Alkylation To Separate Cresol Mixture With Preparation Antioxidant BHT And 300

The Cresols are important chemical intermediates, which are extensively applied to synthetic fiber, engineering plastics, rubber ingredients and antioxidant. They mainly stem from the natural resourse and synthesis process of coal chemical.The Cresol Mixture extracted from coal tar have three cresol isomers containing o-cresol, p-cresol and m-cresol, The o-cresol with the lowest boiling point can be easily separated from m-cresol or p-cresol by distillation. However, p-cresol and m-cresol are difficult to separate because of the very close boiling point. Therefore, it is significant to investigate the separation of cresol mixture.This paper mainly studies the separation of mixed cresol by alkylation reaction and distillation in the specific condition of the synthesized alkylates'boiling point's difference. the influencing factors of alkylation efficiency were investigated, and the better process parameters were optimatized. vacuum distillation separation of alkalization liquid was studied, and the rectification scheme was designed. The mixed cresol was alkylated for 150 min, the temperature was 75℃, the molar ratio of MTBE and Cresol Mixture is 3.5:1, catalyzed by strong acid type cation exchange resin, the catalyst dosage was 55% in mass of cresol mixture, alkylated liquid of 2, 6-di-tert-butyl-4-methyl phenol (short for BHT) and 4, 6-di-tert-buty-m-cresol was acquired. The primrose yellow transparent liquid was obtained by pretreatment, in the condition of atmospheric distillation and water vapor distillation at the temperature 70℃. Then vacuum distillation was carried out, through in the operation states of system pressure 14mmHg, tower bottom temperature 152℃and tower bottom temperature 178℃. The crude BHT and 4, 6-di-tert-buty-m-cresol was achieved. The process parameters of preparation antioxidant 300, taking the separated product 4, 6-di-tert-Buty-m-Cresol as main raw material, was investigated. After reacted 60min at temperature 75℃, vulcanization condensation reaction was conducted for 150min, with 4, 6-di-tert-buty-m-cresol as chief stuff and petroleum ether as solvent, 4, 6-di-tert-buty-m-cresol volume in 2.2:1, sulfur dichloride dissolving in petroleum ether by molar ratio 1.0:1.11, at temperature 5℃. The conversion 77% of antioxidant 300 was acquired.The structures of synthesized products were characterized by means of gas chromatograph, UV-Vis spectrum, infrared spectrometry and melting point determination. The measurement results were consistent with theoretical data or reported data, indicating objective products were BHT and Antioxidant 300. The result also suggested that the technology of adopting alkylation method to separate mixed cresol and co-production BHT and antioxidant 300 is reasonable and feasible.