Aminophenols

Aminophenols are a class of aromatic compounds that contain both an amino group and a phenolic hydroxyl group on a benzene ring. The three principal isomers are o-aminophenol (2-aminophenol), m-aminophenol (3-aminophenol), and p-aminophenol (4-aminophenol). They share the molecular formula C6H7NO and differ in the relative positions of the amino and hydroxyl substituents, which influences their chemical reactivity and industrial uses.

Synthesis and occurrence: In industry, aminophenols are produced as intermediates for dyes and pharmaceuticals. They are commonly generated by the reduction of corresponding nitroarenes or by other amination routes from phenolic substrates. They also occur as intermediates in the production of polymers and pigments.

Applications: p-Aminophenol is a major precursor to paracetamol (acetaminophen) after acetylation. Aminophenols are used in the manufacture of azo dyes, hair dyes, and various pigments. The different isomers have distinct reactivity patterns that tailor them to specific synthetic routes in pharmaceutical and dye chemistry.

Properties: In their pure forms they are usually crystalline solids. The amino group is basic, and the phenolic OH is weakly acidic. They can form salts with acids and bases and show varying water solubility depending on the isomer and substitution pattern.

Safety: Aminophenols can be irritants and skin sensitizers and should be handled with appropriate protective equipment. They may be toxic to aquatic life and are subject to regulatory controls in industrial settings.