EP0000894B1 - 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 PDFInfo
- Publication number
- EP0000894B1 EP0000894B1 EP78100607A EP78100607A EP0000894B1 EP 0000894 B1 EP0000894 B1 EP 0000894B1 EP 78100607 A EP78100607 A EP 78100607A EP 78100607 A EP78100607 A EP 78100607A EP 0000894 B1 EP0000894 B1 EP 0000894B1
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- EP
- European Patent Office
- Prior art keywords
- azeotrope
- methanol
- dimethyl carbonate
- process according
- separation
- 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
- 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
Definitions
- the invention relates to a process for separating dimethyl carbonate from the dimethyl carbonate / methanol azeotrope by distillation.
- Dimethyl carbonate is of great technical importance as a starting material for the production of aromatic carbonates, which in turn are precursors for the production of polycarbonates and crop protection agents (see, for example, Ullmanns Encyklopadie der Technische Chemie, 3 ed., Vol. 9, p. 776 (1957), U.S. Patent 3,933,846, DT Patent 971,790).
- Dimethyl carbonate is produced according to US Pat. No. 2,642,858, US Pat. No. 3,803,201 and DT-OS 2615665 by transesterification of cyclic carbonates, such as ethylene carbonate, with alcohols in the presence of alkaline catalysts. An approximately 30% by weight azeotrope with methanol is obtained.
- Another separation process is based on distillation at a pressure of about 10 atm; whereby after distilling off a methanol-rich top fraction dimethyl carbonate is obtained as a residue (DT-OS 2 607 003).
- a process for obtaining 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 in such a way that a low-boiling azeotrope is obtained from the azeotrope form in question and methanol passes at a temperature of 30 to 63 ° C.
- a low-boiling azeotrope first distills from the relevant mixture of the azeotroping agent with methanol - the boiling point of the azeotrope depends on the type of azeotroping agent used, it lies in the temperature range from 30 ° C to 63 ° C - which depletes the residue of methanol. What remains is almost pure dimethyl carbonate, which in most cases requires no further purification by distillation. 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.
- the process according to the invention ensures a particularly economical, clean and easy to carry out separation of methanol and dimethyl carbonate.
- azeotroping agents are aliphatic hydrocarbons having 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 petroleum ether (boiling range 40 to 80 ° C) light petrol (boiling range 60 to 95 ° 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
- azeotrope formers hexane, heptane, octane, isooctane, petroleum ether, light petrol and / or ligroin, with hexane and heptane being particularly preferred.
- 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 (cf. e.g. 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.
- 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.
- dimethyl carbonate In the bottom of the column, dimethyl carbonate remains as a residue, which can optionally be purified by distillation.
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.
Dimethylcarbqnat ist als Ausgangsstoff zur Herstellung aromatischer Carbonate, die ihrerseits wiederum Vorprodukte zur Herstellung von Polycarbonaten und Pflanzenschutzmitteln darstellen, von großer technischer Bedeutung (vgl. z.B. Ullmanns Encyklopädie der technischen Chemie, 3 Aufl., Bd. 9, S. 776 (1957), US-PS 3 933 846, DT-PS 971 790).Dimethyl carbonate is of great technical importance as a starting material for the production of aromatic carbonates, which in turn are precursors for the production of polycarbonates and crop protection agents (see, for example, Ullmanns Encyklopadie der Technische Chemie, 3 ed., Vol. 9, p. 776 (1957), U.S. Patent 3,933,846, DT Patent 971,790).
Dimethylcarbonat wird gemäß der US-PS 2 642 858, der US-PS 3 803 201 und der DT-OS 2615665 durch Umesterung cyclischer Carbonate, wie Athylencarbonat, mit Alkoholen in Gegenwart von alkalischen Katalysatoren hergestellt. Hierbei wird ein etwa 30 Gew.-%iges Azeotrop mit Methanol erhalten.Dimethyl carbonate is produced according to US Pat. No. 2,642,858, US Pat. No. 3,803,201 and DT-OS 2615665 by transesterification of cyclic carbonates, such as ethylene carbonate, with alcohols 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, from which dimethyl carbonate can be obtained by distillation, is frozen out by cooling to -70 ° C. according to US Pat. No. 3,803,201. The process is in view of the required low temperatures and technically cumbersome filtration level 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 after distilling off a methanol-rich top fraction dimethyl carbonate is obtained as a residue (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 so destilliert dass ein niedrig siedendes Azeotrop aus dem betreffenden Azeotropbildner und Methanol bei einer Temperatur von 30 bis 63°C übergeht.A process for obtaining 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 in such a way that a low-boiling azeotrope is obtained from the azeotrope form in question and methanol passes at a temperature of 30 to 63 ° C.
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 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 using azeotroping agents that are immiscible with methanol in the distillation of the methanol / dimethyl carbonate azeotrope, a low-boiling azeotrope first distills from the relevant mixture of the azeotroping agent with methanol - the boiling point of the azeotrope depends on the type of azeotroping agent used, it lies in the temperature range from 30 ° C to 63 ° C - which depletes the residue of methanol. What remains is almost pure dimethyl carbonate, which in most cases requires no further purification by distillation. 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 Petroläther (Siedebereich 40 bis 80°C) Leichtbenzin (Siedebereich 60 bis 95°C) 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 having 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 petroleum ether (boiling range 40 to 80 ° C) light petrol (boiling range 60 to 95 ° 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.
Bevorzug werden als Azeotropbildner eingesetzt: Hexan, Heptan, Octan, Isooctan, Petroläther, Leichtbenzin und/oder Ligroin, wobei Hexan und Heptan besonders bevorzugt sind.The following are preferably used as azeotrope formers: hexane, heptane, octane, 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 Azeotropzusammensetsung 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 (cf. e.g. 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 erfindungsgemäße Verfahren sei anhand der folgenden Beispiele verdeutlicht, ohne es jedoch auf diese Beispiele einzuschränken.The method according to the invention is illustrated by the following examples, but without restricting it to these examples.
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 gestehendes Gemisch derart erhitzt, daß über Kopf ein im wesentlichen aus Methanol und Heptan bestehendes zweiphasiges Azeotrop bei 58,5°C 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 (n20 D 1,3688). Ausbeute 50% d.Th.On a mirrored packed column filled with glass rings with a filling height of 1 m a mixture consisting of 450 g of dimethyl carbonate / methanol azeotrope (30:70) and 297 g of n-heptane is heated in such a way that a two-phase azeotrope consisting essentially of methanol and heptane is separated off at 58.5 ° 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 remaining in the flask (4.5 g) also consists of pure dimethyl carbonate (n 20 D 1.3688). Yield 50% of theory
Eine Mischung aus 150 g Dimethylcarbonat und 350 g Methanol wird mit 950 g n-Hexan an einer 40 cm hohen Silberspiegelkolonne derart destilliert, daß die Übergangstemperatur 50°C nich übersteigt. Der im Kolben verbleibende Rückstand (95 g) besteht nahezu aus reinem Dimethylcarbonat (n20 1,3675). Ausbeute 60% d.Th.A mixture of 150 g of dimethyl carbonate and 350 g of methanol is distilled with 950 g of n-hexane on a 40 cm high silver mirror column in such a way that the transition temperature does not exceed 50 ° C. The residue (95 g) remaining in the flask consists almost of pure dimethyl carbonate (n2 0 1.3675). Yield 60% of theory
Eine Mischung aus 45 g Dimethylcarbonat und 105 g Methanol wird mit 100 g Isooctan 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 (n20 D 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 (20 g) is almost pure dimethyl carbonate (n 20 D 1.3673). Yield 40% of theory
Ein aus 45 g Dimethylcarbonat und 105 g Methanol bestehendes Gemisch wird mit 85 g Ligroin vom Siedebereich 80-11 10°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 verbleibende Flüssigkeit (24 g) ist nahezu reines Dimethylcarbonat (n20 D 1,3676). Ausbeute 50% d.Th.A mixture consisting of 45 g dimethyl carbonate and 105 g methanol is distilled with 85 g ligroin from the boiling range 80-11 10 ° 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 (n 20 D 1.3676). Yield 50% of theory
Claims (5)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19772737265 DE2737265A1 (en) | 1977-08-18 | 1977-08-18 | PROCESS FOR SEPARATION OF DIMETHYLCARBONATE FROM ITS AZEOTROP WITH METHANOL |
| DE2737265 | 1977-08-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0000894A1 EP0000894A1 (en) | 1979-03-07 |
| EP0000894B1 true EP0000894B1 (en) | 1981-07-15 |
Family
ID=6016734
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP78100607A Expired EP0000894B1 (en) | 1977-08-18 | 1978-08-07 | Process for the separation of dimethyl carbonate from its azeotrope with methanol |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0000894B1 (en) |
| JP (1) | JPS5441820A (en) |
| DE (2) | DE2737265A1 (en) |
| IT (1) | IT1106887B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4129316A1 (en) * | 1991-09-03 | 1993-03-04 | Bayer Ag | METHOD FOR THE CONTINUOUS PRODUCTION OF DIALKYL CARBONATES |
| DE4224770A1 (en) * | 1992-07-27 | 1994-02-03 | Bayer Ag | Process for the separation of methanol from dimethyl carbonate / methanol mixtures |
| 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 |
| DE19623508C2 (en) * | 1996-06-13 | 1998-08-20 | Henkel Kgaa | Process for the preparation of dialkyl carbonates |
| ES2638172T3 (en) | 2007-02-16 | 2017-10-19 | Sabic Global Technologies B.V. | Process for the manufacture of dimethyl carbonate |
| EP2121563B1 (en) | 2007-02-16 | 2016-05-04 | SABIC Global Technologies B.V. | Process for manufacturing dimethyl carbonate |
| JP5915316B2 (en) * | 2012-03-28 | 2016-05-11 | ダイキン工業株式会社 | Method for producing chain carbonate |
| US10517371B2 (en) * | 2016-06-14 | 2019-12-31 | L'oreal | Curing applicator |
| 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 |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1094724B (en) * | 1959-03-02 | 1960-12-15 | Callery Chemical Co | Process for the separation of trimethyl borate from its azeotrope with methanol |
| FR1399555A (en) * | 1961-08-10 | 1965-05-21 | Rhone Poulenc Sa | New process for fractionation of mixtures of ethanol, methanol and water |
| 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 |
| AR204957A1 (en) * | 1974-06-25 | 1976-03-19 | Snam Progetti | PROCEDURE FOR THE PREPARATION OF AROMATIC CARBONATES |
| US3940450A (en) * | 1974-12-16 | 1976-02-24 | Texaco Inc. | Preparation and recovery of ethers |
-
1977
- 1977-08-18 DE DE19772737265 patent/DE2737265A1/en not_active Withdrawn
-
1978
- 1978-08-07 EP EP78100607A patent/EP0000894B1/en not_active Expired
- 1978-08-07 DE DE7878100607T patent/DE2860841D1/en not_active Expired
- 1978-08-16 JP JP9915678A patent/JPS5441820A/en active Pending
- 1978-08-16 IT IT50740/78A patent/IT1106887B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IT7850740A0 (en) | 1978-08-16 |
| EP0000894A1 (en) | 1979-03-07 |
| DE2737265A1 (en) | 1979-03-01 |
| JPS5441820A (en) | 1979-04-03 |
| DE2860841D1 (en) | 1981-10-22 |
| IT1106887B (en) | 1985-11-18 |
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