antibody2 I mean drying methanol with MgSO4. Would that interfere with NaBH4 since MgSO4 is a little acidic and I suppose a little will be dissolved in the methanol. Suggestions?

Will it be enough to dry the methanol with mol sieves or would it be better to dry it with MgSO4 then filter it out and dry it thoroughly with A3 mol sieves?

Sneak, thanks. I don't know what's next to be honest. But something will be happening for sure

As soon as I filter out the xtals I ll let you guys know.

Ok next run will be with mol sieves and i ll keep you updated. So would it be better to strain out the mol sieves adter imine formation or you think it ll be better to leave them in and catch whatever water sbould be present even during addition of NaBH4? Would mol sieves interfere with the reducing agent?

Having the seives in the reaction during the imine formation will help drive the reaction by taking up the formed H2O (imine formation creates H2O as a byproduct), after that you don't really need them, although they shouldn't hurt anything either.

Having the sieves in the reaction during the imine formation will help drive the reaction by taking up the formed H2O (imine formation creates H2O as a byproduct), after that you don't really need them, although they shouldn't hurt anything either.

Good advice from antibody2. Also finely powdered anhydrous sodium sulphate IF you don't want to use molecular sieves.

Sodium sulfate is a neutral salt, which forms aqueous solutions with pH of 7. http://en.wikipedia.org/wiki/Sodium_sulfate#Acid-base

I realised I had some isosafrole in my ketone by redistilling the ketone. So now the ketone used is even purer than before.

I decided to run a 50g scale reductive amination.

I mixed cold ketone with methanol (predried with mol. sieves) + 33% methylamine ethanol solution and added molecular sieves. Extract quantities reported below:

50g MDP2P (0,28 mols)
115ml Methanol
47g Methylamine ethanol solution (0,49 mols of methylamine base)
30g mol. sieves 8-12 mesh (to catch up to 6g water)

I waited 1 hour for imine formation, while stirring the mixture at room temperature. After 1h I cooled everything down to 7°C in an ice water bath and start adding 5g NaBH4 in the usual fashion, stopping each time temp climbed to 15-16°C and start again when temp fell to 7-8°C. I noticed that this time the imine solution turned a kind of brownish orange and some of the mol. sieves started to pulverize due to attrition with oval stirbar and RBF.
 
After 1,5h to 2h ( i don't remember exactly) addition was finished. At this point external cooling was taken away and the mixture was left to its own devices all night and it will go on stirring (not too strongly maybe 200-300rpms) all day until tonight.

I am unsure of how to proceed. Last time I flooded mix with water but I'd rather distill off the methanol and work up from there. Maybe it would be better to make everything slightly acidic first, then distill off the methanol, wash with non polar, add NaOH and extract amine in NP for gassing.

Another thing I am not sure about is whether I did the right thing leaving the mol sieves inside the reaction all the time. The sieves slowly disintegrated into a fine powder. Apart from the cost, (I did't buy bulk so they were not that cheap, although I didn't use much) will their effectiveness be diminished by breaking them into a powder or will that powder interfere with the reduction by reacting with the borohydride?

Maybe next time I should prepare imine in a simple erlenmeyer, leave it there for some time then transfer liquid in RBF to start NaBH4 addition. Do you guy think that imine should be prepare at room temp or at 5°C. I have read different views about this in the various archives and threads (hive mostly).