N-Hydroxyphthalimide (NHPI) is a white to off-white crystalline solid with the molecular formula C8H5NO3. It is a stable, commercially available organic compound featuring a phthalimide core substituted with a hydroxyl group on the nitrogen atom. This structure makes it a versatile reagent in synthetic organic chemistry. Its primary and most significant application is as a highly effective organocatalyst for aerobic oxidations. NHPI, often in combination with transition metal co-catalysts like cobalt or manganese, catalyzes the oxidation of various organic substrates using molecular oxygen as the terminal oxidant. Key reactions include the oxidation of hydrocarbons to alcohols, ketones, and carboxylic acids, as well as the oxidation of alcohols to carbonyl compounds. This makes it a valuable, environmentally friendly catalyst for industrial and laboratory-scale oxidative transformations. Beyond its catalytic role, NHPI serves as a precursor for other reagents, such as phthalimide-N-oxyl (PINO) radical, and finds use in the synthesis of pharmaceuticals and agrochemicals. It is generally considered stable under ambient conditions but should be handled with standard laboratory precautions to avoid inhalation or contact.