Abstract
CAS NO.288-94-8 refers to 1H-Tetrazole, a five-membered heterocyclic compound with the molecular formula CH₂N₄. This article explores the fundamental chemical properties, synthesis pathways, pharmaceutical applications, and safety protocols associated with this versatile building block. Key topics include its role as a bioisostere for carboxylic acids, its function as a coupling reagent in oligonucleotide synthesis, and its growing demand in drug development. Common questions regarding storage, handling, and regulatory classifications are addressed, providing a practical reference for researchers and industry professionals working with this compound.
Table of Contents
- What Is the Chemical Identity of 1H-Tetrazole and Why Does It Matter?
- How Is 1H-Tetrazole Synthesized and What Are the Key Production Considerations?
- Where Is 1H-Tetrazole Most Commonly Applied in Pharmaceutical and Biotech Research?
- What Safety and Handling Protocols Apply to 1H-Tetrazole?
- What Role Does 1H-Tetrazole Play in Oligonucleotide Therapeutics?
- Frequently Asked Questions
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What Is the Chemical Identity of 1H-Tetrazole and Why Does It Matter?
Understanding the chemical identity of a compound is the first step toward appreciating its role in modern science. 1H-Tetrazole, registered under CAS NO.288-94-8, is a nitrogen-rich heterocycle that has earned a distinguished position in organic chemistry and pharmaceutical development.
Molecular Architecture
The compound consists of a five-membered ring containing four nitrogen atoms and one carbon atom. This arrangement creates a planar, aromatic system that is both electron-deficient and remarkably stable under ambient conditions. The molecular formula CH₂N₄ corresponds to a molecular weight of 70.05 g/mol, making it one of the lightest heterocyclic scaffolds used in medicinal chemistry.
| Property | Value | Significance |
|---|---|---|
| Molecular Formula | CH₂N₄ | High nitrogen content enables diverse reactivity |
| Molecular Weight | 70.05 g/mol | Low mass favors efficient synthetic incorporation |
| Melting Point | 156–158 °C | Crystalline solid, stable at room temperature |
| Boiling Point | 220 °C | Decomposes at elevated temperatures |
| Density | 0.798 g/mL at 20 °C | Lightweight crystalline material |
| pKa | 4.9 at 25 °C | Weakly acidic; enables proton transfer in coupling reactions |
| Water Solubility | Soluble | Facilitates aqueous processing in biological systems |
| Appearance | White to light-yellow crystalline powder | Practical indicator of purity and handling conditions |
The pKa value of 4.9 is particularly noteworthy. It places 1H-Tetrazole in a range that allows it to function as an effective proton donor under mild conditions, which is essential for its catalytic role in phosphoramidite chemistry.
Bioisosteric Significance
One of the most compelling reasons researchers seek out 1H-Tetrazole is its ability to serve as a bioisostere for the carboxylate group. This means it can replace a carboxylic acid moiety in a drug molecule while preserving or even enhancing the desired biological activity. Unlike carboxylic acids, which can be metabolically labile and prone to rapid clearance, tetrazole-containing compounds often exhibit improved metabolic stability and altered lipophilicity profiles. This property has made 1H-Tetrazole a valuable scaffold in the design of enzyme inhibitors, receptor antagonists, and other pharmacologically active agents.
Synonyms and Registry Information
- 1H-1,2,3,4-Tetrazole: Systematic name reflecting hydrogen position
- 2H-Tetrazole: Tautomeric form commonly encountered in solution
- Tetraazacyclopentadiene: Descriptive name highlighting ring composition
- 1,2,3,4-Tetrazole: Simplified ring numbering
The compound carries the EC number 206-023-4 and the RTECS designation UW7370000. These identifiers enable regulatory bodies and safety professionals to track the substance across international databases and compliance frameworks.
How Is 1H-Tetrazole Synthesized and What Are the Key Production Considerations?
The synthesis of 1H-Tetrazole presents unique challenges due to the high nitrogen content and energetic nature of the resulting ring system. Industrial and laboratory-scale production methods must balance yield efficiency with rigorous safety controls.
Common Synthetic Routes
The most widely employed laboratory synthesis proceeds through the reaction of sodium azide with hydrogen cyanide or a suitable nitrile precursor under controlled conditions. Alternative routes involve the cyclization of hydrazine derivatives with nitrous acid or the thermal decomposition of metal azide complexes. Each pathway carries distinct advantages and limitations regarding scalability, cost, and safety profile.
- Azide-nitrile cycloaddition: This approach offers high atom economy and is frequently used for laboratory-scale preparation. Strict temperature control is essential to prevent runaway reactions.
- Hydrazine-based cyclization: Provides access to substituted tetrazoles with defined regiochemistry, though the use of hydrazine introduces its own handling requirements.
- Metal-catalyzed routes: Emerging methodologies employ transition metal catalysts to facilitate tetrazole formation under milder conditions, reducing energy input and improving selectivity.
Commercial production typically involves the reaction of sodium azide with triethyl orthoformate or related orthoesters, followed by acidification to liberate the free tetrazole. The product is then purified through recrystallization or sublimation to achieve the high purity levels required for pharmaceutical applications.
Purity and Quality Specifications
For research and pharmaceutical use, 1H-Tetrazole is typically supplied with purity specifications of 98% or higher. The compound may be provided as a crystalline solid or as a standardized solution in acetonitrile, commonly at concentrations of 0.45 M or 3–4% by weight. Solution formulations offer convenience for automated oligonucleotide synthesizers, where precise delivery of the activator is critical for coupling efficiency.
| Form | Typical Specification | Application Context |
|---|---|---|
| Crystalline Solid | ≥98% purity | General organic synthesis, reference standards |
| Acetonitrile Solution | 0.45 M concentration | DNA/RNA synthesizer activator |
| Acetonitrile Solution | 3–4% w/w | Large-scale oligonucleotide production |
| Sublimed Grade | ≥99% purity | Specialized applications requiring ultra-high purity |
Where Is 1H-Tetrazole Most Commonly Applied in Pharmaceutical and Biotech Research?
Few heterocyclic scaffolds enjoy the breadth of application that 1H-Tetrazole commands. Its presence spans from the synthesis of blockbuster drugs to the production of life-saving oligonucleotide therapeutics.
Pharmaceutical Intermediate Role
The compound serves as a critical intermediate in the manufacture of several marketed pharmaceuticals. One notable example is cenobamate, an antiepileptic agent approved for the treatment of partial-onset seizures. The tetrazole moiety contributes to the drug's pharmacological profile by modulating its interaction with sodium channels. Beyond cenobamate, 1H-Tetrazole appears in the synthetic routes for antihypertensive agents, angiotensin II receptor blockers, and various enzyme inhibitors.
Oligonucleotide Synthesis
In the biotechnology sector, 1H-Tetrazole is indispensable as a coupling reagent for the preparation of polynucleotides. During solid-phase oligonucleotide synthesis, the tetrazole derivative acts as an activator, facilitating the coupling of phosphoramidite monomers to the growing oligonucleotide chain. This reaction is fundamental to the production of antisense oligonucleotides, siRNA therapeutics, and CRISPR guide RNAs.
The demand for 1H-Tetrazole in this application has grown substantially as the oligonucleotide therapeutics market has expanded. Companies manufacturing these advanced therapies rely on consistent, high-purity activator solutions to maintain coupling efficiencies above 99% per step, which is essential for producing full-length oligonucleotide sequences.
Material Science and Beyond
- Energetic materials: The high nitrogen content makes tetrazole derivatives attractive candidates for propellants and gas generants, though safety considerations limit widespread use.
- Metal-organic frameworks: Tetrazole-based ligands contribute to the construction of porous coordination polymers with potential applications in gas storage and catalysis.
- Agrochemical development: The scaffold appears in the design of novel pesticides and herbicides, where its metabolic stability is advantageous.
- Diagnostic imaging: Tetrazole-containing compounds are explored as ligands for positron emission tomography tracers.
What Safety and Handling Protocols Apply to 1H-Tetrazole?
Proper handling of 1H-Tetrazole is non-negotiable. The compound presents both physical and health hazards that require diligent attention to established safety protocols.
Hazard Classification
Under the Globally Harmonized System, 1H-Tetrazole is classified as an explosive substance in Division 1.1, carrying the H201 hazard statement for mass explosion hazard. The compound is also harmful if swallowed (H302) and causes serious eye irritation (H319). When dissolved in acetonitrile, the formulation becomes a flammable liquid, introducing additional fire and vapor hazards.
| Hazard Type | Classification | Required Precaution |
|---|---|---|
| Explosive Properties | Division 1.1, H201 | Keep away from shock, friction, and heat sources |
| Acute Toxicity | Category 4, H302 | Avoid ingestion; use appropriate PPE |
| Eye Irritation | Category 2, H319 | Wear chemical safety goggles |
| Flammability | H225 (solution) | Store away from ignition sources; ground equipment |
Storage and Stability
The crystalline solid should be stored in a cool, dry, and well-ventilated area, away from heat and direct sunlight. Containers must remain tightly sealed to prevent moisture absorption. The compound is stable at room temperature when properly stored, but exposure to elevated temperatures approaching its decomposition point of 220 °C can trigger violent decomposition. Solution formulations in acetonitrile require storage under inert gas and protection from light to maintain integrity.
Personal Protective Equipment
- Chemical safety goggles or a face shield for eye protection
- Nitrile or neoprene gloves for hand protection
- Flame-resistant laboratory coat or apron
- Respiratory protection when handling powder or working in poorly ventilated areas
- Grounding and bonding equipment when transferring solutions
Work with 1H-Tetrazole should be conducted in a fume hood or well-ventilated space. Quantities should be limited to the minimum required for the task, and appropriate spill containment materials should be readily available.
What Role Does 1H-Tetrazole Play in Oligonucleotide Therapeutics?
The therapeutic oligonucleotide field has experienced remarkable growth, and 1H-Tetrazole sits at the center of the manufacturing processes that make these medicines possible.
Mechanism of Activation
During phosphoramidite oligonucleotide synthesis, the coupling step requires activation of the phosphoramidite monomer to facilitate nucleophilic attack by the growing chain's terminal hydroxyl group. 1H-Tetrazole accomplishes this by protonating the diisopropylamino group of the phosphoramidite, converting it into a suitable leaving group. The activated species then reacts rapidly with the hydroxyl group, forming the phosphite triester linkage that defines the oligonucleotide backbone.
Performance Requirements
The efficiency of this coupling reaction directly determines the yield and quality of the final oligonucleotide. Even a small reduction in coupling efficiency compounds across the length of the sequence, resulting in truncated or failed products. Consequently, manufacturers demand 1H-Tetrazole solutions that meet stringent specifications for concentration, water content, and particulate contamination.
| Parameter | Typical Requirement | Impact on Synthesis |
|---|---|---|
| Concentration | 0.45 M ± 0.02 M | Ensures stoichiometric activation |
| Water Content | ≤60 ppm | Prevents hydrolysis of phosphoramidite |
| Particulates | 0.2 μm filtered | Protects synthesizer valves and lines |
| Color | Clear, colorless | Indicator of purity and stability |
Market Context
The global market for 1H-Tetrazole was valued at approximately USD 215.4 million in 2025 and is projected to reach USD 412.7 million by 2034, expanding at a compound annual growth rate of 7.7%. This growth trajectory reflects the increasing number of oligonucleotide-based therapies entering clinical development and the corresponding demand for high-quality synthesis reagents.
Frequently Asked Questions
When appropriate precautions are observed, 1H-Tetrazole can be handled safely in a well-equipped laboratory. The key requirements include working in a fume hood, wearing appropriate personal protective equipment, and minimizing quantities. The compound's explosive classification under GHS means that shock, friction, and heat must be avoided during handling and storage. Solution formulations in acetonitrile reduce the risk of dust generation but introduce flammability concerns that require proper grounding and ventilation.
The crystalline solid is stable at room temperature when kept in a tightly sealed container and protected from moisture and light. No refrigeration is necessary under normal conditions. Solution formulations in acetonitrile should be stored under inert gas at ambient temperature, away from ignition sources and direct sunlight. Prolonged exposure to elevated temperatures should be avoided to prevent decomposition.
The tetrazole ring mimics the spatial and electronic properties of the carboxylate group while offering superior metabolic stability. Carboxylic acids are often subject to rapid conjugation and renal clearance, limiting their duration of action. Tetrazole-containing compounds resist these metabolic pathways, leading to improved pharmacokinetic profiles. Additionally, the tetrazole group is less acidic than carboxylic acids (pKa 4.9 vs. approximately 4.2), which can influence membrane permeability and receptor binding characteristics.
5-Substituted tetrazoles carry a functional group at the carbon atom of the ring, which alters their steric and electronic properties. While unsubstituted 1H-Tetrazole serves primarily as a coupling agent and bioisostere precursor, 5-substituted variants are frequently the final pharmacophore in drug molecules. The synthetic routes to these compounds typically involve the same azide-based cycloaddition chemistry but require different starting nitriles or orthoesters.
Reputable suppliers provide a Certificate of Analysis documenting purity, water content, and analytical method, along with a Safety Data Sheet that details hazard classifications, handling precautions, and first-aid measures. For solution formulations, the SDS should address both the tetrazole component and the acetonitrile solvent. Additional documentation may include a technical data sheet specifying recommended storage conditions and compatibility information.
Yes, 1H-Tetrazole is soluble in water and can participate in aqueous reaction systems. However, the presence of water can interfere with certain applications, particularly in oligonucleotide synthesis where anhydrous conditions are essential. For general organic transformations where water is tolerated, aqueous conditions may offer advantages in terms of cost and environmental impact.
Looking for a reliable supply of high-purity 1H-Tetrazole and related heterocyclic building blocks? Run'an Pharmaceutical delivers consistent quality backed by rigorous analytical testing and responsive technical support.
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