Sciencemadness Discussion Board

Coumarin synthesis

Mailinmypocket - 21-2-2013 at 06:38

I'm thinking of trying the synthesis of coumarin as detailed in this paper, and figured I would share the paper in case anyone else wants to try it out:

http://www.pjps.pk/CD-PJPS-23-4-10/Paper-16.pdf

The nice part is that it does not use any acetic anhydride which is relatively hard to come by.

This page has a write up done by somebody who seems to have done the exact procedure scaled down, but did not reference the source:

http://users.jyu.fi/~juhesiit/coumarin.html

Ill report back on the outcome later on if all goes well :)

kavu - 21-2-2013 at 07:12

Quote: Originally posted by Mailinmypocket  

This page has a write up done by somebody who seems to have done the exact procedure scaled down, but did not reference the source:
http://users.jyu.fi/~juhesiit/coumarin.html


That someone happens to be me. IIRC I used Vogels guidelines for most parts of the preparation.

Mailinmypocket - 21-2-2013 at 07:19

Quote: Originally posted by kavu  
Quote: Originally posted by Mailinmypocket  

This page has a write up done by somebody who seems to have done the exact procedure scaled down, but did not reference the source:
http://users.jyu.fi/~juhesiit/coumarin.html


That someone happens to be me. IIRC I used Vogels guidelines for most parts of the preparation.


Very nice! Then I have a question for you, for the steam distillation did you run a source of steam through the mixture or did you simply heat the flask and replace water as it distilled off?

kavu - 21-2-2013 at 07:20

Either one works, for simplicity I just added hot water to the boiling mixture.

Mailinmypocket - 21-2-2013 at 07:28

Sounds good, I will try that as well as I'm not feeling like doing the whole steam setup. I couldn't tell how you did it as my browser isn't displaying the images on your page.

mr.crow - 21-2-2013 at 08:21

Sounds like a good project.

There is an excellent thread by Klute where he makes salicylaldehyde using a different method. Reimer-Tiemann would be interesting to try.

Yeah you can just add water and boil that for steam distillation


[Edited on 21-2-2013 by mr.crow]

kristofvagyok - 21-2-2013 at 12:29

Quote: Originally posted by Mailinmypocket  
This page has a write up done by somebody who seems to have done the exact procedure scaled down, but did not reference the source:

http://users.jyu.fi/~juhesiit/coumarin.html

I have an old book: Praktikum der organisch-präparativen pharmazeutischen Chemie what also describes this reaction, with a little difference: it uses acetic-anhydride instead of glacal acetic acid, because the Perkin reaction needs this.

As far I know it won't work really well with acetic acid. Even with Ac2O it has a little, 37% yield for the coumarin, according to the German book.

Mailinmypocket - 21-2-2013 at 15:24

I was thinking the yield was going to be low also since this was the first time I came across this reaction being done with anhydrous sodium acetate (hence why it caught my interest) Just a bit concerned about how much salicylaldehyde I will need to make given the grim yield predictions...I don't want to burn through a bunch of phenol if the end result is almost nothing.

Kavu, did you happen to weigh the crude product and determine the yield?

kavu - 22-2-2013 at 00:15

The yield is really low, there were visible amounts of product but not enough for any proper use.

Vargouille - 22-2-2013 at 01:20

According to the paper, yields varied from about 5-10% for the glacial acetic acid/ sodium acetate method.

Nicodem - 22-2-2013 at 07:26

Mailinmypocket, if you just want to do some heterocyclic chemistry and you do not specifically want coumarin, I would rather direct you toward the Rap-Stoermer condensations to obtain 2-acyl benzofurans. Can you obtain or prepare any alpha-halo carbonyl compounds such as haloacetic acids and their esters, phenacyl halides or other haloketones? Most of the products are crystalline solids, so that the isolation and purifications is simple and does not require chromatography.

If you don't have any of these, you can try the synthesis of 2-acetylbenzofuran by the condensation of salicyladehyde with chloroacetone in acetone with K2CO3 as the base. The nice thing about it is that a presumably sufficiently pure solution of chloroacetone in acetone is easily prepared by the chlorination of acetone with trichloroisocyanuric acid with less than 1 mol% of sulfuric acid as the catalyst. The cyanuric acid that forms, nearly quantitatively precipitates and can be filtered off. The reaction is simple as long as you follow exactly the patent instructions and don't scale up (you can UTFSE to find the patent number and discussions). Let me know if you need assistance in finding references about the condensation.

Mailinmypocket - 28-2-2013 at 09:10

Quote: Originally posted by Nicodem  
Mailinmypocket, if you just want to do some heterocyclic chemistry and you do not specifically want coumarin, I would rather direct you toward the Rap-Stoermer condensations to obtain 2-acyl benzofurans. Can you obtain or prepare any alpha-halo carbonyl compounds such as haloacetic acids and their esters, phenacyl halides or other haloketones? Most of the products are crystalline solids, so that the isolation and purifications is simple and does not require chromatography.

If you don't have any of these, you can try the synthesis of 2-acetylbenzofuran by the condensation of salicyladehyde with chloroacetone in acetone with K2CO3 as the base. The nice thing about it is that a presumably sufficiently pure solution of chloroacetone in acetone is easily prepared by the chlorination of acetone with trichloroisocyanuric acid with less than 1 mol% of sulfuric acid as the catalyst. The cyanuric acid that forms, nearly quantitatively precipitates and can be filtered off. The reaction is simple as long as you follow exactly the patent instructions and don't scale up (you can UTFSE to find the patent number and discussions). Let me know if you need assistance in finding references about the condensation.


I forgot about this thread, sorry for the delay in responding. I have decided to drop the coumarin synthesis at the moment because, as you suspected, I am only exploring heterocyclic chemistry. Coumarin is not a necessity.

I am seriously considering your suggested synthesis of 2-acetylbenzofuran, as I don't have any haloacetic acids on hand at the moment. The first step right now is preparing some salicylaldehyde. Once that is completed I may hit you up should I need assistance finding references, thanks!