Investigation On Darzens Reaction And N-acylation Reaction In Aqueous Phase

As one of the substances closely related to daily life,water also has a wide range of applications in chemical synthesis.In response to the "Green Chemistry" call,water was developed as a reaction solvent and is considered to be a promising environmental benign.First,water are abundant and inexpensive;second,water has a high specific heat capacity,lower viscosity and density,and stronger mass transfer capacity;and finally,water can be ionized out of H+ and OH-,for some reactions that require acid-base catalysis have a certain catalytic effect and be promoted.In this paper,room temperature water was used as reaction solvent to study two reaction systems,namely the Darzens reaction in the aqueous phase and the N-acylation reaction in the aqueous phase.The first part studied the Darzens reaction in the aqueous phase.The reaction is as follows:Scheme 1A typical Darzens reaction is to synthesize epoxy carbonyl compounds from aldehydes and ?-halogenocarbonyl compounds in ethoxide with ethanolic sodium as base;using butyl ether and toluene as solvents are also reported in other papers.In this paper,water was used as the reaction solvent,and benzaldehyde and 2-bromoacetophenone were used as raw materials.The effects of the reaction time,temperature,bases,amount of base and solubilizer on the reaction were studied.The optimized reaction conditions were obtained: using water as the reaction solvent and adding equimolar sodium hydroxide under the conditions of room temperature to provide basic conditions with a yield of 86%.The Darzens reaction involving different substituted benzaldehydes was further studied and the yields were 55-86%.This method has the advantages of mild reaction conditions and simple operation.The second part studied the N-acylation reaction in the aqueous phase,the reaction is as follows:Scheme 2The N-acylation reaction is a very classic reaction,such as the reaction of an amine with a carboxylic acid and an acid chloride.These reactions are mainly carried out in ethanol,methylene chloride,benzene,and acetic acid,with triethylamine,diethylamine,pyridine as a base.In this paper,aniline and chloroacetyl chloride are used as raw materials,water is used as a solvent,and various common inorganic metal hydroxides are used as base for the reaction.The effects of reaction temperature,reaction time,alkali type and alkali content on the yield of the reaction were studied.The optimized reaction conditions were as follows: water was used as the reaction solvent,and 0.5 molar sodium carbonate was used as the base at room temperature.The reaction time was 10 min and the yield was 81%.Finally,the expansion of the reaction substrate was carried out to obtain the reaction results of different substituents of amines and acid chlorides.This method has a short reaction time and the yields were 56-98%.The post-treatment is simple.Only getting a higher purity target product by the filtration and recrystallization.