Abstract: The invention relates to a process for obtaining a high purity bisphenol from a post-reaction mixture resulting from the step of synthesis of phenol and acetone in the presence of a strong acid cation exhanger catalyst, by the way of crystallation and separation by distillation followed by recovery of bisphenol-A from the step of thermal catalytic decomposition of by product of the principal process technology in a multistage process.

Abstract: The dian is prepared by the condensation of phenol with acetone in the presence of acid ion-exchange catalyst of the type of sulfonated co-polymer of styrene and divinylbenzene. The three-stage process is conducted in two reactors packed with a stationary catalyst bed. In each of the reactors the bed height is 5-20 m and in addition, in both reactors the beds are divided into bottom and upper zones.At various stages of the process, a reaction mixture is circulated with a different linear velocity, the first step of the process being conducted at a temperature of 60.degree.-85.degree. C. in the bed of the first reactor, in succession in the bottom and then upper zone of the catalytic bed; the second stage of the process is accomplished in the bottom zone of the second reactor at a temperature of 70.degree.-90.degree. C.; and the third step is carried out in the upper zone of the second reactor at a temperature of 75.degree.-95.degree. C.

Abstract: The essence of the invention consists in heating the dian waste in the presence of sodium hypophosphite as a catalyst in amount of 0.01 - 0.5% by weight at a temperature of 150 to 250.degree. C and under reduced pressure in the range of 5 to 50 mm Hg. As a result a destillate is obtained containing as main components phenol, o- and p-isopropenyl-phenol and their dimers at yield of about 40-74% by weight calculated in relation to the initial amount of dian waste. The distillate obtained was made up with fresh phenol or with phenol and acetone and brought into contact with strongly acid cation exchanger, such as Wofatit KPS, Zerolit 225, Wofatit OK-80, in consequence the o- and p-isopropenylphenol and their dimers reacted with phenol to obtain the dian, the latter being then separated by known methods.