Urea → Cyanuric acid

300 g of urea prills and 495 g of N-methylpyrrolidone were charged into a 1-liter glass reactor fitted with stirrer, condenser and thermometer. The reaction mixture was heated with a mantle and maintained at reflux for a 2-hour period during which the reaction temperature increased from 185° to 212° C. On cooling, the reaction mixture solidified at about 35° C. The reaction mixture was reheated to about 160° C. to make it stirrable, cooled to 40°-50° C. and filtered. The cake set up in the filter funnel and had to be broken up. On washing with water, the filter cake solidified again into a hard cement-like solid with release of some heat. The solid was broken up, washed further, and dried giving 129 g (60% yield) of impure cyanuric acid containing 5.6% ammelide and 0.4% ammeline.

1. customfitted with stirrer, condenser
2. temperatureThe reaction mixture was heated with a mantle and
3. temperaturemaintained
4. temperatureat reflux for a 2-hour period during which the reaction temperature
5. temperatureincreased from 185° to 212° C
6. temperatureOn cooling
7. customsolidified at about 35° C
8. customwas reheated to about 160° C.
9. temperaturecooled to 40°-50° C.
10. filtrationfiltered
11. washOn washing with water
12. washwashed further
13. customdried

ORD record

ord-b480209d1ef94b459ed1acda458a639a

Source dataset

uspto-grants-1983_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04423216