Improved process for the separation of aromatic isopropyl compounds from phenols

摘要

A mixture containing a phenol and an isopropyl - substituted benzene or napthalene, e.g. a mixture obtained by the decomposition of an organic hydroperoxide, is subjected to fractional distillation under reduced pressure in the presence of water; the distillate is allowed to separate into an aqueous phase and an hydrocarbon phase, and at least part of the aqueous phase is re-introduced into the distilling system while a reflux ratio of less than 3:1 of the hydrocarbon phase of the condensate is employed. For example, in carrying out the separation of a cumenephenol mixture under an absolute pressure of 100 mm., a cumene reflux ratio of 0.8:1 is used, and the resulting distillate of cumene contains only 0.02 per cent of phenol. The separation can also be carried out by introducing into the column as reflux only the aqueous phase of the condensate, while the hydrocarbon phase is completely drawn off as product. The mixture to be separated is fed through line 1 into an intermediate section of column 2. A phenol-containing fraction is discharged from the sump of the column through line 3. Vapours of water and hydrocarbon leave the head of the column through line 5, and are condensed in hea exchanger 6. The condensate is passed to separating vessel 7. The water layer passes through pipe 8 into receiver 9; and is then pumped through pipe 11 to the head of the column. The hydrocarbon layer of the condensate passes through pipe 13 into receiver 14; this hydrocarbon can mostly be withdrawn as substantially phenol-free product through pipe 15, whilst a smaller portion is pumped through line 17 to the head of the column as reflux. The reduced pressure in the system is maintained by vacuum pump 21. The process may be used for the separation of p-cymene from p-cresol, and of beta-isopropylnaphthalene from beta-naphthol. Specification 768,941 is referred to.