Morpholine

Morpholine (tetrahydro-1,4-oxazine) is a six-membered heterocyclic amine containing both nitrogen and oxygen in the ring. It functions as a solvent and corrosion inhibitor in cleaning products, waxes, and metal-working fluids. Its alkaline character (pH ~8.5 in dilute solution) makes it effective as a co-solvent that boosts surfactant penetration into fabric and carpet fibers. At neat concentration, morpholine carries serious health hazards: skin corrosion (Cat 1B), harmful if swallowed/inhaled/in contact with skin, and flammable liquid (Cat 3). In consumer aerosol formulations where it appears at <5% concentration, the mixture classification drops to eye irritation (H319) and the flammable aerosol classification comes from the hydrocarbon propellant rather than morpholine itself. California Right to Know Act disclosures list morpholine as a disclosed ingredient in several aerosol carpet and upholstery cleaners.