4-Aminophenol: Applications and Toxicology

General Description

4-Aminophenol, also known as Mesalamine EP Impurity A, has multiple applications in different industries. Firstly, it plays a vital role in the development process of black-and-white film by acting as a key ingredient in the developer solution. It helps convert latent silver halides into visible metallic silver, thereby creating the desired images on photographic film. 4-Aminophenol influences image contrast and tonal range while ensuring proper fixation and stabilization of the image. Secondly, 4-aminophenol serves as a synthetic intermediate in various industries. In pharmaceuticals, it is used to synthesize analgesics and antipyretics. It is also utilized in the production of dyes and pigments, contributing to the vibrant colors in textiles, plastics, and printing inks. Additionally, 4-aminophenol finds application in the synthesis of specialty chemicals and polymers, enabling the creation of materials with unique properties for industrial use. However, it is important to note that 4-aminophenol poses significant hazards to human health and the environment. It can cause skin, respiratory, and eye irritation, and is considered a major toxic pollutant for aquatic life. Regulatory bodies have set limits to mitigate its toxicological effects, particularly in occupational settings. Proper handling and disposal procedures are necessary to minimize environmental impact.

Figure 1. 4-Aminophenol

Applications

Developer for black-and-white film

4-Aminophenol plays a vital role in the development process of black-and-white film. It acts as a key ingredient in the developer solution, aiding in the conversion of latent silver halides into visible metallic silver. This reaction is essential for creating the desired images on the photographic film. As a developing agent, 4-aminophenol significantly influences image contrast and tonal range while ensuring proper fixation and stabilization of the image. Its chemical properties make it effective in converting exposed silver halide crystals into metallic silver, resulting in high-quality black-and-white photographs. The concentration and formulation of 4-aminophenol in the developer solution are carefully controlled to achieve optimal results in the film development process. Proper handling and disposal of the chemicals involved in film development are necessary to minimize any potential environmental impact. ¹

Synthetic intermediate

4-Aminophenol plays a significant role as a synthetic intermediate in various industries. Its versatility and chemical properties make it an essential component in the production of diverse compounds. In the pharmaceutical industry, 4-aminophenol serves as a key building block for synthesizing drugs. It is used in the production of analgesics (pain relievers) and antipyretics (fever reducers). Through chemical modifications and reactions, 4-aminophenol can be transformed into active pharmaceutical ingredients with therapeutic effects. Furthermore, 4-aminophenol finds application in the production of dyes and pigments. It acts as a starting material for the synthesis of colorants that are widely used in textiles, plastics, printing inks, and other industries. These dyes contribute to the vibrant and varied colors we see in everyday products. Additionally, 4-aminophenol is utilized in the synthesis of specialty chemicals and polymers. By incorporating 4-aminophenol into chemical reactions, manufacturers can produce materials with unique properties suitable for specific industrial applications. These specialty chemicals and polymers find use in areas such as coatings, adhesives, electronic components, and more. Overall, 4-aminophenol plays a crucial role as a synthetic intermediate, enabling the production of a wide range of compounds in the pharmaceutical, dye, and polymer industries, among others. ²

Toxicology

4-Aminophenol poses significant hazards to both human health and the environment. This organic compound, widely used in various industries, is a major toxic pollutant for aquatic life. Due to its widespread presence, 4-aminophenol can enter plants and organisms through skin contact or membranes, making it hazardous both biochemically and environmentally. Phenolic compounds, such as 4-aminophenol, warrant particular attention due to their detrimental effects on humans and the environment. Exposure to 4-aminophenol can cause skin, respiratory, and eye irritation, and it serves as a biological marker for monitoring occupational and toxicological exposure to aniline in human urine. To mitigate the toxicological effects of 4-aminophenol, regulatory bodies like the European and United States Pharmacopeias have set an upper limit of 50 ppm (0.005%, w/w) for pharmaceutical personnel. ³

Reference

1. Calam TT. A modified pencil graphite electrode with 2-thiobarbituric acid for the efficient and cheap voltammetric sensing of 4-aminophenol in water samples and child syrup sample. J Food Compos Anal, 2021, 98.

2. Ahmed J, Rakib RH, Rahman MM, et al. Electrocatalytic Oxidation of 4-Aminophenol Molecules at the Surface of an FeS2 /Carbon Nanotube Modified Glassy Carbon Electrode in Aqueous Medium. Chempluschem, 2019, 84(2):175-182.

3. Karimi-Maleh H, Darabi R, Karimi F, et al. State-of-art advances on removal, degradation and electrochemical monitoring of 4-aminophenol pollutants in real samples: A review. Environ Res, 2023, 222:115338.

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