What Is a Tetrazole?
Tetrazole is a heterocyclic aromatic compound with the molecular formula CH2N4. It has a molecular weight of 70.05 and appears as white, plate-like crystals.
This five-membered ring compound, known as an azole when containing nitrogen in the ring, is termed ‘tetrazole’ due to the prefix ‘tetra’ indicating four nitrogen atoms in its structure. It satisfies the Hückel rule, exhibiting aromatic compound properties.
Tetrazole exists in tautomeric forms as 1H-1,2,3,4-tetrazole and 2H-1,2,3,4-tetrazole. These isomers are indistinguishable in solution.
Uses of Tetrazole
1. Automotive Airbag Systems
The tetrazole derivative, 5-aminotetrazole, releases significant amounts of nitrogen gas upon heating or impact. Leveraging this property, it’s utilized as a gas-generating agent in automotive airbag systems, offering a safer alternative to sodium azide gas generators.
2. Electronic Materials
Tetrazole is employed in electronic materials for etching applications, a surface processing technique involving chemical corrosion.
It aids in forming printed circuit boards and semiconductor circuits by etching away insoluble portions from copper foil on substrates. Tetrazole derivatives in etching solutions for silver help prevent excessive etching.
3. Drug Discovery Chemistry
Known for its high lipid solubility and acidity akin to carboxylic acids, tetrazole is used in drug design. Its incorporation into cephem antibiotics and sartan antihypertensives aims to enhance drug bioavailability in lipid-rich biological cells.
4. Other
Additionally, tetrazole plays a role in nucleic acid drug development, particularly in phosphoramidite synthesis for nucleic acid coupling reactions.
Other Information on Tetrazole
1. Properties of Tetrazole
Tetrazole has a melting point of 89-91 °C and a boiling point of 156-158 °C. It is a white, plate-like crystal that can sublimate.
Soluble in water, ethanol, acetone, and acetic acid, but insoluble in ether and benzene, tetrazole’s hydrogen atoms attached to nitrogen can easily release protons, rendering aqueous solutions acidic. Its metal salts, formed by metal substitution, are explosive when heated or subjected to strong impact.
The proton at the nitrogen atom’s position 1 has a pKa of 8.2, as acidic as a carboxylic acid, making it a functional equivalent in certain applications.
Tetrazole may explode under heat or shock.
2. Tetrazole Production Method
Tetrazole is synthesized by reacting hydrogen cyanide (HCN) with hydrogen azide (HN3). Its derivatives are obtained through cycloaddition reactions between nitriles and azide derivatives.
3. Handling of Tetrazole
Storage requires moisture and heat avoidance, with inert gas preservation. It should be kept away from ignition sources and handled carefully to prevent explosion risks.
Protective gloves and eye gear are recommended due to potential skin and eye irritation. In case of contact, rinse thoroughly with water.