[wonka_vision]

Hi everyone - I'm trying to synthesize an amine with a protected ketone group using a Gabriel synthesis. Basically I'm reacting potassium phthalimide with chloroacetone and then protecting the ketone with ethylene glycol. I can isolate this product, but I'm having trouble with the next step, which is the breaking of the amine from the phthalimide using hydrazine hydrate (shown in image link below). I have tried to do this in ethanol, which leads to an enormous amount of precipitate that is very hard to get rid of, as well as in toluene, both at the reflux temperatures of the respective solvents. The toluene method occurs in two phases since the hydrazine hydrate isn't soluble in the toluene that my starting material is dissolved in. In both cases, I rotavap the solvent off, but I get very little product in the end (even after very long reaction times, and this should be a fairly rapid reaction at high temperature). When I try to isolate the product by taking it up in chloroform, smoke is emitted and the final product goes from yellow to blue slowly; however, there appears to be no degradation of the product in the NMR.

http://i.imgur.com/0AHz4AK.png

So my 3 questions are: Does anyone see how I could improve my yield? Does anyone have any idea why my amine product would slowly turn blue after being isolated? Finally, why would my amine product emit smoke when contacting chloroform?

Thanks!

[discodermolide]

You need to filter off the precipitate before evaporation of the solvent. Perhaps use some filter aid to prevent it clogging the filter.
As to the smoke, do you still have traces of hydrazine left when you dissolve the product in chloroform. Chloroform is quite a reactive compound.
Why don't you isolate the amine as a salt say of a weakish acid like tartaric or benzoic acid? You can then crystallise it.

[wonka_vision]

You need to filter off the precipitate before evaporation of the solvent. Perhaps use some filter aid to prevent it clogging the filter.
As to the smoke, do you still have traces of hydrazine left when you dissolve the product in chloroform. Chloroform is quite a reactive compound.
Why don't you isolate the amine as a salt say of a weakish acid like tartaric or benzoic acid? You can then crystallise it.

Hm I would love to be able to crystallize it. Could you point me in the direction of how I can learn about doing this?

[discodermolide]

No references.
Just dissolve the amine in ethanol, warm and add 1 equivalent of tartaric acid cool and see if it crystallises out.
Do it on a small scale first. If it does not crystallise try a different salt/ solvent.

[wonka_vision]

Will do - thanks!