I am using Nicotinic acid for synthesizing some ester derivatives. I am using EDC/DMAP/DMF. Whenever I tried to purify the ester from reaction mixer with EtOAc or EtOAc-Hexane solvents (liquid-liquid extraction), I was unable to purify the target? Can anyone suggests me how to purify the esters from the reaction mixture?
Nicotinic acid is sparingly soluble in ethers, you might as well try THF or Et2O as solvent. I am also curious that why not use excessive alcohol to consume the Nicotinic acid?
What sort of ester? It may be possible to dissolve the product in DCM and wash the product with NaOH solution to remove the acid. The problem is if the ester is unhindered, there is a possibility of some ester being hydrolysed.
Dear Eugene Yang, Thank you. I would like to synthesize ester using Propargyl Alcohol. But when I used EtOAc to purify the target compound, I found the compounds don't go with EtOAc.
In case you want to consider the separation of nicotinic acid by reactive extraction; cf.: S. Kumar, K.L. Wasewar, B.V. Babu, "Intensification of nicotinic acid separation using organophosphorous solvating extractants by reactive extraction", Chem. Eng. Technol., 31(11) 2008, 1584-1590.
I think base wash will be the best. Some DMF may be left in your crude mixture and affects the column purification. It may be better to use DCM instead.
Alternatively you can do alkylation of propargyl bromide instead, or use excess propargyl alcohol to drive the reaction to completion.
Also you could use a sodium carbonate or bicarbonate was to minimise hydrolysis. I would be surprised if the ester was not readily soluble in dichloromethane.
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