N-Methylmorpholine N-oxide (more correctly 4-methylmorpholine 4-oxide), NMO or NMMO is an organic compound. This heterocyclic amine oxide and morpholine derivative is used in organic chemistry as a co-oxidant and sacrificial catalyst in oxidation reactions for instance in osmium tetroxide oxidations and the Sharpless asymmetric dihydroxylation or oxidations with TPAP. NMO is commercially supplied both as a monohydrate C5H11NO2·H2O and as the anhydrous compound. The monohydrate is used as a solvent for cellulose in the Lyocell process to produce cellulose fibers.

Appearance and properties: colorless to slightly yellow transparent liquid

Density: 1.14g /cm3

Boiling point: 118-119oC

Melting point: 180-184oC

Flash point: 118-119oC

Refractive index: n20/D 1.43

Stability: Stable at room temperature in closed containers under normal storage and handling conditions.

Storage conditions: Store in a tightly closed container. Store in a cool, dry,  well-ventilated area away from incompatible substances. Refrigerator (approx 4oC). Store protected from moisture.