A.
α-Methoxyphenazine (
condensation).
Two hundred grams (0.42 mole) of powdered lead dioxide (Note
1) is added to a solution of
10 g. (0.07 mole) of pyrogallol monomethyl ether (p. 759) in
3 l. of dry benzene in a
1-gal. narrow-necked acid bottle. The bottle and contents are placed in a shaking machine and shaken for 10–20 minutes (Note
2). The reddish brown solid is filtered through an
11-cm. Büchner funnel, and the filter cake is washed once with
400 ml. of benzene. To this filtrate there is added, immediately and with mechanical stirring, a solution of
6 g. (0.06 mole) of o-phenylenediamine (Note
3) in a mixture of
80 ml. of glacial acetic acid and
200 ml. of benzene. The solution, which becomes dark brown, is allowed to stand at room temperature for 1.5 hours; it is then divided into two portions and each portion is washed, in a
3-l. separatory funnel, three times with water, twice with
5% sodium hydroxide solution, and finally twice with water, 100-ml. portions being taken each time. Each of the
benzene solutions is shaken with
50 g. of anhydrous sodium carbonate and
5 g. of Norit and filtered through an 11-cm. Büchner funnel. Each filtrate is stirred with
50–60 g. of activated alumina (Note
4) until a filtered sample shows a light-yellow color. The
alumina is filtered on a folded filter and washed with
benzene until the washings are almost colorless. The
benzene is removed from the combined filtrates by distillation under reduced pressure on a
water bath at 40–50°. The residual light-yellow solid (Note
5) is recrystallized by dissolving it in the least possible amount of hot
pyridine, adding water to the point of incipient precipitation, and cooling. The light-yellow crystals are filtered on a
7-cm. Büchner funnel, washed with water, and air-dried. The yield is about
5 g. (
33%) of a product that melts at
167–169° (Note
6).