Industrial bisphenol A is obtained by condensation of phenol and acetone in an acidic medium:
In order to complete the reaction, acetone should be slightly excess; when sulfuric acid is used as the catalyst, the acid concentration is 72.5-76.3%, and the reaction temperature is about 40 °C. The reaction is carried out in a stirred tank, which can be produced by a batch process or a continuous production unit. The product is neutralized and separated to obtain crude bisphenol A, which is purified by xylene-water extraction to obtain a finished product.
The sulfuric acid method requires less equipment and simple process, but the product quality is poor, the raw material consumption is high, and the “three wastes” are more, which is only suitable for small and medium batch production. In order to obtain a good quality polymer grade bisphenol A, a commonly used industrial process is a method using hydrogen chloride gas as a catalyst. The acetone is mixed with phenol, and the reaction is carried out under normal pressure using dry hydrogen chloride as a catalyst. The reaction is carried out at 50-60 ° C for 8-9 h, and the gas phase hydrogen chloride concentration is maintained at 96% or more.
In addition to the formation of bisphenol A, the reaction also produces some isomers, trihydroxy or monohydroxy by-products. These small amounts of impurities do not affect the use in the manufacture of epoxy resins. However, when used in the manufacture of polycarbonate, it must be refined. The Hooke process is a process of distillation and extraction crystallization under pressure to refine bisphenol A, which reduces the cost of the product.