Molecular conformation, vibrational and electronic transition analysis of 2,4-difluorobenzoic acid has been investigated by experimental techniques (FT-IR, FT-Raman and UV) and quantum chemical calculations.
To a reaction vessel was added 2,4-dinitrotoluene, water, adjusted the pH to 7, and heated to 75 C with stirring. Potassium permanganate, magnesium sulfate and phase transfer catalyst were added in batches. After the addition was completed, the reaction was continued to be stirred at constant temperature for 3 hours. Filter while hot and wash the filter cake with hot water. The filtrates were combined and acidified with 35% hydrochloric acid to pH 2-3, with a large amount of white precipitate to be completely precipitated by crystals, then pumped, washed, recrystallized, and dried to obtain white crystals of 2,4-dinitrobenzene formic acid. 2,4-Dinitrotoluene to potassium permanganate in the ratio of substance of 2.4:1. The product yield of this step was 90.7%.
To a reaction vessel was added N,N-dimethylmethylphthalamide, heated to 100~110C, and preheated for 0.5-1 h. Dry anhydrous potassium fluoride was added with stirring, and preheated at a maintained temperature for 0.5-1 h. Then 2,4-dinitrobenzene carboxylic acid and cetyltrimethylammonium bromide were added to the reaction vessel at one time in a rapid manner, and the reaction vessel was continued to be heated to 120C, maintained at a maintained temperature and continued to be stirred. Reaction. After refluxing the reaction for 7h, the solvent was recovered by distillation and the reaction solution was distilled with water vapor. The collected fraction was white emulsion, after standing for a period of time the oily destination fraction basically sank to the bottom, pour off the upper part of the white clear liquid, the oil cooled and precipitated white crystals to get the crude product; the crude product was recrystallized, filtered, washed and dried to get white crystals of 2,4-difluorobenzoic acid. 2,4-Dinitrobenzoic acid and potassium fluoride in the material amount of the ratio of 2.7:1. The yield of the product in this step was 72.4%.
