7-Chloro-4-Hydroxyquinoline-2-Carboxylic Acid: FAQs

7-chloro-4-hydroxyquinoline-2-carboxylic acid is a halogenated quinoline derivative bearing both a hydroxyl and a carboxylic acid functionality, making it a structurally versatile building block and pharmacological tool compound used in neuroscience and medicinal chemistry research.

CAS Number

Not specified in source material — see product datasheet (C175130)

Molecular Formula

C10H6ClNO3

Molecular Weight

Approximately 223.61 g/mol (calculated from formula)

Key Functional Groups

Chloro substituent (C-7), hydroxyl group (C-4), carboxylic acid (C-2), quinoline ring system

Structural Class

Halogenated 4-hydroxyquinoline-2-carboxylic acid; structural analogue of kynurenic acid

Primary Research Use

Neuropharmacology tool compound; potential NMDA/glycine-site ligand; medicinal chemistry building block

Chemical Identity and Physical Properties

7-Chloro-4-hydroxyquinoline-2-carboxylic acid (Aladdin SKU: C175130) is a bicyclic aromatic compound built on the quinoline scaffold. The molecule carries three key substituents: a chlorine atom at the 7-position, a hydroxyl group at the 4-position, and a carboxylic acid at the 2-position. The 4-hydroxy group exists predominantly in the 4-oxo (lactam) tautomeric form in the solid state, a behaviour common to 4-hydroxyquinolines. The compound is structurally related to kynurenic acid, the endogenous broad-spectrum antagonist of ionotropic glutamate receptors, with the 7-chloro substituent providing enhanced lipophilicity and potential for modulating receptor-binding affinity.

The molecular formula is C₁₀H₆ClNO₃, giving a calculated molecular weight of approximately 223.61 g/mol. The compound is expected to be a pale yellow to off-white solid at room temperature. Solubility in water is anticipated to be limited at neutral pH due to the hydrophobic quinoline core; alkaline aqueous solutions (e.g., dilute NaOH or phosphate buffer pH 8–9) or polar aprotic solvents such as DMSO are recommended for stock solution preparation. Exact physicochemical parameters (melting point, logP, pKa) should be confirmed from the official Certificate of Analysis for lot C175130.

Research Applications and Mechanism of Action

As a halogenated analogue of kynurenic acid, 7-chloro-4-hydroxyquinoline-2-carboxylic acid is of interest primarily in the fields of neuropharmacology and medicinal chemistry. Kynurenic acid and its synthetic analogues are known to interact with the glycine co-agonist site of the NMDA (N-methyl-D-aspartate) subtype of ionotropic glutamate receptors, as well as with AMPA and kainate receptor subtypes. Compounds bearing the 4-hydroxyquinoline-2-carboxylate pharmacophore are therefore investigated as potential neuroprotective agents, tools for dissecting glutamatergic signalling, and as leads for conditions involving excitotoxicity such as epilepsy, ischaemic stroke, and neurodegenerative diseases.

The 7-chloro substitution is a common medicinal chemistry strategy to improve metabolic stability, enhance membrane permeability, and fine-tune binding selectivity relative to the unsubstituted parent compound. In synthetic chemistry, the compound also serves as a versatile heterocyclic building block for the preparation of more complex quinoline-based structures via functionalization at the carboxylic acid (e.g., amide coupling) or displacement of the chloro group (e.g., nucleophilic aromatic substitution).

Note: Specific biological activity data (IC₅₀, K_i) for this exact compound are not provided in the current source material and should be sourced from primary literature before use in quantitative experiments.

Handling, Storage, and Safety Guidelines

As with all fine chemical research reagents, appropriate laboratory safety precautions should be observed when handling 7-chloro-4-hydroxyquinoline-2-carboxylic acid. Standard personal protective equipment (PPE) including nitrile gloves, laboratory coat, and safety spectacles should be worn at all times. The compound should be handled in a well-ventilated fume hood to minimise inhalation exposure to dust or aerosols generated during weighing.

For storage, the compound should be kept in a tightly sealed container away from moisture, light, and incompatible materials (strong oxidisers, strong bases). A recommended storage temperature is 2–8 °C or room temperature under desiccation, but researchers should consult the product label and Certificate of Analysis (CoA) for lot-specific storage conditions. DMSO stock solutions should be prepared under anhydrous conditions and stored in small aliquots at −20 °C to prevent freeze-thaw degradation. Always consult the Safety Data Sheet (SDS) for C175130 prior to use for complete hazard classification, first-aid measures, and disposal guidance in accordance with local regulations.

Preparation of Working Solutions

Due to the limited aqueous solubility of 7-chloro-4-hydroxyquinoline-2-carboxylic acid at physiological pH, careful attention to solvent selection is required when preparing working solutions for biological assays or chemical reactions.

• DMSO stock solutions: Dissolve the compound in anhydrous DMSO to prepare a concentrated stock (e.g., 10–100 mM). Confirm complete dissolution by visual inspection or gentle warming (do not exceed 37 °C). Dilute into the final aqueous assay buffer to achieve the desired working concentration, ensuring the final DMSO content does not exceed vehicle-tolerance thresholds for the biological system (typically ≤0.1–0.5% v/v for cell-based assays).
• Alkaline aqueous solutions: The carboxylic acid (pKa estimated ~2–3) and the lactam/hydroxyl group (pKa estimated ~7–9, needs confirmation) will be ionised at pH 8–9, improving aqueous solubility. Dissolve in a minimum volume of 0.1 M NaOH, then dilute with the appropriate buffer. Adjust pH carefully before use.
• Organic solvents: DMF or acetonitrile may be used for synthetic chemistry applications. Ensure compatibility with downstream reactions.

Always prepare fresh solutions or validate stability data before using stored solutions in sensitive assays. Exact solubility values should be confirmed experimentally or from the CoA.

Ordering, Specifications, and Quality Assurance

7-Chloro-4-hydroxyquinoline-2-carboxylic acid is available from Aladdin Scientific under SKU C175130. Researchers and procurement officers should request the current Certificate of Analysis (CoA) to verify lot-specific purity, analytical data (e.g., HPLC, NMR, MS), and physical characteristics before placing an order or beginning experiments.

When ordering, consider the following:

• Purity grade: Confirm the purity specification meets the requirements of your application (e.g., ≥95% or ≥98% for biological assays). Consult the product page or contact Aladdin Scientific technical support for available grades and pack sizes.
• Quantity: Order quantities appropriate for your experimental needs to minimise unnecessary storage and potential degradation. Aladdin Scientific offers multiple pack sizes for flexibility.
• Documentation: SDS and CoA documents are available upon request or via the product page. These are essential for compliance, safety training, and regulatory submissions.
• Custom synthesis: If a specific purity grade, isotopically labelled form, or larger quantity is required, contact Aladdin Scientific for custom synthesis options.

For questions about specifications, pricing, or order status, please contact Aladdin Scientific customer service or your regional account manager.

Frequently asked questions

What is the molecular weight of 7-chloro-4-hydroxyquinoline-2-carboxylic acid?

The molecular formula of 7-chloro-4-hydroxyquinoline-2-carboxylic acid is C10H6ClNO3, giving a calculated molecular weight of approximately 223.61 g/mol. Always verify the exact value against the Certificate of Analysis (CoA) supplied with your specific lot of C175130, as slight variations may occur depending on the analytical method used.

What solvents can be used to dissolve 7-chloro-4-hydroxyquinoline-2-carboxylic acid?

Due to its hydrophobic quinoline core and limited aqueous solubility at neutral pH, DMSO is the most commonly recommended solvent for preparing stock solutions. Alkaline aqueous buffers (pH 8–9) or dilute NaOH can also improve solubility by ionising the carboxylic acid and hydroxyl groups. For synthetic applications, DMF or acetonitrile are suitable organic solvent options. Exact solubility data should be confirmed experimentally or from the product CoA.

Is 7-chloro-4-hydroxyquinoline-2-carboxylic acid an NMDA receptor antagonist?

The compound belongs to the 4-hydroxyquinoline-2-carboxylic acid class, which is structurally related to kynurenic acid — a known endogenous antagonist at the glycine co-agonist site of NMDA receptors and at AMPA/kainate receptors. The 7-chloro substituent may modulate binding affinity and selectivity compared to the parent scaffold. However, specific pharmacological activity data (IC50, Ki) for this exact compound are not confirmed in the current source material and should be verified from primary peer-reviewed literature before use in receptor pharmacology studies.

How should 7-chloro-4-hydroxyquinoline-2-carboxylic acid be stored?

The compound should be stored in a tightly sealed container, protected from moisture and light, and kept away from strong oxidisers and strong bases. A storage temperature of 2–8 °C under desiccation is generally recommended for long-term stability; DMSO aliquots should be stored at −20 °C. Always refer to the product label and SDS for C175130 for lot-specific and regulatory-compliant storage instructions.

What are typical research applications for this compound?

7-Chloro-4-hydroxyquinoline-2-carboxylic acid is used primarily as a neuropharmacology tool compound for investigating glutamatergic receptor pharmacology, particularly at NMDA receptor glycine sites, and as a medicinal chemistry building block for synthesising more complex quinoline-based molecules. Researchers also explore this compound class as potential leads for neuroprotective drug discovery in the context of excitotoxicity-related conditions such as epilepsy and stroke.

How do I obtain the Safety Data Sheet (SDS) and Certificate of Analysis (CoA) for C175130?

The SDS and CoA for 7-chloro-4-hydroxyquinoline-2-carboxylic acid (SKU: C175130) can be requested directly from Aladdin Scientific customer service or downloaded from the product page on the Aladdin Scientific website. It is essential to obtain the lot-specific CoA to confirm purity and analytical data for your specific batch, and to review the SDS for safety, handling, and disposal information before use.

References

1. Stone TW, Perkins MN. Quinolinic acid: a potent endogenous excitant at amino acid receptors in CNS. European Journal of Pharmacology. 1981;72(4):411-412. [Kynurenic acid and quinoline carboxylate background — verify applicability to this specific compound]
2. Kessler M, Terramani T, Lynch G, Baudry M. A glycine site associated with N-methyl-D-aspartic acid receptors: characterization and identification of a new class of antagonists. Journal of Neurochemistry. 1989;52(4):1319-1328. [Glycine-site antagonist context for 4-hydroxyquinoline-2-carboxylates — verify applicability]
3. Aladdin Scientific. Product Page: 7-Chloro-4-hydroxyquinoline-2-carboxylic acid, SKU C175130. [Consult current product page for up-to-date specifications, CoA, and SDS]

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