Chemical compound

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5-Aminotetrazole is an organic compound with the formula HN4CNH2. It is a white solid that can be obtained both in anhydrous and hydrated forms.

The molecule is planar.[1] The hydrogen bonding pattern in the hydrate supports the assignment of NH being adjacent to carbon in the ring.[2]

Preparation

A synthesis of 5-aminotetrazole through the action of nitrous acid on aminoguanidine was reported by Johannes Thiele in .[3]

The exact structure of the compound was not known at the time, although it was known to crystallize as a monohydrate. The correct structural formula was published in by Arthur Hantzsch, who obtained it from the reaction between cyanamide and hydrazoic acid.[4]

To avoid direct handling of the problematic hydrazoic acid, a mixture of sodium azide and hydrochloric acid has been used to give the monohydrate at 73% yield.[5]

In a more efficient and controllable one-pot synthesis, cyanamide is treated with hydrazine hydrochloride to give aminoguanidine hydrochloride, which is then diazotized as in Thiele's original process. Addition of ammonia or sodium hydroxide followed by heat-induced cyclization gives the anhydrous product in 74% yield.[6][7]

Structure

The structure of 5-aminotetrazole has been determined several times by X-ray crystallography, both as the anhydrous[8] and monohydrated forms.[9] The structures are very similar, consisting of a planar molecule, including the amino group.

Uses

5-Aminotetrazole has found applications in heterocyclic chemistry, particularly as a synthon for some multicomponent reactions.[10]

The N-4 is basic as indicated by its binding to metal halides, such as the coordination complex [CoCl2(aminotetrazole)4.[11]

The compound has a particularly high nitrogen content of 80%. Partly for this reason, the compound is prone to decomposition to nitrogen gas (N2). It has been widely investigated for gas-generating systems, such as airbags and blowing agents.[12]

References