DD227697A1 - METHOD OF ISOLATING DIANE - Google Patents

Abstract

A process for isolating dian from a reaction mixture obtained by hydrogen chloride catalyzed condensation of phenol and acetone. The workup of the reaction mixture comprises the steps a) neutralization of the hydrogen chloride, b) decantation of the neutralization mixture, c) extraction of the organic phase with water, d) distillative removal of the water from the extract, e) distillative removal of the major amount of the phenol, f) removal of the remaining phenol by steam distillation. The distillate obtained in steps (d) and (f) is used in step (c) as extracting agent, the extract of step (c) as dismutating agent in step (a).

Description

VEB Leuna-Werke Leuna, 10.09.1984

"Walter Ulbricht"

LP 8440

Title of the invention

Process for the isolation of dian

Field of application of the invention

The invention relates to a process for the isolation of dian from a formed in the catalyzed by hydrogen chloride condensation of acetone and phenol reaction mixture.

Characteristic of the known technical solutions

The work-up of the reaction mixtures catalyzed by hydrogen chloride in the condensation of phenol and acetone has been described in various ways. For example, it has been proposed to remove the hydrogen chloride from the reaction mixture by distillation (DE-AS 1 030 836) or neutralization (US Pat. No. 2,791,616). The salt formed in the course of neutralization is obtained in the form of an aqueous solution which forms a separate phase and is separated from the organic constituents of the reaction mixture by separation.

Mixed can be separated. Residual amounts of salt remaining in the organic phase can be removed by washing with water. The weereere processing of the mixture erfο Igt, optionally after the separation of the main amount of dian by crystallization of the phenol-dian adduct (US Patent 2,791,616), in a Desti I lative way. The distillates are a phenol-containing water and pure phenol. For the complete removal of the phenol from the dian a steam distillation is proposed (US-PS 2,775,680).

A major disadvantage of these work-up methods is the high water consumption (DD-PS 121 099) and the accumulation of large quantities of phenolic waste water in four stages of the work-up process. As a result, complex measures for wastewater treatment are required, which cause additional costs and adversely affect the specific energy and material consumption of the process.

Object of the invention

The aim of the invention is to reduce the amount of waste water which is produced in the work-up of the acidic reaction mixture of the dianosynthesis.

Explanation of the essence of the invention

The invention has for its object to reduce the accumulation of phenoI-ha It igen wastewater in the workup of the acidic reaction mixture of catalyzed by hydrogen chloride synthesis by multiple use of water streams.

The object is achieved by a process for isolating dian from a reaction mixture obtained by condensation of phenol and acetone under the catalytic action of hydrochloric acid.

material is formed, after which the reaction mixture is subjected to the following processes,

a) Neutralization of the hydrogen chloride with dilute sodium hydroxide solution

b) Decantation of the two-phase neutralization mixture

c) Extraction of the main amount of phenol and dian containing phase with water

d) Distillative removal of the water from the raffinate

e) Distillative removal of the bulk of the phenol from the residue of step (d)

f) removal of the residual phenol from the residue of step (e) by distillation with steam,

According to the invention solved in that only in the step (f) water is supplied in the form of water vapor, that in the steps (d) and (f) resulting distillates as extractant 'for the step (c) and the extract of the step (c ) in step (a) serve as a diluent for the sodium hydroxide solution used and that only in step (a) is drawn off a contaminated with phenol and diene wastewater stream.

The process according to the invention can be used for the work-up of reaction mixtures which are formed in the hydrogen chloride-catalyzed condensation of acetone and phenol in the molar ratio of 1: 3 to 1:15, preferably 1: 5 to 1: 8.

The neutralization (step a) is carried out at a temperature at which the resulting mixture is completely liquid. The required minimum temperature, which depends on the PhenoI-acetone · ratio in the reaction mixture and the sodium chloride concentration of the aqueous phase is 30 to 90 ° C.

The composition of the neutralization mixture in step (a) can be varied within wide limits. It depends on the phenol / acetone ratio of the reaction mixture, its hydrogen chloride content and the amount of water introduced. At a fixed phenol-acetone ratio and the associated saturation concentration of hydrogen chloride in the reaction mixture, the sodium nitrate concentration decreases and therewith the density of the aqueous phase decreases with increasing amount of water, while the density of the organic phase remains approximately constant remains. To ensure a trouble-free phase separation in step (b) the Wasserrnenge is to be dimensioned so that there is a sufficient density difference between the two phases. It is possible to work both above and below the boiling point, concentration at which the densities of the two phases are the same.

The extraction of the organic phase {stage c) can take place in one or more stages in cocurrent or countercurrent. If low levels of ash are to be achieved in the final product, multi-stage extraction is preferable.

The distillations of steps (d) and (e) are carried out in a conventional manner. The step (d) can be operated at normal pressure or under reduced pressure. In step (e), reduced pressure is used to avoid thermal damage to the dian.

By selecting the amount of water in the step (a), the ratio Dian / water vapor is set in the step (f). To ensure the greatest possible phenol removal from the Dian, it is expedient to operate the steam distillation in several stages in countercurrent. Suitable for this are, for example, soil or packed columns. It is also appropriate, the steam distillation with superheated

To operate steam, wherein to avoid thermal damage to the Dian: should exceed.

Damage to the Dian's steam temperature 200 C is not

The entire process is advantageously carried out continuously, but batch operation is also possible.

Embodiment 1

Batchwise workup of a reaction mixture of 3 mo I phenol and 1 mo I acetone, density of the neutralization waste water lower than that of the organic phase.

The reaction mixture of 3 mol of phenol, 1 mol of acetone and 0.18 mol of hydrogen chloride is mixed with 380 g of extract from the following work-up stage and neutralized at 60 ^° C. with 23.4 g of concentrated sodium hydroxide solution. The forming two-phase mixture is separated. The upper phase (235 g) consists predominantly of water and contains about 7% common salt and 3% phenol. The lower phase containing the bulk of phenol and dian is mixed with the combined distillates of steps (d) and (f) of a previous batch (410 g total) and separated again. The aqueous upper phase is used quantitatively as a diluent for a further neutralization batch. The organic lower phase is fed to a distillation. First, under normal pressure up to a bottom phase temperature of 160 C, the main amount of water (stage d), then distilled off under a pressure of 8 kPa, the main amount of phenol (stage e). The phenol contains up to 1.5% water. It is recycled to the Dian synthesis without further purification. The bottom product is blown out at 160 ^° C. with 170 g of steam superheated to 160 ^° C. (step f). The resulting distillate is used together with that of the step (e) for the extraction of a subsequent batch. The bottom product is 208 g of dian obtained in technical grade.

Embodiment 2

Continuous workup of a reaction mixture of 6 mo I phenol and 1 mo! Acetone, density of neutralization wastewater higher than that of the organic phase.

1070 g / h of a reaction mixture of 6 mo I phenol, 1 mo I acetone and 0.66 mol I hydrogen chloride are mixed with 350 g / h of the aqueous extract of the extraction stage and neutralized with 62 g / h of concentrated sodium hydroxide solution at 60 C. The biphasic reaction mixture is fed to a separation tube. As the lower phase 290 g / h of wastewater are discharged, which contains 15% sodium chloride and about 2% phenol. The upper phase is extracted in two successive mixer-settler extractors with 260 g / h each of the combined distillates of steps {d) and (f). The extracts obtained in both settlers are reclassified to the remainder. The product leaving the second settler as the lower phase is fed to the head of a Raschig column, the bottom of which is kept at a temperature of 160.degree. The distillate is recycled together with that of the steam distillation in the extraction stage. _c The bottom product is substantially freed of phenol in a circulation evaporator at 160 C and a pressure of 8 kPa. The resulting in an amount of 603 g / h distillate contains about 1.5% water and is recycled to the synthesis stage. The sump product containing about 6% phenol is applied to a Raschig column into which a stream of 175 g / h of superheated steam at 175 ° C. is introduced at the bottom. The distillate goes back to the extraction stage. The bottom product obtained 375 g / h of a technically pure Dian.

Claims (1)

claim A process for the isolation of dian from a reaction mixture formed by condensation of phenol and acetone under the kata Iytisehen effect of hydrogen chloride, wherein after the reaction, the reaction mixture is subjected to the following processes! a) Neutralization of the hydrogen chloride with dilute sodium hydroxide b) decantation of the biphasic neutralization mixture c) Extraction of the main amount of phenol and dian containing phase with water d) Distillative removal of the water from the raffinate e) Distillative removal of the main amount of phenol from the residue of step (d) f) removal of the residual phenol from the residue of step (e) by distillation with steam, characterized in that water is supplied in the form of water vapor only in step (f), that the distillates obtained in steps (d) and (f) are used as extractants for step (c) and the extract of step (c) in Stage (a) serve as a diluent for the NatronI eye used and that only in step (a) with a phenol and Dian loaded wastewater stream is withdrawn.