Abstract: A preparative method for carboxylic acids is disclosed in the present invention. The method is characterized in that: compounds (II) are reacted in the presence of hydrogen peroxide and base to produce target products (I), as represented by the following reaction scheme: wherein R1 is aryl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, benzothienyl, benzofuranyl, quinolinyl, isoquinolinyl, thiadiazolyl, C1-6 alkyl, C3-6 cycloalkyl, C2-6 alkenyl, C2-6 alkynyl and hydrogen; R2 is alkoxycarbonyl, alkylaminocarbonyl, aminocarbonyl, alkylthiolcarbonyl, cyano, sulfonyl, sulfinyl, carbonyl, aldehyde, carboxyl, nitro, alkyl and hydrogen; R3 is alkoxycarbonyl, alkyl amido carbonyl, aminocarbonyl, cyano, sulfonyl, sulfinyl, carbonyl, carboxyl and nitro. The present invention has the following main benefits: cheap and readily available starting materials, safe processes, high yield, good quality, which facilitates industrial production.

Abstract: A preparative method for carboxylic acids is disclosed in the present invention. The method is characterized in that: compounds (II) are reacted in the presence of hydrogen peroxide and base to produce target products (I), as represented by the following reaction scheme: wherein R1 is aryl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, benzothienyl, benzofuranyl, quinolinyl, isoquinolinyl, thiadiazolyl, C1-6 alkyl, C3-6 cycloalkyl, C2-6 alkenyl, C2-6 alkynyl and hydrogen; R2 is alkoxycarbonyl, alkylaminocarbonyl, aminocarbonyl, alkylthiolcarbonyl, cyano, sulfonyl, sulfinyl, carbonyl, aldehyde, carboxyl, nitro, alkyl and hydrogen; R3 is alkoxycarbonyl, alkyl amido carbonyl, aminocarbonyl, cyano, sulfonyl, sulfinyl, carbonyl, carboxyl and nitro. The present invention has the following main benefits: cheap and readily available starting materials, safe processes, high yield, good quality, which facilitates industrial production.

Abstract: A method for refining a 2-nitro-4-methylsulfonyl benzoic acid and an intermediate thereof are provided, wherein the method includes steps of: using a crude 2-nitro-4-methylsulfonyl benzoic acid (I) as a raw material; using organic amine (II) as a base; synthesizing an intermediate, which is an amine salt (III), in an organic solvent; treating the amine salt (III) with an inorganic base in an aqueous phase to obtain an inorganic metal salt (IV) or an inorganic metal salt (IV?); and acidifying by adding an inorganic acid to obtain a fine 2-nitro-4-methylsulfonyl benzoic acid (I).

Abstract: A preparation method of carfentrazone-ethyl comprises steps of: reacting 1-(5-amino-4-chloro-2-fluorophenyl)-4-difluoromethyl-3-methyl-1H-1,2,4-triazol-5-one with acrylic acid through a diazo arylation reaction to give 2-chloro-3-{2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,3-triazol-1-yl]-4-fluorophenyl}propionic acid; and reacting the 2-chloro-3-{2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,3-triazol-1-yl]-4-fluorophenyl}propionic acid with ethanol through an esterification reaction in a presence of an acidic catalyst to give carfentrazone-ethyl.