RU2556222C1 - Method of producing o-chloroaniline (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: in each of the versions of the method, o-chloroaniline is obtained via catalytic reduction of o-nitrochlorobenzene with molecular hydrogen in the presence of modified palladium-containing nanoparticles in a liquid dispersion medium. According to the first version, o-chloroaniline is obtained at temperature of 30-80°C (303-353 K) and hydrogen pressure of 1 atm (excess); the palladium catalyst precursor used is palladium bis(acetylacetonate); the modifying additive is elementary phosphorus, with the following ratio of components: palladium bis(acetylacetonate)/phosphorus = 1:0.3 to 1:2; and the liquid dispersion medium is N,N-dimethyl formamide. In the second version of the method, o-chloroaniline is obtained at temperature of 30°C (303K) and hydrogen pressure of 1 atm (excess); the palladium catalyst precursor used is palladium dichloride; the modifying additive is elementary phosphorus, with the following ratio of components: palladium dichloride/phosphorus = 1:0.15 to 1:1; and the liquid dispersion medium is N,N-dimethyl formamide.

EFFECT: disclosed versions of the method of producing o-chloroaniline increase selectivity of o-chloroaniline when conducting the process in mild conditions.

2 cl, 4 tbl, 16 ex

Description

The present invention relates to the field of catalytic chemistry, in particular the development of a method for producing chloranilines by catalytic reduction of nitrochloroarenes, and can be used in fine organic synthesis.

The synthesis of aromatic halogenanilines by catalytic reduction of the corresponding nitro derivatives with molecular hydrogen refers to technologically pure processes compared to their preparation by the Becham reaction, which is characterized by a high content of toxic wastes that cause serious environmental pollution. Platinum group metals are commonly used as catalysts for the reduction of nitrohaloarenes [X. Wang, M. Liang, J. Zhang, Y. Wang. Selective Hydrogenation of Aromatic Chloronitro Compounds // Current Organic Chemistry. - 2007. - Vol. 11. - PP. 299-314]. The use of unmodified metal catalysts for hydrogen reduction of nitroarenes containing, along with the nitro group, other functional groups or a halogen atom, is problematic, since the reaction is often accompanied by the reduction of these functional groups or hydrogenolysis of the C-Hal bond. One of the ways to suppress the process of hydrodehalogenation in the synthesis of aromatic halogenamines by reduction of the corresponding nitrohalogenarenes with hydrogen is the use of partially deactivated metal catalysts as a result of the introduction of various modifiers.

Among the metals of the platinum group, palladium catalysts, being relatively cheaper compared to platinum catalysts, are characterized by higher activity in the reduction of the nitro group, but lower selectivity for the target product - halogenanilines compared to platinum, rhodium or ruthenium catalysts [X. Wang, M. Liang, J. Zhang, Y. Wang. Selective Hydrogenation of Aromatic Chloronitro Compounds // Current Organic Chemistry. - 2007. - Vol. 11. - PP. 299-314]. Inhibition of palladium catalysts by various phosphorus, nitrogen, and sulfur compounds allows one to increase their halogenamine selectivity. For example, a method is known for producing aromatic halogenamines by liquid phase reduction with hydrogen of the corresponding aromatic nitrohalogen derivatives of the general formula:

where X = Cl, n = 1, catalyzed by carbon supported palladium catalysts (Pd / C), in the presence of inhibitors. As inhibitors, triphenylphosphite P (OPh) _{3 is used} ; hydrotriphenyl- or hydrotrialkylsilane HSiR ₃ (R = C ₁ -C ₄ ) or a mixture thereof (EP No. 0292682 A2; Bul. No. 88/48 of 11/30/1988).

The reduction of 4-chloro-3-nitrobenzotrifluoride at a temperature of 60-70 ° C and a hydrogen pressure of 15-18 kg · s / cm ² (14.5-17.4 atm) for 10-12 hours in the presence of 0.5 mol. % of the inhibitor - P (OPh) ₃ leads to a sharp suppression of the hydrodechlorination reaction: the formation of 3-aminobenzotrifluoride does not exceed 0.6%. The disadvantage of this method of obtaining is the necessity of carrying out the process under hydrogen pressure (15-18 kg · s / cm ² or 14.5-17.4 atm) and a low yield of 4-chloro-3-aminobenzotrifluoride, which does not exceed 62.4% due to the low conversion of the starting substrate as a result of the inhibition of P (OPh) ₃ catalytically active centers. The reduction of 4-chloro-3-nitrobenzotrifluoride at a temperature of 60-70 ° C and a hydrogen pressure of 15-18 kg · s / cm ² (14.5-17.4 atm), catalyzed by Pd / C, in the presence of 0.1 mol.% Hydrotriphenylsilane HSiPh ₃ for 4-6 hours increases the yield of 4-chloro-3-nitrobenzotrifluoride to 95.3%, however, the contribution of the hydrodechlorination process (3.3% 3-aminobenzotrifluoride) increases. The reduction of 4-chloro-3-nitrobenzotrifluoride under the above conditions in the presence of a mixture of modifiers (P (OPh) ₃ and HSiPh ₃ ) allows to increase the selectivity for chloranilines to 99%. The disadvantage of this method of producing halogenalinins is the need to carry out the process under hydrogen pressure (15-18 kg · s / cm ² or 14.5-17.4 atm), the use of two modifiers at the same time (phosphorus-containing and organosilicon compounds), as well as the multi-stage synthesis of phosphorus-containing and organosilicon inhibitors.

A known method for producing chloranilines by reducing the corresponding nitrochloroarenes in the presence of supported on a coal metal catalysts of the platinum group, modified with organic and inorganic phosphorus-containing compounds: phosphines P (R _a ) _3-n (H) _n ; phosphinic HO-P (H) _m (R _a ) _2-m phosphorous (H ₃ PO ₃ ), hypophosphorous (H ₃ PO ₂ ) acids and their esters (O = P (OH) (H) _m (R _a ) _{2 -m} ; O = P (OH) ₂ R _a ; m = 0, 1, 2; n = 0, 1, 2; 3; R _a = Alk (C ₁ -C ₁₂ ) or Ar (C ₆ -C ₁₆ ) and vanadium compounds (0, II, III, IV, V) or vanadium compounds (V) (VOCI ₃ , VCI ₆ ^- , [VO (SCN) ₄ ] ² -, VOSO ₄ , NH ₄ VO ₃ , VCI ₃ , VOCI, VCI ₂ ) (EP 0842920 B1, 04/07/2004, Bulletin 2004/15) For example, when using a platinum catalyst (Pt / C), modified simultaneously with hypophosphorous acid (H ₃ PO ₂ ) and VO (acac) ₂ (molar ratios P / Pt = 6.3: 1; V / Pt = 2.4: 1) in the reduction of o-nitrochlorobenzene at 100 ° C and a hydrogen pressure of 5 bar, selectivity for o-chlorine aniline for 2 hours was 96.6%. The disadvantage of this method of producing halogenalinins is the need to carry out the process under hydrogen pressure and the use of two modifiers simultaneously: phosphorus and vanadium compounds.

A known method of producing o-chloroaniline by catalytic reduction of o-nitrochlorobenzene in the presence of a Pd / C catalyst in a supercritical fluid - liquefied carbon dioxide (scCO ₂ ) (C. Xi, H. Cheng, J. Hao, S. Cai, F. Zhao. Hydrogenation of o-chloronitrobenzene to o-chloroaniline over Pd / C in supercritical carbon dioxide // J. Molec. Catal. A: Chem. - 2008. - V. 282. - PP. 80-84). As a result of the reduction of o-nitrochlorobenzene with hydrogen in the presence of a Pd / C catalyst under optimal conditions: T = 308 K, CO ₂ pressure _of 8-10 MPa (80-100 atm), pressure of H ₂ 4 MPa (40 atm), selectivity for the target product ( o-chloroaniline) does not exceed 93-94%. The disadvantage of this production method is the harsh process conditions and the need for appropriate autoclave equipment.

A known method for producing o-chloraniline by reducing o-nitrochlorobenzene with hydrogen, catalyzed by colloidal solution of platinum nanoclusters stabilized with polyvinylpyrrolidone (Pt-PVP), in the presence of alkali salts (NaX, KX, LiX), alkaline earth (BaX ₂ ) and transition metals ( CoX ₂ , NiX ₂ , CuX ₂ ). A platinum catalyst colloidal solution was prepared by in situ reduction of H ₂ PtCl _{6 with} hydrogen in the presence of PVP. As a result of the reduction of o-nitrochlorobenzene with hydrogen in the presence of platinum PVP stabilized nanoclusters at a temperature of 303 K and a pressure of Н ₂ 0.1 MPa (1 atm), the selectivity for the target product (o-chloroalanine) at almost complete conversion of the initial substrate is 44.7%. Modification of colloidal solutions of platinum with nickel salts increases the selectivity for o-chloroaniline with almost complete conversion of o-nitrochlorobenzene to 82.9% (X. Yang, H. Liu. Influence of metal ions on hydrogenation of o-chloronitrobenzene over platinum colloidal clusters // Applied Catalysis A : General. 1997. - V. 164. - PP. 197-203). The disadvantage of this method of producing o-chloroaniline is the low selectivity exhibited by colloidal solutions of platinum under mild conditions, which are usually characterized by higher selectivity compared to palladium catalysts when carrying out the process under similar conditions.

The closest known solution to a similar problem in terms of technical nature and the achieved effect is the reduction of o-nitrochlorobenzene with hydrogen, catalyzed by palladium nanoparticles in a colloidal oil-water solution and stabilized with octadecylamine polyoxyethylene ether (OAPE-5) (C. Liang, J. Han, K. Shen, L. Wang, D. Zhao, HS Freeman. Palladium nanoparticle microemulsions: Formation and use in catalytic hydrogenation of o-chloronitrobenzene // Chemical Engineering Journal. - 2010 .-- V. 165. - PP. 709-713). In the reduction of o-nitrochlorobenzene with hydrogen, catalyzed by palladium nanoparticles, at a pressure of 0.6 MPa and a temperature of 50 ° C, the main products are nitrobenzene (44.19%) and aniline (36.48%). The selectivity for o-chloraniline at 84% substrate conversion is 3.42%. The main disadvantage of this method for producing o-chloraniline is the low selectivity of this palladium catalyst and the presence of a large number of products of hydrogenolysis of o-chloraniline.

The objective of the invention is to develop an effective method for the synthesis of o-nitrochlorobenzene in the presence of colloidal solutions of a palladium catalyst, which allows to obtain the target product in high yield. The product yield was calculated by GLC. The numerical value of the yield of o-chloroaniline corresponds to the selectivity of the catalyst for o-chloroaniline.

The task is achieved by the fact that

according to option 1, the method for producing o-chloroaniline consists in the catalytic reduction of o-nitrochlorobenzene (o-HCB) with molecular hydrogen in the presence of modified palladium-containing nanoparticles in a liquid dispersion medium in the temperature range 30-80 ° C (303-353 K) and a hydrogen pressure of 1 h . atm, while palladium bis (acetylacetonate) palladium is used as a precursor of the palladium catalyst; as a modifying additive, elemental phosphorus in the following atomic ratio of components: Pd / P = from 1: 0.3 to 1: 2; and as a liquid dispersion medium, N, N-dimethylformamide (DMF);

according to option 2, the method for producing o-chloroaniline consists in the catalytic reduction of o-nitrochlorobenzene with molecular hydrogen in the presence of modified palladium-containing nanoparticles in a liquid dispersion medium at a temperature of 30 ° C (303 K) and a hydrogen pressure of 1 h. atm, while palladium dichloride is used as a precursor of the palladium catalyst; as a modifying additive, elemental phosphorus in the following atomic ratio of components: Pd / P = from 1: 0.15 to 1: 1; and as a liquid dispersion medium, N, N-dimethylformamide (DMF).

The applicant has not identified sources containing information about technical solutions identical to the present invention, which allows us to conclude that it meets the criterion of "novelty."

A distinctive feature of the present invention is the use of palladium-containing nanoparticles modified with elemental (white) phosphorus formed in the PdX ₂ -PH ₂ system as a catalyst for the reduction of o-nitrochlorobenzene.

The applicant has not found any sources of information containing information about the impact of the claimed distinctive features on the technical result achieved as a result of their implementation. This, according to the applicant, indicates that this technical solution meets the criterion of "inventive step".

The proposed method for producing o-chloroaniline in the presence of a palladium catalyst modified with white phosphorus is as follows.

A solution of white phosphorus in benzene is added to a solution of palladium bis (acetylacetonate) in N, N-dimethylformamide (DMF) placed in a thermostatted duck-type vessel at room temperature in a stream of hydrogen. The reaction mixture was stirred in a hydrogen atmosphere at a temperature of 80 ° C (353 K) and a pressure of 1 gig. atm for 15 minutes Then, the resulting solution of the palladium-containing catalyst is cooled to 30 ° C and the substrate, o-nitrochlorobenzene, is introduced.

Optimal conditions for the reduction of o-nitrochlorobenzene (o-HCB) to o-chloroaniline (o-XA): experiment temperature 30 ° C (303 K) (see tables 1, 3); the ratio modifier / palladium = 1: 0.7 (table. 1).

The method of reduction of o-nitrochlorobenzene in the presence of a nanosized palladium-containing catalyst modified with elemental phosphorus makes it possible to increase the selectivity for o-chloroaniline from 56% for Pd-black (formed during the reduction of Pd (acac) _{2 with} hydrogen in the absence of phosphorus) to 94% at 100% conversion o-nitrochlorobenzene (table. 1, examples 1, 4).

Its advantage compared to the prototype is a higher selectivity for o-chloroaniline under mild process conditions.

Example 1: A solution of Pd (acac) ₂ (5 · 10 ^-5 mol, 0.01522 g) in 10 ml of DMF, placed in a duck-type reaction vessel, heated to 80 ° C and stirred in a hydrogen atmosphere for 10 min. As a result of the hydrogenolysis of Pd (acac) ₂ , Pd black is formed. Next, lower the temperature of the reaction mixture to 30 ° C and introduce the substrate, o-nitrochlorobenzene. Hydrogen reduction is carried out with vigorous stirring, which excludes the reaction in the diffusion region. The process can be monitored by a drop in the hydrogen pressure on the manometer and analyzing the samples by GLC on a chromatograph equipped with a 30 m long capillary column (phase - (phase - 5% diphenyl, 95% dimethylpolysilphenylene siloxane)) and a flame ionization detector (DIP) (table .one).

Example 2: To a solution of Pd (acac) ₂ (5 · 10 ^-5 mol, 0.01522 g) in 9 ml of DMF placed in a duck-type reaction vessel, add 1 ml of a solution of white phosphorus in benzene containing 1.5 · in a stream of hydrogen 10 ^-5 mol of white phosphorus (calculations are given for the atomic form of phosphorus). Stir the reaction mixture for 5 minutes at room temperature. Then close the vessel with a Teflon stopper with a rubber gasket, create a hydrogen pressure of 1 excess atmosphere, heat to 80 ° C and stir the reaction mixture for 10-15 minutes until a dark brown solution forms. Next, lower the temperature of the reaction mixture to 30 ° C and introduce o-nitrochlorobenzene. Hydrogen reduction is carried out with vigorous stirring, which excludes the reaction in the diffusion region. The process can be monitored by the pressure drop on the manometer and analyzing the samples by GLC on a chromatograph equipped with a 30 m long capillary column (phase - (phase - 5% diphenyl, 95% dimethylpolysilphenylene siloxane)) and a flame ionization detector (DIP). The composition of the intermediates and reduction products of o-nitrochlorobenzene was identified by chromatography-mass spectrometry on a GCMS-QP-2010 mass spectrometer (Shimadzu, Japan). Selectivity for o-chloroaniline calculated by the equation:

where C _XA is the concentration of o-chloroaniline; C _{0 (HCB)} and C _(HCB) are the initial and current concentrations of o-nitrochlorobenzene (Table 1).

Examples 3-6: These examples illustrate the effect of the P / Pd ratio on the selectivity of the palladium catalyst for the reduction of o-nitrochlorobenzene to o-chloroaniline and the rotational speed (TOF) of palladium-containing nanoparticles formed in the system based on Pd (acac) ₂ - nP (Table 1 ) The procedure for conducting experiments is similar to example 2.

Examples 7-9: These examples illustrate the effect of the reduction temperature of o-nitrochlorobenzene with hydrogen in the presence of palladium-containing nanoparticles formed in a system based on Pd (acac) ₂ - 0.3 P on o-chloroaniline selectivity and catalytic activity (Table 2). The procedure for conducting experiments is similar to example 2.

Examples 10-12: These examples illustrate the effect of the reduction temperature of o-nitrochlorobenzene in the presence of palladium-containing nanoparticles formed in a system based on Pd (acac) ₂ - 0.7 P on their selectivity for o-chloroaniline and speed (Table 3). The procedure for conducting experiments is similar to example 2.

Examples 13-16 illustrate the influence of the nature of the acidoligand in the PdX ₂ precursor on the selectivity of the PdCl ₂ - 0.3 P catalytic system for o-chloroaniline during the reduction of o-nitrochlorobenzene with hydrogen and the palladium catalyst speed under mild conditions (Table 4). The experimental procedure is as follows.

To a solution of PdCl ₂ (5.10 ^-5 mol, 0.0087 g) in 9 ml of DMF placed in a Schlenk vessel, add 1 ml of a solution of white phosphorus in benzene in an argon atmosphere and mix for 5 min at room temperature. Then transfer the reaction mixture to a temperature-controlled duck-type vessel, close the vessel with a Teflon stopper with a rubber gasket, create a hydrogen pressure of 1 excess atmosphere and mix for 5 minutes at a temperature of 30 ° C. After the formation of the catalyst, introduce the substrate (o-nitrochlorobenzene, 0.5 ml). The recovery is carried out with vigorous stirring, excluding the reaction in the diffusion region. Monitoring the progress of the process is carried out by the pressure drop on the manometer and analyzing the samples by GLC and gas chromatography-mass spectrometry.

The proposed method for producing o-chloroaniline by reduction of o-nitrochlorobenzene with molecular hydrogen in the presence of palladium-containing nanoparticles modified with elemental phosphorus is characterized by a higher selectivity of the catalyst for the target product - o-chloroaniline during the process under mild conditions (at room temperature and a hydrogen pressure of 1 h. atm).

Claims (2)

1. A method of producing o- chloroaniline by catalytic reduction of o- nitrochlorobenzene with molecular hydrogen in the presence of modified palladium-containing nanoparticles in a liquid dispersion medium in the temperature range 30-80 ° C (303-353 K) and a hydrogen pressure of 1 h. atm, characterized in that palladium bis (acetylacetonate) palladium is used as a precursor of the palladium catalyst; as a modifying additive, elemental phosphorus in the following ratio of components: bis (acetylacetonate) palladium / phosphorus = from 1: 0.3 to 1: 2; and as a liquid dispersion medium, N, N-dimethylformamide. 2. A method of producing o- chloroaniline by catalytic reduction of o- nitrochlorobenzene with molecular hydrogen in the presence of modified palladium-containing nanoparticles in a liquid dispersion medium at a temperature of 30 ° C (303 K) and a hydrogen pressure of 1 h. atm, characterized in that palladium dichloride is used as a precursor of the palladium catalyst; as a modifying additive, elemental phosphorus in the following ratio of components: palladium dichloride / phosphorus = from 1: 0.15 to 1: 1; and as a liquid dispersion medium, N, N-dimethylformamide.