DE718454C - Process for the continuous direct production of anhydrous phenols - Google Patents

Description

Process for the continuous direct production of anhydrous Phenols In the representation of phenols by over-exfoliating in front, aromatic halide hydrocarbons with steam at elevated temperature over a catalyst, e.g. B. in the representation of phenol from chlorobenzene and water vapor, with a single throughput only one Fraction saponified. The Promeß only gains practical importance if it is not reacted chlorobenzene (cf. z. B. Patent q.85 31o), after removal of the ; formed phenol and the resulting. Salt fringes repeatedly through the contact furnace-directs. Man. has accordingly proposed the reaction products leaving the catalyst space by alkalis, e.g. B. aqueous sodium hydroxide to conduct. Here are phenol and Hydrochloric acid bound; the unreacted chlorohenzene is mixed with steam fed back to the catalyst chamber.

Accordingly, two moles of sodium hydroxide solution are consumed for every mole of phenol formed.

The present process is based on the object of obtaining the phenol in such catalytic reactions directly in free and at the same time anhydrous form. In the French patent specification 720 720 it has been proposed to carry out a cyclic process in the catalytic production of phenols insofar as unconverted halogenated hydrocarbons and water vapor are continuously fed back into the catalyst. The reaction mixture emerging from the catalyst space was fed to a column and an azeotnopic mixture of chlorobenzene and water vapor was allowed to exit at the top of the column. The phenol formed during the catalytic reaction collected together with the aqueous hydrochloric acid formed at the foot of the column. This mixture was then separated either by decantation or by extraction or distillation. The phenol was obtained in water-containing form and had to be subjected to a distillation process for the purpose of dehydration. Its extraction took place neither in a continuous process nor in an directly anhydrous form.

The production of anhydrous phenol by azeotropic dehydration of hydrous phenols with those halogenated hydrocarbons from which the phenols can be obtained by hydrolysis; is the subject of an older German patent. Reference was also made to the catalytic production of the phenols used as starting materials for dehydration. The direct production of anhydrous phenols in the cycle process is not the subject of this earlier patent. The mere addition of a phenol dehydration process to the continuous catalytic process of French patent 720 720 encounters difficulties because of the hydrogen chloride that occurs during the catalytic use of chlorobenzene.

It has been found that an anhydrous can be obtained continuously Phetiok # arrives after the catalytic process, if that is the case with the catalytic Conversion of chlorobenzene and water resulting mixture of phenol, water, halogenated hydrocarbons and deacidified by hydrogen halide. The vapor mixture leaving the contact furnace becomes freed from acid by the hydrochloric acid formed by the Prooeß immediately or also in the phenol-free part of the column by suitable deacidification devices removed in or outside the column during the process.

The example implementation of the inventive concept is through the accompanying drawing illustrates. In this tt represents a column for continuous operation set up, b your feed vessel for water, c a such for chlorobenzene, i.e. a dephlegmator.

The azeotropic mixture escaping at the top of the column, consisting from about two parts of the volume of chlorobenzene and one part of water (bp 9 1 ') occurs into the contact furnace e via a regulating valve, which is equipped with a catalyst (cf. z. B. Patent q.85 3 1o) filled and by electrical heating or in another appropriately on the. desired temperature is maintained.

The reaction mixture escaping from the catalyst space, consisting of from phenol, hydrochloric acid gas, excess water and chlorobenzene enters the deacidification system fine, for example with lumpy burnt clay or with limestone, magnesite oAgl. -can be filled.

The remaining gases, consisting of phenol, water and chlorobenzene, as such or after condensation in the cooler g, which, if necessary, -an intermediate vessel h is connected, fed back to the column a. In this Column is now the azeotropic separation of phenol on the one hand and water and Chlorobenzene on the other hand carried out. The anhydrous and chlorobenzene-free phenol is withdrawn from the bladder. In order to produce one of the requirements of the trade : corresponding product only needs a simple fractionation.

The arrangement shown here, for example, can of course can be modified in various ways. Should that running back in the column Phenol still contains excess water, so if necessary, under Add more chlorobenzene from your vessel c this water as azeotropic chlorobenzene-waterda: mpf-Ge.-mix are discharged at the top of the column. Conversely, in the presence of an excess of chlorobenzene in the Ko-1on; nenapparat this by supplying water from .dem Vessel b with formation of the azeotropic mixture boiling at 91 ° at the top of the column are distilled off.

This regulation of the separation process ensures that the Phenol in the bladder can always be kept free of water or chlorine-rhenzene.

The process described is used in the manufacture of synthetic Phenols catalytically avoid the alkali which makes the process more expensive simultaneous, continuous extraction of phenols, which are free from water and hydrochloric acid and halocarbon.

Claims (1)

PATENT CLAIMS: i. Process for continuous immediate manufacture of anhydrous phenols by passing halogenated hydrocarbons with water vapor over catalysts with constant azeotropic separation and recycling of the not converted halogenated hydrocarbon, characterized in that one of the Mixture of phenol, water, halogenated hydrocarbons escaping from the catalyst space and hydrogen halide are deacidified and the phenol is azeotropically dehydrated. z. procedure according to claim i, characterized in that for the purpose of complete liberation of the Phenols formed by water in the still as long as halogenated hydrocarbons added until all the water is distilled over with the halogenated hydrocarbon. 3. The method according to claim i, characterized in that for the purpose of more complete Removal of the halogenated hydrocarbons from the phenols formed in the still water until all the halogenated hydrocarbons with the as auxiliary liquid serving water is distilled over.