Background and overview[1]
The molecular formula of 4-aminobenzoic acid is C7H7NO2. Molecular weight 137.14. Monoclinic prism crystals are obtained from dilute ethanol and turn yellow when exposed to light in the air. The melting point is 188~189℃, the relative density is 1.37425, and the UVλmax220, 289nm in ethanol. The solubility in water is 1g soluble in 170ml water at 25℃, 1g soluble in 90ml water at 100℃, 1g also soluble in 8ml ethanol, 50ml ether, soluble in ethyl acetate and acetic acid, slightly soluble in benzene, insoluble in Petroleum ether. Ka=1.21×10-5, Kb=2.3×10-12, 5 at 25℃ % solution pH is 3.5. It reacts with bromine to produce dibromo derivatives, reacts with HCl and KClO3 to produce chloroquinone (tetrachlorobenzene-p-quinone), and reacts with HCl at 180°C to produce aniline and carbon dioxide. It is widely present in nature as a complexing factor of alkali. The mass fraction contained in fermenting yeast is 5×10-6～6×10-6, and in Saccharomyces cerevisiae The mass fraction contained is 10×10-6～100×10-6. Preparation method: obtained by reducing p-nitrobenzoic acid with iron powder.
Purpose[2-5]
4-Aminobenzoic acid is one of the most important aromatic amino acids. It is an important component of substances necessary for the growth and division of body cells. It plays an irreplaceable role in the metabolism of life. It plays an important role in yeast, liver, gluten and so on. The content in skin and malt is very high. 4-Aminobenzoic acid can relieve anemia, viral anemia, sprue and anemia during pregnancy caused by a lack of red blood cells. Vitamin B-100, a high-efficiency nutritional product with 4-aminobenzoic acid as the main component, can effectively improve the body's three major metabolisms, comprehensively combat fatigue and relieve stress. The compatibility of 4-aminobenzoic acid with penicillin or streptomycin can effectively improve the antibacterial effect. 4-Aminobenzoic acid is also an important fine chemical raw material. In medicine, it is a key intermediate for the synthesis of folic acid, a blood supplement, and p-carboxybenzylamine, a procoagulant. It is also used in the manufacture and treatment of rickets, rheumatism, and arthritis. , tuberculosis drugs. In the cosmetics industry, it is an important intermediate for human body sunscreen and hair growth agents; in the organic chemical industry, it is used to prepare various ester products, and can be used as a resin modifier, and can also be used to synthesize reactive dyes, azo Special intermediates for dyes. Examples of its application are as follows:
1) Synthesis of ethyl 4-aminobenzoate, including the following steps: dissolve 4-aminobenzoic acid with alcohol, and prepare a 4-aminobenzoic acid solution with a mass fraction of 5-30%; under the conditions of 0-50°C Add thionyl chloride dropwise to the 4-aminobenzoic acid solution to perform an esterification reaction. After the dropwise addition, raise the temperature to reflux and react for 4-10 hours. After the reaction is completed, cool the reaction material, wait until the solid material precipitates, filter it, and dissolve it with water. For the solid matter, add a weak base to neutralize it to pH 7-8. After the solid matter is precipitated, filter, wash, and dry to obtain the 4-aminobenzoic acid ethyl ester product. The present invention uses 4-aminobenzoic acid as raw material and uses thionyl chloride as dehydrating agent to carry out esterification reaction to prepare 4-aminobenzoic acid ethyl ester. It has fast reaction speed, high yield and high product purity, and has good industrial applications. application prospects.
2) The preparation of adefovir drug cocrystal using 4-aminobenzoic acid as the cocrystal precursor belongs to the field of drug cocrystal technology. The space group of the co-crystal of the drug is the monoclinic crystal system. One adefovir molecule, two 4-aminobenzoic acid molecules and one water molecule are combined together through hydrogen bonds to form the adefovir-aminobenzoic acid drug. The basic structural unit of the eutectic. The solvent selected in the preparation process of the pharmaceutical co-crystal of the present invention is water, and the method used is the solution co-crystallization method. Since adefovir is slightly soluble in cold water and easily soluble in hot water, it is heated, stirred and dissolved and then placed in an oven to keep warm for a period of time. After cooling, crystals will crystallize out. The pharmaceutical cocrystal prepared by the invention not only inherits the characteristics of traditional raw materials in treating hepatitis B disease, but also has obvious improvements in its solubility, stability and bioavailability.
3) Prepare a 4-aminobenzoic acid non-destructive modified carbon fiber reinforced paper-based wet friction material. First add carbon fiber, 4-aminobenzoic acid and excess hydrochloric acid into a three-necked flask. After the reaction reaches a certain temperature, slowly add A certain amount of sodium nitrite is used for a short-time diazotization reaction in an oil bath with magnetic stirring to obtain carbon fibers with benzoic acid grafted on the surface. Then, the modified carbon fiber is mixed with aramid fiber, paper fiber, filler, and resin to prepare a friction material base paper, and then hot-pressed and solidified to obtain a 4-aminobenzoic acid-modified paper-based wet friction material. The friction material sample was tested for friction and wear performance. Its kinetic friction coefficient reached 0.12-0.15 and the wear rate was 0.9×10-8cm3/J-1.2×10-8cm3/J. It showed excellent friction and wear performance, simple process and low cost. , is an efficient and environmentally friendly graft modification treatment method with wide application prospects.
Preparation[5]
The preparation method of 4-aminobenzoic acid is as follows: add 38.0g of p-nitrobenzoic acid, 200mL of water, 20mL of tetrahydrofuran, 0.4g of sodium dodecyl sulfonate and 1.9g of rayon to the autoclave. Nickel, replace with nitrogen three times, fill with hydrogen, adjust the pressure to 0.9±0.1MPa, adjust the temperature to 100±2°C, and keep the temperature and pressure for 4 hours until the reaction is complete. After the reaction, filter and recover the catalyst, let it stand for layering, apply the water layer directly, and apply the tetrahydrofuran layer after distillation and recovery. Then add 1.5g of activated carbon to the 4-aminobenzoic acid mother liquor, and heat and reflux to remove it under nitrogen protection.20min, filter, cool and crystallize the mother liquor, filter, and dry under vacuum at 80~85°C to obtain 30.3g of 4-aminobenzoic acid, with a yield of 97.2%, a melting point of 187.1~187.6°C, and a content of 100.2% (permanent Stop titration method).
Main reference materials
【1】Compound Dictionary
【2】CN201110263348.6 A kind of synthesis method of p-aminobenzoic acid (4-aminobenzoic acid) ethyl ester
【3】CN201410106057.X Adefovir drug cocrystal using p-aminobenzoic acid (4-aminobenzoic acid) as the precursor and its preparation method
【4】CN201611047005.5 Preparation method of non-destructive modified carbon fiber reinforced paper-based wet friction material with p-aminobenzoic acid (4-aminobenzoic acid)
【5】Preparation method of CN201811289557.6 p-aminobenzoic acid (4-aminobenzoic acid)
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