piperonal from pepper
piperonal [merck index]
purification of piperonal 
THE MERCK INDEX on CD-ROM / Version 12:3 / 1999
roempp lexikon chemie version 2.0, cd-rom,
stuttgart / new york: georg thieme verlag 1999
patent JP8099971, 1996-04-16
"purification of piperonal"
HARADA KATSUMASA, SUGIYAMA TOMOSHI; UBE IND LTD
PURPOSE: to obtain nitro compound-free piperonal as a product of high
purity by oxidizing 3,4-methylenedioxymandelic acid with nitric acid.
CONSTITUTION: in the purification of piperonal formed by nitric acid
oxidation of 3,4-methylenedioxybenzene which is synthesized from
1,2- methylenedloxybenzene and glyoxylic acid, the reaction mixture
containing piperonal is treated with a sulfite salt and the piperonal sulfite
is rinsed with an organic solvent, then the salt is decomposed with an
acid or a base to regenerate piperonal.