Stability of pre-distilled MDMA freebase

[biffman]

It may be SWIM's imagination but it seems that if one waits too long (several days) before doing the final freebase distillation after the DCM extracts have been collected the final product is drastically reduced in yield and there is significant volume of darker product in the original distillation flask.  Before when the product was distilled immediately almost all came over and very very little dark residue was left in the original flask. 
  It was noticed after sitting for a few days at least that the flask contents darkened significantly before the distillation was commenced.
  Anybody else experience this?  Perhaps there was still some NaOH remnants in the original product due to slightly sloppy DCM extraction but probably not more than usual.
  A new batch of home-made methylamine was used but this shouldn't be a problem I wouldn't think since it never has been before.
   Any thoughts?

[Midi]

It's pretty much common knoledge that ketone that is not pure, decomposes if left at room temp, giving shit yields.

If you ever have to hold off on the final distilliations the rxn should be stuck in the fridge. Personally, for what ketone is worth per gram, I wouldn't do the rxn if I didn't have the time to see it all the way through to pure ketone. Too much regret otherwise. Yields are never as good.

[biffman]

Sorry if I wasn't being clear but the ketone is fine and it is always kept in the freezer.  I was only referring to the final distillation to bring over the MDMA freebase after the Al reductions and A/B extractions. This time the yeilds were only about 60% of what is normally obtained with the same ketone using the same procedure as normal.  The only difference was that it was allowed to sit several days before the final distillation to the final product.
  As to the ketone being unstable at room temperature, yes I am aware of that however several years ago I was in Slovakia and had the opportunity to use room temperature store legally obtained ketone.  There was approximately 10 litres of the stuff and the reaction that I did gave fairly good yields.  Not as much as could be hoped for but considering that it had sat for years gave between 65-85% of what could be hoped for using the Al reduction method.  Stuff was free so who was i to complain.