Quote: Originally posted by qt314 | During optimization studies I reached 90% yield twice by employing reverse addition (borohydride in ipa/water, nitrile added slowly). Apart from these
2 experiments, all times yield was consistently 20-30%. |
Doesn't it sound like a lower concentration of nitrile and intermediates and/or lower temperature is helping? Dimerization is expected to be a problem
even more so with phenylacetonitriles, which may explain the unpopularity of this route to PEAs (by amateurs). PS instead of increasing the
borohydride it would not be uninteresting to increase the Co from those low levels and see if perhaps a larger amount of the boride is a good thing.
[Edited on 28-1-2019 by S.C. Wack] |