Patent GB-791759-A (GB)
Title: Production of acetone and phenol
Filed: 1954-07-16
Abstract: Phenol and acetone are prepared by a process comprising passing cumene hydroperoxide and an acetone diluent into a reaction zone wherein the mixture is contacted with a strong acid to decompose the hydroperoxide into phenol and acetone whilst cooling the reaction zone with reflux acetone, withdrawing the decomposition mixture from the reaction zone, neutralizing the acid catalyst in the mixture with an aqueous solution of a base, fractionally distilling the neutral mixture in a first distillation zone to separate a low boiling fraction comprising water and acetone and a bottoms fraction comprising phenol, fractionally distilling the low boiling fraction in a second distillation zone to recover a first overhead fraction of purified acetone having a water-content of less than 1.0 per cent by weight and a permanganate retention time in excess of 30 minutes, removing a second overhead fraction of acetone having a watercontent higher than that of the first fraction but below 5 per cent by weight and returning this second fraction to the reaction zone as the specified acetone diluent. The first acetone overhead preferably has a water content of below 0.4 per cent and the recycle acetone overhead one of about 0.75 to 2.5 per cent.  The decomposition reaction is preferably effected using 0.25 to 1.5 mols. of acetone diluent per mol. of cumene hydro peroxide.  The low boiling fraction obtained from the first distillation step is preferably stripped of volatile impurities, e.g. acetaldehyde, before being sent to the second distillation zone.  A continuous process is described wherein cumene hydroperoxide containing some dimethyl phenyl carbinol and other impurities is fed with wet recycle acetone and sulphuric acid catalyst through a decomposition zone maintained at 170 DEG  F. by refluxed acetone; aqueous sodium phenate is added to the issuing reaction product to neutralize the acid, together with aqueous sodium carbonate as buffering agent; the neutral mixture is water-washed or filtered to remove salts and is then treated in a first distillation zone, a stripping zone and a second distillation zone as described above (see also Group III) with recovery of specification acetone, wet recycle acetone and wet phenol.  Reference has been directed by the Comptroller to Specifications 629,429 and 676,771.ALSO:Phenol and acetone are recovered from mixtures thereof comprising also water and possibly minor amounts of volatile impurities, obtained by decomposition of cumene hydroperoxide in an acetone diluent by means of a strong acid (see Group IV (b)), by subjecting the mixture after neutralization of the strong acid to fractionation in a first distillation zone to separate a low boiling fraction comprising acetone and water and a bottoms fraction comprising phenol, and fractionally distillating the low boiling fraction in a second distillation zone to recover a first overhead fraction consisting of purified acetone having a water content of below 1 per cent by weight and a permanganate retention time of at least 30 mins., and a second overhead fraction of acetone having a water content greater than that of the first fraction but below <PICT:0791759/III/1> 5 per cent by weight.  Preferably, the overhead fraction from the first distillation zone is stripped of volatile impurities, e.g. acetaldehyde, before being treated in the second distillation zone. As shown, the wet crude phenol-acetone is continuously fed, preferably after being water-washed, to a distillation column 22 from which are withdrawn a phenol bottoms and a water-acetone overhead which is fed via line 31 to a stripper 32 for removal of volatile impurities.  The stripped material is passed through line 39 to a fractionating column 40 from which, preferably, three overhead fractions are removed: a fraction containing residual impurities which is withdrawn from the reflux system and recycled through line 45 to the stripper 32, a stream of purified acetone withdrawn through line 46 and usually containing about 0.3 per cent of water and a wet acetone stream containing about 1 per cent of water which is passed via line 47 to the decomposition zone as diluent for the cumene hydroperoxide.  Aqueous bottoms are withdrawn from column 40 and part is recycled to the stripper.  Reference has been directed by the Comptroller to Specifications 629,429 and 676,771, [both in Group IV (b]].