Maleic acid conversion to fumaric acid

I didn't have time for the famous potassium synthesis reaction this evening, but having taken the day off at work I decided to be "somewhat productive" and do a little synthesis.

Conversion of maleic acid to fumaric acid

The procedure is found in Vogel's:

B. Conversion of maleic acid into fumaric acid. Dissolve 10 g.
of maleic acid in 10 ml. of warm water, add 20 ml. of concentrated hydrochloric
acid and reflux gently (provide the flask with a reflux condenser) for
30 minutes. Crystals of fumaric acid soon crystallise out from the hot
solution. Allow to cool, filter off the fumaric acid, and recrystallise it
from hot iV-hydrochloric acid. The m.p. in a sealed capillary tube is
286-287°.


10g maleic acid in 100 ml rbf


After dissolving, and adding 20 ml conc HCl


Start stirring and heating on hotplate.


Once the refluxing started a flocculent material appreared, almost like a foam on top comprised of crystalline material.


Viewed from above:


After 30 mins reflux, heat removed and allowed to cool, a crystalline material deposited on the bottom.


Vaccuum dried, and recrystallized product, yield: 8.49g


This was a very quick synthesis done just for fun, mainly due to my not being able to do the K synthesis due to time restrictions. Anyways, hopefully it is enjoyable

[Edited on 30-10-2012 by Mailinmypocket]

Quote: Originally posted by Magpie

Interesting. Where did you get that old bottle of maleic acid? It would be nice if you would include a chemical reaction showing the transformation. If not too much trouble you could show the mechanics too.

I thought so too very easy reaction and simple to isolate. I will scan the mechanisms when I get a chance- although I found lot of good discussions of it online also.

The maleic acid has been hanging around for quite while, can't remember the source. eBay a few years ago I believe.

**edit** Thinking back, now I remember, the maleic acid was given to me in a huge lot of chemicals I received from a family member who works in a lab, they were being thrown away due to age. A waste in my opinion since they are all in very good shape, must have received at least 100 different chemicals in that lot. A happy day indeed The only one that isn't so great is the aluminum chloride(hydrate)... It has become a hard chunk with water in the jar. Still useable for some things though. Here it is, just for curiousity(albeit a bit off topic):




[Edited on 30-10-2012 by Mailinmypocket]

This is one of the nicest paths in organic lab for teaching lots of methods and mechanisms.
After you get fumaric acid, you can brominate it to get 2,3-dibromosuccinic acid (it takes few hours watching a strong mixer mixing a bloody brownish red goo) which you can use for elimination of bromine and hydrogen atom using potassium hydroxide in methanol to yield hydrated acetylenedicarboxylic acid crystals (simple reflux) which can be esterified with methanol (sulphuric acid catalyst, simple reflux) to yield dimethyl acetylenedicarboxylate which can be used in Diels-Alder reactions.

It's a lot of fun work that not only strenghtens students' organic lab techniques, but teaches them a valuable lesson about yields, too. They usually start with a fairly large quantity of maleic anhydride (and do the hydrolysis to turn it to acid) and by the time they get the small amount of the desired product, it's obvious how it's quite valuable.
It also uses ether, and people just love them some ether.


BTW this should go to Organic chemistry.

Quote: Originally posted by Endimion17

This is one of the nicest paths in organic lab for teaching lots of methods and mechanisms. After you get fumaric acid, you can brominate it to get 2,3-dibromosuccinic acid (it takes few hours watching a strong mixer mixing a bloody brownish red goo) which you can use for elimination of bromine and hydrogen atom using potassium hydroxide in methanol to yield hydrated acetylenedicarboxylic acid crystals (simple reflux) which can be esterified with methanol (sulphuric acid catalyst, simple reflux) to yield dimethyl acetylenedicarboxylate which can be used in Diels-Alder reactions. It's a lot of fun work that not only strenghtens students' organic lab techniques, but teaches them a valuable lesson about yields, too. They usually start with a fairly large quantity of maleic anhydride (and do the hydrolysis to turn it to acid) and by the time they get the small amount of the desired product, it's obvious how it's quite valuable. It also uses ether, and people just love them some ether. BTW this should go to Organic chemistry.

Now you have given me some ideas! (Thanks a lot for distracting me from the K synthesis I should be working on... ) anyhow I'm thinking of doing as you mentioned and using the fumaric acid in a 2,3 dibromosuccinic acid synthesis. I will probably follow a scaled up version of this lab I found online. The only tricky part is working with bromine (no fume hood indoors, nosey people outside) so I might have to moderate myself when "scaling up" and use a scrubber for any fugitive Bromine fumes.

And yes, this should be in Organic, my bad! If a moderator could move this it would be great.

Quote: Originally posted by Mailinmypocket

Now you have given me some ideas! (Thanks a lot for distracting me from the K synthesis I should be working on... ) anyhow I'm thinking of doing as you mentioned and using the fumaric acid in a 2,3 dibromosuccinic acid synthesis. I will probably follow a scaled up version of this lab I found online. The only tricky part is working with bromine (no fume hood indoors, nosey people outside) so I might have to moderate myself when "scaling up" and use a scrubber for any fugitive Bromine fumes. And yes, this should be in Organic, my bad! If a moderator could move this it would be great.

LOL, don't mention it.

It is fast, but at what cost? Dry bromine and dry ether (sodium!)... That's a lot of money and you can't make a lot of this compound.
I recommend using the less expensive wet method. It takes three hours, and the bromine doesn't pose a problem. The reaction is slow and the vapors don't rush out through the condenser. You could do it outside the fume hood, by the window, just be sure to have one fan blowing outwards. Most of the bromine will be spent in the reaction itself. The lost vapors climb through the condenser by diffusion only so you can put a cotton plug at the top. No one will notice.
Also, it relies on mixing because the reaction mixture is not homogenous, so a magnetic stirrer is a nice choice.

Quote: Originally posted by Hexavalent

This is a nice example of alkene cis-trans isomerisation and the conversion between them...a nice little experiment IMO. http://www.youtube.com/watch?v=Jz33rBxxsqU