Dear RG members
I design to carry out Bargellini reaction on certain phenol. In this reaction, the first step involves the reaction between NaOH and chloroform. I try to dissolve the first reagent in the other, but I failed. Can anyone suggest how could be dissolved NaOH in chloroform?
Regards
Dear Yasser Fakri Mustafa as you know, the Bargellini reaction involves the reaction of a phenol and a ketone with the trichloromethanide anion which is generated in situ from chloroform and NaOH according to the attached reaction equation (which was taken from Wikipedia). It is not necessary (and impossible anyway) to dissolve the sodium hydroxide in chloroform. Please find attached two original research papers in which this reaction is described. Both articles are cited in the Wikipedia entry. In all cases, powdered NaOH is added to a mixture of the phenol derivative and the ketone, and then the chloroform is added in the final step. So don't worry about "dissolving" NaOH in chloroform.
Dear Frank T. Edelmann
Thank you so much for your opinion and contribution. The employed phenol contains an ester group, is the sequence of addition may affect the ester stability? Also, why NaOH here acts as a base rather than a nucleophile attacking the ketone?
Thanks again
Dear Yasser Fakri Mustafa I'm not that deeply involved in this kind of chemistry to give you a definite answer. However, chloroform is more C–H-acidic than acetone. It has a pKa value of 15.7 according to Wikipedia (https://en.wikipedia.org/wiki/Chloroform) whereas the pKa value of acetone is 26.5 in DMSO (https://en.wikipedia.org/wiki/Acetone). This is certainly due to the resonance stabilization of the trichloromethanide anion, CCl3–, which is isoelectronic with BCl3.
The finding that the ester is not hydrolyzed has certainly something to do with the experimental condition that NaOH is always added as a solid (fine powder) to the reaction mixture. During the reaction, insoluble NaCl is formed as a precipitate so that is is constantly removed from the equilibrium. Please see that attached paper in which it is "thickening of the reaction mixture due to precipitation of sodium chloride" is mentioned.
Dear Frank T. Edelmann
Thank you very much. Your opinion is highly valuable.
Thanks again
Dear Yasser Fakri Mustafa I consider Frank T. Edelmann an expert, and I acknowledge his answers and links (references) in response to your question.
Regards!
Dear Arbind K. Choudhary
Thank you very much for your kind contribution. Professor Frank T. Edelmann is not only an expert but also a supportive and helpful scientist.
Regards
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