[Ada]

Has anyone ever tried to react 3-nitrophthalyic anhydride with N, N dimethylenediamine? I have not taken my organic chemistry class yet but am working in an organic lab this summer and was wondering why the reaction (in xylene) would be forming a gummy solid immediately upon heating and beginning reflux. I have run the reaction for 5 hours but the mass spec and tlc are still not showing the product.

[DavidW]

I have one question... when you analyzed by tlc and mass spec, did you just take a small sample from the solvent, or did you try to analyze the gummy solid?

I've never run this reaction (btw I assume you meant "3-nitrophthalic anhydride"), but I've seen examples of this reaction done in more polar solvents such as acetic acid and water.  I wonder if it's possible that the product you are looking for is insoluble in xylene, and just solidifies and becomes the gummy solid as it's formed.  If that's the case, then you won't be able to see the product if you just analyze the liquid.

[lavoisier]

I think DavisW is right about checking first if you're analyzing correctly your rxn mixture.

If this doesn't solve the problem, the solvent may indeed be unsuitable as he suggested.
In fact, if the amine you're using is N,N-dimethyl-ethylenediamine (Me2NCH2CH2NH2), you have a zwitterionic intermediate coming from the 5-membered ring opening. Add the fact that the reaction produces water (yes, very little, but you never know)... it may be that this intermediate just precipitates in the highly lipophylic medium, and can't react further.

If you want to make phthalimide from phthalic anhydride, you just boil the latter in 32% aqueous ammonia and then heat it to 'death' on a flame (an old Vogel's didactic procedure). I guess they first form the intermediate amide-acid, and the final heating is meant to favour the elimination of water with cyclization to the imide.

Conclusion: you may try a water-miscible solvent or water itself. If you detect by MS the (M+H2O) compound, then you have to make it cyclize in some way.