Study On The Process Of The Photo-Chlorination Of P-Xylene

1,4-bis(trichloromethyl)benzene is not only an important synthetic intermediates of pesticides and pharmaceuticals.It ia also an important chlorinating reagents.As the chlorinating agent in producing acid chloride,it has the advantages of simple production process,high product quality,high yield and low production cost.There were few reports of its uses as chlorinating agent and industrial application.It is important to study the process and development of high purity 1,4-bis(trichloromethyl)benzene.In this paper,the process of synthesizing 1,4-bis(trichloromethyl)benzene with p-xylene as raw material by photo-chlorination was studied.The reaction kinetics was established and obtained.The preexponential factors and activation energies of each step were calculated.Based on the reaction kinetics,the effects of light conditions,chlorine flow rate and reaction temperature on the reaction were further explored.The optimum reaction conditions were obtained in laboratory equipment: using 100 W UV lamp as light source,the chlorine flow rate 60 m L/min.The reaction process was divided into three stages: the first stage was reacted at 50 ? for 40 min,the second stage reacted at 100 ? for 150 min,and the third stage was reacted at 120 ? for 750 min.The purity of 1,4-bis(trichloromethyl)benzene was reached 99.05%.The chlorination reaction of terephthalic acid with 1,4-bis(trichloromethyl)benzene as chlorinating agent was studied and high purity terephthaloyl chloride was obtained.Based on the analysis of the reaction kinetics and the influencing factors,the multi-reactor scheme of continuous production was proposed.The occurrence of side reactions was inhibited and the product purity was improved by controlling the temperature of each reactor.The preparation of 1,4-bis(trichloromethyl)benzene by photo-chlorination of p-xylene as raw material has the advantages of simple process,high product quality and high yield.