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ChemicalBook CAS DataBase List Melamine
108-78-1

Melamine synthesis

14synthesis methods
The standard route to melamine is from urea. Urea is heated in the presence of ammonia at 250-350°C and 4--20 MPa. The reaction probably involves the simultaneous dehydration and hydration of urea to form cyanamide and ammonium carbamate; trimerization of the cyanamide then leads to melamine:


Thus only 50% of the urea used gives melamine in one step and ammonium carbamate has to be separated and converted to urea for recycling. Despite this limitation, the urea route is the most economical of currently available routes.
780722-26-1 Synthesis
Guanidine, cyano-, (E)- (9CI)

780722-26-1
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Yield:108-78-1 93%

Reaction Conditions:

with potassium hydroxide in water monomer;dimethyl sulfoxide;

Steps:

4 EXAMPLE 4

EXAMPLE 4 A solution of 30 g of dicyandiamide and 30 g of solid cyanamide in 120 g of dimethylsulfoxide is added over a period of 11 minutes to a mixture, heated to 180° C, of 4.0 g of potassium hydroxide and 4.0 g of dicyandiamide in 80 g of dimethylsulfoxide. After an additional 5 minutes of reaction time at 180° C the mixture is cooled. The precipitated melamine is removed by filtration, stirred up in water, and again filtered. The first yield amounts to 53.8 g of melamine or 84.1%. As a second yield, an additional 5.7 g of 8.9% of melamine was found in the filtrate and wash water, so that the total yield amounted to 93.0%.

References:

US4069383,1978,A

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