phthalaldehyde

Phthalaldehyde, also known as o-phthalaldehyde or 1,2-benzenedicarboxaldehyde, is an aromatic dialdehyde with the formula C8H6O2. It consists of a benzene ring bearing two formyl groups at adjacent positions (ortho). The compound is a colorless to pale yellow solid that is soluble in many organic solvents and reacts readily at the aldehyde groups.

Chemically, phthalaldehyde is reactive toward nucleophiles such as amines and thiols. It forms Schiff bases with amines and, in the presence of a thiol, yields highly fluorescent isoindole derivatives. This property makes o-phthalaldehyde a widely used reagent for the detection and quantification of primary amines, including amino acids, in fluorescence-based analytical methods such as HPLC and capillary electrophoresis.

Industrial and medical applications center on two main uses. The ortho isomer, commonly abbreviated as OPA, is employed as a high-level disinfectant for heat-sensitive medical devices, often in buffered solutions, due to rapid antimicrobial action and favorable material compatibility. Phthalaldehyde derivatives are also used in analytical chemistry as reagents for amino acid analysis and other biochemical assays.

Safety and handling note that phthalaldehyde is an irritant and can be a sensitizer. It should be handled with appropriate protective equipment in a well-ventilated area, and exposure to skin, eyes, and inhalation should be minimized. Proper storage in tightly closed containers, away from incompatible substances, is recommended.