The Green Low-cost Cresol Preparation Technology

P-Cresol is a very important organic raw material and widely used in the synthesis such as dyes, spices, pesticide, and medicine etc. This paper focuses on the production of p-cresol, the (sulfonation/fusion with alkali) method and (bromination/hydrolysis) method were selected for process research.Firstly, this paper studies (sulfonation/fusion with alkali) process, in this paper, toluenesulfonic acid was prepared by chlorosulfonic acid and toluene, and then p-cresol was prepared by alkali and toluenesulfonic acid. By changing the molar ratio of chlorosulfonic acid to toluene, reaction temperature, catalyst, and analyze the results with the method of chemical, chromatography, distillation, and Karl-Fischer. This paper finely arrives in the conclusion that the best parameters of the process is:sulfonation reaction temperature:20～25℃, molar ratio of toluene to chlorosulfonic acid:1:1, the quantity of acetic acid is 2% of toluene.Secondly, this paper studies (bromination/hydrolysis) process, in this paper, bromotoluene was prepared by liquid bromine and toluene, and then p-cresol was prepared by hydrolysis of bromotoluene. By changing the molar ratio of liquid bromine to toluene, reaction temperature, catalyst, and analyze the results with the method of chemical, chromatography, distillation, and Karl-Fischer. This paper finely arrives in the conclusion that the best parameters of the process is:(1) The optimum parameters for Preparation of bromotoluene:bromination reaction temperature:0℃～5℃, molar ratio of toluene to liquid bromine:1.02:1. Use the mixture of Fe and I2 as catalyst, the total amount the mixture is 2% of toluene.(2) The optimum parameters for preparation of p-cresol:molar ratio of bromotoluene to NaOH:1:2.5, concentration of NaOH:40%, hydrolysis temperature:200℃, catalyst: Cu/CuCl, no phase transfer catalyst.