- Preparation method of 2-amino-5-nitrophenol
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The invention provides a preparation method of 2-amino-5-nitrophenol, which comprises the following steps: (1) carrying out cyclization reaction on 2-aminophenol and thionyl chloride in a solvent and an acid-binding agent to obtain a cyclization compound; (2) carrying out nitration reaction on the generated cyclization compound and a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid to obtain a nitride; and (3) finally hydrolyzing the generated nitride with sodium hydroxide to obtain the 2-amino-5-nitrophenol. According to the method provided by the invention, a large amount of ammonia gas generated by using phosgene, expensive acetic anhydride or a urea method can be avoided; and the preparation method provided by the invention is simple in operation, good in product appearance, good in quality, high in yield, easy in process condition control, and easy for industrial automation and large-scale production.
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Page/Page column 5-8
(2021/05/12)
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- Method for synthesizing benzoxazole compound by using nitration by-products of aromatic hydrocarbon and application of benzoxazole compound
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The invention discloses a method for synthesizing a benzoxazole compound by using nitration by-products of aromatic hydrocarbon and application of the benzoxazole compound. The method comprises the main process: performing step-by-step crystallization on nitration products of a 2,4-dinitrochlorobenzene production enterprise so as to obtain 2,4-dinitrochlorobenzene, 2,6-dinitrochlorobenzene (I) anda small amount of residues, adopting the obtained 2,6-dinitrochlorobenzene (I) as the main starting material, and performing hydrolysis, selective catalytic hydrogenation reduction, cyclization, halogenation, carbon-carbon coupling and other processes so as to synthesize the benzoxazole compound, wherein the obtained compound can be used as a main raw material to synthesize a series of chemical intermediates with important application, and the chemical intermediates include o-aminophenol, 2-amino-4-nitrophenol, 2-amino-5-nitrophenol and hydrochloride of o-aminophenol, 2-amino-4-nitrophenol, 2-amino-5-nitrophenol. Through the method, the industrial by-products are converted into high value-added aromatic aminophenol products, industrial hazardous waste of the 2,4-dinitrochlorobenzene production enterprise is reduced, the scope of products of the enterprise is widened, and the economic benefits of enterprise are increased.
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- Method for producing 5-nitro-2aminophenol
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The invention relates to a method for producing 5-nitro-2aminophenol.Ortho-aminophenol, urea and sulfuric acid have a cyclization reaction in a three-mouth round-bottom flask to obtain a benzoxazolone compound, then the obtained benzoxazolone compound, acidic imidazolium ionic liquid and nitric acid are placed in the round-bottom flask for a nitration reaction to obtain 6-nitryl benzoxazolone, and finally 5-nitro-2aminophenol is obtained through hydrolysis of sodium hydroxide.According to the method, in the step that the obtained benzoxazolone compound, acidic imidazolium liquid and nitric acid are placed in the round-bottom flask for the nitration reaction to obtain 6-nitryl benzoxazolone, the acidic imidazolium ionic liquid takes the place of 1,2-dichloroethane solvent in the prior art, the safety coefficient is remarkably improved, cost is low, and environmental friendliness is achieved.
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Paragraph 0025
(2016/10/09)
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- A convenient method to aniline compounds using microwave-assisted transfer hydrogenation
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The reduction of mononitro and dinitro aromatic compounds to their aniline analogues using microwave-assisted transfer hydrogenation has been demonstrated. The optimised conditions used, with some examples, are described herein. Georg Thieme Verlag Stuttgart.
- Chapman, Nicholas,Conway, Benjamin,O'Grady, Fiona,Wall, Michael D.
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p. 1043 - 1046
(2007/10/03)
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- Fused thiophene compounds and medicinal use thereof
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A condensed thiophene compound of the formula (I) wherein each symbol is as defined in the specification, a pharmaceutically acceptable salt thereof and hydrates thereof. The compound of the formula (I) of the present invention is useful as a novel antipsychotic agent which is effective for both positive symptoms and negative symptoms of schizophrenia, which is associated with less side effects such as extrapyramidal motor disorder and the like and which is less associated with serious side effects such as agranulocytosis and the like. In addition, this compound is also useful as a therapeutic agent of Alzheimer's disease and manic-depressive illness.
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- The vicarious nucleophilic substitution of hydrogen and related reactions in nitrobenzoxazoles
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5- and 6-nitrobenzoxazoles 3 and 4 react with nucleophiles exclusively at C-2, giving ring opening products. If position 2- is blocked with phenyl substituent the reaction takes place in the carbocyclic ring affording the VNS products. 2-Methylthio-5-nitrobenzoxazole 7 and its 6-nitro isomer 8 give products which result from addition of a nucleophile to the carbocyclic ring (VNS) as well as to the heterocyclic ring (S(N)Ar and ring cleavage). 2-Methylthiobenzoxazoles can be readily converted to the corresponding benzoxazolones via oxidative hydrolysis.
- Makosza, Mieczyslaw,Stalewski, Jacek
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p. 7277 - 7286
(2007/10/02)
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- DECOMPOSITION OF 7-NITRO-2,4-DIHYDROXY-1,4-BENZOXAZIN-3-ONE IN AQUEOUS SOLUTIONS
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Kinetic and product studies indicate that the title compound decomposes in aqueous solutions to give 5-nitro-2-aminophenol with the intermediacy of N-(2-hydroxy-4-nitrophenyl)carbamic acid.
- Bravo, Hector R.,Niemeyer, Hermann M.
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p. 1687 - 1691
(2007/10/02)
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- Process for the preparation of nitroanilines
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The invention relates to a process for the preparation of nitroanilines, which consists in reacting an amine RNH2, or ammonia, with 3,4-methylenedioxynitriobenzene to give the products of the formula: STR1 in which R denotes hydrogen, alkyl, monohydroxyalkyl or polyhydroxyalkyl, alkoxyalkyl or aminoalkyl of the formula: STR2 in which R1 and R2, which are identical or different, denote hydrogen, alkyl or monohydroxyalkyl or polyhydroxyalkyl and n denotes an integer from 2 to 4, or of the formula: STR3 in which A denotes OCH2 or STR4 and R1 denotes --CH2 CH2 OH or STR5 or their salts. The invention also relates to the dyeing compositions for keratin fibres, and in particular for hair, which contain a dyestuff of the above formula (I) in which R denotes alkyl, polyhydroxyalkyl, alkoxyalkyl or aminoalkyl of the abovementioned formula, and to the dyestuffs of the formula (I) in which R denotes alkoxyalkyl or aminoalkyl of the above formula, and of the formula (IIB), which are novel.
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- 2-t-BUTYL-5-CHLORO-6-NITROBENZOXAZOLE: A PRACTICAL SYNTHETIC INTERMEDIATE FOR 4-ARYLOXY-5-NITRO-2-AMINOPHENOLS
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On the examination of the anomalous reactivities of several nitrobenzoxazole derivatives 2a-e toward acids and bases it has been found that 2-t-butyl-5-chloro-6-nitrobenzoxazole 2c serves as one of the most convenient and practical synthetic intermediates for 4-aryloxy-5-nitro-2-aminophenols.
- Ono, Mitsunori,Yamakawa, Katsuyoshi,Kobayashi, Hidetoshi,Itoh, Isamu
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p. 881 - 884
(2007/10/02)
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- 4-Hydroxyquinolone-(2)-azomethine copper complex pigments
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A compound having the formula STR1 wherein A denotes an optionally substituted aromatic, isocyclic or heterocyclic residue; R is H, an alkyl residue having from 1 to 6 carbon atoms, an aryl residue having from 6 to 10 carbon atoms or an aralkyl residue having from 7 to 10 carbon atoms; Q is H or a methyl group; X and Y are the same or different and each is a non-water solubilizing group, or X and Y together form a fused aromatic ring system; and R1 and R2 are the same or different and each is H or an alkyl radical having from 1 to 22 carbon atoms, and R3 is hydrogen, an alkyl radical having from 1 to 22 carbon atoms or an aryl radical having from 6 to 10 carbon atoms, the alkyl radicals in R1, R2 and R3 being unsubstituted and uninterrupted or being substituted by an OH, NH2 or CN group and/or being interrupted by an ethylenic group or an oxygen, sulphur or nitrogen bridge, or two or all three of R1, R2 and R3 may form, together with the nitrogen atom to which they are attached, a heterocyclic residue, is useful for pigmenting high molecular weight organic material such as a natural or synthetic polymer or copolymer, or a coating composition for application to the surface of an article, or a printing liquid medium to yield shades from greenish yellow to red brown, exhibiting good fastness properties.
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- Unsymmetrical 1:2-chromium complexes containing an azo compound and an azomethine compound
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Compounds of the formula: STR1 WHICH ARE EMINENTLY SUITABLE FOR DYEING NATURAL AND SYNTHETIC POLYAMIDES AND FOR COLORING SURFACE COATINGS. Dyeings on textile material are distinguished by very good lightfastness and very good fastness to wet treatments, for example fastness to water, perspiration, sea water and washing.
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