To a resin flask equipped with a mechanical stirrer and condenser are added 37.8 gm (0.3 mole) of melamine and 195 gm of 37% (2.4 moles) formaldehyde solution. The pH of the mixture is adjusted with caustic to pH 8.3. The reaction mixture is heated on a water bath with stirring at 50°C for about 70-80 min, at which time all the melamine has gone into solution. On cooling the product separates as a thick white precipitate and is filtered to afford the monohydrate (after drying at 50°C). Yield: 62.5-69.0 gm (68-75%), m.p. 147°-153°C.
Preparation of Hexamethylolmelamine
NOTE: Approximately one-third of the product melts at 120°-140°C.
This reaction can also be carried out at room temperature over a two week period to give a quantitative yield, m.p. 150°-154°C. Infrared absorption data (KBr) are (microns): 2.93 (s), 3.37 (w), 6.40 (s), 6.65 (m), 6.90 (w), 7.20 (m), 7.50 (w), 7.82 (s), 8.35 (w), 10.10 (s), 10.90 (w), 11.45 (w), 12.30 (w) (where s = strong, m = medium and w = weak).
