DE102008038031A1 - Preparing (co)polycarbonate or diaryl carbonate, useful in e.g. sunglasses, comprises converting di-, mono-phenol and phosgene to chloroformic acid aryl ester, oligo- or diaryl-carbonate, and reacting the product under alkaline solution - Google Patents

Abstract

Continuously preparing polycarbonate or copolycarbonate and/or diaryl carbonate comprises (a) continuously producing a mixture of an organic phase containing a solvent suitable for the polycarbonate and/or diaryl carbonate, and aqueous phase containing a solvent suitable for diphenol, monophenol, water and alkaline solution; (b) converting the diphenol, monophenol and phosgene to oligocarbonate and/or chloroformic acid aryl ester and/or diaryl carbonate; and (c) reacting an oligocarbonate, chloroformic acid aryl ester and/or diaryl carbonate under the addition of alkaline solution. Continuous preparation of polycarbonate or copolycarbonate and/or diaryl carbonate after the interfacial phase process of at least a diphenol and/or monophenol, phosgene and at least a catalyst optionally in the presence of at least a chain breaker and/or brancher, comprises (a) continuously producing a mixture of an organic and aqueous phase, where the organic phase contains at least a solvent suitable for the polycarbonate and/or diaryl carbonate and the phosgene and the aqueous phase contains the diphenol, monophenol, water and alkaline solution; (b) converting the diphenol, monophenol and phosgene to oligocarbonate and/or chloroformic acid aryl ester and/or diaryl carbonate; and (c) subsequently reacting an oligocarbonate, chloroformic acid aryl ester and/or diaryl carbonate in at least a reactor under the addition of further alkaline solution, optionally chain breaker and optionally at least a further catalyst, where: the steps (a) and (b) takes place in one or more pump(s), which have at least an inlet for the organic and aqueous phase and optionally further inlet for catalyst, chain breaker, brancher and/or alkali solution, respectively, and at least an outlet for the oligocarbon containing and/or chloroformic acid aryl ester-diaryl carbonate mixture; and the pump has thermostatic temperature and operates in stator-rotor principle.

Description

Process for the preparation of diaryl carbonates

object The present invention is a method for continuous Preparation of diaryl carbonates by reaction of monophenols and phosgene in an inert solvent in the presence of alkali and a catalyst according to the phase boundary method, in which both the mixing of the organic and aqueous Phase as well as the upstream formation of aryl chloroformates and / or diaryl carbonates in a particularly suitable pump.

The Preparation of diaryl carbonates (such as, for example, diphenyl carbonate) is usually carried out by a continuous process, by production of phosgene and subsequent reaction of monophenols and phosgene in an inert solvent in the presence of alkali and a nitrogen catalyst in the interface.

The preparation of diaryl carbonates z. B. by the phase interface process is described in principle in the literature, see, for. In Chemistry and Physics of Polycarbonates, Polymer Reviews, H. Schnell, Vol. 9, John Wiley and Sons, Inc. (1964), p. 50/51 ,

In the published patent application US-A-4 016 190 describes a preparation process of diaryl carbonates, which is operated at temperatures above 65 ° C. The pH is initially set low (pH = 8 to 9) and then high (pH = 10 to 11) in this process.

Optimization of the process by improving mixing and maintaining a tight temperature and pH profile as well as product isolation EP 1219589 A1 . EP 1216981 A2 . EP 1216982 A2 and EP 784048 A1 described.

to Preparation of diaryl carbonate by the interfacial method the phosgenation takes place in aqueous-alkaline Solution or suspension submitted sodium salt of a Monophenols or a mixture of different monophenols in the presence an inert organic solvent or solvent mixture, which in addition to the aqueous a second organic phase formed. The resulting, mainly in the organic Phase present, aryl chloroformate are using suitable catalysts to, dissolved in the organic phase, Diaryl carbonates reacted. The organic phase eventually becomes separated and the diaryl carbonate by various workup steps from it isolated.

The Carrying out the Diarylcarbonatsynthese can continuously or discontinuously. The reaction can therefore be carried out in stirred kettles, Tubular reactors, circulating reactors or stirred tank cascades or combinations thereof, wherein by using the already to ensure that mixing is aqueous and organic phase only then segregate when the synthesis mixture has reacted, d. H. no saponifiable Chlorine of phosgene or chloroformic acid esters more contains.

The first step in the construction of the aryl chloroformates and / or diaryl carbonates is carried out according to the prior art, for example in a circulating pump reactor; see, for. B. EP 1 249 463 A1 . US 2004/0158026 A1 . US 6,613,868 B2 , In Umpumpreaktor doing the mixing of the introduced phosgene with likewise introduced sodium salt of a monophenol (or a mixture of different monophenols) to Aryl chloroformates and / or diaryl carbonates. A certain proportion of the introduced monophenol is still unreacted in the mixture. Although the Umpumpreaktor to the effect that dosing or concentration fluctuations can not undamped penetrate to the final product, but rather by backmixing at set Umpumpverhältnis to inflow or outflow of the reaction mixture, an equilibration of fluctuations is achieved. However, there is a significant disadvantage in that for industrially advantageous parameter settings there are still considerable incompletely converted portions of aryl chloroformate in the product composition. One Another disadvantage is the fact that Umpumpreaktoren represent relatively bulky assemblies.

at However, these known methods prepare a high residual phenolic value in the wastewater of these processes considerable disadvantages. Phenols can polluting the environment and increasing the sewage treatment plants Sewage problems pose and make elaborate cleaning operations required.

So describes WO 03/070639 A1 removal of the organic impurities in the wastewater by extraction with methylene chloride.

Usually becomes the sodium chloride-containing solution of solvents and organic residues released and must then be disposed of.

But it is also known that the purification of sodium chloride-containing wastewater according to the EP 1200359 B1 ( WO 2000078682 A1 ) or US-A-6340736 can be carried out by ozonolysis and then suitable for use in the sodium chloride electrolysis. The disadvantage of ozonolysis is that this process is very costly.

It There was therefore a need for a continuous interfacial process for the preparation of diaryl carbonate, which is the preparation of Diaryl carbonates allows without any concentration fluctuations the chloroformic acid ester undamped until can penetrate to the end product (no plug-flow behavior). Furthermore, there was a need to stress the off of this procedure resulting monophenol content in the waste water on.

Surprised was found to be a significant reduction in monophenol load of the wastewater can be achieved when in the interfacial process for the preparation of diaryl carbonates both the mixture of organic and aqueous phase as well as the precursor aryl chloroformate formation done in a special pump. Advantageously, also beat in this method, concentration fluctuations of the aryl chloroformate not steamed to the end product, so that inventive method the advantages of the known Maintains method according to the prior art, however, its disadvantages are eliminated. Through the more efficient implementation The amount of aryl chloroformate decreases, which is a less Aminkatalysatormenge required and thus to a Reduction of Urethannebenprodukte leads.

A Increased monophenol loading of the waste water is known to be required as a countermeasure, a complicated purification by ozonolysis or extraction. Due to the significantly reduced monophenol load of the wastewater according to the invention Procedures can be such a cleaning that the economy reduced, avoided.

• (a) kontinuierlich eine Mischung der organischen und wässrigen Phase erzeugt wird, wobei die organische Phase wenigstens ein für das Diarylcarbonat geeignetes Lösungsmittel und ganz oder teilweise das Phosgen enthält und die wässrige Phase das oder die Monophenol(e), Wasser und Alkalilauge enthält,
• (b) eine Umsetzung des oder der Monophenol(e) und Phosgen zu Chlorameisensäurearylestern oder Diarylcarbonaten oder einer Mischung aus Chlorameisensäurearylestern und Diarylcarbonaten erfolgt,
• (c) die Chlorameisensäurearylester und/oder Diarylcarbonate anschließend in wenigstens einem Reaktor unter Zugabe von weiterer Alkalilauge, und gegebenenfalls wenigstens eines weiteren Katalysators umgesetzt werden,

und dadurch gekennzeichnet, dass die kontinuierliche Mischung der organischen und wässrigen Phase unter (a) und die Umsetzung zu Chlorameisensäurearylestern und/oder Diarylcarbonaten unter (b) in einer oder mehreren Pumpe(n) erfolgen, die

• – nach dem Stator-Rotor-Peripheralrad-Prinzip arbeitet (arbeiten)
• – thermostatisierbar ist (sind) und
• – wenigstens jeweils einen Zugang für die organische und die wässrige Phase und gegebenenfalls weitere Zugänge für Katalysator und/oder zusätzlich Alkalilauge sowie wenigstens einen Ausgang für die Chlorameisensäurearylester-Diarylcarbonat Mischung aufweist (aufweisen).

The present invention therefore provides a process for the continuous preparation of diaryl carbonates by the interfacial process from at least one monophenol, phosgene and at least one catalyst, wherein

• (a) continuously producing a mixture of the organic and aqueous phases, the organic phase containing at least one solvent suitable for the diaryl carbonate and wholly or partially containing the phosgene and the aqueous phase containing the monophenol (s), water and alkali metal hydroxide,
• (b) a reaction of the monophenol (s) and phosgene to aryl chloroformates or diaryl carbonates or a mixture of aryl chloroformates and diaryl carbonates takes place,
• (c) the aryl chloroformates and / or diaryl carbonates are subsequently reacted in at least one reactor with addition of further alkali metal hydroxide, and optionally at least one further catalyst,

and characterized in that the continuous mixing of the organic and aqueous phases under (a) and the conversion to aryl chloroformates and / or diaryl carbonates under (b) take place in one or more pump (s) which

• - works (works) according to the stator-rotor-peripheral-wheel-principle
• - Is thermostatable (are) and
• - Has at least one access for the organic and aqueous phase and optionally further accesses for catalyst and / or additionally alkali metal hydroxide and at least one outlet for the chloroformate diaryl carbonate mixture (have).

In the process according to the invention for the preparation of diaryl carbonate, at least a part of the da be recycled in the resulting alkali chloride-containing solution in a subsequent alkali chloride electrolysis.

The Pump (s) used in the invention are preferred built according to the single or multi-chamber principle.

The organic phase may be the required phosgene before mixing already completely or partially contained with the aqueous phase. The organic phase preferably contains before the mixture already all the phosgene required including the one used Excess phosgene.

Of the Entry of the phosgene into the organic phase can be gaseous or liquid. The excess used to phosgene, based on the sum of the monophenols used, is preferably between 1 and 100 mol%, more preferably between 2 and 50 mol%.

Of the pH of the aqueous phase may optionally over single or multiple replenishment of caustic during and after the phosgene dosage in the alkaline range preferably between 8.5 and 12 are kept while it is after the catalyst addition should be at 10 to 14.

The Phosgene dosage takes place before mixing with the aqueous Phase completely or partially directly into the organic phase. any Partial quantities of phosgene can also be added before mixing with the aqueous phase in the aqueous phase or after mixing with the aqueous phase in the resulting Emulsion be metered. Furthermore, the phosgene can be whole or partially in a recirculated partial flow of Synthesis mixture of both phases are dosed, this Partial stream preferably recirculated before the catalyst addition becomes. Particularly preferred is the complete phosgene dosage before mixing with the aqueous phase directly into the organic phase. In all these embodiments are observe the pH ranges described above and, if necessary by single or multiple replenishment of alkali or appropriate dosage of monophenol (at) solution to comply. Likewise, the temperature range may need cooling or dilution.

The Synthesis of diaryl carbonates from monophenols and phosgene in the alkaline state Milieu is an exothermic reaction and is in a temperature range from -5 ° C to 100 ° C, preferably 15 ° C to 80 ° C, most preferably 25 to 65 ° C. carried out.

Therefore it is necessary that the invention for the mixture and the preliminary aryl chloroformate formation used pump (s) to a temperature of -5 ° C to 100 ° C, preferably from 15 ° C to 80 ° C, more preferably from 25 ° C to 65 ° C thermostatable is (are).

ever according to solvent or solvent mixture be operated under normal pressure or under pressure. The pump (s) used according to the invention can for system pressures and temperatures up to 350 bar and 450 ° C are designed. They are thus for suitable for use in a wide process window.

At the Phase interface method is preferably in pressure ranges from 1 to 50 bar, more preferably in ranges from 1 to 10 bar, worked.

worin
R Wasserstoff, Halogen oder ein verzweigter oder unverzweigter C₁- bis C₉-Alkylrest oder Alkoxycarbonylrest ist.Particularly suitable monophenols for use in the new process are phenols of the formula (I)

wherein
R is hydrogen, halogen or a branched or unbranched C ₁ - to C ₉ -alkyl radical or alkoxycarbonyl radical.

Prefers are phenol, alkylphenols such as cresols, p-tert-butylphenol, p-cumylphenol, p-n-octylphenol, p-iso-octylphenol, p-n-nonylphenol and p-iso-nonylphenol, halophenols such as p-chlorophenol, 2,4-dichlorophenol, p-bromophenol and 2,4,6-tribromophenol or salicylic acid methyl ester. Particularly preferred is phenol.

The Alkali used to form the phenolate may be an alkali metal hydroxide with hydroxides from the series: be Na, K, Li hydroxide. Prefers is caustic soda, and is preferably 10 in the new process used to 55 wt .-% - solution. The alkali hydroxide used or the alkali metal hydroxide in the case of sodium hydroxide or sodium hydroxide solution for example, by the amalgam process or the so-called membrane process have been produced. Both procedures have been going for a long time used and are familiar to the expert. It is preferred in the case of caustic soda, such prepared by the membrane process used.

The Reaction b) can be catalyzed by catalysts, such as tertiary amines, N-alkylpiperidines or onium salts are accelerated. Prefers Tributylamine, triethylamine and N-ethylpiperidine are used.

Of the used amine catalyst may be open-chain or cyclic, particularly preferred is triethylamine and ethylpiperidine. The catalyst is preferably in the new process as 1 to 55 wt .-% solution used.

By onium salts are meant here compounds such as NR ₄ X, where R can be an alkyl and / or aryl radical and / or an H and X is an anion.

phosgene can in the process step b) liquid, gaseous or dissolved in an inert solvent become.

In the inert process is preferably used in the novel process in step b) Solvents are, for example, dichloromethane, toluene, the various dichloroethanes and chloropropane compounds, chlorobenzene and chlorotoluene. Preferably, dichloromethane is used.

The Reaction procedure for step b) is preferably carried out continuous and most preferably in a plug flow with low backmixing. This can thus, for example done in tubular reactors. The mixing of the two phases (aqueous and organic phase) can be achieved by built-in tube diaphragms, static Mixer and / or example pumps can be realized.

The Reaction according to step b) takes place particularly preferably two stages.

In In the first step of the preferred process, the reaction is carried out Contacting the educts phosgene, the inert solvent, which preferably only as a solvent for the Phosgene, and the monophenol, which preferably already before dissolved in the alkali, started. The residence time is typically in the first stage in the range of 2 seconds to 300 seconds, more preferably in the range of 4 seconds to 200 seconds. The pH of the first stage is determined by the ratio of alkali lye / monophenol / phosgene preferably adjusted so that the pH is in the range of 11.0 to 12.0, preferably 11.2 to 11.8, particularly preferably from 11.4 to 11.6. The reaction temperature the first stage is preferred by cooling below of 40 ° C, more preferably below 35 ° C held.

In In the second step of the preferred process, the reaction becomes Diaryl carbonate completed. The residence time is at preferred process 1 minute to 2 hours, preferably 2 minutes to 1 hour, most preferably 3 minutes to 30 minutes. In the second stage of the preferred process is characterized by permanent Control of the pH (is preferred in the continuous process Measured online according to basically known methods) and appropriate adjustment of the pH by adding the alkali metal hydroxide solution regulated. The amount of supplied alkali is particularly adjusted so that the pH of the reaction mixture in the second Process level in the range of 7.5 to 10.5, preferably 8 to 9.5, very particularly preferably 8.2 to 9.3. The reaction temperature the second stage is by cooling at preferably below of 50 ° C, more preferably below 40 ° C, most preferably kept below 35 ° C.

The in this application listed general or preferred listed parameters or explanations can but also among each other, ie between the respective areas and preferred ranges can be combined as desired.

in the preferred process in step b) is phosgene related to Monophenol in a molar ratio of 1: 2 to 1: 2.2 used. The solvent is mixed in such a way that the diaryl carbonate in a 5 to 60% solution, preferably 20 to 45% Solution after the reaction is present.

As catalysts for the process according to the invention are preferably tertiary amines, such as. B. Triethylamine, tributylamine, trioctylamine, N-ethylpiperidine, N-methylpiperidine or Ni / n-propylpiperidine, quaternary ammonium salts such. For example, tetrabutylammonium, tributylbenzylammonium, tetraethylammonium hydroxide, chloride, bromide, hydrogen sulfate or tetrafluoroborate and the phosphonium compounds corresponding to the abovementioned ammonium compounds. These compounds are described as typical phase interface catalysts in the literature, are commercially available and familiar to those skilled in the art. The catalysts may be added individually, in admixture or also side by side and sequentially to the process according to the invention, if appropriate also prior to phosgenation, but preferred are doses after phosgene introduction, unless an onium compound - ie ammonium or phosphonium compound - or mixtures from onium compounds used as catalysts. In the case of such onium salt catalysis, addition before the phosgene dosage is preferred. The metering of the catalyst or catalysts can be carried out in bulk, in an inert solvent, preferably the one or more of the organic phase in the diaryl carbonate synthesis, or else as an aqueous solution. In the case of using tertiary amines as catalyst, for example, their dosage in aqueous solution as their ammonium salts with acids, preferably mineral acids, in particular hydrochloric acid, take place. When using multiple catalysts or dosing aliquots of the total amount of catalyst, different dosages may also be made at different locations or at different times. The total amount of catalysts used is between 0.0001 and 1.0 mol%, preferably between 0.001 and 0.2 mol%, based on moles of monophenols used.

to Formation of the phenolate is preferably 1 mol of alkali / mol of monophenol to 5.00 moles of alkali / mole of monophenol, more preferably of 1.1 used to 2.5 moles of alkali / mol monophenol. The dissolution processes may consist of solid phenol or even molten phenol out. The alkali hydroxide used or the alkali metal hydroxide can in the case of sodium hydroxide or sodium hydroxide, for example after the amalgam process or the so-called membrane process have been. Both methods are used for a long time and are familiar to the expert. Preference is given in the case of Sodium hydroxide solution prepared by the membrane method.

In such an aqueous solution and / or the aqueous Phase are the or the monophenol (s) in whole or in part in the form the corresponding alkali metal salts.

in the inventive methods are for the mixture of the organic and aqueous phase and the upstream chloroformic acid ester production step one or more pump (s) used. Several pumps can especially on an industrial scale for capacity reasons be used. In case of using multiple pumps can these can be connected both in parallel and in series. Prefers is a parallel connection of several pumps.

The According to the invention used according to pumps the stator-rotor principle. This will be in the mixture of the two In particular, energy travels through shear in the reaction mixture entered. As a result, the resulting emulsion has sufficient large phase interface, allowing for optimal Reaction can take place at this phase interface.

In the case of the pumps used according to the invention, the pump housing preferably represents the stator and inside the pump there are one or more rotors. In the case of multiple rotors, these are preferably applied to the same rotor axis. The pumps used according to the invention are preferably centrifugal pumps. In preferred embodiments, these are centrifugal pumps whose impeller (rotor) has a peripheral design (peripheral wheel pump). In further preferred embodiments, these are centrifugal pumps whose impeller (rotor) has a radial design (radial wheel pump). Particularly preferred according to the invention are pumps which operate on the principle of Peripheralradpumpe. Such centrifugal pumps and their mode of operation are known to the person skilled in the art (cf. DE 42 20 239 A1 ) and commercially available. The principle of such a pump used in the invention is exemplary and schematically in 1 shown. There are both embodiments with single or Mehrfachspalttöpfen such. B. double-gap pots, suitable.

1 : Schematic representation of the principle of a Peripheralradpumpe with rotating inner device

In the 1 used abbreviations stand for

1

Phosgene / solvent influx

2

influx aqueous / alkaline sodium monophenolate solution

3

Caustic soda influx (NaOH-influx)

4

Abgeführtes reaction

R

rotating interior device

S

shovel at the rotating Innevorrichtung

K

circulation channel

RZ

Supply side reaction (Suction side)

RA

Reaction discharge side (Face)

P

static Housing of Peripheralradpumpe with rotating inner device

In the 1 Peripheralradpumpe shown has a static housing P, a rotating inner device R with blades S (here designed as a paddle wheel) and a resulting resulting in the housing channel K from the suction to the pressure side down. The peripheral pump can create relatively high pressures for a flow pump at low flow rates and small size. During conveyance, the transported reaction mixture between the blades S releases its energy to the reaction mixture conveyed in the circulation channel. The increase in pressure takes place by exchange of pulses, in that the fluid flowing at greater speed in the blades of the impeller delivers the energy to the fluid rotating at a lower speed in the circulation channel.

The Pumps used in the invention are thermostatable, d. H. have an inlet and outlet for a Thermostatisierflüssigkeit on. Flow space for this Thermostatisierflüssigkeit and reaction space for the reaction mixture are so separated from each other, that no mass transfer, but a heat exchange can be done.

The pumps used according to the invention have as feed to the reaction space at least one access each for the organic and the aqueous phase and at least one exit for the reaction mixture formed in the first stage (cf. 1 ). In preferred embodiments, further additions for additional caustic and / or monophenol (at) solution are preferred. The catalyst is preferably added at a later time to a downstream residence reactor. A schematic exemplary structure for such a reaction according to the invention is shown in FIG 2 shown. The representation in 2 is to be regarded as merely exemplary in terms of the number of downstream residence reactors. It can also be followed by more or less than two residence reactors.

2 : Schematic structure for the preparation of diaryl carbonate by the interfacial process using a Peripheralradpumpe

In the 2 used abbreviations stand for

1

Phosgene / solvent influx

2

influx aqueous / alkaline sodium monophenolate solution

3

First caustic soda inflow (NaOH inflow 1 )

4

Abgeführtes reaction

5

Second sodium hydroxide feed (NaOH feed 2 )

6

catalyst

pp

Peripheralradpumpe

ST

static mixer

VR1

residence reactor 1

VR2

residence reactor 2 (optional)

WT

heat exchangers

DEH

Booster pump

TG

separation vessel

W

subsequent Laundry

In a further embodiment of the method according to the invention, the pump used according to the invention may also be followed by a circulating pump instead of an immersion reactor. This off variant of the method according to the invention would have the advantage that existing systems could be used by upstream of a pump used in the invention, without far-reaching modifications to the systems would be required. A schematic exemplary structure for such a reaction according to the invention is shown in FIG 2a shown. The representation in 2a is to be regarded as merely exemplary in terms of the number of downstream residence reactors. It can also be followed by more or less than two residence reactors.

In a variant of the method with the invention used Pump downstream Umpumpreaktor the starting materials, such as B. the monophenolate solution or the first sodium hydroxide feed, either completely added to the pump or optionally proportionately supplied only to the downstream Umpumpreaktor become.

2a : Schematic structure for the preparation of diaryl carbonate by the interfacial process using a Peripheralradpumpe with downstream Umpumpreaktor.

In the 2a in addition to the in 2 used abbreviations stand for

2 '

optional Influx of a proportion of aqueous / alkaline sodium monophenolate solution

3 '

optional feed of a portion of the first caustic soda feed (NaOH feed 1' )

EC

degassing vessel

UR

circulating reactor

AT

discharge pump

P

pump to maintain the circulation

The Residence time of the reaction mixture in the invention used Pump is preferably 20 seconds to 10 minutes, especially preferably 30 seconds to 5 minutes and most preferably 30 seconds to 3 minutes.

From the pump or pumps, the chloroformic acid aryl ester and / or diaryl carbonate-containing reaction mixture is converted into diaryl carbonates in at least one reactor with the addition of further alkali metal hydroxide, and optionally at least one further catalyst. In preferred embodiments, this reaction takes place in a cascade of several reactors connected in series. Suitable reactors for this reaction are any reactor designs, such. B. stirred tank, tubular reactors, Umpumpreaktoren, their cascades or combinations thereof in question (see. 2 ).

to Processing of the reacted, at most still traces, preferably less than 2 ppm of aryl chloroformates containing, at least two-phase reaction mixture to settle for phase separation. The aqueous alkaline Phase is optionally completely or partially combined with washing phases fed to wastewater treatment, where solvent and catalyst portions separated by stripping and optionally be recycled to the diaryl carbonate synthesis. In another variant of the workup is after separation the organic impurities, in particular of solvents and catalyst residues, and optionally after adjustment of a certain pH, z. B. by addition of hydrochloric acid, the Salt solution separated, which z. As the chloralkali electrolysis can be fed while the aqueous Phase optionally fed back to the Diarylcarbonatsynthese becomes.

The organic, diaryl carbonate-containing phase can subsequently to remove contaminants alkaline, ionic or catalytic Nature are purified in various ways known in the art.

The organic phase usually also contains one or more settling operations, optionally supported by passages through settling tanks, stirred tanks, coalescers or separators or combinations of these measures - optionally water in each or some separation steps under certain circumstances using active or passive mixing devices can be added - still shares the aqueous alkaline phase in fine droplets and the catalyst or the (s). After this coarse separation of the alkaline, aqueous phase, the organic phase can be washed one or more times with dilute acids, mineral, carbon hydroxycarboxylic and / or sulfonic acids. Preference is given to aqueous mineral acids, in particular hydrochloric acid, sulfuric acid or mixtures of these acids. The concentration of these acids should preferably be in the range from 0.001 to 50% by weight, preferably from 0.01 to 5 % By weight. Furthermore, the organic phase can be washed repeatedly with desalted or distilled water. The separation of, optionally dispersed with parts of the aqueous phase, organic phase after the individual washing steps by means of settling, stirred tank, coalescers or separators or combinations of these measures, the washing water between the washing steps are optionally metered using active or passive mixing devices can.

The Isolation of the diaryl carbonate from the solution can be achieved by Evaporation of the solvent by means of temperature, vacuum or a heated towing gas or preferably distillation.

The produced by the process according to the invention Diaryl carbonates are characterized by particularly high purity (GC> 99.95%) and very good Transesterification behavior, so that subsequently a polycarbonate can be produced in excellent quality can.

The use of the diaryl carbonates for the preparation of aromatic oligo- / polycarbonates by the melt transesterification process is known from the literature and is described, for example, in US Pat Encyclopedia of Polymer Science, Vol. 10 (1969), Chemistry and Physics of Polycarbonates, Polymer Reviews, H. Schnell, Vol. 9, John Wiley and Sons, Inc. (1964) or the US-A-5 340 905 described.

Surprised could also with the inventive method the monophenol load of the waste water can be reduced.

• – nach dem Stator-Rotor-Peripheralrad-Prinzip arbeitet (arbeiten)
• – thermostatisierbar ist (sind) und
• – wenigstens jeweils einen Zugang für eine organische und eine wässrige Phase und gegebenenfalls weitere Zugänge für Katalysator und/oder zusätzlich Alkalilauge sowie wenigstens einen Ausgang für die Chlorameisensäurearylester- und/oder Diarylcarbonathaltige Mischung aufweist (aufweisen),

The use of pumps with triple function as a mixing unit, reaction space for the upstream chloroformate and / or Diarylcarbonatherstellungsschritt and delivery unit is not described for the interfacial process for the preparation of diaryl carbonates in the literature. The present invention therefore furthermore relates to the use of one or more pumps for the continuous production of diaryl carbonate by the interfacial method, wherein the pump (s)

• - works (works) according to the stator-rotor-peripheral-wheel-principle
• - Is thermostatable (are) and
• At least one access for each of an organic phase and an aqueous phase and, if appropriate, further accesses for catalyst and / or additionally alkali metal hydroxide solution and at least one outlet for the chloroformic acid aryl ester and / or diaryl carbonate-containing mixture,

In This pump (s) can handle both the continuous mixing the organic and aqueous phase, wherein the organic Phase at least one suitable for the diaryl carbonate Solvent and wholly or partly contains the phosgene and the aqueous phase, the monophenol (s), water and alkali metal hydroxide, as well as the reaction of or the monophenol (e) and phosgene to aryl chloroformate and / or diaryl carbonates.

For this use is the preceding for the invention Method already described pumps. In particular, are suitable for this centrifugal pumps, particularly preferably Peripheralradpumpen.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 4016190 A [0004]
• - EP 1219589 A1 [0005]
• - EP 1216981 A2 [0005]
• - EP 1216982 A2 [0005]
• EP 784048 A1 [0005]
• - EP 1249463 A1 [0008]
• - US 2004/0158026 A1 [0008]
• - US 6613868 B2 [0008]
• WO 03/070639 A1 [0010]
• - EP 1200359 B1 [0012]
• WO 2000078682 A1 [0012]
• US 6340736A [0012]
• - DE 4220239 A1 [0046]
• - US 5340905 A [0065]

Cited non-patent literature

• - Chemistry and Physics of Polycarbonates, Polymer Reviews, H. Schnell, Vol. 9, John Wiley and Sons, Inc. (1964), p. 50/51 [0003]
• - Encyclopedia of Polymer Science, Vol. 10 (1969), Chemistry and Physics of Polycarbonates, Polymer Reviews, H. Schnell, Vol. 9, John Wiley and Sons, Inc. (1964) [0065]

Claims (15)

A process for the continuous preparation of diaryl carbonates by the interfacial process from at least one monophenol and phosgene in the presence of an inert solvent and in the presence of alkali and a nitrogen catalyst, wherein (a) continuously a mixture of the organic and aqueous phases is produced, wherein the organic phase at least one for the diaryl carbonate suitable solvent and wholly or partially the phosgene and the aqueous phase containing the monophenol (s), water and alkali, (b) a reaction of the monophenol (s) and the phosgene to aryl chloroformates or diaryl carbonates or a (B) the aryl chloroformates or diaryl carbonates or a mixture of aryl chloroformates and diaryl carbonates are subsequently reacted in at least one reactor with the addition of further alkali metal hydroxide, and thereby g characterized in that the continuous mixing of the organic and aqueous phase under (a) and the conversion to aryl chloroformates and / or diaryl carbonates under (b) in one or more pump (s), which - works according to the stator-rotor peripheral wheel principle (work) - is thermostatable (are) and - at least each has an access for the organic and the aqueous phase. A method according to claim 1 characterized characterized in that in step (c) at least one further catalyst is used. A method according to claim 1 or 2 characterized in that the pump (s) further accesses for additional alkali and at least one Exit for the aryl chloroformates and / or Diaryl carbonate-containing mixture has (have). Method according to one of the claims 1 to 3, characterized in that the pump (s) one or more Having rotors. Method according to one of the claims 1 to 4, characterized in that the pump (s) to a temperature from -5 ° C to 100 ° C thermostatable is (are). Process according to one of Claims 1 to 5, characterized in that compounds of the formula (I) are used as monophenol (e):

in which R = hydrogen, halogen or a branched or unbranched C ₁ - to C ₉ -alkyl radical or alkoxycarbonyl radical. Method according to one of the claims 1 to 6, characterized in that as monophenol (s) phenol, Cresols, p-tert-butylphenol, p-cumylphenol, p-n-octylphenol, p-iso-octylphenol, p-n-nonylphenol and p-iso-nonylphenol, p-chlorophenol, 2,4-dichlorophenol, p-bromophenol and 2,4,6-tribromophenol or salicylic acid methyl ester or a mixture of these compounds. Method according to one of the claims 1 to 7, characterized in that it is at the pump or the pumps used in (a) and / or (b), a centrifugal pump is. A method according to claim 8 thereby in that the centrifugal pump is a peripheral wheel pump is. Method according to one of the claims 1 to 9, characterized in that the pump after the on or Multi-chamber principle is constructed. Use of one or more pumps for the continuous production of diaryl carbonate by the interfacial method, wherein the pump (s) works according to the stator-rotor-peripheral-wheel principle - Is thermostatable (are) and - has at least one access for each of an organic and an aqueous phase. Use of one or more pump (s) according to claim 11, characterized in that the pump (s) further accesses for catalyst and / or additionally alkali metal hydroxide and at least one exit for the aryl chloroformates and / or diaryl carbonate-containing mixture. Use of one or more pump (s) according to claim 12 characterized in that in this / these pumps both the continuous mixture of organic and aqueous Phase, wherein the organic phase at least one for the Diaryl carbonate suitable solvent and all or part the phosgene and the aqueous phase contains the or containing monophenol (s), water and alkali, as also the reaction of the monophenol (s) and phosgene to aryl chloroformates or diaryl carbonates or a mixture of aryl chloroformates and diaryl carbonates. Use of one or more pump (s) according to claim 12 or 13, characterized in that it at the or Pump (s) are centrifugal pumps. Use of one or more pump (s) according to claim 14, characterized in that it is at the or the centrifugal pump (s) um Peripheralradpumpen acts.