Study On Synthesis And Technology Of 2-phenylpropionic Acid

2-Phenylpropionic acid is an important intermediate widely used in the synthesis of pharmaceuticals, perfumes and agricultural chemicals. In this dissertation, the 2-phenylpropionic acid was synthesized in a total yield of 63.4% by Darzens condensation, hydrolysis of ester, decarboxylation and oxidation with acetophenone and ethyl chloroacetate as starting materials. Some technological parameters for the synthesis process were discussed and optimized in details.Various strong base catalysts such as sodium alcoholate, metal sodium, and sodium amide were used for catalytically synthesizing ethyl 3-methyl-3-phenyl glycidate by Darzens condensation from acetophenone and ethyl chloroacetate in the presence of hydrohalcite additive. It was found that 78.6% yield in selectivity of 94.7% was achievd using hexane as solvent, sodium amide as catalyst and a small amount of hydrohalcite as additive, in which 83.0% acetophenone was converted.In the process of synthesizing 2-phenylpropanal from ethyl 3-methyl-3-phenyl glycidate via hydrolysis of ester and decarboxylation, several parameters were investigated. Sodium salt of 89.6% yield was obtained in the presences of ethanol and 30% sodium hydroxide. A 95.4% yield of 2-phenylpropanal in 97.0% selectivity was achieved by refluxing the mixture of sodium salt and 1.2 mol/L hydrochloric acid for 4 h.Oxidants, organic/inorganic acids, organic/inorganic bases and phase-transfer catalysts were discussed in the oxidation of 2-phenylpropanal to 2-phenylpropionic acid. It was found 96.5% 2-phenylpropanal was transformed and 94.5% 2-phenylpropionic acid was gained with 97.9% selectivity under sodium dihydrogen phosphate buffer solution using 30% hydrogen peroxide and tetra-n-butyl ammonium bromide at 60℃for 4 h.One-pot synthesis of 2-phenylpropionic acid from ethyl 3-methyl-3-phenyl glycidate was studied. The 2-phenylpropionic acid was obtained in 59.6% yield using 1 mol/L hydrochloric acid, tetra-n-butyl ammonium bromide and 30% hydrogen peroxide, in which 60.4% of ethyl 3-methyl-3-phenyl glycidate was converted.