Patent GB-873604-A (GB)
Title: Separation of substantially pure phenol from reaction mixtures by distillation
Filed: 1958-05-08
Abstract: <PICT:0873604/IV (b)/1> In a process for the separation of pure phenol from a reaction-mixture, obtained by oxidation of cumene and subsequent catalytic decomposition of the cumene hydroperoxide, by submitting the reaction-mixture to fractional distillation, an aqueous solution of an alkali metal or an alkaline-earth metal hydroxide or carbonate, or an ammonium or organic base, is added to the vapour-pipe, condenser or reflux-pipe of at least one of the fractionating-columns wherein the reactionmixture, previously wholly or partly freed from low-boiling components, is being distilled, whereby aliphatic acid by-products are neutralized and there is obtained a final phenol-product which gives a clear solution in water.  The initial removal of the low-boiling components, e.g. mesityl oxide, from the hydrolysed reaction-mixture may be effected by azeotropic distillation or by extractive distillation in the presence of water.  The components higher-boiling than phenol are separated in column 2 which is provided with a condenser 6 and a reflux-line 8.  Since however a small residual proportion of the low-boiling components enter column 2 through tube 1, the distillate from column 2 is introduced into column 41 where it is distilled in the presence of water.  The low-boiling components distil off with water vapour; and the condensate forms two liquid layers in decanter 45, from which the water-layer is returned to column 41, while the oil phase is withdrawn through tube 47.  The sump-product, withdrawn from column 41, is distilled in column 51.  Water-vapour leaves the top of column 51 and is introduced into the lower section of column 41.  Dehydrated phenol is withdrawn from the sump of column 51, and is purified by fractionation in column 10, which is provided with a condenser 13 and a reflux-line 15. Neutralizing-agent, e.g. 10% soda lye, is introduced directly through tubes 7 and 14 into condensers 6 and 13 respectively.  A vaporous side-stream from column 10 is introduced into auxiliary column 34.  Pure phenol is obtained as distillate at the head of column 34 and is withdrawn from the system through pipe 39; while the liquid, withdrawn from the sump of this column, is returned to column 10.  In another embodiment, the condensation of the overhead vapours from each of the two main columns is effected in two stages; and the neutralization agent is added to the first-stage condensates.  Specification 745,343 is referred to.ALSO:<PICT:0873604/III/1> In a process for the separation of pure phenol from a reaction-mixture, obtained by oxidation of cumene and subsequent catalytic decomposition of the cumene hydroperoxide, by submitting the reaction-mixture to fractional distillation, an aqueous solution of an alkali metal or an alkaline-earth metal hydroxide or carbonate, or ammonia or an organic base, is added to the vapour-pipe, condenser or reflux-pipe of at least one of the fractionating-columns wherein the reaction-mixture, previously wholly or partly freed from low-boiling components, is being distilled, whereby aliphatitc acid by-products are neutralized and there is obtained a final phenol-product which gives a clear solution in water.  The initial removal of the low-boiling components, e.g. mesityl oxide, from the hydrolysed reaction-mixture may be effected by azeotropic distillation or by extractive distillation in the presence of water.  As shown, the components higher-boiling than phenol are separated in column 2 which is provided with a condenser 6 and a reflux-line 8.  Since, however, a small residual proportion of the low-boiling components enters column 2 through tube 1, the distillate from column 2 is introduced into column 41, where it is distilled in the presence of water.  The low-boiling components distil off with water-vapour and the condensate forms two liquid layers in decanter 45, from which the water-layer is returned to column 41, while the oil phase is withdrawn through tube 47.  The sump-product, withdrawn from column 41, is distilled in column 51. Water-vapour leaves the top of column 51 and is introduced into the lower section of column 41.  Dehydrated phenol is withdrawn from the sump of column 51, and is purified by fractionation in column 10, which is provided with a condenser 13 and a reflux line 15.  Neutralizing-agent, e.g. 10% soda lye, is introduced directly through tubes 7 and 14 into condensers 6 and 13 respectively.  A vaporous side-stream from column 10 is introduced into auxiliary column 34.  Pure phenol is obtained as distillate at the head of column 34 and is withdrawn from the system through pipe 39 while the liquid, withdrawn from the sump of this column, is returned to column 10.  In another embodiment, the condensation of the overhead vapours from each of the two main columns is effected in two stages, and the neutralization agent is added to the first-stage condensates.  Specification 745,343 is referred to.