2-Chloro-5-fluoro-6-methoxynicotinic Acid: Handling & Use Protocol

2-Chloro-5-fluoro-6-methoxynicotinic acid is a polyfunctional halogenated pyridinecarboxylic acid building block widely employed in medicinal chemistry and pharmaceutical synthesis as a versatile scaffold for the preparation of biologically active compounds.

Product Name

2-Chloro-5-fluoro-6-methoxynicotinic acid

SKU / Catalog Number

C188501

Molecular Formula

C7H5ClFNO3

Molecular Weight

209.57 g/mol

Functional Groups

Carboxylic acid, chloro, fluoro, methoxy on pyridine ring

Primary Application

Pharmaceutical intermediate and medicinal chemistry building block

Recommended Storage

Cool, dry, dark conditions; away from moisture and incompatible materials

Scope and Purpose

This protocol describes the safe receipt, storage, preparation, and use of 2-Chloro-5-fluoro-6-methoxynicotinic acid (Aladdin Scientific SKU C188501) in laboratory settings. The compound is a halogenated, methoxy-substituted pyridine-3-carboxylic acid bearing three distinct reactive or directing substituents — a C-2 chloro group, a C-5 fluoro group, and a C-6 methoxy group — in addition to the carboxylic acid at C-3. This combination of functional groups makes it a valuable polyfunctional building block for the synthesis of structurally complex heterocyclic pharmaceutical intermediates, agrochemical candidates, and other fine-chemical targets.

This document is intended for research scientists, synthetic chemists, and laboratory managers who will handle this compound routinely. All personnel should read the associated Safety Data Sheet (SDS) before commencing work.

Materials, Equipment, and Safety Precautions

Personal Protective Equipment (PPE): Wear appropriate laboratory coat, nitrile gloves, and safety glasses or goggles at all times when handling this compound. Use a chemical fume hood for weighing and dissolution steps to minimize inhalation exposure to fine particulates or solvent vapors.

Recommended Solvents: 2-Chloro-5-fluoro-6-methoxynicotinic acid is expected to show good solubility in polar aprotic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and acetonitrile, as well as in alcohols such as methanol and ethanol. Solubility in water is generally limited for compounds of this class; aqueous solubility may be improved under basic conditions (e.g., dilute NaOH or K2CO3 solution) due to carboxylate salt formation. Solubility should be confirmed empirically for each application.

Incompatibilities: As a carboxylic acid derivative, avoid contact with strong bases, strong oxidizing agents, and reactive amines without appropriate controls. The aryl chloride and aryl fluoride bonds are susceptible to nucleophilic aromatic substitution (SNAr) under forcing or catalyzed conditions; handle reaction mixtures accordingly.

Waste Disposal: Dispose of all waste in accordance with local, institutional, and governmental regulations for halogenated organic waste streams.

Step-by-Step Protocol: Dissolution and Stock Solution Preparation

Step 1 — Receipt and Inspection: Upon receipt, inspect the packaging for integrity. Record the lot number, purity, and any certificate of analysis (CoA) data provided by Aladdin Scientific. Store the unopened material according to label instructions in a cool, dry, well-ventilated area away from light and moisture.

Step 2 — Pre-weighing Equilibration: Allow the container to equilibrate to room temperature before opening, especially if retrieved from cold storage, to prevent condensation of atmospheric moisture onto the compound.

Step 3 — Weighing: Tare an appropriate glass vial or weighing vessel. Using a calibrated analytical balance, weigh the required quantity of 2-Chloro-5-fluoro-6-methoxynicotinic acid (C188501) inside a chemical fume hood. Re-seal the bulk container promptly after use.

Step 4 — Dissolution: Transfer the weighed solid to a clean, dry, appropriately sized glass vessel. Add the chosen solvent (e.g., DMSO for biological assay stock solutions, or DMF for synthetic intermediary solutions) in portions with gentle swirling or stirring to achieve complete dissolution. Confirm clarity of solution before proceeding. If full dissolution is not achieved, warm gently (do not exceed 50 °C) or switch to a higher-polarity solvent.

Step 5 — Concentration Verification: For critical applications, verify the actual concentration by UV-Vis spectrophotometry or other validated analytical method. Calculate the theoretical concentration based on the mass weighed and the molecular weight (209.57 g/mol, to be confirmed against CoA).

Step 6 — Labeling and Storage: Label the stock solution with compound name, SKU (C188501), concentration, solvent, date of preparation, and preparer's initials. Store DMSO stock solutions at −20 °C in aliquots to avoid repeated freeze-thaw cycles. Store DMF solutions at 2–8 °C in sealed containers under inert atmosphere if extended storage is required.

Applications in Synthetic Chemistry

2-Chloro-5-fluoro-6-methoxynicotinic acid serves as a multifunctional scaffold in pharmaceutical and agrochemical synthesis. The key reactive handles include:

• Carboxylic acid (C-3): Can be activated for amide coupling (e.g., using EDC/HOBt, HATU, or T3P reagents) to generate nicotinamide derivatives, which are common pharmacophores in kinase inhibitors and other targeted therapeutics. The acid can also be converted to the corresponding acid chloride, ester, or reduced to the alcohol.
• C-2 Chloro group: Amenable to transition-metal-catalyzed cross-coupling reactions (e.g., Suzuki-Miyaura, Buchwald-Hartwig, Negishi couplings) as well as SNAr displacement with O-, N-, or S-nucleophiles under appropriate conditions.
• C-5 Fluoro group: The strategic placement of fluorine at C-5 modulates the electron density of the ring, influences acidity of the carboxylic acid, and can be exploited in SNAr reactions or retained in the final drug candidate to optimize metabolic stability and membrane permeability.
• C-6 Methoxy group: Provides an additional directing and electronic modulating effect; under forcing conditions the methoxy group can undergo demethylation or SNAr-mediated exchange.

Researchers are encouraged to consult primary literature for specific reaction conditions applicable to this class of substituted nicotinic acids. Reaction optimization should be conducted on small scale before scale-up.

Troubleshooting and Quality Considerations

Poor solubility: If the compound does not dissolve readily in the chosen solvent, switch to DMSO as a universal solvent for stock preparation, then dilute into the working solvent. Sonication in a water bath (room temperature, ≤5 min) may assist dissolution; avoid prolonged heating.

Unexpected reactivity: Because this compound bears multiple electrophilic sites (C-2 Cl, C-5 F), unintended SNAr reactions may occur when nucleophilic solvents or reagents are used at elevated temperatures. Use non-nucleophilic solvents (e.g., THF, dioxane, toluene, DCM) where selectivity is required.

Purity verification: Before use in sensitive assays, verify compound purity by HPLC or NMR. Reference the Certificate of Analysis (CoA) provided with each lot. Contact Aladdin Scientific customer support if purity specifications are not met.

Moisture sensitivity: Although aryl carboxylic acids are generally stable, prolonged exposure to humidity may degrade analytical purity. Always reseal containers under inert atmosphere (N2 or Ar) when handling hygroscopic lots.

Long-term storage: For extended shelf life, store the bulk material under inert gas at cool temperatures. DMSO stock solutions may be stored at −20 °C in single-use aliquots to preserve compound integrity.

Frequently asked questions

What solvents are recommended for dissolving 2-Chloro-5-fluoro-6-methoxynicotinic acid (C188501)?

DMSO and DMF are the preferred solvents for general dissolution and stock solution preparation. Methanol and ethanol also offer reasonable solubility. Aqueous solubility is limited but can be improved under basic conditions through carboxylate salt formation. Actual solubility should be confirmed empirically for each specific application.

How should 2-Chloro-5-fluoro-6-methoxynicotinic acid be stored to maintain its stability?

The bulk solid should be stored in a cool, dry, dark location, away from moisture and incompatible reagents, under an inert atmosphere (N2 or Ar) when possible. DMSO stock solutions should be aliquoted and stored at −20 °C to prevent degradation from repeated freeze-thaw cycles. Always consult the product label and CoA for lot-specific storage guidance.

What types of chemical reactions can be performed using the reactive groups on this compound?

The carboxylic acid at C-3 is suitable for amide coupling, esterification, and reduction reactions. The C-2 chloro group can undergo transition-metal-catalyzed cross-coupling (e.g., Suzuki, Buchwald-Hartwig) or SNAr substitution. The C-5 fluoro group can participate in SNAr reactions under appropriate nucleophilic conditions or be retained in the product to modulate physicochemical properties. This multifunctionality makes the compound a highly versatile building block in medicinal chemistry.

How do I verify the purity of C188501 before use in a sensitive assay?

Purity can be verified by reverse-phase HPLC with UV detection or by 1H and 19F NMR spectroscopy, referencing the Certificate of Analysis (CoA) provided by Aladdin Scientific for each lot. If results fall below the stated specification, contact Aladdin Scientific customer support for assistance or replacement.

Is 2-Chloro-5-fluoro-6-methoxynicotinic acid moisture sensitive?

Aryl carboxylic acids of this class are generally not highly moisture sensitive under normal handling conditions; however, prolonged exposure to atmospheric humidity may reduce analytical purity over time. It is best practice to store the compound sealed under inert gas and to equilibrate the container to room temperature before opening to prevent condensation.

References

1. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. General reference for carboxylic acid reactivity, amide coupling, and cross-coupling reactions.
2. Roughley, S. D.; Jordan, A. M. The medicinal chemist's toolbox: an analysis of reactions used in the pursuit of drug candidates. J. Med. Chem. 2011, 54, 3451–3479. doi:10.1021/jm200187y
3. Schlosser, M. Parametrization of substituents: effects of fluorine and other heteroatoms on OH, NH, and CH acidities. Angew. Chem. Int. Ed. 1998, 37, 1496–1513.
4. Aladdin Scientific Certificate of Analysis for 2-Chloro-5-fluoro-6-methoxynicotinic acid, SKU C188501. Aladdin Scientific, Shanghai. (Consult current lot CoA for specific purity and physicochemical data.)

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