Dear researchers,
For the first rxn, I performed Claisen Schmidt condensation reaction to form an animated- diarylpentadienone product in cold conditions by dissolving aminoacetophenone in ethanol with 6M NaOH as a catalyst and then adding cinnamaldehyde. After an overnight reaction, a yellow product spot was formed on the TLC.
However, the issue begins during the second rxn. For 2nd rxn, sulfonamide-containing diarylpentadienone synthesized via condensation of the equimolar quantity of 4-trifluoromethylbenzene sulfonylchloride and aminated diarylpentadienone in methanol before the addition of pyridine (catalyst). The rxn is not completed after running overnight for 24 hours. According to the TLC, both the starting material (SM) spots and product spots look exactly similar with the same Rf value, showing the rxn does not happen. if the rxn continues longer than 24 hours, the product spot starts to vanish. 1H NMR shows the rxn is not working with some missing H peaks from the second rxn for the sulfonamide compound.
For both rxn 1 & 2:-
8:2 (hexane: ethyl acetate) is used as a mobile phase for TLC.
I have tried TEA as a catalyst replacing pyridine for rnx 2 still the reaction is still not working. I really need help.
Any explanation or suggestions regarding my current issue will be highly appreciated.
You are trying the N-sulfonylation in 2nd rexn.
I would suggest you to use dichloromethane as solvent and triethylamine as catalyst. Make it sure that you provide moisture free conditions to the reaction mixture at 0⁰C. The reaction might not undergo 100% completion, but you can recrystallize the product if so.
Rubina Munir thank you for the suggestion. May I know why my previous rxn wasn't working according to your perspective? What could be the factor? I will try out this new method. So, since I can recover my product via recrystallisation. Should I skip column chromatography before recrystallization? Can I use ethanol for recrystallisation? thank you
Please share the reported method so that I may see it. Some times, the reported procedures don't work with our reactants.
Moreover, ethanol is a protic solvent which also contains moisture content in it which reacts with your sulphonyl chloride and converts it into sulphonic acid.
You can try to recrystallize your product with ethanol.
I think, column will not needed.
N-sulphonylation is better carried out in polar aprotic or less polar solvents as this is an SN2 type reaction.
Rubina Munir noted I will share the paper with you. thank you again !!
- Badges
- Science topic
- Similar topics
- Chemistry
- Organic Chemistry