Reaction #2329074

Reaction equation

Sodium hydroxide

2-(3-Carboxy-4-methyl-phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-[1,2,4]triazine-6-carboxylic acid

sodium hydroxide

mercaptoacetic acid

→

title compound

Yield 73.9%

5-(3,5-Dioxo-4,5-dihydro-3H-[1,2,4]triazin-2-yl)-2-methyl-benzoic acid

Yield 73.9%

Solvents

toluene

water

ethyl acetate

toluene

water

Conditions

Workup

1. 1
   TemperatureThe reaction mixture was heated
2. 2
   OtherThe water layer was separated
3. 3
   workup.ADDITIONtreated with 2N HCl
4. 4
   OtherAt pH 2 solids precipitated out
5. 5
   Temperaturethe slurry was cooled to <10° C
6. 6
   FiltrationThe solids were filtered off in a slow filtration
7. 7
   Otherdried in a vacuum oven

Procedure

2-(3-Carboxy-4-methyl-phenyl)-3,5-dioxo-2,3,4,5-tetrahydro-[1,2,4]triazine-6-carboxylic acid (110 gm) was added to 8 volumes of water with 2.4 equivalents of sodium hydroxide and 1.1 equivalents of mercaptoacetic acid. The reaction mixture was heated to reflux (100-105° C.) for approximately 18 hours at which point the reaction was complete by HPLC. 30% Sodium hydroxide and toluene were added and the resulting mixture was stirred. Upon settling a large interface was noted. More water, toluene and some ethyl acetate were added. The interface was minimized. The water layer was separated and treated with 2N HCl. At pH 2 solids precipitated out and the slurry was cooled to <10° C. The solids were filtered off in a slow filtration and dried in a vacuum oven to give 69 gm of the title compound.

Source