Background and overview[1]
Organic carboxylates are an important class of chemical and pharmaceutical intermediates, and their applications cover all aspects of production and life. The synthesis methods of organic carboxylic acid esters often use inorganic acids as catalysts. This method has many problems such as poor selectivity, difficulty in separating products and catalysts, corrosion of equipment, and waste acid pollution of the environment. Therefore, the development of efficient and environmentally friendly alkyd esterification catalysts not only has important economic benefits, but also has good social benefits. Butyl anthranilate is an organic carboxylic acid ester that can be used as a pharmaceutical synthesis intermediate.
Preparation[1]
The preparation of butyl anthranilate is as follows:
1) Dissolve 0.1 mol of benzothiazole in 50 mL of absolute ethanol solution, add it to a three-necked flask and cool it to 10°C, then accurately weigh 0.13 mol of p-toluenesulfonic acid and dissolve it in 20 mL of water, and drop it while stirring thoroughly Add, complete the dropwise addition in about 1.5 hours, and then continue the reaction at room temperature for 4 hours. After the reaction, the solvent was distilled off to obtain a crude product, which was washed with 3 × 10 mL of ethyl acetate, and then recrystallized in absolute ethanol. After drying, colorless prismatic crystals were obtained, which is benzothiazole p-toluenesulfonate, with a melting point of 120°C. .
2) Add 0.05 mol benzothiazole p-toluenesulfonate ionic liquid, 0.10 mol anthranilic acid and 0.40 mol n-butanol into a round-bottomed flask equipped with a reflux condensation water separation device, and raise the temperature to bring the system temperature to Keep it at 110°C, perform a water-separating reaction for 8 hours with sufficient stirring, stop the reaction, cool, and let it stand. The benzothiazole p-toluenesulfonate ionic liquid will crystallize out from the reaction system. Filter to separate the ester phase and recover the ionic liquid. The ester phase was distilled under reduced pressure to collect n-butyl anthranilate, with a yield of 94.0%. The ionic liquid was used directly for the next use without treatment.
Main reference materials
[1] (CN101863855) Preparation of temperature-sensitive acidic ionic liquid and method for catalytic alkyd esterification
