Synthesis
600 mL of toluene was placed in a 1500 mL four-necked flask (R)-2-(4-hydroxyphenoxy)propionic acid 367.6 g (2.0 mol),224.2 g (3.0 mol) of n-butanol, 36.8 g of concentrated sulfuric acid catalyst, stirring. Then, the temperature is raised to 85-90 C, and the reaction is kept for 4 hours. Continue to raise the temperature to 105-108 C, extract a mixture of excess n-butanol and toluene, sample HPLC analysis, to (R)-2-(4-hydroxyphenoxy)propionic acid <0.3%. The reaction is over. Reduce to room temperature, add 150 mL of water to wash, and let stand for stratification. Wash again with 100 mL of water, desolvate to dryness, and get oil. That is, 473.0 g of Butyl (R)-(+)-2-(4-hydroxyphenoxy)propionate, yield: 99.2%, content: 99.1%, optical 99.4%.
