3-Chloro-5-methylpyrazin-2-amine: Handling & Use Protocol

3-Chloro-5-methylpyrazin-2-amine is a chlorinated heterocyclic amine building block widely employed in medicinal chemistry and drug discovery as a versatile pyrazine scaffold for the synthesis of biologically active compounds.

Product Name

3-Chloro-5-methylpyrazin-2-amine

SKU

C195628

Molecular Formula

C5H6ClN3

Molecular Weight

143.57 g/mol

Core Structure

Pyrazine ring with 2-amino, 3-chloro, and 5-methyl substituents

Primary Application

Heterocyclic building block for medicinal chemistry synthesis

Recommended Storage

Cool, dry place; away from light and moisture

Materials and Safety Precautions

Before working with 3-Chloro-5-methylpyrazin-2-amine (Aladdin SKU: C195628), ensure that a current Safety Data Sheet (SDS) has been consulted. This compound contains a reactive aryl chloride and a primary amine group; appropriate personal protective equipment (PPE) must be worn at all times, including chemical-resistant gloves, a laboratory coat, and safety glasses.

Work should be performed in a well-ventilated fume hood. Avoid inhalation of dust or vapors and contact with skin, eyes, and clothing. Keep the compound away from strong oxidizers, strong acids, and strong bases. All waste materials must be disposed of in accordance with local institutional and governmental regulations for halogenated organic compounds.

Required materials:

• 3-Chloro-5-methylpyrazin-2-amine (C195628, Aladdin Scientific)
• Analytical balance (±0.1 mg sensitivity)
• Appropriate anhydrous organic solvent (DMSO, DMF, ethanol, or dichloromethane as required)
• Amber glass vials or screw-cap vessels
• Desiccant (e.g., silica gel or molecular sieves)
• PPE: nitrile gloves, lab coat, safety glasses

Stock Solution Preparation

3-Chloro-5-methylpyrazin-2-amine is a solid at room temperature. Its solubility is highest in polar aprotic solvents such as DMSO and DMF; moderate solubility is observed in ethanol and dichloromethane. Aqueous solubility is limited and should be assessed empirically for each intended application.

Protocol for stock solution preparation:

1. Allow the sealed container to equilibrate to room temperature before opening to prevent condensation on the solid.
2. Accurately weigh the required amount of compound using a calibrated analytical balance in the fume hood.
3. Transfer the weighed compound to a clean, dry amber vial.
4. Add the appropriate volume of anhydrous solvent (DMSO is recommended as a first choice for general use) to achieve the desired concentration (e.g., 10–100 mM for biological screening; higher concentrations for synthetic stock solutions).
5. Vortex or sonicate gently (30–60 seconds) until complete dissolution is confirmed visually.
6. If a clear solution is not obtained, warm gently to 40–50 °C in a water bath and re-vortex. Do not exceed 60 °C.
7. Label the vial clearly with compound name, SKU, concentration, solvent, preparation date, and operator initials.
8. Aliquot into single-use volumes to minimize freeze-thaw cycles and store under inert atmosphere (argon or nitrogen) if long-term stability is required.

Note: Molecular weight = 143.57 g/mol. To prepare a 10 mM stock in 1 mL DMSO, dissolve 1.436 mg of compound.

Synthetic Applications and Reaction Guidance

3-Chloro-5-methylpyrazin-2-amine serves as a multifunctional building block in synthetic organic and medicinal chemistry. The compound offers three distinct sites for chemical elaboration:

• C-3 Aryl Chloride: Participates in palladium-catalyzed cross-coupling reactions (e.g., Suzuki-Miyaura, Buchwald-Hartwig amination, Negishi, and Stille couplings) to introduce aryl, heteroaryl, or amino substituents at the 3-position.
• C-2 Primary Amine: Amenable to acylation, sulfonylation, reductive amination, and condensation reactions to form amides, sulfonamides, and imines.
• C-5 Methyl Group: Can be functionalized via radical or directed metalation strategies for further chain elongation.

General guidance for cross-coupling at C-3:

1. Combine 3-Chloro-5-methylpyrazin-2-amine with the appropriate boronic acid or amine nucleophile in a suitable solvent (e.g., dioxane/water for Suzuki coupling).
2. Add palladium catalyst (e.g., Pd(PPh3)4 or Pd(dppf)Cl2) and base (e.g., K2CO3 or Cs2CO3) under inert atmosphere.
3. Heat the reaction mixture at 80–100 °C for 4–16 hours; monitor by TLC or LC-MS.
4. Upon completion, cool to room temperature, dilute with ethyl acetate, wash with water and brine, dry over anhydrous Na2SO4, and concentrate under reduced pressure.
5. Purify the product by column chromatography or recrystallization as appropriate.

Reaction conditions should be optimized for each specific transformation. The above guidance represents typical starting conditions only.

Storage, Stability, and Quality Control

Storage conditions: Store 3-Chloro-5-methylpyrazin-2-amine in a tightly sealed container in a cool (2–8 °C or as indicated on the product label), dry location, protected from light and moisture. The primary amine functionality may be susceptible to oxidation and reaction with atmospheric CO2 over extended periods; storage under inert gas is recommended for long-term archiving.

Stability considerations:

• Solid material: Expected to be stable for at least 12 months when stored as directed. Verify with product certificate of analysis (CoA).
• DMSO stock solutions: Stable for up to 6 months at −20 °C when protected from light and sealed under inert gas; avoid repeated freeze-thaw cycles.
• Aqueous solutions: Not recommended for long-term storage due to potential hydrolysis of the aryl chloride under acidic or basic conditions.

Quality control checks before use:

1. Inspect the material visually; it should appear as a uniform solid (typical appearance: off-white to light yellow powder or crystals).
2. Compare the batch Certificate of Analysis (CoA) against the claimed purity specification.
3. If purity is critical, confirm identity by 1H NMR (characteristic aromatic/pyrazine ring proton signals) and purity by HPLC prior to use in sensitive applications.
4. Record lot number and CoA data in the laboratory notebook.

Troubleshooting

The following guidance addresses common issues encountered when working with 3-Chloro-5-methylpyrazin-2-amine:

Problem	Probable Cause	Recommended Action
Incomplete dissolution	Insufficient solvent volume or incorrect solvent choice	Increase solvent volume; switch to DMSO or DMF; apply gentle warming (max 50 °C)
Poor coupling yield	Catalyst deactivation, insufficient base, moisture ingress	Use freshly prepared catalyst; ensure anhydrous/inert conditions; increase base equivalents
Compound discoloration	Oxidation of amine or moisture exposure	Check CoA; if purity is compromised, re-purify by column chromatography before use
Solution precipitation on dilution	Aqueous incompatibility of DMSO stock	Limit DMSO to ≤1% v/v in aqueous assays; use co-solvents such as PEG400 or Cremophor if needed
Unexpected by-products	Reaction at amine site under harsh conditions	Use milder conditions or protect the amine (e.g., Boc group) before performing reactions at C-3

Frequently asked questions

What solvents are recommended for dissolving 3-Chloro-5-methylpyrazin-2-amine?

DMSO and DMF are the preferred solvents due to the compound's high solubility in polar aprotic media. Ethanol and dichloromethane offer moderate solubility and are suitable for many synthetic applications. Aqueous solubility is limited; any aqueous formulation should be prepared fresh and used promptly.

How should 3-Chloro-5-methylpyrazin-2-amine be stored to maintain stability?

The solid compound should be stored in a tightly sealed container at 2–8 °C (or as specified on the product label), protected from light and moisture. For long-term storage of stock solutions, maintain at −20 °C under inert gas and avoid repeated freeze-thaw cycles. Always consult the product Certificate of Analysis for lot-specific storage recommendations.

Which cross-coupling reactions can be performed using the C-3 chloro substituent?

The aryl chloride at C-3 is compatible with a range of palladium-catalyzed cross-coupling reactions, including Suzuki-Miyaura (with aryl/heteroaryl boronic acids), Buchwald-Hartwig amination (with primary or secondary amines), Negishi coupling (with organozinc reagents), and Stille coupling (with organotin reagents). Reaction conditions, including catalyst, base, solvent, and temperature, should be optimized for each specific transformation.

How do I calculate the amount of compound needed to prepare a specific stock solution concentration?

Use the formula: mass (mg) = concentration (mM) × volume (mL) × molecular weight (g/mol) ÷ 1000. For 3-Chloro-5-methylpyrazin-2-amine (MW = 143.57 g/mol), to prepare 1 mL of a 10 mM stock solution, dissolve 1.436 mg of compound in the chosen solvent.

Is 3-Chloro-5-methylpyrazin-2-amine suitable for use in biological assays?

This compound is primarily a synthetic building block for medicinal chemistry applications. If used directly in biological assays, researchers should prepare fresh stock solutions, minimize DMSO content in final assay wells (typically ≤0.1–1% v/v), include appropriate vehicle controls, and verify that the compound does not interfere with the assay readout. Consult relevant literature for specific biological activity data.

References

1. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (General reference for heterocyclic chemistry and cross-coupling reactions.)
2. Johansson Seechurn, C. C. C.; Kitching, M. O.; Colacot, T. J.; Snieckus, V. Palladium-Catalyzed Cross-Coupling: A Historical Contextual Perspective to the 2010 Nobel Prize. Angew. Chem. Int. Ed. 2012, 51, 5062–5085. doi:10.1002/anie.201107017
3. Aladdin Scientific Product Certificate of Analysis, 3-Chloro-5-methylpyrazin-2-amine, SKU C195628. (Consult current batch CoA for lot-specific purity and physical data.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.