Sciencemadness Discussion Board

condensation reaction with cinnamaldehyde

Trifluoroacetic - 18-5-2011 at 17:19

Ok folks I have a question. Cinnamaldehyde will condense with acetone in the presence of NaOH to form Dicinnamalacetone. I happened to notice that DMSO has a structure similar to acetone so I was wondering if it would undergo a condensation reaction with cinnamaldehyde.

So I mixed cinnamaldehyde and DMSO in a 2:l ratio and added aqueous NaOH. The sloution turned light yellow and heated up. A reaction appeared to happen. The solution was turbid from un-reacted cinnamaldehyde. So I did the reaction with even less cinnamaldehyde. I placed to drops in a larger ammount of DMSO then I added the NaOH. This time the solution turned blood red and heated up. I repeated the experiment and ommited the Cinnamaldehyde to see if the NaOH was reacting with the DMSO. Nothing happened.

So my question is the cinnamaldehyde condensing with itself or with the DMSO?

DJF90 - 18-5-2011 at 17:25

Did you try a control experiment using just the cinnamaldehyde and the NaOH..?

Trifluoroacetic - 18-5-2011 at 17:33

no but I will. I'll solvate it in some ethanol.

Trifluoroacetic - 18-5-2011 at 17:46

Quote: Originally posted by Trifluoroacetic  
no but I will. I'll solvate it in some ethanol.
I added a few drops of cinnamaldehyde to isoproponol then added NaoH solution. Slight yellowing occurred but nothing else happened.

Trifluoroacetic - 18-5-2011 at 18:02

something strange appears to be taking place with the DMSO/cinnamaldehyede/NaOH reaction. IF very little DMSO is used almost nothing happens but if a substatntially large ammount is used the reaction takes place and the solution turnsdark

DJF90 - 18-5-2011 at 18:04

I was thinking perhaps you got a Canizzaro reaction occuring.

Trifluoroacetic - 18-5-2011 at 18:12

HMM I detect an almond oder in the solution when just enough DMSO is added to turn it dark yellow. If the solution turns dark red the Almond oder is weaker.

Trifluoroacetic - 18-5-2011 at 18:18

Quote: Originally posted by DJF90  
I was thinking perhaps you got a Canizzaro reaction occuring.
I think you might be right. I wonder if this coul be useful for anything?

The solution smells good! Perhaps it will taste good too?

DJF90 - 18-5-2011 at 18:29

Well I'm not sure I'd want to taste it. Something you could do is check the pH (dissolve a small amount of reaction mix in water first). The odour could be either the acid, the alcohol, or the ester (perhaps admixed with the odour of cinnamaldehyde itself). I cant think of any other reasonable explanation at the moment in time.

Trifluoroacetic - 18-5-2011 at 18:50

Hmm? I took the Isopropanol mixture and added potassium metabisulfite to it and as expected it crystalized due to the formation of a bisulfite adduct. Then I added the bisulfite to the DMSO solution and no adduct formed. This is strange. A dark precipitate is now forming in the DMSO solution that didn't have any metabisulfite added to it.

ThatchemistKid - 18-5-2011 at 19:02

Would cinnamaldehyde not under go 1,4 addition with nucleophiles? I am not sure if it would occur over a cannizzaro though?

Trifluoroacetic - 18-5-2011 at 19:12

The yellow solution is quite basic as it turned my universal indicator slip dark blue. Perhaps I have a bunch of worthless condensation products. I'll put this in a mini distilling flask and se what comes off tomorrow.