Dinitrogen monoxide
[CAS# 10024-97-2]

Identification

• Classification: API >> Anesthetic agents >> General anesthetics
• Name: Dinitrogen monoxide
• Synonyms: Laughing gas; Factitious air; Hyponitrous acid anhydride
• Molecular Formula: N₂O
• Molecular Weight: 44.01
• CAS Registry Number: 10024-97-2
• EC Number: 233-032-0
• SMILES: [N-]=[N+]=O

Properties

• Solubility: Soluble (73.9 g/L) (25 °C), Calc.^*
• Density: 1.23 g/cm³ (-89 °C) (Expl.)
• Melting point: -90.8 °C (Expl.)
• Boiling point: -88.41 °C (Expl.)
• Refractive index: 1.380 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (©1994-2013 ACD/Labs)

Safety Data

• Hazard Symbols: GHS03;GHS04;GHS07 Danger
• Risk Statements: H270-H280-H281-H336
• Safety Statements: P220-P244-P261-P271-P282-P304+P340-P319-P336+P317-P370+P376-P403-P403+P233-P405-P410+P403-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Oxidising gases	Ox. Gas	1	H270
Gases under pressure (compressed)	Press. Gas (Comp.)		H280
Gases under pressure (refrigerated liquid)	Press. Gas (Ref. Liq.)		H281
Gases under pressure (liquid)	Press. Gas (Liq.)		H280
Specific target organ toxicity - single exposure	STOT SE	3	H336
Acute toxicity	Acute Tox.	2	H330

• Transport Information: UN 1070 2.2

Discovery and Applications

Dinitrogen monoxide is a simple inorganic compound composed of two nitrogen atoms and one oxygen atom, with the molecular formula N₂O. It is commonly known as nitrous oxide and has been known since the late eighteenth century, when it was first prepared by thermal decomposition of ammonium nitrate. Early investigations into its properties revealed its characteristic sweet odor and its physiological effects, which led to its historical use in public demonstrations and later in medical practice.

The molecule has a linear structure with the atoms arranged as N–N–O, and it can be described by resonance forms that distribute electron density along the nitrogen–nitrogen and nitrogen–oxygen bonds. It is a colorless gas at room temperature, relatively nonreactive under standard conditions, but capable of acting as an oxidizing agent at elevated temperatures. Its stability and ease of handling contributed to its early adoption in both laboratory and industrial contexts.

One of the most important applications of dinitrogen monoxide is in medicine, where it has long been used as an inhalation anesthetic and analgesic. Its ability to produce rapid onset of pain relief with relatively low toxicity made it valuable in dentistry and minor surgical procedures. It is often administered in controlled mixtures with oxygen to ensure patient safety. The reversible nature of its effects allows for quick recovery after exposure, which has supported its continued use in clinical settings.

In addition to its medical applications, dinitrogen monoxide has been widely used as an oxidizer in propulsion systems. It has found application in rocket propellants and hybrid rocket engines because it decomposes exothermically to release oxygen, supporting combustion of fuels. Its relative stability compared to other oxidizers allows it to be stored and handled more easily, which has made it useful in both experimental and practical propulsion technologies.

Dinitrogen monoxide has also been employed in the food industry as a propellant and foaming agent. It is used in aerosol products such as whipped cream dispensers, where it dissolves readily in fats and helps create stable foams when released. Its non-toxic nature at low concentrations and lack of strong reactivity under normal conditions make it suitable for such applications.

In chemical synthesis, dinitrogen monoxide can act as a mild oxidizing agent or a source of oxygen atoms in certain reactions. It has been used in laboratory-scale transformations and in studies of reaction mechanisms involving nitrogen oxides. However, its reactivity is generally lower than that of other oxidizing agents, which limits its use to specific applications.

The environmental impact of dinitrogen monoxide has also been recognized. It is a naturally occurring gas produced by microbial processes in soils and oceans, but human activities such as agriculture and industrial processes have increased its atmospheric concentration. It is a potent greenhouse gas and also participates in reactions that affect the ozone layer in the upper atmosphere. These environmental considerations have led to increased study of its sources, behavior, and methods for emission control.

Overall, dinitrogen monoxide is a historically significant and widely used inorganic compound with applications in medicine, food technology, propulsion, and chemical research. Its combination of stability, mild reactivity, and physiological effects has made it an important substance across multiple fields of science and industry.

References

2025. [Nitrous oxide: Between therapeutic application and abuse]. Der Nervenarzt.
DOI: 10.1007/s00115-025-01811-z

2025. Towards rational design of Cu-SSZ-13 catalysts with less N2O formation in NH3-SCR reaction: The effect of Brønsted acid sites. Journal of environmental sciences (China).
DOI: 10.1016/j.jes.2024.12.001

2025. Advances in accounting methodology of nitrous oxide emissions from the adipic acid industry. Journal of environmental sciences (China).
DOI: 10.1016/j.jes.2024.03.014