|4-Aminophenol Chemical Properties|
|4-Aminophenol Usage And Synthesis|
|Aminophenol||Aminophenol, also known hydroxy-aniline, amino hydroxy benzene, have three kind of isomers, namely o-aminophenol, m-aminophenol, and p-aminophenol (4-amino-phenol). In1874, Baeyer et al had first successfully obtained aminophenol. Owing to the difference of the relative positions of hydroxy group and amino group, the three kinds of isomers also have different physical chemical properties. This product exhibits weak alkalinity and weak acidicity and a strong reduction capability. Owing to the simultaneous existence of both amino group and phenol group, it has the property of both of them. It is very unstable upon air and sunlight, and is especially sensitive to oxygen to oxygen in the humid air, and can have its color further deepened due to that the ortho-position and para-position are more susceptible to oxidation. It mainly generates amino phenoxazine derivatives after oxidation. |
The main function of aminophenol is being used as a photographic developer and dye intermediates. It can be used for production of acid dyes, direct dyes, sulfur dyes, azo dyes, fur dyes and mordant dyes. The m-Aminophenol and para-aminophenol can be used as the raw materials of pharmaceutical purpose as the raw materials of herbicides, fungicides and insecticides and thermal dye material. O-aminophenol can also be used as the inhibitor of alkaline metal corrosion, dyes, the anti-aging agents of rubber anti-aging, antioxidants, stabilizers, oil additives, and catalyst of organic reaction, chemical reagents (m-aminophenol can be used as the analysis agent of gold and silver assay) as well as the organic synthesis intermediates.
The above information is edited by the Chemicalbook of Dai Xiongfeng.
|p-Aminophenol||p-Aminophenol is a kind of commonly used intermediate of refined chemical industrial product presented in China. In the dye industry, it is applied to the synthesis of weakly acidic yellow 6G, weak acid yellow 5G, vulcanization blue 3R, Sulphur Blue CV, vulcanization Brilliant Green GB, sulfur red brown B3R, C.I.Sulphur Black 6(53295) and so on. In the pharmaceutical industry, it is used for the synthesis of paracetamol, clofibrate and so on. It is also used in the preparation of the developer, antioxidants and oil additives and other products. |
P-aminophenol, also known as 4-aminophenol, p-hydroxy aniline, 4-amino-1-hydroxybenzene, and 4-hydroxyaniline, have two patterns: α-type which is precipitated from water, ethanol and ethyl acetate and is white to pale yellow orthorhombic lamellae; double-cone type crystal which is precipitated from acetone. It has a strong reduction capability and is susceptible to air oxidation. It will exhibit gray brown color upon exposure to the light or air, especially in the wet air. It has a melting point of 189.6~190.2 ℃ and can subject to sublimation without decomposition at 110 ℃ (1.467 × 103Pa). It has a boiling point of being 284 (decomposition). It is slightly soluble in benzene, chloroform and petroleum ether, and can be dissolved in ethanol, ethyl ether and water. Its solubility in water: 1.1 upon 0.0 ℃, 3.01 upon 59.0 ℃, 6.44 upon 77.0 ℃, 10.09 upon 86.7 ℃, 19.53 upon 96.6 ℃, and 33.42 upon 102.0 ℃. It quickly becomes brown after being dissolved in alkaline solution.
Upon reaction with inorganic acids, it can generate water-soluble salts. When coming across ferric chloride or sodium hypochlorite, its aqueous solution will exhibit purple color. The oxidation of this product in diethyl ether with silver oxide generates quinone imine while oxidation with lead dioxide or silver nitrate generates p-benzoquinone. Reaction of this product with excess amount of chlorine generates multi-chloranil. Sulfonated with fuming sulfuric acid can generate 4-amino-phenol-sulfonic acid. Under mild conditions, using acetic anhydride for acylation can produce N-acetyl phenol. The reaction with sodium nitrite can cause diazotization. Rat-oral-LD50:1270mg/kg.
Aminophenol is mainly used in the manufacture of antipyretic analgesic paracetamol as well as manufacturing of various kinds of dyes such as sulfur vulcanization Blue FBL, Sulphur Blue CV, vulcanization Brilliant Green GB, sulfur red brown B3R, black sulfide reduction CLG, vulcanization blue 3R, fur dye brown fur P and so on. It can also used for synthesis of the stabilizer of polymer materials such as 4-hydroxy-diphenylamine, N, N'-diphenyl-1, 4-phenylenediamine, and N-(4-hydroxyphenyl)-2-naphthylamine. Moreover, it can applied to the synthesis of photographic developer N-methyl-p-amino phenol.
|Preparation||There are various ways for production it including iron reduction, nitrification phenol method, and coupling reduction method. 1. Iron reduction; it can be produced by the reduction of the p-nitro phenol. Fixed material consumption: 1388 kg/t of dinitrophenol (industrial), 1778 kg/t of iron powder, as well as 200 kg/t of 30% hydrochloric acid. 2. Phenol nitrosation method; it can be produced by phenol which goes through nitrosation, reduction and acid precipitation. 3. The coupling reduction; it can be made using aniline which goes through diazotization, coupling, and reduction through iron powder. 4. The catalytic hydrogenation of nitrobenzene; it is generally using platinum, palladium, or both of them as the catalyst for the hydrogenation and reduction of nitrobenzene into phenylhydroxylamine in 10-20% sulfuric acid aqueous solution; then it is further converted to p-aminophenol with the yield being 70-80%. Supplement of surface active agent in the reaction system has certain effect on increasing the yield. 5. The electrolytic reduction of nitrobenzene; Mitsui Toatsu Fine Chemicals companies has applied electrolytic reduction of nitrobenzene in sulfuric acid solution; it further undergoes transposition via phenylhydroxylamine into p-amino phenol; In June 1977, the company built a plant with annual production of 1000 tons in Omuta.|
p-nitro chlorobenzene can subject to hydrolysis in sodium hydroxide to sodium p-nitrophenol, which can be reduced by iron powder to become 4-amino-phenol reduction after acidification.
Prepare a sodium hydroxide solution of a concentration of 137 to 140 g/L in the kettle and then add it to the hydrolysis reactor; add into the molten nitro chlorobenzene and heat up to 152 ℃ with the pressure in the autoclave being 0.4~0.42MPa (gauge pressure); stop heating and the heat released from the hydrolysis reaction can increase the temperature and pressure temperature to 165 ℃, 0.6MPa (gauge pressure) respectively for reaction of 3 hours, take the sample for analysis. After the oil distillate content is lower than 0.5%, the hydrolysis reaction has reached to the end point. Cool to 120 ℃, add water and 98% concentrated sulfuric acid to the first crystallization vessel, and then pressed into the hydrolyzate and cool to 50~55 ℃; further add concentrated sulfuric acid to ensure the Congo red test paper exhibiting purple color and continue for cooling to 30 ℃; Perform centrifugal filtration for dehydration.
Add the last round of mother liquor which has been subject to p-amino-phenol purification and filtration into the reduction kettle, heat to 90 ℃ and add iron powder and 30% hydrochloric acid; Alternately add iron powder and p-nitro-phenol under boiling state with the feeding process depending on the reaction conditions for example upon overflow pan, we should fill the cold purified and filtrated mother liquor. Upon boiling and reduction to the end (add the droplet of the reaction liquid on the white filter paper should yield no color for the infiltration ring), supply a certain amount of heat refined mother liquor and add magnesium oxide until to the reaction mixture without iron ions. Stand static for 30 minutes; discharge the supernatant; the iron mud in the under layer was subject to crystallization under 98 ℃; Filter the mother liquor and perform pulping, filter again with the filtrate beaten into the second crystallizer.
In the second crystallizer, lower the temperature within 4 hours to 60~65 ℃ and transfer into the third crystallizer within 4 hours for further reducing the temperature to 25 ℃; Maintain for 30 minutes and perform centrifugation again.
Prepare a sodium bisulfite solution with the SO2 content being 4% to 5% in the refining kettle of 4% to 5%, add the crystallized and filtered cake and stir for 1.5 hours, centrifuge and filtrate with the filter cake being subject to vacuum air drying to generate the finished product of p-aminophenol. The refined mother liquor can be recycled to be used in the next round of reduction reaction.
|Toxicity and protection||It is toxic. The p-amino phenol has double toxicity of both aniline and phenol. Absorption of it through the skin can cause dermatitis as well as cause methemoglobinemia and asthma. The contact of its hydrochloride with the skin can cause severe itching or eczema. Subcutaneous injection-cats-half lethal dose-LD50: 37mg/kg.
|Chemical Properties||It is white or light yellow-brown crystals. It is slightly soluble in water and ethanol but insoluble in benzene and chloroform. It will quickly exhibit brown color after being dissolved in alkaline solution.
|Uses||It can be used for the production of Sulphur Blue FBG and weak acid dyes such as yellow 5G. It can be used for the manufacturing of drugs such as paracetamol and clofibrate as well as being used as developer and antioxidants, etc. |
It can be used as the reagents for the analysis.
The product is the intermediate of pharmaceutical intermediates, dyes and other fine chemicals. It can be used for the production of paracetamol, azo dyes, sulfur dyes, acid dyes, fur dye and developer, antioxidants as well as oil additive.
It is widely used in the synthesis of pharmaceuticals, dyes and other organic products and is mainly for the synthesis of paracetamol, clofibrate ketone, vitamin B1 and compound nicotinamide.
It can be used as the raw material of medicine and dyes, antioxidants and the developer.
It can be used for gold assay as well as determination of copper, iron, magnesium, vanadium, nitrite and cyanate, antioxidants.
|Toxicity grading||highly toxic
|Acute toxicity||oral-rat LD50: 375 mg/kg; intraperitoneal-mouse LDL0: 100 mg/kg.
|Skin irritation data||Rabbit 12.5 mg/24 hours Mild; Eyes-rabbit mild 100 mg.
|Flammable and hazardous characteristics||it is combustible upon fire and can be subject to thermal decomposition; burning of it release toxic fumes of nitrogen oxide.
|Storage characteristics||Treasury: ventilation, low-temperature and drying; oxidants, store it separately from food additives.
|Chemical Properties||Off white granular powder|
|Usage||Nephrotoxic metabolite of Acetaminophen (A161220) and Phenacetin (P294580).|
|Extinguishing agents||carbon dioxide, foam, powder, sand, water spray.
|Professional standard||STEL 1 mg/m3
|General Description||White or reddish-yellow crystals or light brown powder. Turns violet when exposed to light.|
|Air & Water Reactions||Insoluble in water.|
|Reactivity Profile||Heat (decomposition forming HCN, nitrous vapors, CO); water (CO2); reacts violently with acids, bases, alcohols and amines causing fire and explosion hazards [Handling Chemicals Safely 1980 p. 647].|
|Fire Hazard||Flash point data are not available for 4-Aminophenol. 4-Aminophenol is probably combustible.|
|4-Aminophenol Preparation Products And Raw materials|