HMPA is "Hexamethylphosphoramide. Your NH2 as a nucleophile is very poor. You have to forcé it to enter into reaction. Alternatively you may use the acid chloride of phthalic acid, which is much more reactive.

Use HMPA and microwaves

Thank you very much Sir.

Do HMPA is "Hexamethylphosphoramide"..

Meaning is all the reaction should perform under microwave.

Actually I have done trying with NMP, DMAc, DMF also DMSO both at ambient and higher temperature but the result still negative.

Thanks

HMPA is "Hexamethylphosphoramide. Your NH2 as a nucleophile is very poor. You have to forcé it to enter into reaction. Alternatively you may use the acid chloride of phthalic acid, which is much more reactive.

Thank you very much sir...

This is very useful basic fundamental, and help me to unlock my brain :) ...

I'll do some optimization in term of to increase nucleopilicity for the next synthesis ...

Maybe HMPA is toxic, no?

Sir Arnaud Gautier: yeahh maybe HMPA toxic, I agreed but it ''maybe''. thus, as a chemist we should know how to deal with toxic materials..this is the 1st time I deal with HMPA....thanks for reminding. I'll do some precaution during handling this ;)

Sir Teodoro: Yeahh..you are right... HMPA is quite selectively solvates cations due to its molecules are tetrahedral core and a P-O bond is highly polarized.. since I performe SN2 reaction it will accelerates forward reactions... ;) am I right

Think so! Good luck

Maybe you should start from trichlorocyanuric acid better than melanine?

The reaction was successful in the presence of HCl under nitrogen gas. However, the result has a low molecular weight and brittle in a form of film.

Thus this is another challenge for me to produce high molecular weight and flexible film form. Now it's about processing.

So. What kind of optimization should I consider..

Use acetic acid as solvent; I am wondering whether product is fluorescence compound? I worked for similar compound which was fluorescence and purified with basic alumina treatment where your SM can be removed efficiently, but product was phthalimide not free carboxilic acid.

Thank you...That good to hear from you...

I wondering by using acetic acid (protic) as solvent, it will enhance the bacisity. regarding the fundamental in polyimide synthesis, aprotic solvent (nmp, dmso, dmf etc) contributing to increase nucleophilicity forward reaction. Thus, maybe acetic acid taking role to react with melamin not anhydride.

however, you have try it..did your sample in solid form or else??.

I am prefer to prepare a flexible film...but until now my sample very brittle

In my case it was solid. pKa in your melamine is 5.39, 3.05, and 0.7 so you need not to very about the protic solvent. Moreover your melamine is a very weak base so reaction completion may be difficult beacuse as it reats with anhydride, its basicity will decrease.

I would agree with Arnaud to start from Cyanuric chloride. You should be able to replace the chlorines by phthalimide successfully. Partial hydrolysis of the resulting compound should yield the desired product.

I would suggest to try to use water as solvent; dissolve the amine in water and slowly add the anhydride. There are several examples of reactions where water apparently should be avoided and they work better when it’s used as solvent...

Dr. Othman, so could successfully make anhydride-melamine based Polyimides using HCl ? How about HMPA ? Was it useful ?