METHOD FOR PRODUCTION OF IMAZAPYR Russian patent published in 2022 - IPC A01N43/50 A01N43/40 A01N35/04 A01P13/00 C07D213/16 C07D271/06 C07D233/32 

FIELD: agriculture; chemistry.

SUBSTANCE: invention relates to the field of production of pesticides, more specifically to a method for the production of imazapyr, which is a non-selective herbicide of a wide range of action of an imidazolinone class, having a chemical structure of (2-(4-methyl-5-oxo-4-propane-2-yl-1H-imidazole-2-yl)pyridine-3-carboxylic acid

The method for the production of imazapyr includes primary esterification of 2,3-pyridinedicarboxylic acid with low alcohol in the presence of mineral acid, when heating, with subsequent distillation of excessive low alcohol. Next, reaction mass is treated with an aqueous base solution, and a reaction product is extracted with an aromatic solvent to obtain a solution of corresponding diester of 2,3-pyridinedicarboxylic acid in this solvent. Then, a concentration of diester of 2,3-pyridinedicarboxylic acid is corrected, and it is dehydrated by removal of part of the solvent by azeotropic distillation at atmospheric or reduced pressure. Next, the resulting anhydrous solution with a necessary concentration of diester of 2,3-pyridinecarboxylic acid is introduced, without its actual individual isolation, into a reaction with 2-amino-2,3-dimethylbutanamide in the presence of alkaline metal alcoholate in inert gas atmosphere or in air without access of moisture with obtainment of a target product, its isolation and purification. Methyl, ethyl, or n-propyl alcohol is used as low alcohol. Sulfuric or phosphoric acid is used as mineral acid. Sodium or potassium carbonate, sodium or potassium hydrocarbonate, or sodium, potassium, or ammonia hydroxide are used as the base. Toluene, ethylbenzene, cumene, o-, m-, or p-xylol, or a mixture thereof, or o-, m-, or p-diethylbenzene, or a mixture thereof are used as the aromatic solvent. Sodium or potassium methylate, sodium or potassium ethylate, sodium or potassium isopropylate, sodium or potassium tert-butylate, sodium or potassium neopentylate are used as alkaline metal alcoholate. Nitrogen or argon are used as inert gas.

EFFECT: proposed method for the production of imazapyr provides improvement of technical and economical indicators of a technological process of the production of imazapyr from 2,3-pyridinedicarboxylic acid, reduction in a number of technological operations of the process and its duration, simplification of its instrumentation, obtainment of a target product of high quality with yield of 65-78%, possibility of regeneration of the used solvent with its partial return to the process, which reduces production waste.

7 cl, 7 ex