Process for the preparation of the herbicide ethyl α-2-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorobenzenepropanoate
AssigneeFMC Corporation
InventorsJohn W. Ager, Craig A. Polsz
Life of this patent
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Abstract
A process is disclosed for the preparation of the herbicide ethyl α-2-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorobenzenepropionate by the simultaneous diazotization of 4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chloro-phenyl)-1H-1,2,4-triazole (the Amine) and arylation of ethyl acrylate with the diazotized Amine. In the process the following reagents are added in sequence and, under specified conditions, to a cooled, stirred solution of the Amine in acetone: cuprous chloride, hydrochloric acid, ethyl acrylate, and sodium nitrite.
Claims18
A process for the preparation of ethyl α2-dichloro-5-[4-(difluoro-methyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorobenzenepropionate (the Product) formula (I) by the simultaneous diazotization of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chlorophenyl)-1H-1,2,4-triazole (the Amine) and arylation of ethyl acrylate with the diazotized Amine, wherein formula (I) is:
- which consists of process comprises the following steps in which the amounts of all components other than the Amine are given in molar equivalents relative to one molar equivalent of the Amine:
- (a) adding a Meerwein arylation catalyst to a stirred solution of the Amine in 10 to 30 equivalents of acetone 0.05 to 0.5 equivalents of cuprous chloride ;
- (b) cooling the solution to a temperature in the range of −20° to 30° C. and maintaining the temperature in that range while stirring and adding sufficient hydrochloric acid to convert the Amine to the hydrochloride salt;
- (b) maintaining the temperature in the range of −20° to 30° C. and adding a sufficient amount of hydrogen chloride to form a salt of the Amine;
- (c) maintaining the temperature below about 10° C. while adding to the resultant slurry, with stirring, 5 to 20 equivalents of ethyl acrylate;
- (d) bringing the temperature of the stirred reaction mixture to about 0° C. and adding 1.0 to 2.0 equivalents of sodium nitrite over a period of 1 to 6 hours while maintaining the temperature below about 20° C. and then continuing stirring for 15 to 90 minutes;
- and
- (e) recovering the Product formula (I).
A process for the preparation of formula (I):
- comprising:
- (i) forming a diazotized salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chlorophenyl)-1H-1,2,4-triazole by reacting a salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chlorophenyl)-1H-1,2,4-triazole with sodium nitrite;
- and (ii) simultaneously reacting said diazotized salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chlorophenyl)-1H-1,2,4-triazole, as it is produced in step (i), with ethyl acrylate in the presence of a Meerwein arylation catalyst to obtain said formula (I).
A process for the preparation of formula (I):
- comprising the step of adding aqueous sodium nitrite to a solution comprising a salt of 4-difluoro-methyl-4,5-dihydro-3-methyl-5-oxo-1-(5-amino-2-fluoro-4-chlorophenyl)-1H-1,2,4-triazole, ethyl acrylate, and a Meerwein arylation catalyst to form formula (I).
Dependencies are inferred from the claim text.