Cub ran his first NaBH4 reduction few days ago and found that this reaction is simply amazing.Only the dissolution of methylamine in methanol was bit complicated as methanol had to be constantly cooled during bubbling.Methanol was weighed before and after gassing and about 30 grams of methylamine had been dissolved in methanol.Added 80 grams of ketone(solution turned orange) and prepared an ice bath.Reduction took place in 1 liter round-bottom.Temp was kept below 15C with a bath filled with ice/NH4NO3 and everytime it dropped to 7-8C more borohydride was added which caused foaming and rise in temperature.Total of 14 grams of borohydride was used but when about 9 grams had been already added further addition didn't make temperature rise like it had been(probably all that there was to reduce was already reduced),still that 5 grams was thrown in and left solution to stir for 12 hours at low speed.Next morning cub discovered that colour of solution had turned to bright yellow(it was orange just after addition of ketone to MeOH/MeNH2).Solution was poured to sep funnel and added 1 liter of water and some 100 mls of DCM.Sepped off bottom layer and washed other one with some DCM.DCM and bottom layer was poured together.Evapped DCM to yield about 70 mls of almost colourless liquid with a distictive smell(little like methylamine or isosafrole glycol).Cub has never got such nice freebase from Al/Hg reduction.Freebase was dissolved in 600 mls of xylene and result was a colourless liquid.It was gassed and whoah,just like a toothpaste.Filtered at vacuum and gassed again,same result.Filtered and tested xylene to contain no more freebase(it was acidic).Bright white powder was rxtalled from acetonitrile(1 gr and 7 mls),dried.Yield was 70 grams of white powder that tasted quite bitter.This makes w/w yield nearly 90%,cub has never got such yield and purity with an Al/Hg reduction(w/w yields rarely exceeded 75%).NaBH4 is the shit,cub will never run an Al/Hg again.This was cub's first NaBH4 reduction and results are impressive.
PMK used was 96% pure confirmed by nMR(C13 and something else,sorry,cub knows nearly nothing about analysis,if needed could post some charts with some peaks,dunno how these are called),other 4% was safrole.
Borohydride,methylamine and methanol were all lab grade.
Special thanks to LabTop for posting such nice writeup(check rhodium site).