A
250 mL, one-necked, round-bottomed flask equipped with a magnetic stirring bar is charged with
96.5 g (0.65 mol) of phthalic anhydride (Note
1) and
52.5 g (0.50 mol) of 2-nitro-1-propanol (Note
2). A
10-cm vacuum-insulated Vigreux column, a
stillhead fitted with a thermometer, a
condenser, a
50-mL, round-bottomed receiving flask, and a
water aspirator are installed in due order, and the reaction vessel is placed in an
oil bath and evacuated to 110 mm (Note
3). The bath temperature is raised to 150°C and maintained for 30 min while the
phthalic anhydride melts to give a homogeneous solution. The receiving flask is immersed in an
ice bath, stirring is started, and the bath temperature is raised to 180°C. As the reaction mixture darkens, green-colored
2-nitropropene is gradually distilled off with water, bp
50–65°C (110 mm). The bath temperature is held at 180–185°C until the distillation ceases (ca. 1 hr). The distillate is transferred into a
50-mL separatory funnel, and the lower layer is separated from water (Note
4) and dried over anhydrous
magnesium sulfate. Redistillation under reduced pressure through a
10-cm vacuum-insulated Vigreux column (Note
5) gives
25.0–31.4 g (
57–72%) of
2-nitropropene, which is collected in an
ice-cooled receiving flask as a transparent green liquid, bp
56–57°C (86 mm),
nD20 1.4348 [lit.
2 bp
58°C (90 mm),
nD19 1.4292,
d201.0492] (Note
5). The distilling flask is cooled to room temperature before the vacuum is released.