EP0564478A1 - Procede pour la nitration en continu de composes aromatiques aptes a la nitration - Google Patents

Procede pour la nitration en continu de composes aromatiques aptes a la nitration

Info

Publication number
EP0564478A1
EP0564478A1 EP92900191A EP92900191A EP0564478A1 EP 0564478 A1 EP0564478 A1 EP 0564478A1 EP 92900191 A EP92900191 A EP 92900191A EP 92900191 A EP92900191 A EP 92900191A EP 0564478 A1 EP0564478 A1 EP 0564478A1
Authority
EP
European Patent Office
Prior art keywords
reaction
acid
nitration
water
aromatic compound
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.)
Withdrawn
Application number
EP92900191A
Other languages
German (de)
English (en)
Inventor
Udo Dettmeier
Walter Landgraf
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.)
Hoechst AG
Original Assignee
Hoechst AG
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 Hoechst AG filed Critical Hoechst AG
Publication of EP0564478A1 publication Critical patent/EP0564478A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B43/00—Formation or introduction of functional groups containing nitrogen
    • C07B43/02—Formation or introduction of functional groups containing nitrogen of nitro or nitroso groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
    • C07C201/06—Preparation of nitro compounds
    • C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups

Definitions

  • the present invention relates to a process for the continuous nitration of nitratable aromatic compounds with nitrating acids using an excess of nitric acid.
  • Nitrohalobenzenes are valuable intermediates for the synthesis of dyes, photographic developers, antioxidants and inhibitors in the rubber industry.
  • nitration of aromatic compounds for example the nitration of chlorobenzene to a mixture of o- and p-nitr ochlorobenzene, is known.
  • monochlorobenzene is reacted with nitric acid and another acid, such as sulfuric acid or phosphoric acid, which is added in excess.
  • the excess of nitrating acid serves as a heat transfer medium for the strongly exothermic nitration reaction. Since stoichiometric amounts of water are formed during nitration, the nitrating acid must be concentrated again in separate apparatus. This workload is increased by the use of excess nitrating acid. Concentration also requires large amounts of energy and is only possible in equipment made of expensive materials that must be resistant to acids.
  • DE 24 22 306 describes the nitration of chlorobenzene with nitric acid in the presence of strong acids, such as phosphoric acid. To decrease the yield of nitrated halogen aromatic compounds due to the shift in equilibrium due to the formation of water To avoid during the reaction, this process is carried out in the presence of polyvalent metals or their soluble compounds. The used nitrating acid is also concentrated again.
  • nitrided product mixtures are generally worked up in several stages, with unconverted nitrating acid initially being extracted with water or alkaline solutions (NaHC0 3 , NaOH). The resulting wastewater flow must be treated biologically.
  • EP-PS 39 556 describes a process for the continuous nitration of aromatic compounds, in which the water formed during the reaction is removed by stripping with inert gases at 120 to 140 ° C. This process requires large amounts of inert gas in order to be able to safely master the heat of the highly exothermic nitration.
  • DE-PS 3 244 293 describes a process for the nitration of chlorobenzene using at most stoichiometric amounts of nitric acid to chlorobenzene in the presence of concentrated phosphoric acid. This measure and the use of a reaction temperature of generally below 100 ° C. are intended to reduce the formation of undesired dinitrated products. However, this process requires relatively long reaction times.
  • the heat of reaction occurring in the strongly exothermic reaction is to be dissipated in a technically safe manner, the processing of the nitrating acid is to be avoided and the pollution of waste water is to be reduced. It has now been found that this object can be achieved by carrying out the reaction using a molar ratio of nitric acid to the aromatic compound of at least 1.1. The temperature and the pressure are coordinated so that the reaction mixture boils.
  • the nitrating acid is recycled to the reaction without further intermediate treatment, the product mixture is extracted with water and the eluate for recycling nitrating acid is also returned to the reaction.
  • the molar ratio of nitric acid to the aromatic compound is generally 1.1 to 4.0, preferably 1.2 to 2.5, particularly preferably 1.3 to 2.0. It was not to be expected from the prior art that dinitrations hardly occur when this high excess of nitric acid is used.
  • Chlorobenzene, benzene or toluene are used in particular as the nitratable aromatic compound which forms an azeotrope with water. In general, however, all compounds which form an azeotropic mixture with water are suitable.
  • the nitriding is expediently carried out at temperatures from 60 to 120 ° C., preferably 75 to 105 ° C., and a pressure of 100 to 900 mbar, preferably 200 to 400 mbar.
  • the nitriding is carried out with evaporative cooling, i.e. the heat of reaction is removed via the transition components of the boiling reaction mixture and the organic condensate is returned to the reactor.
  • the water formed during the reaction is removed from the reaction mixture as an azeotrope with the nitrable aromatic compound and the unreacted nitric acid.
  • Sulfuric acid and / or phosphoric acid are particularly suitable as nitrating acid. If mixtures of phosphoric acid and sulfuric acid are used, the conversion is increased by increasing the proportion of sulfuric acid in relation to phosphoric acid.
  • the process according to the invention is explained in more detail with the aid of the enclosed process scheme.
  • the nitrating acid water and phosphoric acid and / or sulfuric acid
  • the aromatic compound are placed in reactor 1.
  • the proportion of water in the nitrating acid presented is generally 10 to 30% by weight.
  • the desired pressure is set and the mixture is heated to the boiling point.
  • the aromatic compound A and nitric acid B are then metered in continuously in the desired ratio. Heat can be added to the reactor to maintain the boiling of the reaction mixture.
  • the distillate from reactor 1 is fractionated in column 2 and then liquefied in condenser 3.
  • the organic phase is returned to column 2 from the two-phase condensate (tank 4) and the aqueous phase is discharged.
  • the reaction product of the reactor 1 is continuously removed as an overflow as a specifically lighter phase and fed to the phase separator 5.
  • the specifically heavier phase (nitrating acid) is returned to the reactor, the specifically lighter organic phase is fed into the extraction unit 6.
  • the product mixture that is extracted also contains dissolved portions of sulfuric acid, phosphoric acid and nitric acid.
  • the known extraction apparatuses are suitable as extraction units, e.g. a mixer settler. Water is added as the extractant. The amount of water can be selected so that either a specifically lighter (as described) or a specifically heavier eluate is formed.
  • the aqueous phase is drawn off and returned to reactor 1.
  • the organic phase is fed to the column 7, in which unreacted chlorobenzene is distilled off overhead, condensed in the condenser 8 and returned to the reactor 1.
  • the bottom of the column is the product mixture, which after usual procedures is worked up (see, for example, Ulimanns Enzyklopadie der Techn. Chemie, 4th ed., vol. 17 (1979), p. 396).
  • the distribution of the para-ortho isomers can be influenced by varying the excess of nitric acid and the ratio of phosphoric acid to sulfuric acid, without an increase in the formation of the metal isomer or the formation of dinitrided products being observed.
  • the conversion of the aromatic compound can also be increased by the excess of nitric acid without increasing the dinitration.
  • Another advantage of the process according to the invention is that hardly any wastewater is obtained, which must then be cleaned since the product mixture is extracted with water and the aqueous eluate can be returned to the nitration reactor without impairing the conversion.
  • the heat of reaction can be safely removed technically, the space-time yields are very high and a concentration of the nitrating acid is avoided.
  • Chlorobenzene was nitrided in the apparatus described above. 1067 g of a mixture of 753 g of H 3 PO 4 , 182 g of H 2 SO 4 and 132 g of H 2 O were placed in reactor 1. A boiling temperature of 105 ° C. was set at 270 mbar. 604 g / h of chlorobenzene and 503 g / h of HNO 3 were continuously added dropwise in the course of 6 hours. 798 g / h of crude product and 342 g / h of distillate were obtained. The crude product was washed with 33 g / h of water in extractor F6. The eluate was returned to the reactor. The washing effect is shown in Table 1: Table 1
  • a conversion of chlorobenzene of 75% and a p / o ratio of 1.4 were achieved.
  • the dinitrochlorobenzene content was less than 0.1%.
  • the space-time performance was 980 g / l-h.
  • Example 1 was repeated, but the reaction time was 60 hours. After the reaction had been stopped, the amount of acid (H 3 P0 4 , H 2 S0 4 and H 2 0) was weighed in the reactor and gave 1089 g (cf. using 1067 g in Example 1), so that it can be assumed within the scope of the analysis accuracy is that the amount of H 3 P0 4 and H 2 S0 4 and the ratio of these two acids to one another have remained constant even in the endurance test.
  • the table shows that despite the high reaction temperature, dinitrations do not occur even with mixtures of nitric acid of different strengths.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Procédé pour la nitration en continu d'un composé aromatique apte à la nitration et constituant un azéotrope avec l'eau. Ce procédé qui consiste à traiter le composé avec de l'acide nitrique en présence d'acides de nitration se caractérise par le fait que la réaction se fait avec un rapport molaire de l'acide nitrique au composé aromatique d'au moins 1:1, la température et la pression concordant à un point tel que le mélange de réaction bout, et également par le fait que l'acide de nitration est recyclé sans traitement intermédiaire, que le mélange obtenu est extrait avec de l'eau et que le produit résiduel de l'élution est recyclé dans le dispositif de réaction pour reconduire l'acide de nitration.
EP92900191A 1990-12-24 1991-12-10 Procede pour la nitration en continu de composes aromatiques aptes a la nitration Withdrawn EP0564478A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4041775 1990-12-24
DE4041775 1990-12-24

Publications (1)

Publication Number Publication Date
EP0564478A1 true EP0564478A1 (fr) 1993-10-13

Family

ID=6421438

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92900191A Withdrawn EP0564478A1 (fr) 1990-12-24 1991-12-10 Procede pour la nitration en continu de composes aromatiques aptes a la nitration

Country Status (8)

Country Link
EP (1) EP0564478A1 (fr)
JP (1) JPH05508865A (fr)
KR (1) KR960009567B1 (fr)
CN (1) CN1062899A (fr)
BR (1) BR9107188A (fr)
CA (1) CA2099108A1 (fr)
MX (1) MX9102783A (fr)
WO (1) WO1992011227A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4225023A1 (de) * 1992-07-29 1994-02-03 Bayer Ag Verfahren zur Herstellung von 2,3-Dichlor-nitrobenzol
DE19512114C2 (de) 1995-04-04 2000-04-27 Meissner Gmbh & Co Kg Josef Rückgewinnung von Salpetersäure aus Nitrierprozessen
PT2352718E (pt) * 2008-11-14 2016-06-06 Noram Int Ltd Método para reduzir a formação de subprodutos de dinitrobenzeno em produtos de mononitrobenzeno
KR101726351B1 (ko) 2011-02-17 2017-04-12 노람 인터내셔널 리미티드 니트로화 공정에서 비-방향족 불순물의 제거
CN104649910B (zh) * 2013-11-25 2017-01-11 江苏扬农化工集团有限公司 一种酸套用连续化硝化制备2,5-二氯硝基苯的方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL127396C (fr) * 1962-04-30
US3780116A (en) * 1972-06-15 1973-12-18 Zaverchand & Co Method for nitration of aromatic hydrocarbon compounds
DE3705091A1 (de) * 1987-02-18 1988-09-01 Bayer Ag Verfahren zur abtrennung von schwefelsaeure und salpetersaeure aus bei der nitrierung von toluol erhaltenen dinitrotoluolgemischen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9211227A1 *

Also Published As

Publication number Publication date
CN1062899A (zh) 1992-07-22
JPH05508865A (ja) 1993-12-09
BR9107188A (pt) 1994-09-27
KR930703237A (ko) 1993-11-29
KR960009567B1 (en) 1996-07-20
MX9102783A (es) 1992-06-01
CA2099108A1 (fr) 1992-06-25
WO1992011227A1 (fr) 1992-07-09

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