Process for the preparation of 4-amino-N-tert-butyl-4,5-dihydro-3-isopropyl-5-oxo-1H-1,2,4-triazole-1-carboxamide (Amicarbazone)

1. A method for the preparation of Amicarbazone comprising reacting 4-Amino-2,4-dihydro-5-(1-methylethyl)-3H-1,2,4-triazol-3-one (TAZ) with tert-Butyl isocyanate (TBIC) having low purity to form Amicarbazone,

wherein said low purity TBIC has a purity of less than or equal to 85%, and

wherein 18% or more molar excess of TBIC with respect to TAZ is used.

2. The process according to claim 1 , comprising:

a) preparing a solution of TAZ, potassium hydroxide, and toluene;

b) raising the temperature of the solution obtained in step (a) to the range of 50° C. to 70° C.;

c) adding the low purity TBIC without distillation to the solution of step (b);

d) heating the solution obtained in step c) at temperature in the range of 60° C. to 75° C.; and

e) cooling the solution obtained in step (d) to form the Amicarbazone.

3. The process as claimed in claim 2 , wherein the solution in step (e) is cooled to the temperature in the range of 40° C. to 50° C.

4. The process as claimed in claim 2 , wherein the cooled solution of step e) is optionally seeded with Amicarbazone.

5. The process as claimed in claim 1 , wherein the TBIC has a purity equal to or less than 80%.

6. The process as claimed in claim 1 , wherein the molar excess of TBIC with respect to TAZ is in the range of 18% to 22%.

7. The process as claimed in claim 2 , wherein the purity of Amicarbazone obtained in step (e) is more than 97%.