A kind of method of carboxylic acid continuous preparation amides

Abstract

The invention discloses a method for continuously preparing amides from carboxylic acids, which comprises the following steps: raw material carboxylic acid and a catalyst are dissolved in a solvent as material A, an acid chloride reagent or an acid chloride reagent is dissolved in a solvent as material B, amination Reagent or amination reagent is dissolved in water as material C, and material A and material B are respectively transported into tubular reactor I by infusion pump for acyl chloride reaction, and the obtained intermediate product acyl chloride enters the tube together with material C transported by infusion pump 3. The amination reaction is carried out in the tubular reactor II, and after the reaction mixture flows out of the tubular reactor II, the target amide is obtained through post-treatment. The present invention adopts the above-mentioned technology, which can ensure the continuous and controllable whole process, less online raw materials, high safety, and easy to realize closed, continuous and automatic production; the present invention uses cheap protonic acid for catalytic reaction, and its cost is low , The post-processing is simple, easy to separate and remove, avoiding the generation of carcinogens from the source, and meeting the requirements of green environmental protection.

Description

technical field [0001] The invention relates to a method for continuously preparing amides from carboxylic acids. Background technique [0002] There are usually two ways to prepare amides from carboxylic acids. The first is the "two-step method", that is, the carboxylic acid is first reacted with an acid chloride reagent to form an acid chloride and then aminated to form an amide. Commonly used acid chloride reagents include thionyl chloride, oxytrichloride Phosphorus, phosphorus pentachloride, phosgene and BTC, etc., such as: Wang Jun et al. (Fine Chemical Intermediates, 2007,37(5):61-63.) used thionyl chloride to synthesize specific acid chlorides; Zhang Jin et al. (Journal of Shenyang Institute of Chemical Technology, 2001,15(1):47-49.) Trimethylacetyl chloride was synthesized by using phosphorus oxychloride as an acylating reagent; phosgene is often used more safely because it is highly toxic and its industrial application is limited. (Journal of Zhejiang University of...

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Problems solved by technology

[0002] There are usually two ways to prepare amides from carboxylic acids. The first is the "two-step method", that is, the carboxylic acid is first reacted with an acid chloride reagent to form an acid chloride and then aminated to form an amide. Commonly used acid chloride reagents include thionyl chloride, oxytrichloride Phosphorus, phosphorus pentachloride, phosgene and BTC, etc., such as: Wang Jun et al. (Fine Chemical Intermediates, 2007,37(5):61-63.) used thionyl chloride to synthesize specific acid chlorides; Zhang Jin et al. (Journal of Shenyang Institute of Chemical Technology, 2001,15(1):47-49.) Trimethylacetyl chloride was synthesized by using phosphorus oxychloride as an acylating reagent; phosgene is often used more safely because it is highly toxic and its industrial application is limited. (Journal of Zhejiang University of Technology, 2010, 38(4):376-379) used BTC to prepare p-chlorophenylhydrazone acetyl chloride, the chlorination and amination reactions involved in the two-step method Both belong to dangerous processes, and the traditional kettle production method has outstanding problems such as large safety hazards and low automation level; the second is the "one-step method", that is, carboxylic acid is directly catalyzed by amidation to prepare amide compounds, as reported in patent CN107673986A, using composite catalysis The system acts as a catalyst to directly construct an amide bond in one step. This method involves issues such as catalyst recovery, product purification and cost.

[0003] At present, most of the catalysts used to catalyze the formation of acid chlorides from carboxylic acids are alkalis, such as TEA, DIEA, etc. Among them, the most commonly used classic catalyst is DMF, but DMF is not easy to remove in the post-treatment process because of its good water solubility and high boiling point. carcinogen dimethylcarbamoyl chloride

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