Actually I have synthesized N,N-substituted pyridine-2,6-dicarboxamides and I am trying to synthesize its Pd pincer complex by using Pd(OAc)2. I followed one procedure to do that (refluxing dicarboximide and Pd(OAc)2 in ACN and DCM for 12 hrs) but i didnt get any solid when cooled reaction mixture to room temperature(getting solid at the end is mentioned in many articles). Whats going wrong in my case?
Can anyone help me regarding this?
It's possible that your product is either too soluble to precipitate at room-temp from the reaction mix--which you can fix by: a) concentrating your product solution b) cooling your product solution or c) adding an antisolvent like pentane (or some combination thereof).
It is also possible that you produced a mixture of many products or didn't form the desired compound at all.
I think it is worth taking a sample of your product solution and removing all the solvent from it, so you can take NMR 1H spectra as well as IR to see if you have formed any of the desired compound
Aaron's suggestions are top notch. The best thing to do at this point is to completely strip all solvent from a small portion of your complex, and analyze it - just as Aaron's suggested.
Products need not always crash out, even if that is what the prep suggests.
I am asking this more out of curiosity: Are you displacing the -OAc's on the Pd? (i.e., is your amide mono- or di-substituted?) If you are indeed displacing the acetates, you may want to read-up about the stability of the Pd-complex you are making (which is perhaps why you are even adding ACN), and accordingly decide on the use of anti-solvents.
Good luck
Thanks Aaron and Sudarsan for your suggestions.
Actually I checked TLC of that reaction mixture and it is showing single spot so i think there is only one product. As per your suggestions, if I check the NMR and suppose my expected product is formed, then will I get different NMR spectra than my starting material???
sudarsan, my starting compound is N,N-substituted pyridine-2,6-dicarboxamides, which has three N and which generaly acts as a tridentate ligand.
There is no any specific reason behind adding ACN, I just reffered one article whos material is similar to my compound.
(Guys as this field is new for me, please dont mind if I am asking you stupid doubts)
Once again thanks :)
Yes Shrikant, if you did HNMR or CNMR you will find a difference in the peak's chemical shifts if the product is formed, and it is better to analyze both the ligand and your product to compare. Also inorder to precipitate you can try to exchange your counter anions ( actetate) with another anions such as hexaflourophosphate using its ammonium hexafluorophosphate salt solution.
Good Luck
Mr. Pharande,
Generally the employment of Pd(OAc)2 is not good decision, studying coordination processes. There is better to use PdCl2 salt.
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