EP0217897A1 - Process for the manufacture of 2.5 - dichlorphenol - Google Patents
Process for the manufacture of 2.5 - dichlorphenolInfo
- Publication number
- EP0217897A1 EP0217897A1 EP19860902391 EP86902391A EP0217897A1 EP 0217897 A1 EP0217897 A1 EP 0217897A1 EP 19860902391 EP19860902391 EP 19860902391 EP 86902391 A EP86902391 A EP 86902391A EP 0217897 A1 EP0217897 A1 EP 0217897A1
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- EP
- European Patent Office
- Prior art keywords
- dichlorophenol
- water
- separated
- weight
- crystals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/70—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment
- C07C37/84—Purification; separation; Use of additives, e.g. for stabilisation by physical treatment by crystallisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/685—Processes comprising at least two steps in series
Definitions
- the invention relates to a process for the preparation of 2,5-dichlorophenol with a content of 95 to over 99% from a mixture of about 80% 2,5-dichlorophenol, about 20% 2,4-dichlorophenol and minor other phenolic impurities by multi-stage Crystallization in the presence of water.
- 2,5-dichlorophenol is of particular importance as a starting compound for the production of valuable agricultural chemicals.
- German patent 1,493,493 now describes a method for separating this mixture with the aid of urea.
- the 2,5-dichlorophenol is separated off via the water-insoluble urea adduct.
- the process requires significant amounts of urea that are lost with the water. So it cannot be considered environmentally friendly. A recovery of the urea would be very expensive.
- US Pat. No. 2,800,324 describes a process in which 1-bromo-2,5-dichlorobenzene is reacted with sodium hydroxide solution and methanol in an autoclave at elevated temperature and pressure in the presence of a copper catalyst and the reaction product is purified by extraction and distillation .
- the process is complex and initially requires the production of 1-bromo-2,5-dichlorobenzene, which is generally associated with high costs.
- the object of the invention is accordingly to provide an improved process for producing a largely pure 2,5-dichlorophenol.
- the process should be simple to carry out and enable the separation of 2,4-dichlorophenol from its mixtures with 2,5-dichlorophenol in a more economical manner than is the case in the prior art.
- This object is achieved according to the invention with a process for the preparation of 2,5-dichlorophenol, which is characterized in that a liquid mixture of about 8 parts by weight of 2,5-dichlorophenol and about 2 parts by weight of 2,4-dichlorophenol with hot water above the solidification temperature mixes, the crystals obtained after cooling are separated off, again transferred to the melt, mixed with hot water, cooled and the crystals which have separated out are separated off.
- Mixtures of 2,5-and 2,4-dichlorophenol of any origin which contain about 8 parts by weight of 2,5-dichlorophenol and about 2 parts by weight of 2,4-dichlorophenol can be used for the process according to the invention.
- Such mixtures are obtained, for example, according to US Pat. No. 2,799,714 in large amounts when reacting 1,2,4-trichlorobenzene with sodium hydroxide solution in the presence of methanol in an autoclave at elevated temperatures and pressures.
- the process according to the invention is carried out in at least two crystallization stages.
- the 2,5- / 2,4-dichlorophenol mixture which is expediently liquefied by melting, is thoroughly mixed, for example, with 0.15 to 0.5 part by weight of water, the addition of 0.2 part by weight of water being particularly preferred in order to achieve a good cleaning effect is. Care must be taken during mixing that the organic phase does not solidify prematurely, which can expediently be achieved by maintaining a temperature of 50 to 70 ° C.
- the mixture is then cooled, preferably to 5 to 25 ° C, depending on the desired degree of purity, the prepurified 2,5-dichlorophenol crystallizing out, while most of the 2,4-dichlorophenol remains in the mother liquor.
- the crystals thus obtained are separated off by customary methods, for example by filtration, decanting, centrifuging or the like, and it may be expedient to keep the mixture in a stirrable state by adding water to facilitate the separation.
- the crystals obtained in this way are transferred to a second cleaning stage either immediately or advantageously after one or more washes with cold water.
- the crystal mass is melted and mixed again with 1.5 to 3 parts by weight of hot water, the use of 2 parts by weight of water having proven particularly advantageous for achieving a particularly good cleaning effect. It is then cooled, depending on the desired degree of purity, preferably to 20 to 35 ° C, whereupon crystallization occurs.
- the crystals are separated off by one of the methods indicated above and expediently washed once or more times with water. In this way, largely pure 2,5-dichlorophenol with a purity of 95 to 99% is obtained. In most cases, these products are already sufficiently pure for further use. In cases in which products with a particularly high degree of purity are desired, the crystallization step described last can be repeated one or more times.
- the method according to the invention is particularly environmentally friendly.
- the water used is circulated after the organic phase introduced during the process has been separated off.
- the wastewater problem can be solved in a particularly simple and environmentally friendly manner.
- the organic phases of the second and, if appropriate, further crystallization stages are returned to the first crystallization stage for renewed purification, as a result of which the yield can be significantly improved.
- the dichlorophenol mixture is distilled over a column in a water jet vacuum.
- the fraction (257g) which transitions at 89 to 91 ° C / 12mm contains: 82.6% 2,5-dichlorophenol, 16.9% 2,4-dichlorophenol and 0.5% 3,4-dichlorophenol.
- 255ml (330g) 2,5- / 2,4-dichlorophenol mixture are mixed with 65ml water at 60 ° C and cooled to 20 ° C with stirring. After crystallization has started and the temperature has risen, 200 ml of cold water are added for dilution. The mixture is cooled further to 15 ° C, the crystals are suctioned off and washed twice with 500 ml of cold water. The mother liquor and the washing filtrates are combined and separated in the heat in a separating funnel. The water is reused, the organic phase is discarded or can be used for other reactions.
- 200ml (255g) of melted filter cake from the 1st stage are mixed with 400ml of water at 70oC and cooled to 30oC with stirring. After crystallization has started and the temperature has risen, cooling is continued to 30 ° C. The crystals are suctioned off and washed with 150 ml of cold water. The mother liquor and the washing filtrate are combined and separated in the heat in a separating funnel. The water is reused, the organic phase becomes the feed product of the 1st S tu fe fed.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Un procédé permet de produire du 2,5-dichlorphénol ayant une teneur comprise entre 95% et 99%. Un mélange de 2,5-dichlorphénol et de 2,4-dichlorphénol est recristallisé plusieurs fois en présence de l'eau. L'eau résultant de la séparation des substances solides est remise en circulation et la phase organique séparée du filtrat lors de la deuxième étape et des étapes suivantes est rajoutée au produit de base.One process produces 2,5-dichlorphenol having a content between 95% and 99%. A mixture of 2,5-dichlorphenol and 2,4-dichlorphenol is recrystallized several times in the presence of water. The water resulting from the separation of the solid substances is recirculated and the organic phase separated from the filtrate in the second step and the following steps is added to the basic product.
Description
Verfahren zur Herstellung von 2 ,5-DichlorphenolProcess for the preparation of 2, 5-dichlorophenol
Die Erfindung betrifft ein Verfahren zur Herstellung von 2,5-Dichlorphenol mit einem Gehalt von 95 bis über 99% aus einem Gemisch von etwa 80% 2,5-Dichlorphenol, etwa 20% 2,4-Dichlorphenol und geringen anderen phenolischen Verunreinigungen durch mehrstufige Kristallisation in Gegenwart von Wasser.The invention relates to a process for the preparation of 2,5-dichlorophenol with a content of 95 to over 99% from a mixture of about 80% 2,5-dichlorophenol, about 20% 2,4-dichlorophenol and minor other phenolic impurities by multi-stage Crystallization in the presence of water.
2,5-Dichlorphenol ist als Ausgangsverbindung für die Herstellung wertvoller landwirtschaftlicher Chemikalien von besonderer Bedeutung.2,5-dichlorophenol is of particular importance as a starting compound for the production of valuable agricultural chemicals.
Ein besonderes Problem bei der Herstellung eines möglichst hochprozentigen 2,5-Dichlorphenols ist vor allem die Abtrennung des isomeren 2, 4-Dichlorphenols.A particular problem in the production of as high a percentage of 2,5-dichlorophenol as possible is above all the separation of the isomeric 2,4-dichlorophenol.
Die deutsche Patentschrift 1.493.493 beschreibt nun eineMlethode zur Trennung dieses Gemisches mit Hilfe von Harnstoff. Dabei wird das 2,5-Dichlorphenol über das wasserunlösliche Harnstoffaddukt abgetrennt. Das Verfahren benötigt beträchtliche Mengen Harnstoff, die mit dem Wasser verlorengehen. Es kann also nicht als umweltfreundlich betrachtet werden. Eine Rückgewinnung des Harnstoffs wäre sehr aufwendig.German patent 1,493,493 now describes a method for separating this mixture with the aid of urea. The 2,5-dichlorophenol is separated off via the water-insoluble urea adduct. The process requires significant amounts of urea that are lost with the water. So it cannot be considered environmentally friendly. A recovery of the urea would be very expensive.
Die US-PS 2.800.324 beschreibt ein Verfahren, bei welchem 1 -Brom-2, 5-dichlorbenzol bei höherer Temperatur und höherem Druck in Gegenwart eines Kupferkatalysators im Autoklav mit Natronlauge und Methanol umgesetzt wird und das Reaktionsprodukt über eine Extraktion und Destillation gereinigt wird. Das Verfahren ist aufwendig und erfordert zunächst die Herstellung von 1-Brom-2,5-dichlorbenzol, was in der Regel mit hohen Kosten verbunden ist.
Aufgabe der Erfindung ist demnach die Bereitstellung eines verbesserten Verfahrens zur Herstellung eines weitgehend reinen 2,5-Dichlorphenols. Außerdem soll das Verfahren einfach durchzuführen und die Abtrennung von 2,4-Dichlorphenol aus dessen Gemischen mit 2,5-Dichlorphenol auf wirtschaftlichere Weise ermöglichen als es dem Stand der Technik entspricht.US Pat. No. 2,800,324 describes a process in which 1-bromo-2,5-dichlorobenzene is reacted with sodium hydroxide solution and methanol in an autoclave at elevated temperature and pressure in the presence of a copper catalyst and the reaction product is purified by extraction and distillation . The process is complex and initially requires the production of 1-bromo-2,5-dichlorobenzene, which is generally associated with high costs. The object of the invention is accordingly to provide an improved process for producing a largely pure 2,5-dichlorophenol. In addition, the process should be simple to carry out and enable the separation of 2,4-dichlorophenol from its mixtures with 2,5-dichlorophenol in a more economical manner than is the case in the prior art.
Diese Aufgabe wird erfindungsgemäß gelöst mit einem Verfahren zur Herstellung von 2,5-Dichlorphenol, welches dadurch gekennzeichnet ist, daß man ein flüssiges Gemisch aus etwa 8 Gewichtsteilen 2,5-Dichlorphenol und etwa 2 Geuichtsteilen 2,4-Dichlorphenol mit, heißem Wasser oberhalb der Erstarrungstemperatur mischt, die nach dem Abkühlen erhaltenen Kristalle abtrennt, wiederum in die Schmelze überführt, mit heißem Wasser mischt, kühlt und die ausgeschiedenen Kristalle abtrennt.This object is achieved according to the invention with a process for the preparation of 2,5-dichlorophenol, which is characterized in that a liquid mixture of about 8 parts by weight of 2,5-dichlorophenol and about 2 parts by weight of 2,4-dichlorophenol with hot water above the solidification temperature mixes, the crystals obtained after cooling are separated off, again transferred to the melt, mixed with hot water, cooled and the crystals which have separated out are separated off.
Für das erfindungsgemäße Verfahren können Gemische aus 2,5-und 2,4-Dichlorphenol beliebiger Herkunft verwendet werden, die etwa 8 Gewichtsteile 2,5-Dichlorphenol und etwa 2 Gewichtsteile 2,4-Dichlorphenol enthalten. Solche Gemische werden beispielsweise gemäß der US-PS 2.799.714 in großen Mengen bei der Umsetzung von 1,2,4-Trichlorbenzol mit Natronlauge in Gegenwart von Methanol im Autoklaven bei höheren Temperaturen und Drücken erhalten.Mixtures of 2,5-and 2,4-dichlorophenol of any origin which contain about 8 parts by weight of 2,5-dichlorophenol and about 2 parts by weight of 2,4-dichlorophenol can be used for the process according to the invention. Such mixtures are obtained, for example, according to US Pat. No. 2,799,714 in large amounts when reacting 1,2,4-trichlorobenzene with sodium hydroxide solution in the presence of methanol in an autoclave at elevated temperatures and pressures.
Das erfindungsgemäße Verfahren wird in mindestens zwei Kristallisationsstufen durchgeführt. In der ersten Kristallisationsstufe wird das zweckmäßigerweise durch Schmelzen verflüssigte 2,5-/2,4-Dichlorphenolgemisch beispielsweise mit 0,15 bis 0,5 Gewichtsteilen Wasser gründlich vermischt, wobei zur Erreichung eines guten Reinigungseffektes die Zugabe von 0,2 Gewichtsteilen Wasser besonders bevorzugt
ist. Während des Mischens muß darauf geachtet werden, daß die organische Phase nicht vorzeitig erstarrt, was zweckmäßigerweise durch Einhaltung einer Temperatur von 50 bis 70ºC erreicht werden kann. Anschließend wird das Gemisch gekühlt, je nach gewünschtem Reinheitsgrad bevorzugt auf 5 bis 25ºC, wobei das vorgereinigte 2,5-Dichlorphenol auskristallisiert, während der grbβte Teil des 2,4-Dichlorphenols in der Mutterlauge verbleibt. Die so erhaltenen Kristalle werden nach üblichen Methoden, beispielsweise durch Filtrieren, Dekantieren, Zentrifugieren oder dergleichen, abgetrennt, wobei es zweckmäßig sein kannj durch Zugabe von Wasser die Mischung zur Erleichterung der Abtrennung in rührfähigem Zustand zu halten. Die so erhaltenen Kristalle werden entweder unmittelbar oder vorteilhafterweise nach einem oder mehrmaligem Waschen mit kaltem Wasser in eine zweite Reinigungsstufe übergeführt. Dazu wird die Kristallmasse geschmolzen und erneut mit 1,5 bis 3 Gewichtsteilen heißen Wassers vermischt, wobei sich zur Erzielung eines besonders guten Reinigungseffektes die Verwendung von 2 Gewichtsteilen Wasser als besonders vorteilhaft erwiesen hat. Anschließend wird abgekühlt, je nach gewünschtem Reinheitsgrad bevorzugt auf 20 bis 35ºC, wobei Kristallisation eintritt. Die Kristalle werden nach einer der oben angegebenen Methoden abgetrennt und zweckmäßigerweise einmal oder mehrmals mit Wasser gewaschen. Man erhält auf diese Weise weitgehend reines 2,5-Dichlorphenol mit einem Reinheitsgrad von 95 bis 99%. Diese Produkte sind in den meisten Fällen für die Weiterverwendung bereits ausreichend rein. In Fällen, in denen Produkte mit besonders hohem Reinheitsgrad erwünscht sind, kann der zuletzt beschriebene Kristallisationsschritt noch einmal oder mehrmals wiederholt werden.
Das erfindungsgemaße Verfahren gestaltet sich besonders umweltfreundlich. In einer bevorzugten Ausführungsform des Verfahrens wird das eingesetzte Wasser nach Abtrennung der während des Verfahrens eingebrachten organischen Phase im Kreislauf geführt. Auf diese Weise kann das Abwasserproblem besonders einfach und umweltfreundlich gelöst werden. In einer weiteren, besonders vorteilhaften Ausführung des Verfahrens werden die organischen Phasen der zweiten und gegebenenfalls weiteren Kristallisationsstufen in die erste Kristallisationsstufe zur erneuten Reinigung zurückgeführt, wodurch die Ausbeute noch wesentlich verbessert werden kann. Das erfindungsgemaße Verfahren wird durch das beiliegende Blockschema und das Verfahrensbeispiel näher erläutert.
The process according to the invention is carried out in at least two crystallization stages. In the first crystallization stage, the 2,5- / 2,4-dichlorophenol mixture, which is expediently liquefied by melting, is thoroughly mixed, for example, with 0.15 to 0.5 part by weight of water, the addition of 0.2 part by weight of water being particularly preferred in order to achieve a good cleaning effect is. Care must be taken during mixing that the organic phase does not solidify prematurely, which can expediently be achieved by maintaining a temperature of 50 to 70 ° C. The mixture is then cooled, preferably to 5 to 25 ° C, depending on the desired degree of purity, the prepurified 2,5-dichlorophenol crystallizing out, while most of the 2,4-dichlorophenol remains in the mother liquor. The crystals thus obtained are separated off by customary methods, for example by filtration, decanting, centrifuging or the like, and it may be expedient to keep the mixture in a stirrable state by adding water to facilitate the separation. The crystals obtained in this way are transferred to a second cleaning stage either immediately or advantageously after one or more washes with cold water. For this purpose, the crystal mass is melted and mixed again with 1.5 to 3 parts by weight of hot water, the use of 2 parts by weight of water having proven particularly advantageous for achieving a particularly good cleaning effect. It is then cooled, depending on the desired degree of purity, preferably to 20 to 35 ° C, whereupon crystallization occurs. The crystals are separated off by one of the methods indicated above and expediently washed once or more times with water. In this way, largely pure 2,5-dichlorophenol with a purity of 95 to 99% is obtained. In most cases, these products are already sufficiently pure for further use. In cases in which products with a particularly high degree of purity are desired, the crystallization step described last can be repeated one or more times. The method according to the invention is particularly environmentally friendly. In a preferred embodiment of the process, the water used is circulated after the organic phase introduced during the process has been separated off. In this way, the wastewater problem can be solved in a particularly simple and environmentally friendly manner. In a further, particularly advantageous embodiment of the process, the organic phases of the second and, if appropriate, further crystallization stages are returned to the first crystallization stage for renewed purification, as a result of which the yield can be significantly improved. The process according to the invention is explained in more detail by the enclosed block diagram and the process example.
Beispielexample
Herstellung des AusgangsmaterialsProduction of the starting material
370g technisch reines 1 ,2,4-Trichlorbenzol 96%ig, enthaltend 4% 1,2,3-Trichlorbenzol, werden in bekannter Weise mit methylalkoholischer Natronlauge im Autoklav verseift, das entstandene Dichlorphenolgemisch wird abgetrennt. Ausbeute: 315g370 g of technically pure 1, 2,4-trichlorobenzene 96%, containing 4% 1,2,3-trichlorobenzene are saponified in a known manner with methyl alcoholic sodium hydroxide solution in an autoclave, the dichlorophenol mixture formed is separated off. Yield: 315g
Das Dichlorphenolgemisch wird über eine Kolonne im Wasserstrahlvakuum destilliert. Die bei 89 bis 91°C/12mm übergehende Fraktion (257g) enthält: 82,6% 2,5-Dichlorphenol,16,9% 2,4-Dichlorphenol und 0,5% 3,4-Dichlorphenol.The dichlorophenol mixture is distilled over a column in a water jet vacuum. The fraction (257g) which transitions at 89 to 91 ° C / 12mm contains: 82.6% 2,5-dichlorophenol, 16.9% 2,4-dichlorophenol and 0.5% 3,4-dichlorophenol.
Herstellung von 2,5-Dichlorphenol 1.StufeProduction of 2,5-dichlorophenol 1st stage
255ml (330g) 2,5-/2,4-Dichlorphenolgemisch werden mit 65ml Wasser bei 60ºC vermischt und unter Rühren bis auf 20ºC gekühlt. Nach Einsetzen der Kristallisation und erfolgtem Temperaturanstieg werden zur Verdünnung 200ml kaltes Wasser zugegeben. Das Gemisch wird bis auf 15ºC weitergekühlt, die Kristalle werden abgesaugt und zweimal mit je 500ml kaltem Wasser gewaschen. Die Mutterlauge und die Waschfiltrate werden vereinigt und in der Wärme in einem Scheidetrichter getrennt. Das Wasser wird wiederverwendet, die organische Phase wird verworfen oder kann für andere Umsetzungen verwendet werden.255ml (330g) 2,5- / 2,4-dichlorophenol mixture are mixed with 65ml water at 60 ° C and cooled to 20 ° C with stirring. After crystallization has started and the temperature has risen, 200 ml of cold water are added for dilution. The mixture is cooled further to 15 ° C, the crystals are suctioned off and washed twice with 500 ml of cold water. The mother liquor and the washing filtrates are combined and separated in the heat in a separating funnel. The water is reused, the organic phase is discarded or can be used for other reactions.
2. Stufe2nd stage
200ml (255g) geschmolzenes Nutschgut der 1.Stufe werden mit 400ml Wasser bei 70ºC vermischt und unter Rühren bis auf 30ºC gekühlt. Nach Einsetzen der Kristallisation und erfolgtem Temperaturanstieg wird weiter bis auf 30ºC gekühlt. Die Kristalle werden abgesaugt und mit 150ml kaltem Wasser gewaschen.
Die Mutterlauge und das Waschfiltrat werden vereinigt und in der Wärme im Scheidetrichter getrennt. Das Wasser wird wiederverwendet, die organische Phase wird dem Einsatzprodukt der 1 . S tu fe zugeführt.200ml (255g) of melted filter cake from the 1st stage are mixed with 400ml of water at 70ºC and cooled to 30ºC with stirring. After crystallization has started and the temperature has risen, cooling is continued to 30 ° C. The crystals are suctioned off and washed with 150 ml of cold water. The mother liquor and the washing filtrate are combined and separated in the heat in a separating funnel. The water is reused, the organic phase becomes the feed product of the 1st S tu fe fed.
Es werden 205g 2,5-Dichlorphenol 97,3%ig erhalten. Ausbeute:205 g of 2,5-dichlorophenol 97.3% are obtained. Yield:
62,1%, bezogen auf das eingesetzte Gemisch ohne Rückführung der 2. Stufe und 72,1%, bezogen auf den 2,5-Gehalt im eingesetzten Gemisch.
62.1%, based on the mixture used without recycling the second stage and 72.1%, based on the 2.5 content in the mixture used.
Claims
1. Verfahren zur Herstellung von 2,5-Dichlorphenol, dadurch gekennzeichnet, daß man ein flüssiges Gemisch aus etwa1. A process for the preparation of 2,5-dichlorophenol, characterized in that a liquid mixture of about
8 Gewichtsteilen 2,5-Dichlorphenol und etwa 2 Gewichtsteilen 2,4-Dichlorphenol mit heißem Wasser oberhalb der Erstarrungstemperatur mischt, die nach dem Abkühlen erhaltenen Kristalle abtrennt, wiederum in die Schmelze überführt, mit heißem Wasser mischt, kühlt und die ausgeschiedenen Kristalle abtrennt.8 parts by weight of 2,5-dichlorophenol and about 2 parts by weight of 2,4-dichlorophenol are mixed with hot water above the solidification temperature, the crystals obtained after cooling are separated off, again transferred to the melt, mixed with hot water, cooled and the crystals separated off.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man im ersten Kristallisationsschritt 1 Gewichtsteil des Gemisches mit 0,2 Gewichtsteilen Wasser mischt, je nach gewünschtem Reinheitsgrad auf 5 bis 25ºC abkühlt, die ausgeschiedenen Kristalle abtrennt und mit Wasser wäscht.2. The method according to claim 1, characterized in that 1 part by weight of the mixture is mixed with 0.2 part by weight of water in the first crystallization step, cooled to 5 to 25 ° C, depending on the desired degree of purity, the separated crystals are separated off and washed with water.
3. Verfahren nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß man im zweiten Kristallisationsschritt die geschmolzenen Kristalle mit 2 Gewichtsteilen Wasser mischt, je nach gewünschtem Reinheitsgrad auf 20 bis 35ºC abkühlt, die ausgeschiedenen Kristalle abtrennt und mit Wasser wäscht.3. The method according to any one of claims 1 or 2, characterized in that in the second crystallization step, the molten crystals are mixed with 2 parts by weight of water, cooled to 20 to 35 ° C, depending on the desired degree of purity, the separated crystals are separated off and washed with water.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß man je nach gewünschtem Reinheitsgrad noch einen oder mehrere Kristallisationsschritte anfügt.4. The method according to any one of claims 1 to 3, characterized in that one or more crystallization steps are added depending on the desired degree of purity.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß Filtrat und Waschwasser aus den Kristallisationsstufen nach Abtrennung der organischen Phasen im Kreislauf geführt werden. 5. The method according to any one of claims 1 to 4, characterized in that the filtrate and wash water from the crystallization stages are circulated after separation of the organic phases.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß man die organischen Phasen der Filtrate der zweiten und jeder weiteren Kristallisationsstufe abtrennt und in die erste Kristallisationsstufe zurückführt.6. The method according to any one of claims 1 to 5, characterized in that the organic phases of the filtrates of the second and each further crystallization stage are separated off and returned to the first crystallization stage.
7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß man ein Gemisch von 2,5- und 2,4- Dichlorphenol einsetzt, wie es in bekannter Weise durch Druckverseifung von 1,2,4-Trichlorbenzol erhalten wird. 7. The method according to any one of claims 1 to 6, characterized in that a mixture of 2,5- and 2,4-dichlorophenol is used, as is obtained in a known manner by pressure saponification of 1,2,4-trichlorobenzene.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3512877 | 1985-04-11 | ||
| DE19853512877 DE3512877C1 (en) | 1985-04-11 | 1985-04-11 | Process for the recovery of 2,5-dichlorophenol from a mixture of isomers with 2,4-dichlorophenol |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0217897A1 true EP0217897A1 (en) | 1987-04-15 |
Family
ID=6267649
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP19860902391 Withdrawn EP0217897A1 (en) | 1985-04-11 | 1986-04-01 | Process for the manufacture of 2.5 - dichlorphenol |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0217897A1 (en) |
| DE (1) | DE3512877C1 (en) |
| WO (1) | WO1986006062A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4861919A (en) * | 1988-02-29 | 1989-08-29 | The Dow Chemical Company | Countercurrent multi-stage water crystallization of aromatic compounds |
| DK3052462T3 (en) | 2013-10-04 | 2018-12-17 | Basf Se | SELECTIVE HYDROLYSIS AND ALCOHOLYSIS OF CHLORED BENZENES |
| EP3077353B1 (en) | 2013-12-04 | 2019-02-06 | Basf Se | Process for purifying 2,5-dichlorophenol |
| WO2015086698A1 (en) | 2013-12-11 | 2015-06-18 | Basf Se | Process for providing dihalogen substituted salicylic acid derivatives |
| AR100506A1 (en) | 2014-05-19 | 2016-10-12 | Basf Se | PROCESS OF OBTAINING THE DICAMBA HERBICIDE |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2708209A (en) * | 1953-10-29 | 1955-05-10 | Olin Mathieson | Process for selective crystallization of 2, 5-dichlorophenol |
-
1985
- 1985-04-11 DE DE19853512877 patent/DE3512877C1/en not_active Expired
-
1986
- 1986-04-01 EP EP19860902391 patent/EP0217897A1/en not_active Withdrawn
- 1986-04-01 WO PCT/EP1986/000196 patent/WO1986006062A1/en not_active Application Discontinuation
Non-Patent Citations (1)
| Title |
|---|
| See references of WO8606062A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3512877C1 (en) | 1986-11-27 |
| WO1986006062A1 (en) | 1986-10-23 |
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