4hydroxyquinoline2carboxylic

4-Hydroxyquinoline, also called quinolin-4-ol, is a heterocyclic aromatic compound consisting of a quinoline ring system bearing a hydroxy group at the 4-position. It is an individual member of the broader class of hydroxyquinolines and serves as a versatile building block in organic synthesis. Its molecular formula is C9H7NO.

In terms of structure and properties, 4-hydroxyquinoline is a planar, nitrogen-containing aromatic compound. The hydroxy group at position 4 enables hydrogen-bonding interactions and can influence the compound’s acidity and reactivity relative to non-hydroxylated quinoline. It is typically a crystalline solid with limited water solubility and greater solubility in organic solvents.

Synthesis and occurrence in nature are primarily concerned with laboratory preparation. 4-Hydroxyquinoline is not widely reported as a natural product; it is mainly prepared synthetically through functionalization of the quinoline framework or via cyclization strategies that introduce the 4-hydroxy group onto a quinoline core. Routes described in the chemical literature often involve nucleophilic aromatic substitution, oxidation, or condensation sequences applied to suitably substituted precursors.

Applications and reactivity are driven by the presence of the quinoline nitrogen and the 4-hydroxy group. It is used as a synthetic intermediate for the preparation of more complex heterocycles, dyes, and pharmaceutical or agrochemical precursors. The compound can undergo further derivatization to form ethers, esters, or N- and O-alkylated products, and it can act as a ligand in coordination chemistry, owing to the lone pair on nitrogen and the phenolic oxygen.

Safety considerations are similar to other heterocyclic aromatics: handling should minimize inhalation and skin contact, with standard laboratory precautions and appropriate personal protective equipment.