piperidine

Piperidine is a heterocyclic amine consisting of a six-member ring with five carbon atoms and one nitrogen atom. Its chemical formula is C5H11N, and the nitrogen is part of the ring, giving piperidine its characters as a secondary amine. In its pure form it is a colorless liquid with a characteristic odor, miscible with water and many organic solvents. It has a boiling point of about 106 °C and a melting point around −3 °C.

Chemically, piperidine is a moderate base and forms salts with acids, such as piperidinium chloride. The conjugate acid has a pKa around 11, reflecting the ring nitrogen’s basicity. It readily undergoes nucleophilic substitution and electrophilic reactions typical of secondary amines, including N-alkylation, N-acylation, and oxidation to piperidinones or related derivatives. Its reactivity makes it a versatile building block in organic synthesis.

Production and supply in industry typically involve catalytic hydrogenation of pyridine or related precursors, often using metal catalysts under hydrogen pressure. Piperidine serves as an important scaffold in medicinal chemistry and is used as a solvent, a chemical reagent, and a precursor to a variety of pharmaceuticals and agrochemicals. Many piperidine-containing drugs include that ring as a core structural element, such as certain antihistamines, local anesthetics, and psychotropic agents.

Safety and handling considerations include its status as a flammable liquid and an irritant to skin, eyes, and the respiratory tract. It should be used in well-ventilated areas, with appropriate protective equipment, and stored away from oxidizers and heat sources.