2.4.2. Synthesis of 4-methoxyphenol
Twenty-three grams H2O2 (30%) was added to 19 ml
HCOOH (98–100%) to synthesize performic acid. The latter
was added to an intensely stirred solution of 4-methoxy-
benzaldehyde (12 ml) in 200 ml DCM (DCM was chosen
since it is inert towards H2O2
). The stirred mixture was
allowed to reflux at 39 8C for ca. 20 h. The performic acid
was added in 5 ml quantities with 15 min intervals. Initially,
the reaction mixture was colorless, but after half an hour, a
pale yellowish shine appeared. During the reaction, the color
became more intense and changed to yellow-brown. When
the reaction was finished, the DCM phase was isolated and
the solvent removed via vacuum distillation. Then, 200 ml
NaOH (20%) and 75 ml MeOH were added. The mixture
was stirred for 1 h. MeOH was removed with vacuum
distillation and the alkaline mixture was acidified with
HCl (32%) till pH 1. The mixture was extracted with 2-
150 ml DCM. The DCM extracts were combined and the
solvent was removed via vacuum distillation. The 10.5 g of a
brown liquid that easily solidified upon contact with air
remained. GC-HSPME/MS analysis indicated 4-methoxy-
phenol as main component. Purified 4-methoxyphenol was
white