GB775813A - Recovery of phenols - Google Patents

Abstract

A process for the manufacture of resorcinol by the catalytic cleavage of a reaction mixture containing meta-di-isopropylbenzene dihydro-per oxide derived from the oxidation of meta-di-isopropylbenzene is characterized by the step of decomposing by the action of heat the material contained in the cleavage reaction product which is less volatile than resorcinol while passing an inert gas through the reaction product and simultaneously distilling off the additional quantities of resorcinol and the meta-isopropenylphenol so formed. The decomposition is preferably effected at a temperature within the range 170 DEG to 300 DEG C. and more preferably between 200 DEG and 270 DEG C. The initial cleavage product is preferably first treated to remove or neutralize the catalyst (e.g. sulphuric acid) and stripped of low boiling materials such as acetone and unchanged hydrocarbons. The heat treatment may be applied after removal or partial removal, before removal or concurrently with the removal of the main batch of resorcinol from the cleavage reaction product. Specified inert gases are steam, nitrogen, carbon dioxide and flue gas, the steam being preferably superheated and, if desired, generated in situ by heating an aqueous solution of the cleavage reaction product. The steam is preferably employed in such a volume that the resulting vapour phase when condensed forms a 20 to 40 per cent aqueous solution of resorcinol. Alternatively, the vapours resulting from the passage through the inert reaction product are condensed into water until a 20 to 40 per cent aqueous solution of resorcinol is obtained. Where an inert gas which cannot be condensed is employed such gas, after removal of condensable vapour, is preferably recycled to the reactor in which decomposition takes place. The resorcinol and meta-isopropenyl phenol are preferably separated from one another by selective solvation, e.g. using benzene, toluene, a - or b -methylnaphthalene or mixtures thereof, or chloroform or carbon tetrachloride. The vapours containing the resorcinol and metaisopropenyl phenol may be passed directly into the selective solvent, and when steam is employed as the inert gas two layers are formed, an aqueous layer containing resorcinol and an organic solvent layer containing the metaisopropenyl phenol.