In a
2-l. round-bottomed flask fitted with a
reflux condenser is placed
970 g. (1200 cc., 13.1 moles) of n-butyl alcohol. This is warmed, and
180 g. (3 moles) of urea is added to the warm liquid in small portions, with shaking. While the temperature rises, care must be taken that the
urea goes into solution without melting and does not form a layer of molten
urea beneath the solution (Note
1). The last portions of the
urea are finally dissolved by boiling the liquid. The solution is then refluxed for thirty hours (Note
2), during which time
ammonia escapes from the top of the condenser (Note
3). The reflux condenser is then removed and the liquid is distilled through an
efficient column until the temperature of the liquid reaches 150°. The distillate consists of
butyl alcohol containing
ammonia and may be used directly in another run. The material which remains in the flask solidifies on cooling. It is boiled with
1 l. of ligroin (b.p.
60–90°) (Note
4), filtered, and the undissolved solid again boiled with two 100-cc. portions of
ligroin, filtered, and finally washed on the filter with
100 cc. more of warm ligroin. The white gritty material which remains undissolved is practically pure
cyanuric acid (Note
5). The yield of
cyanuric acid is
12–18 g. (
9–14 per cent of the theoretical amount).
The combined
ligroin filtrates and washings are distilled under atmospheric pressure, using a column, until the temperature of the liquid reaches 150°. The residue is then distilled under reduced pressure and the fraction boiling at
108–109°/14 mm. (Note
6) is collected. The product is pure and melts at
53–54°. The yield is
263–266 g. (
75–76 per cent of the theoretical amount).