Introduction
Pyrazinecarbonitrile (also written 2-cyanopyrazine, pyrazinonitrile or pyrazine-2-carbonitrile, CAS 19847-12-2) is a heterocyclic nitrile built on a pyrazine ring. At room temperature it is a colorless liquid and a compact, high-purity building block for pharmaceutical, agrochemical and specialty chemical synthesis. The nitrile group can be converted into amides, amidines, carboxylic acids, esters and amines, while the pyrazine ring supplies a 1,4-diazine scaffold found in many bioactive molecules.
Chemical and Physical Properties
Pyrazinecarbonitrile is a pyrazine ring carrying a single cyano group at the 2-position. The electron-poor diazine ring and the strongly electron-withdrawing nitrile make the molecule both a useful electrophile and a convenient handle for further functionalisation.
| Property | Value |
|---|---|
| CAS number | 19847-12-2 |
| Molecular formula | C5H3N3 |
| Molecular weight | 105.10 g/mol |
| Appearance | Colorless liquid |
| Chemical family | Heterocyclic nitrile (pyrazine) |
| SMILES | C1=CN=C(C=N1)C#N |
The two ring nitrogens lower the basicity of the ring relative to pyridine and make the ring resistant to electrophilic substitution, so chemistry on pyrazinecarbonitrile generally takes place on the nitrile group or through directed metalation rather than by aromatic substitution.
The Pyrazinamide Connection
Pyrazinecarbonitrile is closely related to pyrazinamide, a first-line antitubercular drug. It is the nitrile analogue of pyrazinamide (the carboxamide) and is controlled as a known process impurity (listed as Pyrazinamide EP Impurity B) in the manufacture and quality control of the drug. That relationship keeps steady demand for the material both as a synthetic intermediate and as an analytical reference standard.
Production and Synthetic Routes
Pyrazinecarbonitrile is produced by installing a nitrile group on the pyrazine ring. The most common routes start from a simple pyrazine and apply cyanation or dehydration chemistry:
- Cyanation of a halopyrazine. Displacement of chlorine from 2-chloropyrazine with a cyanide source – often under transition-metal catalysis – gives the nitrile directly.
- Ammonoxidation and oxidative routes. A methyl group on the ring (from 2-methylpyrazine) can be oxidised and converted to the nitrile over a catalyst.
- Dehydration of the amide. Pyrazine-2-carboxamide can be dehydrated to the nitrile with a dehydrating agent, a convenient route when the amide is already on hand.
The crude product is purified by distillation to remove water and residual starting material, which is why GC purity and moisture are the parameters most often written into the specification.
Reactivity of the Nitrile Group
Most downstream chemistry exploits the nitrile while tolerating the ring:
- Hydrolysis to pyrazine-2-carboxamide or pyrazine-2-carboxylic acid.
- Addition of alcohols or amines to give imidates, amidines and related intermediates.
- Reduction to the primary amine, a common entry point to further heterocyclic elaboration.
- Cycloaddition and coupling chemistry that builds larger pyrazine-containing frameworks.
Because the nitrile carbon is electrophilic, these steps usually run under controlled conditions with an acid or base catalyst, and the product is isolated by crystallisation or distillation.
Major Industrial Applications
Pharmaceuticals
Pyrazinecarbonitrile is used to build pyrazine-containing active pharmaceutical ingredients and to prepare reference impurities for pyrazinamide. The nitrile is a convenient precursor to amide, amidine and amine pharmacophores found in anti-infective and other drug classes.
Agrochemicals
In agrochemistry the pyrazine scaffold appears in fungicides, herbicides and plant-health actives, and pyrazinecarbonitrile serves as a compact starting material for these heterocyclic cores.
Specialty and Functional Chemicals
The nitrile group is also used to attach chelating or coordinating groups to a pyrazine core, giving ligands and functional building blocks for coordination and materials chemistry.
Quality and Specifications
Commercial pyrazinecarbonitrile is sold against a small set of parameters. The grade below is typical for fine-chemical use.
| Parameter | Specification |
|---|---|
| Appearance | Colorless liquid |
| Purity (GC) | 99.9% min |
| Moisture (K.F) | 0.1% max |
| Molecular formula | C5H3N3 |
| Molecular weight | 105.10 g/mol |
High GC purity and low moisture are important when the material is used as an analytical reference or in moisture-sensitive reactions. Detailed information on grades, packaging and documentation is collected in the pyrazinecarbonitrile buying guide, and the downstream chemistry is covered in the companion article on pyrazinecarbonitrile in pharmaceutical and agrochemical synthesis.
Handling, Safety and Storage
Pyrazinecarbonitrile is a nitrile and should be treated with care. Nitriles can release hydrogen cyanide on contact with strong acids or through certain decomposition pathways, so the material is handled with appropriate personal protective equipment, in well-ventilated areas, and away from strong acids, bases, oxidants and heat. Store it cool and dry in a tightly closed container. Always consult the current safety data sheet for detailed guidance.
Frequently Asked Questions about Pyrazinecarbonitrile
What is pyrazinecarbonitrile used for?
It is used mainly as a fine-chemical intermediate to build pyrazine-containing pharmaceuticals and agrochemicals, and as a reference impurity for pyrazinamide analysis.
Is pyrazinecarbonitrile a liquid or a solid?
It is a colorless liquid at room temperature, typically supplied at 99.9% min GC purity with 0.1% max moisture.
How is pyrazinecarbonitrile produced?
Industrially it is made by installing a nitrile group on a pyrazine ring – for example by cyanating 2-chloropyrazine or converting 2-methylpyrazine – followed by distillation purification.
Where can I buy pyrazinecarbonitrile?
PolyBlueChem supplies pyrazinecarbonitrile (CAS 19847-12-2) with COA and MSDS. Contact our team for specifications, packaging and a quotation.
References
- PubChem Compound Summary for pyrazinecarbonitrile (CAS 19847-12-2).
- Manufacturer specification sheets for fine-chemical-grade pyrazinecarbonitrile.
- Pharmacopoeial impurity monograph for pyrazinamide (Pyrazinamide EP Impurity B).
Disclaimer: This article is provided for general informational purposes only and does not constitute technical, regulatory or safety advice. Always refer to the current safety data sheet and applicable regulations before handling this material.
PolyBlueChem, as the chemical supplier of all categories, is the supplier of pyrazinecarbonitrile (CAS 19847-12-2) as well. Contact our team for specifications, packaging and a quotation.