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4-アミノ安息香酸
4-アミノ安息香酸 · 4-アミノベンゼンカルボン酸 · パバシド · 4-カルボキシアニリン · ビタミンH' · ロマビット · アンベン · パラミノール
識別子と物理属性
| CAS No. | 150-13-0 |
|---|---|
| 分子式 | C7H7NO2 |
| 平均分子量 | 137.14 g/mol |
| 単同位体質量 | 137.04767846 g/mol |
| SMILES | Nc1ccc(C(=O)O)cc1 |
| InChIKey | ALYNCZNDIQEVRV-UHFFFAOYSA-N |
| PubChem CID | 978 |
| ChEMBL | CHEMBL542 |
| ChEBI | CHEBI:30753 |
| EC No. | 205-753-0 |
| DTXSID | DTXSID6024466 |
| 現地名 | 4-アミノ安息香酸 |
化学・物理的性質
| XLogP | 0.8 |
|---|---|
| 極性表面積 | 63.3 |
| 水素結合供与体数 | 2 |
| 水素結合受容体数 | 3 |
| 回転可能結合数 | 1 |
| 重原子数 | 10 |
| 形式電荷 | 0 |
| 複雑度 | 128 |
| 物質分類 | Other Uses -> Sunscreens |
| 医薬品 | PharmaceuticalsPharmaceuticals -> Listed in ZINC15 |
| 化粧品 | Uv filterUv absorber |
| pH | pH (0.5% solution): 3.53.5 (5g/l, H2O, 20℃) |
| LogP（分配係数） | log Kow = 0.83 |
| 臭い | Odorless無臭 |
| 食品添加物 | NUTRIENT SUPPLEMENT -> FDA Substance added to food |
| 密度 | 1.37 (NTP, 1992) - Denser than waterwill sink1.374 g/mL at 25 °C(lit.) |
| Color/Form | Monoclinic prisms from dilute alcoholLight buff crystalswhite when pureYellowish to red crystals or prismsWhite or slightly yellow crystals or crystalline powder |
| 溶解度 | In water, 5,390 mg/L at 25 °C6,110 mg/L at 30 °COne gram dissolves in 90 mL boiling waterin 8 ml alcohol, in 60 mL ether. Soluble in ethyl acetate, glacial acetic acidslightly soluble in benzenepractically insoluble in petroleum ether.Freely soluble in alcoholSoluble in alkalis and ethane (C2H6)For more Solubility (Complete) data for 4-AMINOBENZOIC ACID (8 total), please visit the HSDB record page.95% エタノール: 可溶 5%、透明からわずかにかすんだ、無色から黄色4.7g/L(20℃) |
| 融点 | 370 to 372 °F (NTP, 1992)188.5 °C188 °C187-189 °C(lit.) |
| 蒸気圧 | 0.000278 [mmHg]4.5X10-6 mm Hg at 25 °C /Extrapolated from measurements at higher temperatures/0Pa at 25℃ |
| 沸点 | 251.96°C (rough estimate) |
| 屈折率 | 1.5323 (estimate) |
| 引火点 | 250 °C |
| 貯蔵条件 | 2-8°C |
| 外観・状態 | 結晶性粉末 |
| pKa（酸解離定数） | 2.50, 4.87(at 25℃) |
| 色 | 白色～淡黄色 |
| 由来生物 | synthetic (organic) |
| 比熱容量 | Cp(crystal): 1.3 J/(g·K), at 25℃ |
| Merck | 14,423 |
| BRN | 471605 |
| ヘンリー定数 | 6.6×104 mol/(m3Pa) at 25℃, HSDB (2015) |
| 安定性 | 安定。強力な酸化剤とは相容れない。可燃性。光や空気に敏感。光に当たると変色することがあります。 |
| 主な用途 | ペプチド合成 |
| 化粧品成分の機能 | 光安定剤紫外線吸収剤 |
| InChI | 1S/C7H7NO2/c8-6-3-1-5(2-4-6)7(9)10/h1-4H,8H2,(H,9,10) |
| InChIKey | ALYNCZNDIQEVRV-UHFFFAOYSA-N |
| SMILES | Nc1ccc(cc1)C(O)=O |
| LogP（分配係数） | 0.96 at 25℃ |
| CAS データベース | 150-13-0(CAS DataBase Reference) |
| NISTの化学物質情報 | p-Aminobenzoic acid(150-13-0) |
| EPAの化学物質情報 | p-Aminobenzoic acid (150-13-0) |
化学的特性
colorless needle-like crystals. turns light yellow in the air or in light. Soluble in hot water, ether, ethyl acetate, ethanol and glacial acetic acid, insoluble in water, benzene, and insoluble in petroleum ether.
安全性と法規制
| GHS 分類 | This chemical does not meet GHS hazard criteria for 21.9% (53 of 242) of reports.WarningH315 (32.2%): Causes skin irritation [Warning Skin corrosion/irritation]P261, P264, P264+P265, P271, P272, P273, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P333+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)Aggregated GHS information provided per 242 reports by companies from 33 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies. |
|---|---|
| 規制情報 | Chemical: Benzoic acid, 4-amino-Status: Active Update: 13-10-2022 https://echa.europa.eu/registration-dossier/-/registered-dossier/171094-Aminobenzoic acid: Does not have an individual approval but may be used under an appropriate group standard |
| その他の安全情報 | IMAP assessments - Benzoic acid, 4-amino-: Environment tier I assessment |
| 健康有害性 | SYMPTOMS: Large doses by mouth can cause nausea, vomiting, skin rash, methemoglobimemia and possibly toxic hepatitis. |
| 有害性の概要 | Oral LD50 = 1000 mg/kg (dog), 1830 mg/kg (rabbit), and 6000 mg/kg (rat)Causes acute hepatic necrosis in dogs given 2-3 g/kg[HSDB] May cause irritationMay induce methemoglobinemia[MSDSonline] May cause allergic dermatitis when applied as a sunscreenNo skin sensitization reported in occupational setting[AIHA] Patients may be allergic or photoallergic to PABA. If photoallergic, they may not react to PABA alone, but only with sun exposure. [Marks, p. 212] |
| FDA 要件 | Sunscreen active ingredients. The active ingredient of the product consists of any of the following, within the concentration specified for each ingredient, and the finished product provides a minimum SPF value of not less than 2 as measured by the testing procedures established in subpart D of this part: Aminobenzoic acid (PABA) up to 15 percent is included on this list. |
| 反応性グループ | Acids, Carboxylic |
| Reactivity Profile | P-AMINOBENZOIC ACID is incompatible with ferric salts and oxidizing agents. (NTP, 1992) |
| History and Incidents | PABA is known as a sunscreen agent in cosmetics. It absorbs UVB radiation strongly. In the 1940's, dermatologists began to prescribe it in 2-5 % strengths in aqueous creams or in 70 % alcoholic solutions as a sunscreen. PABA was very popular as a sunscreen agent through the 1950's and 1960's and used as such throughout the world. The use of PABA has declined during the last decade/s/. |
| Air and Water Reactions | No rapid reaction with air. No rapid reaction with water. |
| Hazard Classes and Categories | Skin Irrit. 2 (32.2%) |
| Skin, Eye, and Respiratory Irritations | Derivatives of PABA, benzophenone, cinnamic acid, and salicylate and 2-phenylbenzimidazole-5-sulfonic acid have caused skin irritation including burning, stinging, pruritus, and erythema on rare occasions. /Sunscreens/ |
| Hazardous Reactivities and Incompatibilities | Incompatible materials: Strong oxidizing agents.Incompatible with ferric salts and oxidizing agents. |
| 消火 | This compound is not very flammable but any fire involving this compound may produce dangerous vapors. You should evacuate the area. All firefighters should wear full-body protective clothing and use self-contained breathing apparatuses. You should extinguish any fires involving this chemical with a dry chemical, carbon dioxide, foam, or halon extinguisher. (NTP, 1992) |
| 応急処置 | EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. |
| Firefighting Hazards | Special hazards arising from the substance or mixture: Carbon oxides, nitrogen oxides (NOx). |
| 消火手順 | Advice for firefighters: Wear self contained breathing apparatus for fire fighting if necessary.Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide. |
| 保管条件 | Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Recommended storage temperature: 2 - 8 °C. Air and light sensitive. |
| 清掃方法 | Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust.Environmental precautions: Do not let product enter drains.Methods and materials for containment and cleaning up: Pick up and arrange disposal without creating dust. Sweep up and shovel. Keep in suitable, closed containers for disposal. |
| 非火災時の漏出対応 | STORAGE PRECAUTIONS: You should protect this chemical from exposure to light. Keep the container tightly closed under an inert atmosphere, and store under refrigerated temperatures. (NTP, 1992) |
| 処分方法 | Product: Offer surplus and nor-recyclable solutions ot a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material. Contaminated packaging: Dispose of as unused product.SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air qualitypotential migration in soil or watereffects on animal, aquatic, and plant lifeand conformance with environmental and public health regulations. |
| Preventive Measures | Precautions for safe handling: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Provide appropriate exhaust ventilation at places where dust is formed.Appropriate engineering controls: Handle is accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of the workday.Skin protection: ... Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. |
| Protective Action Criteria (PAC) | 15 [mg/m3]69 [mg/m3]410 [mg/m3] |
| Personal Protective Equipment (PPE) | RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)Eye/face protection: Face shield and safety glasses. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (USA) or EN 166(EU).Respiratory protection: For nuisance exposures use type P95 (US) or type P1 (EU EN 143) particle respirator. For higher level protection use type OV/AG/P99 (US) or type ABEK-P2 (EU EN 143) respirator cartridges. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).Skin protection: Handle with gloves.Body Protection: Complete suit protecting against chemicals. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. |
| Other Standards Regulations and Guidelines | Workplace Environmental Exposure Level (WEEL): 8-hr Time-weighted Average (TWA) 5 mg/cu m. |
| 相互作用 | Sulfonamides act by competitive inhibition of PABA in the microorganism. PABA administration in sufficient doses thus antagonized the antibacterial effect of the sulfonamides.PABA appears to block the formatin of salicyluric acid from salicylic acid, resulting in increased salicylate blood levels.Aminosalicylic acid appears to act on tubercle bacilli in a manner similar to that of sulfonamides on other organisms (by competing with PABA). Thus the administration of PABA may be expected to inhibit the antimicrobial activity of aminosalicylic acid.Interferon titers induced by 0.007% PABA and poludan were compatible after both injections in the conjunctiva but not in the anterior chamber humor.For more Interactions (Complete) data for 4-AMINOBENZOIC ACID (14 total), please visit the HSDB record page. |
| 環境中動態 | TERRESTRIAL FATE: According to a classification scheme(1), measured Koc values ranging from 19.9 to 316(2-4) suggest that 4-aminobenzoic acid is expected to have very high to moderate mobility in soil. The pKa values of 4-aminobenzoic acid are 2.38 (acid group)(5) and 4.85 (amino group)(6), indicating that this compound will exist almost entirely in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(7). However, aromatic amines are expected to bind strongly to humus or organic matter in soils due to the high reactivity of the aromatic amino group(8,9), suggesting that mobility may be much lower in some soils(SRC). Volatilization of 4-aminobenzoic acid from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.5X10-10 atm-cu m/mole(SRC), based upon its vapor pressure, 4.5X10-6 mm Hg(10), and water solubility, 5390 mg/L(11). 4-Aminobenzoic acid is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure. An 82% of theoretical BOD using activated sludge in the Japanese MITI test classifies 4-aminobenzoic acid as readily biodegradable(12). Results of other screening studies(13,14) also suggest that biodegradation may be an important fate process(SRC).AQUATIC FATE: According to a classification scheme(1), measured Koc values ranging from 19.9 to 316(2-4) indicate that 4-aminobenzoic acid may have no to moderate adsorption to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(5) based upon an estimated Henry's Law constant of 1.5X10-10 atm-cu m/mole(SRC), derived from its vapor pressure, 4.5X10-6 mm Hg(6), and water solubility, 5390 mg/L(7). According to a classification scheme(8), an estimated BCF of 3(SRC), from its log Kow of 0.83(9) and a regression-derived equation(10), suggests the potential for bioconcentration in aquatic organisms is low(SRC). An 82% of theoretical BOD using activated sludge in the Japanese MITI test classifies 4-aminobenzoic acid as readily biodegradable(11). Results of other screening studies(12,13) also suggest that biodegradation may be an important fate process(SRC). 4-Aminobenzoic acid is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(5). Using simulated solar irradiation in aqueous solutions, the direct photolysis of 4-aminobenzoic acid followed pseudo-first order kinetics with the rate constant increasing with increasing pH(14)the direct photolysis rate constants were determined to be 3.46X10-6/sec, 12.57X10-6/sec and 14.96X10-6/sec at respective pH values of 4.8, 7.8 and 9.2(14) which correspond to respective half-lives of 2.32 days, 15.3 hours and 12.9 hours(SRC)it was determined that direct photolysis was the dominant phototransformation process in sunlit natural water with sensitized photolysis occurring at a much slower rate(14)p-hydroxybenzoic acid was identified as a photodegradation product with the photodegradation pathway including di(tri)-polymerization(14).ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 4-aminobenzoic acid, which has a vapor pressure of 4.5X10-6 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase 4-aminobenzoic acid is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC)the half-life for this reaction in air is estimated to be 9.5 hours(SRC), calculated from its rate constant of 4.0X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase 4-aminobenzoic acid may be removed from the air by wet and dry deposition(SRC). 4-Aminobenzoic acid has been shown to degrade through direct photolysis in the sunlight spectrum(4,5), therefore, photolysis may have some importance as a fate process in the atmosphere(SRC). |
| 食品調査値 | 4-Aminobenzoic acid (PABA) is a chemical found in the folic acid vitamin and also in several foods including grains, eggs, and meat(1). It may also occur in Brewer's yeast, liver, molasses, mushrooms, and spinach(2). |
| 有害作用 | Occupational hepatotoxin - Secondary hepatotoxins: the potential for toxic effect in the occupational setting is based on cases of poisoning by human ingestion or animal experimentation. |
| Milk Concentrations | 4-Aminobenzoic acid (PABA) is a chemical found in the folic acid vitamin and also in several foods including milk(1). |
| Plant Concentrations | 4-Aminobenzoic acid was detected, not quantified in Sesame (Sesamum indicum) seed(1). |
| Effluent Concentrations | 4-Aminobenzoic acid was detected in ammunition plant wastewater (concn unspecified)(1). |
| Soil Adsorption/Mobility | In a Chernozem soil of pH 7.5, the Koc of 4-aminobenzoic acid was determined to be 19.9(1). Using OECD Guideline 106 and three different soils of pH values of 2.8, 6.7 and 7.1, 4-aminobenzoic acid was found to have respective Koc values of 239, 46 and 55(2). A measured log Koc of 2.5 has been reported for 4-aminobenzoic acid(3) which corresponds to a Koc of 316. According to a classification scheme(4), these Koc values suggests that 4-aminobenzoic acid is expected to have very high to moderate mobility in soil. The pKa values of 4-aminobenzoic acid are 2.38 (acid group)(5) and 4.85 (amino group)(6), indicating that this compound will exist almost entirely in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(7). However, aromatic amines are expected to bind strongly to humus or organic matter in soils due to the high reactivity of the aromatic amino group(8,9), suggesting that mobility may be much lower in some soils(SRC). |
| Natural Pollution Sources | 4-Aminobenzoic acid is widely distributed in nature as a B complex factor(1). Baker's yeast contains 5 to 6 ppm 4-aminobenzoic acid(1)brewer's yeast contains from 10 to 100 ppm 4-aminobenzoic acid(1). 4-Aminobenzoic acid (PABA) is a chemical found in the folic acid vitamin and also in several foods including grains, eggs, milk, and meat(2). |
| Human Toxicity Excerpts | /HUMAN EXPOSURE STUDIES/ In a dermatological clinic in Norway 23 patients with reactions to sunscreen preparations were seen during the years 1980-1982. The symptoms were eczema, redness, stinging or burning of the face following sun exposure. Patch tests and photopatch tests were carried out on the patients. Allergy to PABA was demonstrated in 11 patients (48%), of which 6 had plain contact allergy (26%) (PABA on non irradiated test sites) and 5 (21.7%) reacted to PABA only after irradiation./SIGNS AND SYMPTOMS/ Applications of 5% PABA in sunscreen formulation on human skin have shown that irritation is negligible./CASE REPORTS/ Human tests performed on patients contacting a dermatological clinic with a suspected skin disease shows that PABA has a potential to cause photo allergy reactions. Considering the fact that the results are based on patients with suspected dermatological problems rather than the general population, the prevalence is likely to be lower in the general population than in the studied groups. The highest photo allergy reaction to PABA was found in a Norwegian study from 1980 - 82 on 23 patients where 21.7% reacted. In most ... /studies/ the reaction to PABA was in the range 0 - 3%./CASE REPORTS/ A case report described that the potassium salt of PABA (administered orally 4 g three times a day for about 2 months) to a 64-year-old woman led to hepatotoxicity in a patient with scleroderma, as evidenced by elevated serum alanine aminotransferase and aspartate aminotransferase. /Potassium salt of PABA/For more Human Toxicity Excerpts (Complete) data for 4-AMINOBENZOIC ACID (13 total), please visit the HSDB record page. |
| Artificial Pollution Sources | 4-Aminobenzoic acid's production and use in the manufacturer of various esters, folic acid, azo dyes(1), as a cross-linking agent for polyurethane resins(2) and as UV absorber in suntan lotions(3) may result in its release to the environment through various waste streams(SRC). |
| Environmental Biodegradation | AEROBIC: 4-Aminobenzoic acid was decomposed by soil microflora using fill and draw operations at 20 °C. Using adapted activated sludge as the inoculum and 14C-labeled 4-aminobenzoic acid as the sole carbon source, 96.2% chemical oxygen demand removal was observed with a rate of 12.5 mg chemical oxygen demand/g dry inoculum/hr. A lag period for degradation of 16 mg/L was observed for wastewater or soil at pH 7.3 and 30 °C. At 100 mg/L of test sample, no inhibition of ammonia oxidation by Nitrosomonas species was observed.AEROBIC: 4-Aminobenzoic acid, present at 100 mg/L, reached 82% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test which classified the compound as readily biodegradable(1). 4-Aminobenzoic acid, present at 50 ppm C, reached 74% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test(2). Other screening studies give similar results(2,3) indicating that 4-aminobenzoic acid is readily biodegradable(SRC).ANAEROBIC: Screening studies indicate that 4-aminobenzoic acid may biodegrade under anaerobic conditions(SRC). 4-Aminobenzoic acid, present at 50 ppm C, reached 30-75% of its theoretical methane production in 56 days using 10% of digester sludge(1). However, in a screening test in which fresh sewage was added every 7 days, 4-aminobenzoic acid remained recalcitrant(2). |
| 水環境危害等級（WGK） | 3 |
| TSCA 収載状態 | TSCA listed |
| RTECS 番号 | DG1400000 |
| 毒性 | LD50 in mice, rats (g/kg): 2.85, >6.0 orally (Scott, Robbins)LD50 in rabbits (g/kg): 2.0 i.v. (Richards)1.83 orally (Cronheim) |
| 税関コード | 29224995 |
| 危険文句（R） | 22-36/37/38-43 |
| 化審法 | (3)-1454 |
| 危険表示 | Xn,Xi |
| 安全措置（S） | 26-36-37/39 |
| 危険等級 | Aquatic Chronic 3 |
| 貯蔵分類 | 11 - Combustible Solids |
| 有害物質データ | 150-13-0(Hazardous Substances Data) |
用途
用途
有機合成原料。
説明
4-Aminobenzoic acid (also known as para-aminobenzoic acid or PABA because the number 4 carbon in the benzene ring is also known as the para position) is an organic compound with the formula H2NC6H4CO2H. PABA is a white solid, although commercial samples can appear gray. It is slightly soluble in water. It consists of a benzene ring substituted with amino and a carboxyl groups. The compound occurs naturally. The potassium salt is used as a drug against fibrotic skin disorders, such as Peyronie's disease, under the trade name Potaba. PABA is also occasionally used in pill form by sufferers of irritable bowel syndrome to treat its associated gastrointestinal symptoms, and in nutritional epidemiological studies to assess the completeness of 24-hour urine collection for the determination of urinary sodium, potassium, or nitrogen levels.
使用
4-aminobenzoic acid is an aminobenzoic acid isomer that combines with pteridine and glutamic acid to folic acid. The fact that 4-aminobenzoic acid absorbs light throughout the UVB range has also resulted in its use as an ingredient in sunscreens. Also it is used as a component of some medicines e.g analgesic or anesthetic preparations sunscreen agents and bentiromide.
一般的な説明
Colorless crystals that discolor on exposure to light and air.
製法・合成法
製造方法
4-Aminobenzoic acid synthesis method: add 38.0g of p-nitrobenzoic acid, 200mL of water, 20mL of tetrahydrofuran, 0.4g of sodium dodecyl sulfonate and 1.9g of Raney nickel to the autoclave, nitrogen replacement Three times, fill with hydrogen, adjust the pressure to 0.9±0.1MPa, adjust the temperature to 100±2°C, and keep the reaction under pressure for 4h to complete. After the reaction, the catalyst was recovered by filtration, left to stand for stratification, the water layer was directly applied mechanically, the tetrahydrofuran layer was distilled and recovered and applied mechanically, then 1.5 g of activated carbon was added to the 4-aminobenzoic acid mother liquor, and under nitrogen protection, heating and refluxing for decolorization for 20min, Filtration, cooling and crystallization of mother liquor, filtration, drying under vacuum at 80-85 °C to obtain 30.3 g 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) .
純化方法
Purify p-aminobenzoic acid by dissolving it in 4-5% aqueous HCl at 50-60o, decolorising with charcoal and carefully precipitating it with 30% Na2CO3 to pH 3.5-4 in the presence of ascorbic acid. It can be recrystallised from water, EtOH or EtOH/water mixtures. [Beilstein 14 IV 1126.]