Help!! Advice needed, SWIM is having problems with workup of a LAH reduction of 2,5-Dimethoxy Beta-Nitrostyrene.
From a new, sealed can of LAH, 20g was added to stirring dry THF in an ice bath. No fizzing was noticed throughout the addition. The THF was from a new bottle and dried overnight over MgSO4. 23g of 2,5-DMBNS (orange needles recrystalized from IPA) was dissolved in 350ml dry THF. The DMBNS solution was slowly added to the LAH/THF in a way such that the temperature never exceeded 15C. Mixture was refluxed w/stirring for 20h. Afterwards, mixture was grey.
25ml of 50:50 THF/H2O was added slowly to the rxn mixture, followed by ~10ml IPA, then 20ml 4M NaOH, then an additional 60ml H2O. There was a lot of foaming and heating of the solution. Flask was once again placed in an icewater bath. Stirring was continued for 1hour, and here's where SWIM is stuck!
SWIM expected the mixture to turn pasty white, then the Li/Al hydroxide salts would fall out as filterable granules. But this didn't happen! After 1 hour stirring, mixture was still grey. SWIM added ~10ml more IPA (still stirring of course) and no fizzing was noted, so SWIM assumed all LAH is destroyed. SWIM proceeded to slowly add ~50ml of ~20% NaOH. Solution was now light brown, but there was no pasty sludge or precipitate nicely settling out.
This was all done under light Argon flow by the way.
SWIM is letting the suspension settle out as much as possible, then SWIM will try to vac filter slowly as much as SWIM can. The mother liquor becoming visible during settling is deep red in color. What might SWIM do? If SWIM can get the mother liquor away from all suspension, is it safe to remove THF/H2O (under reduced pressure SWIM supposes) and proceed to either vac distill what is hopefully 2C-H, or take it through an acid/base extraction?
Just when SWIM thinks they know what they're doing, something unexplainable to SWIM happens! SWIM considered continuing to add NaOH solution and hope something happens, but they've added what seems to be far more than required in other bee's writeups. pH is ~9-10 right now.
Thank you, any prompt recommendations would bee appreciated.
SpicyBrown