Sodium hydrazide

Sodium hydrazide

Names
IUPAC name Sodium hydrazide
Other names Sodium aminoazanide
Properties
Chemical formula	NaN2H3 NaNH-NH2
Molar mass	54.027 g/mol
Appearance	White to yellow crystalline solid
Odor	Odorless
Melting point	100 °C (212 °F; 373 K) (Decomposes)
Boiling point	Decomposes
Solubility in water	Reacts
Solubility	Reacts with alcohols, acids Soluble in anh. ammonia, hydrazine Insoluble in ethers, hydrocarbons
Vapor pressure	~0 mmHg
Hazards
Safety data sheet	None
Related compounds
Related compounds	Hydrazine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium hydrazide is an organic chemical compound, a yellow crystalline compound that is known to explode violently in contact with air. It has the chemical formula NaN₂H₃.

Properties

Chemical

Sodium hydrazide explodes on contact with air or when heated at high temperatures. It also reacts with water violently, yielding sodium hydroxide and hydrazine.

NaNH-NH₂ + H₂O → NaOH + NH₂-NH₂

Moisture and alcohol are also reported to result in explosion.

Sodium hydrazide does not attack compounds containing isolated double bonds, apart from those in which the bond angle is strained. On the other hand, it adds onto C=C double bonds that are conjugated with a phenyl residue or another C=C double bond. Styrene, for example, adds on sodium hydrazide in ether very rapidly, even at 0 °C.

Sodium hydrazide reacts with nitriles, followed by water, at low temperatures to yield amidrazones.

Pyridine can be converted directly into 2-hydrazinopyridine by treatment with sodium hydrazide/hydrazine and subsequent hydrolysis with water. If no free hydrazine is present, the reaction of sodium hydrazide with aromatic nitrogenous heterocycles like pyridine produces hydrazo compounds.

Aliphatic ethers are unaffected by sodium hydrazide at 60 °C. Ethers with one or two aromatic residues are also fairly resistant: when heated at 50 °C for five hours with sodium hydrazide in benzene containing free hydrazine, anisole and diphenyl ether are split to the extent of only 9 and 21 %, respectively.

Physical

Sodium hydrazide is a white to yellowish crystalline compound, very soluble in anh. hydrazine insoluble in organic solvents, but reacts (potentially explosively) with water and acids. It is known to react explosively in open air, or when heated at high temperatures.

Explosive

Sodium hydrazide is known to explode violently on contact with oxygen, such as atmospheric air, and also when heated above 100 °C. While most sources indicate that it is stable in an oxygen-free atmosphere, some sources claim it can be explosive even under nitrogen or hydrogen atmosphere, but no indications why.

Availability

Sodium hydrazide is not sold by suppliers and has to be made in situ.

Preparation

Sodium hydrazide can be prepared by reacting finely divided sodium amide with anhydrous hydrazine, under inert atmosphere. If the sodium amide is not finely divided, the reaction is very slow.

NaR + H₂N-NH₂ → NaNH-NH₂ + R-H (R = NH₂ or H)

Another way is the reaction of sodium metal with absolutely anhydrous hydrazine with benzene layered on top of it:

2 Na + 3 N₂H₄ → 2 NaNHNH₂ + 2 NH₃

On very careful distillation (removing benzene and excess hydrazine) using a water bath at no more than 70 °C, very pure sodium hydrazide is left behind.

Projects

• Pyrotechnic demonstration
• Prepare amidrazones

Handling

Safety

Sodium hydrazide is explosive in contact with air and poses a serious fire hazard.

Storage

Should not be stored and used immediately.

Disposal

Can neutralized by reacting it with esters or alcohols, under inert gas and diluted in another solvent. Very slow decomposition under benzene using a dilute solution of alcohol in benzene has been used to decompose the substance without explosion. Afterwards (!) the solution can be neutralized with dilute aq. acids.