EP0000894A1 - Process for the separation of dimethyl carbonate from its azeotrope with methanol - Google Patents

Process for the separation of dimethyl carbonate from its azeotrope with methanol Download PDF

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Publication number
EP0000894A1
EP0000894A1 EP78100607A EP78100607A EP0000894A1 EP 0000894 A1 EP0000894 A1 EP 0000894A1 EP 78100607 A EP78100607 A EP 78100607A EP 78100607 A EP78100607 A EP 78100607A EP 0000894 A1 EP0000894 A1 EP 0000894A1
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azeotrope
methanol
dimethyl carbonate
distillation
separation
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German (de)
French (fr)
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EP0000894B1 (en
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Hans-Josef Dr. Buysch
Heinrich Dr. Krimm
Hans Dr. Rudolph
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Bayer AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C68/00—Preparation of esters of carbonic or haloformic acids
    • C07C68/08—Purification; Separation; Stabilisation

Abstract

1. Process for isolating dimethyl carbonate from its azeotrope with methanol by distillation, characterised in that the azeotrope is distilled under normal pressure with azeotrope-forming agents which are methanol-immiscible.

Description

Die Erfindung betrifft ein Verfahren zur Abtrennung von Dimethylcarbonat aus dem Dimethylcarbonat/Methanol-Azeotrop durch Destillation.The invention relates to a process for separating dimethyl carbonate from the dimethyl carbonate / methanol azeotrope by distillation.

Dimethylcarbonat ist als Ausgangsstoff zur Herstellung aromatischer Carbonate, die ihrerseits wiederum Vorprodukte zur Herstellung von Polycarbonaten und Pflanzenschutzmitteln darstellen, von großer technischer Bedeutung (vgl. z.3. Ullmanns Encyklcpädie der technischen Chemie, 3 Aufl., Bd. 9, S. 776 (1957), US-PS 3 933 846, DT-PS 971 730).Dimethyl carbonate is of great technical importance as a starting material for the production of aromatic carbonates, which in turn are intermediates for the production of polycarbonates and crop protection agents (cf. e.g. 3. Ullmanns Encyklcpädie der technical chemistry, 3 ed., Vol. 9, p. 776 ( 1957), U.S. Patent 3,933,846, DT Patent 971,730).

Dinethylcarbonat wird gemäß der US-PS 2 642 858, der US-PS 3 803 201 und der DT-OS 2 615 665 durch Umesterung cyclischer Carbonate, wie Äthylencarbonat, mit Alkcholen in Gegenwart von alkalischen Katalysatoren hergestellt. Hierbei wird ein etwa 30 Gew.-%iges Azeotrop mit Methanol erhalten.Dinethyl carbonate is prepared according to US Pat. No. 2,642,858, US Pat. No. 3,803,201 and DT-OS 2,615,665 by transesterification of cyclic carbonates, such as ethylene carbonate, with alkchols in the presence of alkaline catalysts. An approximately 30% by weight azeotrope with methanol is obtained.

Zur Gewinnung von Dimethylcarbonat aus dem Azeotrop wird gemäß der US-PS 3 803 201 durch Kühlen auf -70°C ein an Dimethylcarbonat reiches kristallines Produkt ausgefroren, aus dem Dimethylcarbonat durch Destillation gewonnen werden kann. Das Verfahren ist angesichts der erforderlichen tiefen Temperaturen und der technisch umständlichen Filtrationsstufe von geringem technischen Interesse.To obtain dimethyl carbonate from the azeotrope, a crystalline product rich in dimethyl carbonate is frozen out from the dimethyl carbonate by cooling to -70 ° C. according to US Pat. No. 3,803,201 Distillation can be obtained. In view of the low temperatures required and the technically complicated filtration stage, the process is of little technical interest.

Auch das Verfahren der DT-PS 2 450 856, nach dem eine Trennung durch eine Extraktivdestillation unter Verwendung von Wasser als Lösungsmittel möglich sein soll, ist in Anbetracht der hohen Wasserlöslichkeit und leichten Verseifbarkeit des Dimethylcarbonats verlustreich und somit unwirtschaftlich.The process of DT-PS 2,450,856, according to which separation by extractive distillation using water as the solvent should be possible, is lossy in view of the high water solubility and easy saponifiability of the dimethyl carbonate and is therefore uneconomical.

Ein weiteres Trennverfahren beruht auf einer Destillation bei einem Druck von etwa 10 atü, wobei nach Abdestillieren einer methanolreichen Kopffraktion Dimethylcarbonat als Rückstand erhalten wird (DT-OS 2 607 003).Another separation process is based on distillation at a pressure of about 10 atm, whereby dimethyl carbonate is obtained as a residue after distilling off a methanol-rich top fraction (DT-OS 2 607 003).

Es wurde ein Verfahren zur Gewinnung von Dimethylcarbonat aus seinem Azeotrop mit Methanol durch Destillation gefunden, das dadurch gekennzeichnet ist, daß man das Azeotrop mit solchen Azeotropbildnern, die mit Methanol nicht mischbar sind, bei Normaldruck destilliert.A process for the recovery of dimethyl carbonate from its azeotrope with methanol by distillation was found, which is characterized in that the azeotrope is distilled at atmospheric pressure with those azeotrope formers which are immiscible with methanol.

Durch die Mitverwendung von mit Methanol nicht mischbaren Azeotropbildnern bei der Destillation des Methanol/Dimethylcarbonat-Azeotrops destilliert zunächst ein niedrig siedendes Azeotrop aus dem betreffenden Gemisch des Azeotropbildners mit Methanol - der Siedepunkt des Azeotrops ist abhängig von der Art des verwendeten Azeotropbildners, er liegt im Temperaturbereich von etwa 30°C bis 63°C -, wodurch der Rückstand an Methanol verarmt. Zurück bleibt nahezu reines Dimethylcarbonat, das in den meisten Fällen keiner weiteren Reinigung durch Destillation mehr bedarf. Es war überraschend, daß diese Azeotropdestillation gelingt, obwohl bekanntermaßen die unten aufgeführten Azeotropbildner sowohl mit Methanol als auch mit dem Dimethylcarbonat azeotropsiedende Gemische bilden.By the co-use of with methanol-immiscible azeotrope-in distillation of the methanol / dimethyl carbonate azeotrope was distilled initially a low boiling A zeotropic from the corresponding mixture of the azeotrope former with methanol - the boiling point of the azeotrope depends on the nature of the azeotrope former used, it is in the Temperature range from about 30 ° C to 63 ° C -, which depletes the residue of methanol. What remains is almost pure dimethyl carbonate, which in most cases no further purification by distillation is required. It was surprising that this azeotropic distillation succeeds, although it is known that the azeotrope formers listed below form azeotropic boiling mixtures with both methanol and dimethyl carbonate.

Das erfindungsgemäße Verfahren gewährleistet eine besonders wirtschaftliche, sauber und einfach durchzuführende Trennung von Methanol und Dimethylcarbonat.The process according to the invention ensures a particularly economical, clean and easy to carry out separation of methanol and dimethyl carbonate.

Als Azeotropbildner seien zum Beispiel aliphatische Kohlenwasserstoffe mit 5 - 10, bevorzugt 6 - 7, Kohlenstoffatomen genannt, wie Pentan, Hexan, Heptan, Octan, 2-Methylhexan, 2-Methylheptan, 3-Methylheptan, 4-Methylheptan, 2,2-Dimethylpentan, 2,3-Dimethylpentan, 2,4-Dimethylpentan, 3,3-Dimethylpentan, 2,5-Dimethylhexan und 2,2,4-Trimethylpentan (Isooctan), ferner Kohlenwasserstoffe enthaltende technische Benzinfraktionen, wie 0 Petroläther (Siedebereich 40 bis 80 C) Leichtbenzin (Siedebereich 60 bis 950C) und Ligroin (Siedebereich 80 bis 110 C). Die Kohlenwasserstoffe und die Kohlenwasserstoffe enthaltenden technischen Benzinfraktionen können sowohl einzeln als auch im Gemisch untereinander als Azeotropbildner verwendet werden.Examples of azeotroping agents are aliphatic hydrocarbons with 5-10, preferably 6-7, carbon atoms, such as pentane, hexane, heptane, octane, 2-methylhexane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2-dimethylpentane , 2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,5-dimethylhexane and 2,2,4-trimethylpentane (isooctane), as well as technical gasoline fractions containing hydrocarbons, such as 0 petroleum ether (boiling range 40 to 80 C) light petrol (boiling range 60 to 95 0 C) and ligroin (boiling range 80 to 110 C). The technical grade petrol fractions containing hydrocarbons and the hydrocarbons can be used both individually and as a mixture with one another as azeotroping agents.

Bevorzugt werden als Azeotropbildner eingesetzt: Hexan, Heptan, Oetan, Isooctan, Petroläther, Leichtbenzin und/ oder Ligroin, wobei Hexan und Heptan besonders bevorzugt sind.The following are preferably used as azeotrope formers: hexane, heptane, oetane, isooctane, petroleum ether, light petrol and / or ligroin, with hexane and heptane being particularly preferred.

Die Azeotropbildner werden zweckmäßig in solcher Menge eingesetzt, die eben ausreicht, um alles Methanol überzudestillieren. Die zuzusetzende Menge an Azeotropbildnern kann den bekannten Tabellen (vgl. z.B. Handbook of Chemistry and Physics, 51. Edition (1970), The Chemical Rubber Company, Cleveland/Ohio) mit den Angaben über die jeweilige Azeotropzusammensetzung entnommen oder durch einfache Vorversuche ermittelt werden.The azeotroping agents are expediently used in an amount which is just sufficient to distill over all of the methanol. The amount of azeotroping agents to be added can be found in the known tables (see, for example, Handbook of Chemistry and Physics, 51st Edition (1970), The Chemical Rubber Company, Cleveland / Ohio) with the information about the respective azeotrope composition or can be determined by simple preliminary tests.

Das zunächst über Kopf destillierende Azeotrop trennt sich in der Vorlage in eine im wesentlichen aus Methanol bestehende Phase, die wieder in die Dimethylcarbonat-Produktionsanlage zurückgeführt werden kann, und in eine im wesentlichen aus Kohlenwasserstoff(en) bestehende Phase, die in der Trennanlage wiederverwendet werden kann, auf.The azeotrope, which initially distills overhead, separates in the receiver into a phase consisting essentially of methanol, which can be returned to the dimethyl carbonate production plant, and into a phase consisting essentially of hydrocarbon (s), which are reused in the separation plant can on.

Im Sumpf der Kolonne verbleibt als Rückstand Dimethylcarbonat, das gegebenenfalls durch Destillation gereinigt werden kann.In the bottom of the column, dimethyl carbonate remains as a residue, which can optionally be purified by distillation.

Das irfindungsgemäße Verfahren sei anhand der folgenden Beispiele verdeutlicht, ohne as jedoch auf diese Beispiele einzuschränken.The method according to the invention is illustrated by the following examples, but without restricting it to these examples.

Beispiel 1example 1

An einer mit Glasringen beschickten verspiegelten Füllkörperkolonne mit 1 m Füllhöhe wird ein aus 450 g Dimethylcarbonat/ Methanol-Azeotrop (30:70) und 297 g n-Heptan bestehendes Gemisch derart erhitzt, daß über Kopf ein im wesentlichen aus Methanol und Heptan bestehendes zweiphasiges Azeotrop bei 58,50C abgetrennt wird. Sobald die Sumpftemperatur 83°C erreicht hat, wird die Kolonne entfernt und der Rückstand (86 g) über eine 10 cm hohe Kolonne fraktioniert. Bei 89 - 90°C gehen 63 g reines Dimethylcarbonat über. Der im Kolben verbleibende Rückstand (4,5 g) besteht ebenfalls aus reinem Dimethylcarbonat (

Figure imgb0001
1,3688). Ausbeute 50 % d.Th.A mixture consisting of 450 g of dimethyl carbonate / methanol azeotrope (30:70) and 297 g of n-heptane is heated on a mirrored packed column with a filling height of 1 m in such a way that a two-phase azeotrope consisting essentially of methanol and heptane is heated overhead is separated at 58.5 0 C. As soon as the bottom temperature has reached 83 ° C., the column is removed and the residue (86 g) is fractionated over a 10 cm high column. At 89 - 90 ° C, 63 g of pure dimethyl carbonate pass over. The residue (4.5 g) remaining in the flask also consists of pure dimethyl carbonate (
Figure imgb0001
 1.3688). Yield 50% of theory

Beispiel 2Example 2

Eine Mischung aus 150 g Dimethylcarbonat und 350 g Methanol wird mit 950 g n-Hexan an einer 40 cm hohen SilbErspiegel- kolonne derart destilliert, daß die Übergangstemperatur 50°C nicht übersteigt. Der im Kolben verbleibende Rückstand (95 g) besteht nahezu aus reinem Dimethylcarbonat (

Figure imgb0002
1,3675). Ausbeute 60 % d.Th.A mixture of 150 g of dimethyl carbonate and 350 g of methanol is treated with 950 g of n-hexane on a 40 cm high column Silb E rspiegel- so distilled, that the transition temperature does not exceed 50 ° C. The residue (95 g) remaining in the flask consists almost of pure dimethyl carbonate (
Figure imgb0002
 1.3675). Yield 60% of theory

Beispiel 3Example 3

Eine Mischung aus 45 g Dimethylcarbonat und 105 g Methanol wird mit 100 g lsooctan an einer 1 m hohen Silberspiegelkolonne derart fraktioniert, daß das zweiphasige Azeotrop bei 58,5°C übergeht. Die im Kolben zurückbleibende Flüssigkeit (20 g) ist nahezu reines Dimethylcarbonat (

Figure imgb0003
1,3673). Ausbeute 40 % d.Th.A mixture of 45 g of dimethyl carbonate and 105 g of methanol is fractionated with 100 g of isooctane on a 1 m high silver mirror column in such a way that the two-phase azeotrope passes at 58.5 ° C. The liquid remaining in the flask (2 0 g) is almost pure dimethyl carbonate (
Figure imgb0003
 1.3673). Yield 40% of theory

Beispiel 4Example 4

Ein aus 45 g Dimethylcarbonat und 105 g Methanol bestehendes Gemisch wird mit 85 g Ligroin vom Siedebereich 80 - 110°C über eine 50 cm hohe Silberspiegelkolonne im Laufe von 7 1/2 h destilliert, bis die Sumpftemperatur 90°C erreicht hat. Die im Kolben vexbleibende Flüssigkeit (24 g) ist nahezu reines Dimethylcarbonat (

Figure imgb0004
1,3676). Ausbeute 52 % d.Th.A mixture consisting of 45 g dimethyl carbonate and 105 g methanol is distilled with 85 g ligroin from the boiling range 80-110 ° C over a 50 cm high silver mirror column in the course of 7 1/2 hours until the bottom temperature has reached 90 ° C. The liquid remaining in the flask (24 g) is almost pure dimethyl carbonate (
Figure imgb0004
 1.3676). Yield 52% of theory

Claims (5)

1. Verfahren zur Gewinnung von Dimethylcarbonat aus seinem Azeotrop mit Methanol durch Destillation, dadurch gekennzeichnet, daß man das Azeotrop mit solchen Azeotropbildnern, die mit Methanol nicht mischbar sind, bei Normaldruck destilliert.1. A process for the production of dimethyl carbonate from its azeotrope with methanol by distillation, characterized in that the azeotrope is distilled at atmospheric pressure with those azeotrope formers which are immiscible with methanol. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man als Azeotropbildner aliphatische Kohlenwasserstoffe mit 5 - 10 Kohlenstoffatomen verwendet.2. The method according to claim 1, characterized in that aliphatic hydrocarbons having 5 - 10 carbon atoms are used as the azeotrope. 3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man als Azeotropbildner Kohlenwasserstoffe enthaltende technische Benzinfraktionen verwendet.3. The method according to claim 1, characterized in that technical gasoline fractions containing hydrocarbons are used as the azeotrope. 4. Verfahren nach Ansprüche 1 und 2, dadurch gekennzeichnet, daß man als aliphatische Kohlenwasserstoffe Hexan, Heptan, Octan und/oder Isooctan einsetzt.4. Process according to Claims 1 and 2, characterized in that hexane, heptane, octane and / or isooctane are used as aliphatic hydrocarbons. 5. Verfahren nach Ansprüche 1 und 3, dadurch gekennzeichnet, daß man als Kohlenwasserstoffe enthaltende technische Benzinfraktionen Petroläther, Leichtbenzin und/ oder Ligroin einsetzt.5. Process according to Claims 1 and 3, characterized in that petroleum ether, light petrol and / or ligroin are used as the technical petrol fractions containing hydrocarbons.
EP78100607A 1977-08-18 1978-08-07 Process for the separation of dimethyl carbonate from its azeotrope with methanol Expired EP0000894B1 (en)

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DE19772737265 DE2737265A1 (en) 1977-08-18 1977-08-18 PROCESS FOR SEPARATION OF DIMETHYLCARBONATE FROM ITS AZEOTROP WITH METHANOL

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5231212A (en) * 1991-09-03 1993-07-27 Bayer Aktiengesellschaft Process for the continuous preparation of dialkyl carbonates
EP0581115A2 (en) * 1992-07-27 1994-02-02 Bayer Ag Process for separating methanol from dimethyl carbonate/methanol mixtures
US5986125A (en) * 1996-06-13 1999-11-16 Henkel Kommanditgesellschaft Auf Aktien Process for the production of dialkyl carbonates
US7799940B2 (en) 2007-02-16 2010-09-21 Sabic Innovative Plastics Ip B.V. Process for manufacturing dimethyl carbonate
US7803961B2 (en) 2007-02-16 2010-09-28 Sabic Innovative Plastics Ip B.V. Process for manufacturing dimethyl carbonate
US20170354235A1 (en) * 2016-06-14 2017-12-14 L'oreal Curing applicator
CN114634415A (en) * 2022-04-22 2022-06-17 天津凯美特化工科技有限公司 Method for separating azeotrope of dimethyl carbonate and methanol and producing ethyl methyl carbonate by diethyl carbonate reaction

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4234525A1 (en) * 1992-10-13 1994-04-14 Bayer Ag Process for the separation of alkanols from oxygen-containing organic compounds with a higher carbon number
DE4319570A1 (en) * 1993-06-14 1994-12-15 Bayer Ag Process and separation of alkanols from other organic compounds with a higher carbon number
DE4342713A1 (en) 1993-12-15 1995-06-22 Bayer Ag Process for the separation of methanol from a mixture of dimethyl carbonate and methanol
JP3881386B2 (en) * 1994-10-21 2007-02-14 多摩化学工業株式会社 Process for producing dialkyl carbonate
JP5915316B2 (en) * 2012-03-28 2016-05-11 ダイキン工業株式会社 Method for producing chain carbonate

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US3239435A (en) * 1961-08-10 1966-03-08 Rhone Poulenc Sa Fractional distillation of methanol in the presence of an entrainer
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US3239435A (en) * 1961-08-10 1966-03-08 Rhone Poulenc Sa Fractional distillation of methanol in the presence of an entrainer
FR1490688A (en) * 1966-06-22 1967-08-04 Melle Usines Sa Process for separating the constituents of azeotropic mixtures of methanol and lower aliphatic ester
DE2528412A1 (en) * 1974-06-25 1976-01-08 Snam Progetti PROCESS FOR THE PRODUCTION OF AROMATIC CARBONATES
US3940450A (en) * 1974-12-16 1976-02-24 Texaco Inc. Preparation and recovery of ethers

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5231212A (en) * 1991-09-03 1993-07-27 Bayer Aktiengesellschaft Process for the continuous preparation of dialkyl carbonates
EP0581115A2 (en) * 1992-07-27 1994-02-02 Bayer Ag Process for separating methanol from dimethyl carbonate/methanol mixtures
EP0581115A3 (en) * 1992-07-27 1994-05-18 Bayer Ag Process for separating methanol from demiethyle carbonate/methanol mixtures
US5986125A (en) * 1996-06-13 1999-11-16 Henkel Kommanditgesellschaft Auf Aktien Process for the production of dialkyl carbonates
US7799940B2 (en) 2007-02-16 2010-09-21 Sabic Innovative Plastics Ip B.V. Process for manufacturing dimethyl carbonate
US7803961B2 (en) 2007-02-16 2010-09-28 Sabic Innovative Plastics Ip B.V. Process for manufacturing dimethyl carbonate
US20170354235A1 (en) * 2016-06-14 2017-12-14 L'oreal Curing applicator
CN114634415A (en) * 2022-04-22 2022-06-17 天津凯美特化工科技有限公司 Method for separating azeotrope of dimethyl carbonate and methanol and producing ethyl methyl carbonate by diethyl carbonate reaction
CN114634415B (en) * 2022-04-22 2024-03-22 天津凯美特化工科技有限公司 Method for separating azeotrope of dimethyl carbonate and methanol by diethyl carbonate reaction and producing methyl ethyl carbonate

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JPS5441820A (en) 1979-04-03
EP0000894B1 (en) 1981-07-15
IT7850740A0 (en) 1978-08-16
DE2860841D1 (en) 1981-10-22
DE2737265A1 (en) 1979-03-01
IT1106887B (en) 1985-11-18

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