METHOD FOR PRODUCING ANILINE OR AN ANILINE DERIVATIVE

Abstract

The invention relates to a method for producing aniline or an aniline derivative, in which a solution of aminobenzoic acid in aniline with a mass fraction of aniline in the solution, in relation to the total mass of aminobenzoic acid and aniline, in the region of 20% to 85%, is subject to a thermal decarboxylation at a temperature in the region of 165° C. to 500° C. without the presence of a non-system catalyst, such that the aminobenzoic acid is converted into aniline. The obtained aniline can be converted into derivatives, such as di- and polyamines of the diphenylmethane series.

Claims

1. A process for preparing aniline, comprising: (I) providing a solution of aminobenzoic acid in aniline, wherein aniline is present in the solution in an amount of 20% to 85% by mass, based on the total mass of aminobenzoic acid and aniline; and (II) converting aminobenzoic acid in the solution provided in step (I) to aniline in a reactor by thermal decarboxylation at a temperature of 165° C. to 500° C. without the presence of any catalyst extraneous to the system.

2. The process as claimed in claim 1, in which step (I) is performed by mixing aminobenzoic acid and aniline in a batchwise or continuous mixer.

3. The process as claimed in claim 2, in which the mixer and the reactor are operated continuously.

4. The process as claimed in claim 2, in which step (I) is performed using multiple batchwise mixers connected in parallel and the reactor is operated continuously, wherein, at any time in the continuous operation of the reactor, the solution of the aminobenzoic acid from one of the mixers is introduced into the reactor, while the mixing of the aminobenzoic acid into aniline is proceeding in another of the mixers.

5. The process as claimed in claim 1, in which the thermal decarboxylation of the aminobenzoic acid is a first partial step (II)(1) of step (II), which is followed by a second partial step (II)(2) in which aniline formed in partial step (II)(1) is purified.

6. The process as claimed in claim 5, in which the aniline used in step (I) is taken from the aniline formed in partial step (II)(1), from the aniline purified in partial step (II)(2) or from the aniline formed in partial step (II)(1) and from the aniline purified in partial step (II)(2).

7. The process as claimed in claim 1, in which, in step (I), aminobenzoic acid is dissolved in aniline at a temperature of −6° C. to 120° C.

8. The process as claimed in claim 7, in which aminobenzoic acid and aniline are first mixed at a temperature of −6° C. to 100° C. and then heated in an inert gas atmosphere to a temperature of >100° C. to 120° C.

9. The process as claimed in claim 1, in which the thermal decarboxylation in step (II) is performed at a pressure of 4.0 bar.sub.(abs.) to 30 bar.sub.(abs.).

10. The process as claimed in claim 54, in which a liquid, aniline-containing stream and a gaseous, carbon dioxide- and gaseous aniline-containing stream are taken continuously from the reactor, wherein the gaseous stream passes through a condenser in which gaseous aniline is liquefied and from which carbon dioxide is discharged in gaseous form, wherein liquid aniline obtained in the condenser is fed to partial step (II)(1) and/or to partial step (II)(2).

11. The process as claimed in claim 1, in which the providing of the solution of aminobenzoic acid in aniline in step (I) comprises the chemical preparation of aminobenzoic acid.

12. The process as claimed in claim 1, in which the providing of the solution of aminobenzoic acid in aniline in step (I) comprises: (I)(1) fermenting a raw material comprising at least a fermentable carbon compound and a nitrogen compound, in a fermentation reactor using microorganisms to obtain an am inobenzoate- and/or aminobenzoic acid-containing fermentation broth, (I)(2) obtaining aminobenzoic acid from the fermentation broth; and (I)(3) dissolving the aminobenzoic acid obtained from the fermentation broth in step (I)(1) in aniline.

13. The process as claimed in claim 12, in which the microorganisms used in step (I)(1) comprises any one or more of Escherichia coli, Pseudomonas putida, Corynebacterium glutamicum, Ashbya gossypii, Pichia pastoris, Hansenula polymorpha, Kluyveromyces marxianus, Yarrowia lipolytica, Zygosaccharomyces bailii and Saccharomyces cerevisiae.

14. The process as claimed in claim 1, in which the aminobenzoic acid used to provide the solution of aminobenzoic acid in aniline in step (I) comprises water in an amount of 0.1% to 40% by mass, based on the total mass of aminobenzoic acid.

15. The process as claimed in claim 16, wherein the conversion comprises an acid-catalyzed reaction of aniline with formaldehyde to form di- and polyamines of the diphenylmethane series; an acid-catalyzed reaction of aniline with formaldehyde, followed by reaction with phosgene to form di- and polyisocyanates of the diphenylmethane series; or (III)(3) a conversion of aniline to an azo compound.

16. A process for preparing an aniline conversion product, comprising converting aniline obtained by the process of claim 1 to the aniline conversion product.

Description

EXAMPLES

[0154] Chemicals Used:

[0155] 2-Aminobenzoic acid, CAS 118-92-3 (short form hereinafter: oAB): purity ≥98%, Sigma-Aldrich Chemie GmbH.

[0156] Aniline, CAS 62-53-3 (short form hereinafter: ANL): purity ≥99%, Sigma-Aldrich Chemie GmbH.

[0157] Demineralized water (short form hereinafter: H.sub.2O): “HPLC Grade” purity, Sigma-Aldrich Chemie GmbH.

[0158] 2-Amino-N-phenylbenzamide, CAS 4424-17-3 (short form hereinafter: amide): purity ≥98%, Sigma-Aldrich Chemie GmbH.

[0159] Methanol, CAS 67-56-1 (short form hereinafter: MeOH): “HPLC Grade” purity, Sigma-Aldrich Chemie GmbH.

[0160] Phosphoric acid “ACS reagent”, CAS 7664-38-2 (short form hereinafter: H.sub.3PO.sub.4): purity ≥85%, Sigma-Aldrich Chemie GmbH.

[0161] Catalyst (for Comparative Examples):

[0162] CBV 600 (CAS 1318-02-1), Zeolyst International, Inc., surface area 660 m.sup.2/g, pore size 2.43 nm, Si/Al ratio 2.5. The catalyst was calcined prior to use at 300° C. in air for 3 h.

[0163] General Experimental Method for Experiments with Catalyst (Comparative Examples):

[0164] An initial charge of 1.33 g of oAB, 2 mL of ANL and 0.08 g of catalyst in a 10 mL pressure reactor was purged with argon as protective gas, and the reactor was closed. Subsequently, argon was injected to a pressure of 3 bar, the mixture was stirred at 800 rpm for 2 min and the pressure was dropped to 1 bar. This operation was repeated 3 times before the reactor was brought to the reaction temperature (see table 1). After the appropriate reaction time (see table 1), the pressure reactor was cooled down from reaction temperature to room temperature in an ice bath, and the pressure was subsequently dropped. The catalyst was separated from the reaction mixture by means of centrifugation (5 min, 5000 rpm). The composition of the liquid supernatant was analyzed by means of HPLC analysis (for data see table 1).

[0165] General Experimental Method for Experiments without Catalyst (Working Examples):

[0166] The reaction procedure was analogous to “General experimental method for experiments with catalyst”, except that no catalyst was employed and method steps relating to the catalyst are thus omitted.

[0167] HPLC Analyses:

[0168] Quantitative analysis of oAB, ANL and amide in the reaction mixture was accomplished by high-performance liquid chromatography (HPLC) analysis. For HPLC analysis, a setup from Agilent was used with UV detection (DAD, measured at 254.4 nm). For separation, a column from Agilent (Eclipse XDB-C18; 5 m; 4.6×150 mm) was used. The element used was a mixture of MeOH and H.sub.2O (ratio 40:60, pH 3 established with H.sub.3PO.sub.4) at a flow rate of 0.7 mL/min. The temperature of the column oven was 25° C. The sample was diluted in MeOH at a ratio of 1:10; the injection volume was 1 μL. The retention times of the individual ANL, oAB and amide components were: [0169] ANL=2.87 min; [0170] oAB=6.00 min; [0171] amide=18.67 min.

[0172] The peak areas are converted to area percent (A %). The quantification of the individual components in percent by mass (% by mass) based on the reaction mixture was enabled by calibration with pure substances beforehand. Tabulated in table 1 are all product compositions for the working and comparative examples for a given reaction time.

[0173] Determination of Reaction Rates:

[0174] The reaction rate was determined by ascertaining the rate constant k (in min.sup.−1) of the conversion of oAB. The basis used was pseudo-first-order conversion kinetics based on oAB, and the conversion of oAB was determined experimentally for different reaction times. For calculation of k, the natural logarithms of the relative oAB concentrations were plotted against reaction time (in min) and subjected to a linear fit. The slope of the linear equation thus obtained corresponds to k in min.sup.−1. Tabulated in table 1 are all k values for the working and comparative examples.

TABLE-US-00001 TABLE 1 Working examples (without catalyst) and comparative examples (with catalyst) Composition of product mixture ΣA % of these after oAB [% by ANL [% by Amide [% by components in # Note T [° C.] k [min.sup.−1] [min] mass] mass] mass] HPLC 1 without catalyst 200 0.053 60 10.9 88.9 0.2 100 2 230 0.091 60 3.2 96.5 0.3 100 3 250 0.118 30 0.8 98.8 0.4 100 4 270 0.143 30 0.4 99.2 0.4 100 5 without catalyst 200 0.032 60 14.1 85.7 0.3 100 6 with 5% by mass of H.sub.2O based 225 0.052 60 3.9 95.7 0.3 100 on oAB 7 without catalyst 200 0.031 60 14.1 85.7 0.2 100 8 with 30% by mass of H.sub.2O 225 0.054 60 3.6 96.1 0.4 100 based on oAB 9 with catalyst 200 0.052 60 2 n. d. n. d. n. d. 10 with catalyst 200 0.030 60 1.4 98 0.6 >99 with 5% by mass of H.sub.2O based on oAB 11 with catalyst 200 0.041 60 0.9 99 0.1 100 with 30% by mass of H.sub.2O based on oAB Elucidation of abbreviations: n.d. = not determined, ΣA % = sum total of the area percentages (of the three components oAB, ANL and amide)