Hi all!
I've been registered for about one year but this is my first post.
Since I'm trying to find an OTC preparation for Malonic acid on a post of the hive I found the following idea: Linoleic acid double bond cleavage;
Soybean oil is the oil with the highest linoleic acid content; the oil is made of:
Saturated fatty acids: 16% (insoluble in water, don't react with KMnO4, no problem with separation from water)
Unsaturated fatty acids:
-Linoleic acid, 50% (breaks into Nonanoic acid, Malonic acid and Hexanoic acid)
-alfa linoleic acid, 7-10% (breaks into Nonanoic, Malonic acid and propanoic acid)
-oleic acid, 23% (breaks into nonanoic and nonandioc acid).
The major problem is to separate Hexanoic from Malonic acid
This is the experiment (qualitative):
To a beacker about 50 ml of soybean oil and 40 of water are added with 15g of sulfuric acid, stirring is turned on and everything is heated to 80°C.
15g of potassium permanganate are added slowly to the mixture, as KMnO4 is added manganese dioxide will form.
After all the permanganate is added the mixture is filtered and the water layer is collected. (the oil volume diminished)
Now in the water solution we should have Hexanoic acid and Malonic acid.
Sodium hydroxide is added until the mixture reach a pH of 14 and some sodium hexanoate should start to precipitate becouse of its low solubility in
water (0,2mol/L from: https://core.ac.uk/download/pdf/42338019.pdf)
while Sodium malonate should stay in solution (solubility: 148 g/l).
Everything is boiled down until Malonic acid start to precipitate along with some sodium hexanoate.
Everything is filtered and washed with ethanol.
Now, I'm not 100% sure that what I've obtained is sodium malonate but from the solubility data it should be.
There is anyway I can test if it really is sodium malonate?
If this method worked I'll do it on a quantitative scale. unionised - 22-8-2019 at 10:25
Dissolve in water and add HCl or H2SO4 untill you get no more precipitation. Go on until pH is 2-3 or so. Now heat the whole until boiling and cool
slowly to RT. See if the organics crystallize, and at what temperature.
Good chance it won't, if not try the workup of the sodium salt you did before again and again until you can at the right temperature, or somewhere in
the 100 Celsius range.
Soy and reagents are cheap. Keep us posted.Boffis - 22-8-2019 at 11:02
Can you remove the fatty mono-acids by steam distillation of the initial acid filtrate Or will it froath too much?
Also could you saponify the oil first so that you can carry out the oxidation in alkaline and homogeneous conditions?
How do you remove the nonanoic andnonandioc acid?DraconicAcid - 22-8-2019 at 11:38
Malonic acid and malonates are pretty water-soluble (lead and silver malonates aren't; other transition metals complex with the malonate anion). (See
http://chemister.ru/Database/properties-en.php?dbid=1&id... ) You won't be able to recrystallize it directly from water or an alcohol, but
you might be able to precipitate it from, say, rubbing alcohol by adding petroleum ether.Tsjerk - 22-8-2019 at 12:06
You won't be able to recrystallize it directly from water or an alcohol, but you might be able to precipitate it from, say, rubbing alcohol by adding
petroleum ether.
Who, I missed that. I didn't expect that number (73.5 g/100g (20°C))... I would suggest saturated brine, as that also helps with e.g. isopropanol,
but still, brine can only do so much.
Ok, now I look at it like I would look at acetic acid, I get it, or oxalic acid, I was thinking about it like a fatty acid... which it is hardly.
but you might be able to precipitate it from, say, rubbing alcohol by adding petroleum ether.
I like your solution, the sodium salt of the acid used to acidify could be filtered of. Even if an alcohol would be used in the first place you don't
necessarily need petroleum. From that time on you could do with vacuum or patience.
[Edited on 22-8-2019 by Tsjerk]stinkypower96 - 22-8-2019 at 12:13
Thank you all for the advices!
1) I think that carrying out the oxidative cleavage won't work in basic condition and the workup would be more difficult if the reaction is
saponified; nonanoic and nonanedioc acid are almost insoluble in cold water.
2)Maybe all the Malonic acid has decomposed (thanks to unionised for the paper)
3)Since the only compound that should be in solution with a little (almost trascurable amount of sodium exanoate) I will evaporate the solution and
consuct the workup on the obtained solid. From what I found solubility of sodium malonate in enough for a water crystalization.
I didn't say it before but the solid doesn't seem soluble in ethanol.
And since I'm waiting to recieve my funnel for vacuum filtration right now filtrations would take a lot of time.
[Edited on 22-8-2019 by stinkypower96]Tsjerk - 22-8-2019 at 13:45
I didn't say it before but the solid doesn't seem soluble in ethanol.
And since I'm waiting to recieve my funnel for vacuum filtration right now filtrations would take a lot of time.
[Edited on 22-8-2019 by stinkypower96]
There are very few if any sodium salts soluble in ethanol. The cases mentioned here are about crystallization from ethanol as the acid. If it doesn't
crystallize; just dry and evaporate.
2)Maybe all the Malonic acid has decomposed (thanks to unionised for the paper)[Edited on 22-8-2019 by stinkypower96]
Glyoxylic acid I suppose it would oxidize too? That would be a pity and could also throw you off guard as it melts at 80 degrees.. but no worries if
you get above 80-90 I would say.
Knowing what I learned just here, I would go for drying some ethanol with sodium / magnesium sulfate or something comparable, just to get it above 96
and proceed like this:
Add a 1 -1.5 molar amount of NaHSO4 compared to the maximum amount of acids in the carboxylates mixture, and see if this reacts to some extent
(exothermic I guess?). If it doesn't, add a bit of water. If it starts, or not, slowly heat and hope for it to go to completion**. Now cool down and
wait for the hydrates of Na2SO4 to form. Extract the malonic acid (and other organic acids) with the dry ethanol and take of the water as the
azeotrope. This could be as simple as an open beaker boiling slowly (water bath e.g.) . Don't go over 100 degrees. No need to and below that nothing
should decompose or boil.
Sodium bisulfate has a pKa of 2, more than enough to protonate the acids. The benefits of sodium bisulfate are that the conjugate base crystallizes
itself, is insoluble in ethanol and absorbs water while at it. If there is any water left it will be taken away by the boiling ethanol.
If you get something that is soluble in ethanol but will stay or turn solid after all ethanol evaporated on a water bath I think you have a good
chance of actually having made malonic acid.
**this mixture should be highly water soluble, a small amount of water should be enough to dissolve the whole thing and make it possible for the
reactants to react, if warm enough it should be possible to do the whole thing in less water the produced sodium sulfate can absorb upon cooling.
Let me know what you guys think of this! Almost makes me want to do it myself... maybe I will.
[Edited on 22-8-2019 by Tsjerk]Metacelsus - 23-8-2019 at 02:52
If you can make NaCN and sodium chloroacetate (from chlorinating ethyl acetate), you could try this. (Be careful, of course!)stinkypower96 - 23-8-2019 at 05:09
Ok, now I should have the calcium salt off the acid(s), it is a fine, wihite crystalline precipitate, better than the yellowish one I had before, I'll
try to crystallize the acid from it now.
Quote:
If you can make NaCN and sodium chloroacetate (from chlorinating ethyl acetate), you could try this. (Be careful, of course!)
I'm trying to find if this method works becouse I can't make NaCN and sodium chloroacetate (ventilation problems) Boffis - 24-8-2019 at 23:22
I am interested in this idea so I have done a bit of research and it appears to have been developed as a method of analysing the structure of multiple
double bonded fatty acid rather than isolating fatty acids but in the attached paper they talk about the Bertram separation procedure but the
reference is a book. Does anyone have a reference to the procedure or known what is consists of basically?
