GB796327A - Recovering synthetic phenol and other components of cumene hydroperoxide cleavage mixture by distillation - Google Patents

Abstract

Crude phenol, obtained by oxidation of cumene and subsequent acid-catalysed decomposition of the peroxide compound, is subjected to fractional distillation to remove acetone, and the acetone-free mixture is then subjected to fractional distillation under vacuum and in the presence of water to distil off overhead a mixture of cumene, a -methyl styrene and water, which is substantially free of phenol; the head product is condensed and separates into an aqueous phase and an oil phase, and a major part of the aqueous phase and a minor part of the oil phase are returned to the fractionating column as reflux, whereby an adequate concentration of water is maintained in the lower sections of the column, so that condensation of phenol with methylstyrene, and the poly <PICT:0796327/III/1> merization of the latter, are avoided. Pure phenol is then separated by distillation from the mixture obtained at the sump of the vacuum column. Reaction mixture is pumped from container 1 into column 4; and water is introduced, if desired, through pipe 3. The temperature at the sump of th column is maintained at 100-105 DEG C. by heater 5, the pressure at this point being 900-1000 mm. Hg. Acetone is obtained at the head of column 4. The mixture withdrawn from the sump of column 4 is pumped to column 8 which is maintained under vacuum by pumping-means joined to condenser 9 at connection 10. Water is introduced into the head of column 8 through pipe 13. An azeotropic mixture of cumene + methyl styrene + water is distilled off from column 8 at a temperature of 60 DEG to 85 DEG C. The condensate forms an aqueous layer and an oily layer in separator 11. The aqueous layer is introduced through pipe 12 into the head of column 8. The oily layer is collected in container 14; part of it is pumped to column 8 as reflux, and the remainder is introduced into vacuum-column 17. Cumene is withdrawn from the head of column 17; and methyl styrene is obtained at the base. The mixture obtained in the sump of column 8 is introduced on to the top plate of column 24. Water-vapour is driven out of the mixture as it descends column 24; and this vapour is passed through pipe 26 into column 8. The water-free mixture, withdrawn from the sump of column 24, is pumped into vacuum-column 28. Substantially pure phenol is obtained at the head of column 28. The residue flowing from the base of column 28 is pumped to vacuum-column 33. A mixture of phenol and acetophenone is obtained at the head of column 33; while the residue, which is discharged from the base, contains cumyl phenol. In a modification the liquid withdrawn from the sump of column 8 is allowed to separate into two layers, viz. an aqueous layer containing phenol and an oily layer containing acetophenone, and these two layers are worked up separately. Specification 770,650 is referred to.