From: chm4sdw$##$leeds.ac.uk
Date: Sun Apr 23 2006 - 15:36:04 EDT
I recently carried out a Mannich reaction with N-(2-hydroxybenzyl)-p-toluidine,
paraformaldehyde and potassium hydroxide in methanol. All the reactants were
in the solid state. The product (theoretically
3-(p-methylphenyl)-2H-1,3-benzoxazine), which was inititally isolated by rotary
evaporation, should have been a white solid but was instead an extremely
viscous orange liquid the colour of burnt sugar, which could not be
recrystallised from aqueous ethanol (as the manual suggested).
My lab supervisor, who is highly experienced, believes this undesired product to
have been caused by polymerisation of the paraformaldehyde. Can anyone suggest
a way to isolate the product from the paraformeldehyde, or (failing that) to
stop the paraformaldehyde polymerising in the first place? This reaction is
quick (20 minutes) and theoretically easy, so it can easily be repeated if
necessary.
Thank you in advance,
Sam Woodman (2nd year chemistry undergraduate, Leeds University)
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