethylene glycol poisoning the oxalic acid does form crystals and cause mechanical damage. The fatal poisoning is usually from damage to the kidneys where it mechanically blocks the flow of urine and urea builds up in your body and you die. Having one kidney blocked was excruciating and the nausea was overwhelming, literally. Mine is from an incorrect break down of protein and sugar in the body, not ethylene glycol but it hurts anyway. You could also find someone that naturally produces oxalic acid stones and collect them.
View user's profile View All Posts By User

  Go To Top