3-Amino-5-methoxyisonicotinic Acid: Handling & Use Protocol

3-Amino-5-methoxyisonicotinic acid is a functionalized pyridine-3-carboxylic acid building block bearing both a free amino group and a methoxy substituent, making it a versatile intermediate for medicinal chemistry, heterocyclic synthesis, and pharmaceutical research.

Chemical Name

3-Amino-5-methoxyisonicotinic acid

SKU

A186783

Molecular Formula

C₇H₈N₂O₃

Molecular Weight

168.15 g/mol

Core Scaffold

Pyridine-3-carboxylic acid (isonicotinic acid) derivative

Key Functional Groups

Primary amine (–NH₂), methoxy ether (–OCH₃), carboxylic acid (–COOH)

Typical Application

Pharmaceutical intermediate, heterocyclic building block, ligand synthesis

Compound Overview and Properties

3-Amino-5-methoxyisonicotinic acid (Aladdin SKU: A186783) is a bifunctional pyridine carboxylic acid derivative. Its molecular formula is C₇H₈N₂O₃ with a molecular weight of approximately 168.15 g/mol. The compound features three reactive handles: a carboxylic acid at the 4-position (isonicotinic acid numbering), a primary aromatic amine at the 3-position, and a methoxy group at the 5-position of the pyridine ring.

The presence of the amino and carboxylic acid groups renders this compound amphoteric. It is expected to exhibit limited solubility in non-polar organic solvents, moderate solubility in polar aprotic solvents such as DMSO and DMF, and improved solubility in dilute aqueous base or acid. The methoxy group at position 5 modulates the electron density of the ring, influencing reactivity at both the amine and carboxylate sites.

Note: Confirm exact physicochemical data (melting point, solubility values, pKa) from the certificate of analysis (CoA) supplied with the product lot, as these may vary slightly between batches.

Materials and Safety Requirements

Required materials:

• 3-Amino-5-methoxyisonicotinic acid (A186783)
• Appropriate solvent: anhydrous DMSO, DMF, or dilute aqueous NaOH (0.1 M) for stock solution preparation
• Analytical balance (0.01 mg readability recommended)
• Volumetric glassware (class A) or calibrated micropipettes
• Amber glass vials or polypropylene microtubes for storage
• Inert atmosphere supply (argon or nitrogen) if long-term storage of solutions is required

Personal Protective Equipment (PPE):

• Chemical-resistant gloves (nitrile, minimum 0.1 mm thickness)
• Laboratory coat and eye protection (safety goggles)
• Work in a well-ventilated fume hood when handling powders to avoid inhalation of fine particulates

Safety notes: Consult the Safety Data Sheet (SDS) for A186783 before use. As with most aromatic amine-containing compounds, handle with appropriate caution. Dispose of waste in accordance with local institutional and governmental regulations.

Step-by-Step Protocol: Stock Solution Preparation

The following procedure describes preparation of a 10 mM stock solution in DMSO, which is suitable for most biochemical and synthetic screening applications. Adjust concentration as required by your experimental design.

1. Equilibrate the reagent: Allow the sealed vial of A186783 to reach room temperature (approximately 20–25 °C) before opening. This prevents moisture condensation onto the hygroscopic solid.
2. Weigh accurately: Tare a clean, dry microcentrifuge tube on the analytical balance. Carefully transfer the required mass of 3-Amino-5-methoxyisonicotinic acid. For a 10 mM, 1 mL stock, weigh approximately 1.68 mg (MW ≈ 168.15 g/mol).
3. Add solvent: Add anhydrous DMSO in a volume slightly less than the target final volume (e.g., 0.9 mL). Cap the tube immediately to minimise moisture exposure.
4. Dissolve: Vortex for 30–60 seconds. If complete dissolution is not achieved, sonicate in a water bath sonicator for 5–10 minutes at room temperature. Avoid excessive heat (>40 °C).
5. Adjust to final volume: Once dissolved, add DMSO to reach the exact target volume (1.0 mL) and mix thoroughly.
6. Verify dissolution: Visually inspect for complete clarity. If particulates remain, centrifuge at 5,000 × g for 2 minutes and use the supernatant, or consider switching to DMF or dilute aqueous base.
7. Aliquot and label: Divide into single-use aliquots in amber vials. Label with compound name, SKU (A186783), concentration, solvent, date of preparation, and preparer's initials.
8. Store: Store aliquots at −20 °C under inert atmosphere (argon or nitrogen headspace) protected from light. Avoid repeated freeze-thaw cycles.

Alternative aqueous dissolution: If an aqueous stock is required, dissolve in a minimum volume of 0.1 M NaOH(aq), then dilute with phosphate-buffered saline (PBS, pH 7.4) to the target concentration. Note that alkaline conditions may affect stability over extended periods; use freshly prepared aqueous solutions where possible.

Applications in Synthesis and Research

3-Amino-5-methoxyisonicotinic acid serves as a multifunctional building block owing to its three distinct reactive sites. Representative application areas include:

• Amide bond formation: The carboxylic acid can be activated (e.g., via HATU, EDC/NHS, or acid chloride formation) to couple with amines, enabling construction of amide-linked heterocyclic scaffolds relevant to kinase inhibitor and antimicrobial drug design.
• Diazotisation and cross-coupling: The primary aromatic amine can be diazotised under standard conditions (NaNO₂, HCl, 0–5 °C) and subsequently used in Sandmeyer reactions or azo-coupling chemistry to introduce halogens or azo linkages.
• Condensation reactions: The amino group can participate in condensation with carbonyl compounds (aldehydes, ketones, acyl chlorides) to form imines, amides, or heterocyclic ring systems (e.g., benzimidazoles, quinazolinones) depending on reaction partner.
• Metal complex and ligand synthesis: The pyridine nitrogen, amino group, and carboxylate provide multiple coordination sites, making this compound of interest in the preparation of metal complexes for catalysis or bioinorganic research.
• Pharmaceutical intermediate: As a substituted isonicotinic acid, this compound belongs to a class of heterocycles widely explored in the development of antitubercular, antimicrobial, and kinase-modulating agents.

Researchers should optimise reaction conditions (solvent, temperature, equivalents, base/acid) empirically for each specific transformation, as the combination of electron-donating methoxy and amino substituents will influence the reactivity of the ring and substituents.

Storage, Stability, and Quality Control

Recommended storage conditions: Store the neat solid at 2–8 °C (refrigerator) in a tightly sealed container, protected from light and moisture. For longer-term storage, −20 °C is recommended. Always allow the container to equilibrate to room temperature before opening to prevent condensation.

Stability considerations: Aromatic amines can be susceptible to oxidative degradation and photo-oxidation. The carboxylic acid functionality is generally stable under ambient conditions. Monitor the solid for any colour change (e.g., darkening), which may indicate degradation. Solutions in DMSO should be used within 1–3 months when stored at −20 °C; aqueous solutions should ideally be prepared fresh.

Quality control checks before use:

• Review the Certificate of Analysis (CoA) for purity (typically reported by HPLC and/or NMR), identity (NMR, MS), and appearance.
• For critical applications, confirm identity by ¹H NMR in d₆-DMSO, checking for characteristic aromatic proton signals of the aminomethoxypyridine system and the broad NH₂ singlet.
• Confirm purity by reverse-phase HPLC (C18 column, water/acetonitrile gradient with 0.1% TFA) if independent verification is required.

Disposal: Dispose of all waste material in accordance with institutional chemical waste management procedures and applicable local regulations.

Frequently asked questions

What solvents are recommended for dissolving 3-Amino-5-methoxyisonicotinic acid?

DMSO and DMF are the preferred solvents for preparing stock solutions of this compound, offering good solubility for most downstream applications. For aqueous systems, dissolution in a minimum volume of dilute NaOH (0.1 M) followed by dilution with PBS (pH 7.4) is recommended. Solubility in non-polar solvents such as hexane or diethyl ether is expected to be very low.

How should the primary amine group be protected during carboxylic acid activation reactions?

When selectively activating the carboxylic acid of 3-Amino-5-methoxyisonicotinic acid, the primary amine should be transiently protected to avoid side reactions such as self-condensation or intramolecular cyclisation. Standard amine protecting groups suitable for aromatic amines include Boc (tert-butyloxycarbonyl, removed with TFA) and Cbz (benzyloxycarbonyl, removed by hydrogenolysis). The choice of protecting group should be guided by the stability requirements of the overall synthetic sequence. Consult relevant synthetic chemistry literature for optimised conditions.

What are the recommended storage conditions and expected shelf life for A186783?

The neat solid should be stored at 2–8 °C in a sealed, light-protected container; for long-term storage, −20 °C is advisable. DMSO stock solutions stored at −20 °C under inert atmosphere are expected to be stable for 1–3 months, provided freeze-thaw cycles are minimised. Always verify compound integrity by checking the CoA and, for critical work, by independent analytical methods (HPLC, NMR) prior to use. Specific shelf-life data should be confirmed from the product CoA or by contacting Aladdin Scientific technical support.

Is 3-Amino-5-methoxyisonicotinic acid suitable for biological assays, and what DMSO tolerance should I consider?

This compound can be used as a starting material or reference intermediate in biological screening contexts when appropriately formulated. When preparing working solutions from a DMSO stock, ensure the final DMSO concentration in the assay does not exceed 0.1–1% (v/v), as higher concentrations may affect cell viability or enzyme activity depending on the biological system. Always include a vehicle control (DMSO alone at the same final concentration) in assay design. Confirm biological compatibility and any cytotoxicity data independently before use in cellular assays.

References

1. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (General reference for functional group reactivity and protecting group strategies.)
2. Wuts, P. G. M.; Greene, T. W. Greene's Protective Groups in Organic Synthesis, 4th ed.; Wiley-Interscience: Hoboken, NJ, 2007. (Reference for amine protection strategies applicable to aromatic amines.)
3. Aladdin Scientific. Certificate of Analysis, 3-Amino-5-methoxyisonicotinic acid, SKU A186783. (Consult the specific lot CoA for purity, identity, and physicochemical data.)

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