Method for synthesizing para aminophenylmethylether by catalytic hydrogenation of paranitroanisole

Abstract

The invention provides a method for synthesizing para aminophenylmethylether by catalytic hydrogenation paranitroanisole. In the method, the paranitroanisole is subjected to catalytic reduction reaction with hydrogen to generate the para aminophenylmethylether in the presence of a load type palladium catalyst in a supercritical carbon dioxide reaction medium under mild conditions. Compared with the traditional processes, such as a nitrobenzene method, a sodium sulfide or ferrum reduction method, a method for synthesizing the para aminophenylmethylether by reducing the paranitroanisole by activated carbon load type palladium catalyst hydrazine hydrate, and the like, the invention has the advantages of mild reaction condition, fast reaction, clean reaction process and easy product separation, achieving the product yield more than 99 percent, and the like; in addition, in the invention, reaction temperature is reduced from 75-125 DEG C in the nitrobenzene method to 50-80 DEG C, and reaction time is reduced from 130 minutes in the method for synthesizing the para aminophenylmethylether by reducing the paranitroanisole by the activated carbon load type palladium catalyst hydrazine hydrate to 10-30 minutes without adding any organic solvent and additive or generating any side products in the reaction process.

Description

technical field [0001] The present invention relates to a new method for synthesizing p-aminoanisole by hydrogenation of p-nitroanisole, in particular to the synthesis of p-aminoanisole by catalyzing the hydrogenation of p-nitroanisole with a supported palladium catalyst in a supercritical carbon dioxide reaction medium Methods. Background technique [0002] P-aminoanisole (also known as p-methoxyaniline or p-anisidine) prepared by catalytic hydrogenation of p-nitroanisole is a colorless crystal and is a fine chemical widely used in medicine and photographic materials , agricultural chemicals, polymers, dyes and other fields. Researching and preparing high-yield p-aminoanisole has important application value and broad application prospect. As a dye intermediate, it can be used for ice dyeing coupling components 11, 13, 35, C.I. Disperse Orange 15, Blue 64, C.I. Vat Red 29, C.I. Reactive Violet 8, 46, C.I. Basic Yellow 13, 20, 28 and other dyes It can also be used for the ...

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Problems solved by technology

Reduction methods include: (a) sodium sulfide reduction method: the product of this reduction method contains sodium hydroxide and sodium thiosulfate, which are difficult to separate and have a low utilization rate of sodium sulfide; (P-aminoanisole process technology research, Henan Chemical Industry, 1992 (2))(b) Iron reduction method: The raw materials of this method are easy to get and cheap, and have low requirements on equipment, but the wastes discharged by this reduction method are difficult to deal with, causing great environmental pollution, and do not conform to the development route of "green chemistry"; (Using p-nitrochlorobenzene as raw material to synthesize p-aminoanisole, Liaoning Chemical Industry, 2002, 31 (6)) (c) catalytic hydrogenation method: A: using ammonia synthesis gas as hydrogen source to prepare p-aminobenzene by catalytic hydrogenation Methyl ether, this method uses ammonia synthesis gas instead of pure hydrogen catalytic hydrogenation, the process flow is short, the investment is small, the cost is low, the product quality and yield are basically the same as the pure hydrogen process, and it has significant economic benefits and technical competitiveness, but the reaction temperature Higher, longer time, low efficiency; (Synthesis of p-aminoanisole, Fine and Specialty Chemicals, 2001 (13)) B: Preparation of p-aminoanisole, tetrahydrofuran by selective catalytic hydrogenation of skeleton ruthenium-nickel carbon (THF) is solvent, although this method temperature is suitable, and pressure requirement is lower, and target product selectivity is very high, but THF belongs to organic solvent, has certain harm to environment; Anisole, Fine Chemical Industry, 2006, 23(5)) C: Synthesis of p-aminoanisole by liquid-phase catalyst hydrogenation method, although it overcomes the Achilles heel of serious pollution in the alkali sulfide reduction process, and the product yield is high and the quality is good , but the temperature requirement is higher; (liquid-phase catalyst hydrogenation method to synthesize p-aminoanisole, China Chlor-Alkali, 2003 (5)) D: Fe-Al / C catalyzed hydrazine hydrate reduction p-nitroanisole to prepare p-aminobenzene Methyl ether has the advantages of small investment, high reduction yield, no waste residue, etc. It is mainly suitable for the production of small batches and short-circuit aromatic amine compounds; (Fe-Al / C catalyzed synthesis of p-aminoanisole, dyes and dyeing, 2008, 45(3)) E: Pd / C catalyzes hydrazine hydrate to synthesize p-aminoanisole, the reaction medium is isopropanol, and the reaction time is long, which does not meet the requirements of green chemical technology; (Pd / C catalyzes the synthesis of p-aminoanisole Anisole, Journal of Central South University of Forestry and Technology, 2008 (3)) F: three-phase catalytic method to prepare p-aminoanisole, although this method is convenient for product purification and separation, and is conducive to catalyst recycling, but the operation process is more complicated

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