DE1258859B - Process for the production of terephthalic acid free of nuclear chlorine - Google Patents

Process for the production of terephthalic acid free of nuclear chlorine

Info

Publication number
DE1258859B
DE1258859B DEB46750A DEB0046750A DE1258859B DE 1258859 B DE1258859 B DE 1258859B DE B46750 A DEB46750 A DE B46750A DE B0046750 A DEB0046750 A DE B0046750A DE 1258859 B DE1258859 B DE 1258859B
Authority
DE
Germany
Prior art keywords
terephthalic acid
stage
production
acid
chlorine
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
Application number
DEB46750A
Other languages
German (de)
Inventor
Dr Anton Benning
Dr Otto Grosskinsky
Dr Heinrich Fruehbuss
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bergwerksverband GmbH
Original Assignee
Bergwerksverband GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Bergwerksverband GmbH filed Critical Bergwerksverband GmbH
Priority to DEB46750A priority Critical patent/DE1258859B/en
Publication of DE1258859B publication Critical patent/DE1258859B/en
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
    • C07C51/27—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with oxides of nitrogen or nitrogen-containing mineral acids
    • C07C51/275—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with oxides of nitrogen or nitrogen-containing mineral acids of hydrocarbyl groups

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Description

Verfahren zur Herstellung von kernchlorfreier Terephthalsäure Gemäß Patent 976 342 wird Terephthalsäure durch Oxydation von p-Chlormethyltoluol in der Weise hergestellt, daß p-Chlormethyltoluol in einer ersten Stufe 2 Stunden mit einer etwa 320/0eigen Salpetersäure bei erhöhter Temperatur zu einem im wesentlichen aus p-Toluylsäure bestehenden Zwischenprodukt oxydiert, dieses abgetrennt und in der zweiten Stufe 2 Stunden mit 320/,der Salptersäure unter Druckerhitzen auf etwa 160"C zu Terephthalsäure weiter oxydiert wird. Die Reaktion gelangt besonders rasch zum Abschluß und führt zu außerordentlich reinen Säuren, wenn für die erste Arbeitsstufe eine etwa 32 bis 460/0ige Salpetersäure, hingegen in der Druckstufe eine etwa 30 bis 350/,ige Säure zur Anwendung gelangt (deutsche Auslegeschrift B 32054 IVb/120).Process for the preparation of terephthalic acid free from nucleus chlorine According to Patent 976,342 is terephthalic acid by oxidation of p-chloromethyltoluene in the Way prepared that p-chloromethyltoluene in a first stage 2 hours with a about 320/0 pure nitric acid at elevated temperature to a substantially off p-toluic acid existing intermediate oxidized, this separated and in the second stage 2 hours with 320 /, the nitric acid under pressure heating to about 160 "C is further oxidized to terephthalic acid. The reaction comes to the particularly quickly Completion and leads to extremely pure acids if for the first stage of work about 32 to 460/0 nitric acid, however in the pressure stage about 30 up to 350% acid is used (German interpretation B 32054 IVb / 120).

Bei der technischen Durchführung dieses Verfahrens stellte sich heraus, daß hin und wieder Terephthalsäure erhalten wurde, die gewisse Mengen an kernchlorierter Terephthalsäure enthielt. Diese Verunreinigung ist von großem Nachteil, da Chlorterephthalsäure nicht ohne weiteres von Terephthalsäure zu trennen ist. During the technical implementation of this process, it turned out that that now and then terephthalic acid was obtained which contained certain amounts of nuclear chlorinated Contained terephthalic acid. This contamination is a major disadvantage because chloroterephthalic acid cannot easily be separated from terephthalic acid.

Überdies ist eine auch nur mit Spuren an Chlorverbindungen verunreinigte Terephthalsäure praktisch wertlos.In addition, one is only contaminated with traces of chlorine compounds Terephthalic acid is practically worthless.

Es wurde nun überraschenderweise gefunden, daß man zu absolut kernchlorfreier Terephthalsäure gelangt, wenn man die Oxydation in der ersten Stufe bei einer Temperatur <1050C, insbesondere <1000 C durchführt. Es kommt also darauf an, ein Sieden des Reaktionsgemisches zu vermeiden. Selbstverständlich kann man nur auf 80 oder 900 C erhitzen, wodurch zwangläufig die Reaktionszeit für die erste Stufe verlängert wird, ein Nachteil, der im Interesse einer absolut reinen Terephthalsäure ohne weiteres in Kauf genommen werden kann. It has now been found, surprisingly, that one is absolutely free of nuclear chlorine Terephthalic acid arrives when you start the oxidation in the first stage at one temperature <1050C, especially <1000C. So it comes down to a simmering to avoid the reaction mixture. Of course you can only go to 80 or Heat 900 C, which inevitably increases the reaction time for the first stage becomes, a disadvantage that is readily apparent in the interest of an absolutely pure terephthalic acid can be accepted.

Beispiel 100 Teile eines technischen p-Chlormethyltoluols (25 ovo o-Chlormethyltoluol) werden mit der 6fachen Menge 430/0iger Salpetersäure auf 95 bis 1000 C erhitzt. Nach 2 Stunden läßt die Entwicklung der braunen Dämpfe merklich nach. Das Reaktionsgemisch wird sodann in einen Druckgefäß übergeleitet und darin 1 Stunde auf 180"C bei 20 atü erhitzt. Example 100 parts of a technical p-chloromethyltoluene (25 ovo o-Chloromethyltoluene) are increased to 95 with 6 times the amount of 430/0 nitric acid heated to 1000 C. After 2 hours the development of the brown vapors is noticeable after. The reaction mixture is then transferred to a pressure vessel and therein Heated for 1 hour to 180 ° C at 20 atm.

Die erhaltene Terephthalsäure (88 Teile, Säurezahl 674) ist absolut frei von Spuren an Chlorterephthalsäure.The terephthalic acid obtained (88 parts, acid number 674) is absolute free from traces of chloroterephthalic acid.

Wird zum Vergleich in der ersten Stufe das Reaktionsgemisch bis zum Sieden, also auf 112 bis 114"C erhitzt, so enthält das Endprodukt 9,2 01o gebundenes Chlor. If for comparison in the first stage the reaction mixture up to Boiling, i.e. heated to 112 to 114 "C, the end product contains 9.2 01o bound Chlorine.

Claims (1)

Patentanspruch: Verfahren zur Herstellung von kernchlorfreier Terephthalsäure durch Oxydation von p-Chlormethyltoluol mit Salpetersäure in einer ersten Stufe, bei erhöhter Temperatur und Normaldruck zu einem im wesentlichen aus p-Toluylsäure bestehenden Zwischenprodukt und unmittelbare Weiteroxydation in einer zweiten Stufe unter Druck undTemperaturerhöhung, d a d u r c h g e k e n nz e i c h n e t, daß man die Oxydation in der ersten Stufe bei einer Temperatur < 1050 C durchführt. Claim: Process for the production of chlorine-free terephthalic acid by oxidation of p-chloromethyltoluene with nitric acid in a first stage, at elevated temperature and normal pressure to form essentially one of p-toluic acid existing intermediate product and immediate further oxidation in a second stage under pressure and temperature increase, it is not indicated that the oxidation is carried out in the first stage at a temperature <1050 C.
DEB46750A 1957-11-11 1957-11-11 Process for the production of terephthalic acid free of nuclear chlorine Pending DE1258859B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DEB46750A DE1258859B (en) 1957-11-11 1957-11-11 Process for the production of terephthalic acid free of nuclear chlorine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEB46750A DE1258859B (en) 1957-11-11 1957-11-11 Process for the production of terephthalic acid free of nuclear chlorine

Publications (1)

Publication Number Publication Date
DE1258859B true DE1258859B (en) 1968-01-18

Family

ID=6968026

Family Applications (1)

Application Number Title Priority Date Filing Date
DEB46750A Pending DE1258859B (en) 1957-11-11 1957-11-11 Process for the production of terephthalic acid free of nuclear chlorine

Country Status (1)

Country Link
DE (1) DE1258859B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3979448A (en) * 1973-06-19 1976-09-07 Bergwerksverband Gmbh Processes for the continuous production of aromatic carboxylic acids by oxidation with nitric acid of aromatic compounds containing oxidizable acyclic substituents

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3979448A (en) * 1973-06-19 1976-09-07 Bergwerksverband Gmbh Processes for the continuous production of aromatic carboxylic acids by oxidation with nitric acid of aromatic compounds containing oxidizable acyclic substituents

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