1,2,4-Trichlorobenzene (TCB), 50 wt% aqueous NaOH and methanol were added to a pressure reactor at a molar ratio of 1.0:2.4:10. The reactor was sealed and heated to 190°C under stirring conditions and maintained at this temperature for 90 minutes. Continuous stirring was maintained during the reaction. Upon completion of the reaction, the reactor was cooled to room temperature using an ice water bath. The reaction mixture was transferred to a separatory funnel and acidified with 10% H2SO4 to a pH below 1.5. Subsequently, dichloromethane was extracted three times with an aqueous layer. The final yield of 2,5-dichlorophenol was 64.6%. The ratio of regioselectivity (2,5-dichlorophenol to 2,5-dichloroanisole/2,4-dichlorophenol to 2,4-dichloroanisole/3,4-dichlorophenol to 3,4-dichloroanisole) was 71.9:15.5:12.6 as analyzed by gas chromatography (GC).
