CN101121667A - Method for preparing m-nitroaniline by selective reduction of m-dinitrobenzene - Google Patents

Abstract

The invention relates to a preparation method for the m-nitroaniline by selectively deoxidize the m-dinitrobenzene nitrobenzene; the m-dinitrobenzene is used as the raw material and the iron is used as the reductant; with the carbon dioxide / water - ethanol system, the temperature of 40 to 130 Celsius system, and the pressure of 1.6 to 10.0 MPa, the reaction can be done to make the m-nitroaniline; the conversion rate of the reaction is more than 98 percent; the selectivity of the m-nitroaniline is more than 99 percent. In the method of the invention, the carbon dioxide, water, ethanol and the left iron in the reaction can be reused; the invention avoids the problem of the wastewater discharge. At the same time, the invention has the advantages of the high collection rate of the reaction and the good selectivity of the product.

Description

The method of preparing m-nitroaniline by m-dinitrobenzene selectivity reduction

Technical field

The present invention relates to the method for field of fine chemical preparing m-nitroaniline by m-dinitrobenzene selectivity reduction.

Background technology

Nitro aromatic amine is widely used in fields such as medicine, agricultural chemicals, dyestuff as an important organic synthesis intermediate of big class and a raw material.Prepare nitro aromatic amine by the partial reduction of dinitrobenzene aromatic compound and have important industrial significance.At present, be the important method of preparation nitro aromatic amine by fragrant dinitro compound selective reduction, but method is few.Being used for industrialized dinitro compound process for selective reduction mainly contains: and the sodium sulphite reduction [Xu Kexun. fine chemical material and intermediate handbook, Beijing: Chemical Industry Press, 2001,5-531-532], tin protochloride reduction [Wen-Kang Xing and Yoshiro Ogata et al.Effectof Meta and Para Substituents on the Stannous Chloride Reduction of Nitrobenzenesin Aqueous Ethanol.J.Org.Chem., 1983,48,2515-2520] iron powder reducing [(1), Wulfman DS, Cooper C F.Monoreduction of dinitroarenes with iron/acetic acid.Synthesis, 1978, (12): 924; (2) DE67018] finish this process.

The sodium sulfide reducing method, reaction relatively relaxes, and the Sulfothiorine that generates in this method reaction is water-soluble, can directly separate with water-fast arylamine, and the product aftertreatment is fairly simple.But production cost is higher, and yield is generally low than iron powder reducing method, and a large amount of sulphur-bearing waste solution that produces.[Gao Lei opens modest Para-Anisidine Study on Process [J]. Henan chemical industry, 1992, (2): 25-28].

Metal catalytic hydrogenation method [(1) US5105012; (2) Veena L.Khilnani and S.B.Chandalia SelectiveHydrogenation.ll.m-Dinitrobenzene To m-Nitroaniliine Using Palladium on CarbonAs Catalyst.Organic Process Research ﹠amp; Development, 2001,5,263-266].Shortening subject matter is to use hydrogen, because hydrogen is inflammable gas, danger is very big aborning, and store, the transportation difficulty, be subjected to the restriction of high quality hydrogen source.In addition, also has catalytic hydrogen transfer [Parasuraman Selyam et al.Heterogeneouscatalytic transfer hydrogenation of aromatic nitro and carbonyl compounds overcobalt (ll) substituted hexagonal mesoporous aluminophosphate molecular sieves.Tetrahedron Letters, 2002,43,8527-8529], hydrazine hydrate catalytic reduction method [Nagaraj R.Ayyangar, Uttam R et al.Partly reduction of dinitrobenzenes to nitroanilineswith hydrazine hydrate.Bulletin of the Chemical Society ofJapan, 1983,56 (10), 3159-64], sodium borohydride reduction [Behzad Zeynizadeh and Davood Setamdideh.NaBH ₄/ Charcoal:A New Synthetic Method for Mild and Convenient Reduction ofNitroarenes.Synthetic Commun., 2006,36,2699-2704] and selenium to make catalyzer with the report of carbon monoxide aqueous phase to dinitrobenzene arylamine selective reduction [CN1403437].

Traditional iron powder reducing method applied range, many amines all are to be got with iron powder reducing by its corresponding nitro-compound.Reaction needs to carry out under strong acidic condition, must add the alkali neutralizing acid after the reaction to separate the arylamine of alkalescence, thereby produce corresponding salt, contain amine waste water and iron mud in a large number, the treatment cost height [Zhang Xiucheng, Li Shenhui. recycle to extinction technology administers 2, the reducing waste water [J] during the 4-xylidine is produced. chemical industry environmental protection, 1999,19 (2): 93-95].But, the iron powder reducing method have technology simple, low for equipment requirements, applied widely, produce more easy to control, advantage such as side reaction is few, product yield is high, selectivity is high and quality is good.Simultaneously, but the iron mud coproduction iron oxide pigment that the iron powder method produces, and German Bayer company and U.S. Mobay chemical company still keep a part of iron powder method and produce aniline, by-product iron oxide pigment " M ".So in many arylamine production processes, still adopt iron powder reducing technology.Known in the process of iron powder reducing nitro-compound, solution must have enough acidity could promote that reaction is feasible.In the pure water medium, iron powder almost can not reduce to nitro-compound, (the C.Boix such as professor Poliakoff of Britain Nottingham university, M.Poliakoff.J.Chem.Soc., Perkin Trans 1,1999 1487-1490) uses the method (employing near-critical water) that improves temperature of reaction to realize the iron powder reducing of nitro-compound, (pressure 100bar) reaction is 2.5 hours under 250 ℃, and nitrobenzene reduction only has 10% aniline yield rate; Under same temperature, use zinc powder to make nitrobenzene reduction can obtain 90% aniline yield rate.This shows that the method that only depends on the reinforcement reaction conditions is also not really desirable.(Lei Wang such as Wang Lei, Pinhua Li et al.Synthesis, 13,2001-2004,2003) once reported the applying nano iron powder is realized nitro-compound under near-critical water (210 ℃ of temperature) condition reduction, reacted 2 hours, nitrobenzene reduction can be realized 95% arylamine yield, but the raw materials cost height of nanometer iron powder.The reaction process that professor Poliakoff and Wang Lei etc. reported does not relate to all that selective reduction prepares N-methyl-p-nitroaniline for the dinitrobenzene arylamine.

Summary of the invention

The present invention seeks at traditional iron powder-existing pollution problem of strong acid aqueous solution reduction system and the wayward problem of selectivity, provide a kind of iron powder reducing Meta-dinitrobenzene to prepare the novel method of m-nitraniline, this method need not to use traditional strong acid, the advantage that had both had the iron powder reducing method has been avoided the pollution problem of brine waste to environment again.

The technical solution adopted in the present invention is: the method for preparing m-nitraniline with Meta-dinitrobenzene by the iron powder selective reduction, be in autoclave, adding mol ratio is 1: the Meta-dinitrobenzene of 1.0-8.0 and iron powder, add entry and ethanol again, making required water of 1g Meta-dinitrobenzene and ethanol mixed volume is 10-30ml, water and alcoholic acid volume ratio are 124-1: 1-24, feeding carbonic acid gas then makes its pressure reach 1.6-10.0MPa, temperature of reaction is 40-130 ℃, stir reaction down 1-16 hour, the cooling cooling, emit carbonic acid gas, with product in the ethyl acetate extraction still, analyze m-nitraniline and other component with TLC, use gas chromatographic analysis all components and content again.

Between above-mentioned Meta-dinitrobenzene reduction preparation in the method for nitro aromatic amine, preferred reaction conditions is that the mol ratio of Meta-dinitrobenzene and reductive agent is 1: 2 to 1: 8, required water of 1g Meta-dinitrobenzene and ethanol mixed volume are 15-30ml, water and ethanol volume ratio are 50-1: 1-10, pressure carbon dioxide is 1.6-8.0M Pa in the reaction, temperature of reaction is 40-100 ℃, and the reaction times is 3-6 hour.

The present invention proposes to realize the iron powder selective reduction of Meta-dinitrobenzene under carbonic acid gas/water-ethanol system.Promoting reaction to carry out required acidity provides by being dissolved in the acid that carbonic acid gas and water and pure original position form in the solvent.

Known CO soluble in water ₂Form carbonic acid (H ₂CO ₃) acidity of system is increased, and the solubility with pressure in water increases and increases; CO ₂Acid obviously increase in the-aqueous systems, the pH value of solution is very easy to be dropped near 3, suitable with the acidity of 1M acetic acid water solution; And the acidity of the acid that alcohol and carbonic acid gas original position form even be better than carbonic acid, CO in the methanol-water system ₂Molar weight is 5.6%, CO ₂The pH value of-water-methanol system reaches 4.22, only a small amount of CO under the alcohol-water system ₂Can improve acidity greatly.Dissolved CO ₂The acidity that acid provided that forms with water and pure original position can promote reaction to carry out, so carry out the iron powder reducing of dinitro compound in carbonic acid gas/water-ethanol system, can realize single nitroreduction by the control reaction parameter; And reaction is got rid of CO after finishing ₂, reaction mixture does not contain the salt that is formed by strong acid and resultant arylamine, thereby need not to add alkali during separated product amine; Separate the back aqueous phase and do not contain salt, water and ethanol can recycle directly in secondary response down, no longer include the emission problem of brine waste in the reaction process, the pollution problem of avoiding to environment.

Major advantage and effect that Meta-dinitrobenzene selective reduction of the present invention prepares the nitro aromatic amine method are: reaction system promptly has can realize nitro aromatic amine between Meta-dinitrobenzene preparation accordingly, selectivity＞99%, reduction reaction yield height, transformation efficiency＞98% reductive agent low cost and other advantages, carbonic acid gas, water, ethanol and unreacted iron powder can reuse, the pollution problem of having avoided discharge of wastewater that environment is brought.

Embodiment

Embodiment 1

In the 75mL stainless steel autoclave, add 0.42g Meta-dinitrobenzene, 0.42g iron powder, 11.1mL water, 1.4mL ethanol, magneton screws autoclave, uses CO ₂Displaced air 5 times, put into 80 ℃ of oil baths after charging into the 2.8MPa carbonic acid gas, start stirring, react 6 hours stopped reaction, the cooling cooling, emit carbonic acid gas, with product in the ethyl acetate extraction still, TLC assay products component, with each component concentration of gas chromatographic analysis, the result shows, Meta-dinitrobenzene transformation efficiency＞99%, m-nitraniline selectivity＞99%.

Embodiment 2-10, the concrete operations condition is seen embodiment 1

Embodiment	Meta-dinitrobenzene/g	Iron powder amount/g	Water/ml	Ethanol/ml	CO 2Pressure/M Pa	Temperature/℃	Reaction times/h	Selectivity (m-nitraniline)/%	Yield (m-nitraniline)/%
										2 3 4 5 6 7 8 9 10	0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42 0.42	0.42 0.42 0.42 0.42 0.14 1.12 0.14 0.42 0.14	11.1 11.1 11.1 11.1 4.2 12 0.5 3.6 12.4	1.4 1.4 1.4 1.4 8.3 0.5 12 0.6 0.1	3.4 3.2 1.6 3.4 2.8 8.5 9.8 3.2 3.2	80 60 80 60 40 130 100 60 60	5 3 6 1 16 2 6 3 3	98.0 99.8 99.7 98.0 100 98.9 99.2 100 100	97.7 99.8 92.0 2.9 2.2 9.0 1.5 90.7 7.3

Claims (2)

1. A method for preparing m-nitroaniline through iron powder selective reduction with m-dinitrobenzene, characterized in that the method is in an autoclave, adding m-dinitrobenzene with a molar ratio of 1: 1.0-8.0 and iron powder, then add water and ethanol, so that the mixed volume of water and ethanol required for 1g m-dinitrobenzene is 10-30ml, and the volume ratio of water and ethanol is 124-1:1-24, and then carbon dioxide is introduced to make it The pressure reaches 1.6-10.0MPa, the reaction temperature is 40-130°C, and the reaction is carried out for 1-16 hours under stirring, the temperature is lowered and cooled, carbon dioxide is released, the product in the kettle is extracted with ethyl acetate, and m-nitroaniline and other components are analyzed by TLC. All components and contents were then analyzed by gas chromatography. 2. according to the method for the selective reduction of m-dinitrobenzene described in claim 1 to prepare m-nitroaniline, it is characterized in that the preferred reaction condition of the method is: the mol ratio of m-dinitrobenzene and reducing agent is 1: 2 To 1:8, 1g m-dinitrobenzene required water and ethanol mixing volume is 15-30ml, water and ethanol volume ratio is 50-1:1-10, carbon dioxide pressure in the reaction is 1.6-8.0MPa, reaction temperature is 40-100°C, the reaction time is 3-6 hours.