Studies On The Synthesis Of The 4-chlorophthalic Anhydride

Base on the summary and analysis of the actual documents, we find it has been six ways to synthesis 4-chloro phthalic anhydride. And according to the circumstance that Juhua Groups are in great need of phthalocyanine blue, so we put forward a new technological route. We use phthalic anhydride and base as raw material and carry out the reaction, and then chloridize with chlorine to synthesis the sodium salt of 4-chloro phthalic anhydride, which is contained more than 72% in the reaction mixture. After the procedures of acidification, dewatering and rectification, the product 4-chloro phthalic anhydride are gained with purity more than 98.5%. The above way operate conveniently and needs simple equipment, both intermediate and finished product can on sale.The experiments are first carried out to proof the locative affection of liquid substance with phenyl in the electrophilic substitution reaction. We also do experiments to study the all aspect influent factors to the conversion percent and selectivity; these factors are temperature, pH level, water content, reaction time etc. We conclude that the better reaction condition are with temperature 55-650C, pH among 4.5-5.5, reaction time between 180-220 minutes, the molar ratio of water to phthalic anhydride is 2 to 2.2.We also study the influence of solid particle diameter to the reaction rate in the reaction system that contain three phases as solid, liquid and gas. We conclude that the smaller of the particle diameter, the higher of the chlorine absorption rate and reaction efficient. The experiments of purification through rectification are also done and discussed in the paper.