Sodium hydride
[CAS# 7646-69-7]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Hydride, nitride, azide >> Hydride
• Name: Sodium hydride
• Molecular Formula: NaH
• Molecular Weight: 24.00
• CAS Registry Number: 7646-69-7
• EC Number: 231-587-3
• SMILES: [H-].[Na+]

Properties

• Density: 0.92 g/mL (Expl.)
• Melting point: 800 °C (Decomposes) (Expl.)
• Water solubility: REACTS

Safety Data

• Hazard Symbols: GHS02;GHS05 Danger
• Risk Statements: H228-H260-H290-H314-H318
• Safety Statements: P210-P223-P231+P232-P234-P240-P241-P260-P264-P264+P265-P280-P301+P330+P331-P302+P335+P334-P302+P361+P354-P304+P340-P305+P354+P338-P316-P317-P321-P363-P370+P378-P390-P402+P404-P405-P406-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Substances or mixtures which in contact with water emit flammable gases	Water-react.	1	H260
Flammable solids	Flam. Sol.	1	H228
Serious eye damage	Eye Dam.	1	H318
Skin corrosion	Skin Corr.	1A	H314
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Skin corrosion	Skin Corr.	1	H314
Skin irritation	Skin Irrit.	2	H315
Skin corrosion	Skin Corr.	1B	H314
Eye irritation	Eye Irrit.	2	H319

• Transport Information: UN 1427

Discovery and Applications

Sodium hydride is an inorganic compound composed of sodium and hydrogen with the chemical formula NaH. It is a powerful and commonly used reducing agent and strong base in organic and inorganic chemistry. Sodium hydride appears as a gray to white solid, often in the form of a powder or granules. It is highly reactive, especially toward moisture and air, and must be handled under inert atmospheres such as nitrogen or argon to prevent hazardous reactions.

Sodium hydride was first synthesized in the late 19th century through the direct combination of sodium metal and hydrogen gas. Its ability to act as a hydride donor, supplying H^– ions, makes it a valuable reagent in synthetic chemistry.

In practical applications, sodium hydride is primarily used as a strong base for deprotonating weak acids, including alcohols, amines, and thiols. This property enables the generation of reactive nucleophiles that can participate in further synthetic transformations such as alkylations, condensations, and substitutions. For example, sodium hydride is widely employed to convert alcohols into alkoxides, which can then react with alkyl halides to form ethers.

Sodium hydride is also used as a reducing agent in certain chemical reactions, although its base properties are more commonly exploited. Its strong basicity and hydride-donating ability allow it to reduce metal halides and other electrophiles under controlled conditions.

Due to its reactivity, sodium hydride must be stored carefully, usually as a dispersion in mineral oil to reduce exposure to air and moisture. Contact with water or protic solvents causes vigorous release of hydrogen gas, which is flammable and poses explosion hazards. As a result, strict safety protocols are required when using sodium hydride, including working in well-ventilated areas and employing appropriate protective equipment.

Sodium hydride plays a critical role in industrial and laboratory synthesis, facilitating the preparation of pharmaceuticals, agrochemicals, and specialty chemicals. Its versatility in promoting deprotonation reactions has made it a staple reagent in organic synthesis since its introduction.

Physically, sodium hydride has a melting point of approximately 800 °C and crystallizes in a rock salt structure. It is insoluble in most organic solvents but can react vigorously in suspension.

Overall, sodium hydride’s discovery and development have provided chemists with a highly effective reagent for base-catalyzed transformations and selective reductions. Its continued use underpins many important synthetic methodologies and advances in chemical manufacturing.

References

1983. Synthesis of (±)-disparlure. Journal of Chemical Ecology, 9(2).
DOI: 10.1007/bf00988038

1993. Multigram synthesis of 1-alkylamido phospholipids. Lipids, 28(1).
DOI: 10.1007/bf02536361

2024. Synthesis of New 3-(Benzo[d]Oxazol-2-Yl)-3-(4-Fluorophenyl)Propanoic Acid Intermediate and its Derivatives as Antimicrobial Agent, Molecular Docking Studies. Chemistry Africa.
DOI: 10.1007/s42250-024-01140-9