DE1004162B - Process for purifying dimethyl terephthalate - Google Patents
Process for purifying dimethyl terephthalateInfo
- Publication number
- DE1004162B DE1004162B DEV9752A DEV0009752A DE1004162B DE 1004162 B DE1004162 B DE 1004162B DE V9752 A DEV9752 A DE V9752A DE V0009752 A DEV0009752 A DE V0009752A DE 1004162 B DE1004162 B DE 1004162B
- Authority
- DE
- Germany
- Prior art keywords
- dimethyl terephthalate
- distillation
- ethylene glycol
- purifying dimethyl
- purifying
- 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.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/62—Use of additives, e.g. for stabilisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
- C07C67/54—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation by distillation
Description
Verfahren zum Reinigen von Dimethylterephthalat Die Reinigung von Dimethylterephthalat kann entweder durch Destillation oder durch Umkristallisation, z. B. aus Methanol oder Tetrachlorkohlenstoff, vorgenommen werden. Bei der Destillation unter Atmosphärendruck wird eine extreme Reinigung deswegen nicht erreicht, weil bei den relativ hohen Temperaturen Zersetzungserscheinungen unvermeidbar sind, welche neuerliche Verunreinigungen hervorrufen. Der Nachteil bei der Umkristallisation liegt darin, daß große Mengen Mutterlauge anfallen, deren Aufarbeitung umständlich ist und erhebliche Verluste nach sich zieht. Man hat bereits vorgeschlagen, die Destillation von Dimethylterephthalat in einem kontinuierlichen Prozeß durchzuführen, wobei drei Destillationszonen durchlaufen werden. Auch diese Art der Reinigung ist wegen der umfangreichen Apparaturen umständlich und läßt keine extreme Reinigung zu, wie sie für die Weiterverarbeitung von Dimethylterephthalat zu entsprechenden Polykondensaten unbedingt notwendig ist.Process for purifying dimethyl terephthalate The purification of Dimethyl terephthalate can be produced either by distillation or by recrystallization, z. B. from methanol or carbon tetrachloride. During the distillation Extreme cleaning is not achieved under atmospheric pressure because at the relatively high temperatures decomposition phenomena are unavoidable, which cause renewed contamination. The disadvantage of recrystallization lies in the fact that large amounts of mother liquor are obtained, which is laborious to work up and entails considerable losses. It has already been suggested that To carry out distillation of dimethyl terephthalate in a continuous process, whereby three distillation zones are passed through. This type of cleaning is also there because of the extensive equipment cumbersome and does not allow extreme cleaning as to how they are used for the further processing of dimethyl terephthalate Polycondensate is absolutely necessary.
Es wurde gefunden, daß man Dimethylterephthalat einer extremen Reinigung unterziehen kann, wenn man das rohe Dimethylterephthalat in Gegenwart von Äthylenglykol unter Vakuum einer Destillation unterwirft. Dieser Befund ist deshalb überraschend, weil durch eine Destillation mit z. B. Methanol keine Reinigung in gewünschtem Sinne möglich ist. Beim vorliegenden Verfahren wird erreicht, daß der rohe Dimethylester, welcher entweder durch Depolymerisation von Polyäthylenterephthalat oder durch Veresterung von Terephthalsäure gewonnen wurde, in einem Arbeitsgang destillativ gereinigt wird. Das zur Destillation verwendeteÄthylenglykol kann sofort wieder zur weiteren Destillation verwendet werden, ohne daß es vorher redestilliert wird. Der geringe Äthylenglykolgehalt des durch Abnutschen vom überschüssigen Glvkol befreiten Dimethylterephthalats macht jede Zwischentrocknung überflüssig und bedeutet eine wesentliche Beschleunigung des gesamten Arbeitsvorganges. Das Dimethylterephthalat ist sofort zur Umesterung bzw. anschließenden Polykondensation zu Polyäthylenterephthalat geeignet. Man erhält Polykondensate hoher Viskositätsgrade mit K-Werten von 50 bis 57.It has been found to give dimethyl terephthalate an extreme purification can undergo if you take the crude dimethyl terephthalate in the presence of ethylene glycol subjected to distillation under vacuum. This finding is therefore surprising because by distillation with z. B. methanol does not purify in the desired sense is possible. In the present process it is achieved that the crude dimethyl ester, which either by depolymerization of polyethylene terephthalate or by esterification was obtained from terephthalic acid, is purified by distillation in one operation. The ethylene glycol used for the distillation can immediately be used again for further distillation can be used without being redistilled beforehand. The low ethylene glycol content of the dimethyl terephthalate freed from excess glycol by suction filtration any intermediate drying is superfluous and means a significant acceleration of the entire work process. The dimethyl terephthalate is immediately ready for transesterification or subsequent polycondensation to polyethylene terephthalate. You get Polycondensates of high viscosity with K values from 50 to 57.
Beispiel 30 g rohes Dimethylterephthalat werden mit 270 g Äthylenglykol in einem Kolben gemischt und unter Einleiten von trockenem Stickstoff in einer Kolonne von 30 cm bei etwa 44 Torr destilliert. Das Azeotrop, welches aus etwa 97 % Dimethylterephthalat besteht, geht bei etwa 120° in eine gekühlte Vorlage über. Das durch Absaugen vom Äthylenglykol abgetrennte Dimethylterephthalat kann sofort zur Umesterung bzw. zur Polykondensation verwendet werden.Example 30 g of crude dimethyl terephthalate are mixed with 270 g of ethylene glycol mixed in a flask and with bubbling dry nitrogen in a column distilled from 30 cm at about 44 torr. The azeotrope, which consists of about 97% dimethyl terephthalate exists, goes into a cooled template at about 120 °. That by suction from Ethylene glycol separated dimethyl terephthalate can be used immediately for transesterification or for Polycondensation can be used.
Claims (1)
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEV9752A DE1004162B (en) | 1955-11-18 | 1955-11-18 | Process for purifying dimethyl terephthalate |
| CH346535D CH346535A (en) | 1955-11-18 | 1956-09-27 | Process for purifying dimethyl terephthalate |
| BE551364A BE551364A (en) | 1955-11-18 | 1956-09-28 | PROCEDURE FOR PURIFICATION OF DIMETHYLTEREPHTALATE. |
| FR1163410A FR1163410A (en) | 1955-11-18 | 1956-10-08 | Process for purifying dimethyl terephthalate |
| GB32597/56A GB802067A (en) | 1955-11-18 | 1956-10-25 | A process for purifying dimethyl terephthalate by distillation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEV9752A DE1004162B (en) | 1955-11-18 | 1955-11-18 | Process for purifying dimethyl terephthalate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DE1004162B true DE1004162B (en) | 1957-03-14 |
Family
ID=7572808
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DEV9752A Pending DE1004162B (en) | 1955-11-18 | 1955-11-18 | Process for purifying dimethyl terephthalate |
Country Status (5)
| Country | Link |
|---|---|
| BE (1) | BE551364A (en) |
| CH (1) | CH346535A (en) |
| DE (1) | DE1004162B (en) |
| FR (1) | FR1163410A (en) |
| GB (1) | GB802067A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3468763A (en) * | 1966-06-21 | 1969-09-23 | Halcon International Inc | Purification of terephthalonitrile by azeotropic distillation with ethylene glycol |
-
1955
- 1955-11-18 DE DEV9752A patent/DE1004162B/en active Pending
-
1956
- 1956-09-27 CH CH346535D patent/CH346535A/en unknown
- 1956-09-28 BE BE551364A patent/BE551364A/en unknown
- 1956-10-08 FR FR1163410A patent/FR1163410A/en not_active Expired
- 1956-10-25 GB GB32597/56A patent/GB802067A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CH346535A (en) | 1960-05-31 |
| GB802067A (en) | 1958-09-24 |
| FR1163410A (en) | 1958-09-25 |
| BE551364A (en) | 1959-12-18 |
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