Iodine azide () is an explosive inorganic compound, which in ordinary conditions is a yellow solid. Formally, it is an inter-

pseudohalogen Pseudohalogens are polyatomic analogues of halogens, whose chemistry, resembling that of the true halogens, allows them to substitute for halogens in several classes of chemical compounds. Pseudohalogens occur in pseudohalogen molecules, inorganic ...

Preparation

Iodine azide can be prepared from the reaction between silver azide and elemental iodine: : Since silver azide can only be handled safely while moist, but even small traces of water cause the iodine azide to decompose, this synthesis is done by suspending the silver azide in dichloromethane and adding a drying agent before reaction with the iodine. In this way, a pure solution of iodine azide results, which can then be carefully evaporated to form needle-shaped golden crystals. This reaction was used in the original synthesis of iodine azide in 1900, where it was obtained as unstable solutions in ether and impure crystals contaminated by iodine. Iodine azide can also be generated ''in situ'' by reacting

iodine monochloride Iodine monochloride is an interhalogen compound with the formula . It is a red-brown chemical compound that melts near room temperature. Because of the difference in the electronegativity of iodine and chlorine, this molecule is highly polar an ...

and sodium azide under conditions where it is not explosive.

Properties

In the solid state, iodine azide exists as a one-dimensional polymeric structure, forming two polymorphs, both of which crystallize in an orthorhombic lattice with the

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

''Pbam''. The gas phase exists as monomeric units. Iodine azide exhibits both high reactivity and comparative stability, consequences of the polarity of the I–N bond. The group introduced by substitution with iodine azide can frequently undergo subsequent reactions due to its high energy content. The isolated compound is strongly shock- and friction-sensitive. Its explosivity has been characterized as follows: These values lie significantly lower in comparison to classical explosives like

TNT Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...

RDX RDX (abbreviation of "Research Department eXplosive") or hexogen, among other names, is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a ...

, and also to acetone peroxide. Dilute solutions (< 3%) of the compound in dichloromethane can be handled safely.

Uses

Despite its explosive character, iodine azide has many practical uses in chemical synthesis. Similar to

bromine azide Bromine azide is an explosive inorganic compound with the formula . It has been described as a crystal or a red liquid at room temperature. It is extremely sensitive to small variations in temperature and pressure, with explosions occurring at Δp ...

, it can add across an alkene double bond via both ionic and radical mechanisms, giving ''anti'' stereoselectivity. Addition of to an alkene followed by reduction with lithium aluminium hydride is a convenient method of

aziridine Aziridine is an organic compound consisting of the three-membered heterocycle . It is a colorless, toxic, volatile liquid that is of significant practical interest. Aziridine was discovered in 1888 by the chemist Siegmund Gabriel. Its derivati ...

synthesis.

Azirine Azirines are three-membered heterocyclic unsaturated (i.e. they contain a double bond) compounds containing a nitrogen atom and related to the saturated analogue aziridine. They are highly reactive yet have been reported in a few natural products s ...

s can also be synthesized from the addition product by adding base to eliminate HI, giving a vinyl azide which undergoes

thermolysis Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is req ...

to form an

azirine Azirines are three-membered heterocyclic unsaturated (i.e. they contain a double bond) compounds containing a nitrogen atom and related to the saturated analogue aziridine. They are highly reactive yet have been reported in a few natural products s ...

. Further radical modes of reactivity include radical substitutions on weak C-H bonds to form α‐azido ethers, benzal acetals, and aldehydes, and the conversion of

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

s to acyl azides.

External links

Raman spectrum of iodine azide

References

{{Azides Iodine compounds Azido compounds Explosive polymers Inorganic polymers Pseudohalogens