8-Bromoquinoline-2-carboxylic Acid: Properties & Applications

8-Bromoquinoline-2-carboxylic acid is a halogenated heterocyclic carboxylic acid that serves as a valuable bifunctional building block in medicinal chemistry, coordination chemistry, and materials science research.

CAS Number

Verify with supplier (SKU B195794)

Molecular Formula

C10H6BrNO2

Molecular Weight

252.06 g/mol

Key Functional Groups

Bromine at C-8, carboxylic acid at C-2, quinoline nitrogen

Appearance

Solid (exact form to be confirmed with CoA)

Primary Use

Synthetic intermediate for cross-coupling, metal complexation, and drug discovery

Chemical Structure and Key Properties

8-Bromoquinoline-2-carboxylic acid (SKU B195794) is a bicyclic aromatic compound consisting of a quinoline ring system bearing two distinct reactive sites: a bromine substituent at the C-8 position and a carboxylic acid group at the C-2 position. Its molecular formula is C₁₀H₆BrNO₂, corresponding to a molecular weight of approximately 252.06 g/mol.

The quinoline scaffold provides an electron-deficient aromatic system with a ring nitrogen that can participate in coordination bonding. The C-2 carboxylic acid is positioned adjacent to the ring nitrogen, creating a bidentate coordination motif commonly exploited in metal-complex formation. The C-8 bromine atom is peri to the nitrogen, conferring steric and electronic properties that can influence both reactivity and metal-binding geometry.

Researchers should consult the Certificate of Analysis (CoA) supplied with each batch of B195794 for confirmed purity, melting point, and spectroscopic data, as exact physical constants may vary by lot.

Synthetic Utility and Reactivity

The dual functionality of 8-Bromoquinoline-2-carboxylic acid makes it a highly versatile intermediate in organic synthesis. The aryl bromide at C-8 is well-suited for palladium-catalyzed cross-coupling reactions, including Suzuki–Miyaura, Buchwald–Hartwig, and Sonogashira couplings, enabling introduction of diverse aryl, amino, or alkynyl groups onto the quinoline core.

The carboxylic acid at C-2 can be exploited through standard carboxyl-group transformations: esterification, amide bond formation (e.g., using HATU or DCC coupling reagents), reduction to the alcohol, or conversion to an acyl chloride. These transformations allow construction of complex molecular architectures from a single, convenient starting material.

Sequential or orthogonal functionalization of both sites enables medicinal chemists to generate structurally diverse compound libraries from a single scaffold, which is particularly valuable during lead optimization campaigns in drug discovery.

Applications in Coordination Chemistry and Materials Science

Quinoline-2-carboxylic acid derivatives are well-established bidentate N,O-donor ligands in coordination chemistry. In 8-Bromoquinoline-2-carboxylic acid, the carboxylate oxygen and the quinoline nitrogen together form a five-membered chelate ring upon metal coordination, a motif known to form stable complexes with a range of transition metals including copper, zinc, ruthenium, and palladium.

The additional bromine substituent at C-8 can serve as a handle for post-complexation modification or can sterically and electronically tune the properties of the resulting metal complex. This tunability is attractive for the design of luminescent materials, catalytic systems, and metal-organic frameworks (MOFs), where precise control of the ligand electronic environment is essential.

In materials science contexts, brominated quinoline ligands have been explored as components of organic light-emitting diode (OLED) materials and as photosensitizers, although specific data for this exact compound should be verified against primary literature before application.

Handling, Storage, and Safety Considerations

As with all aryl halide and carboxylic acid-containing research reagents, appropriate laboratory safety practices must be observed when handling 8-Bromoquinoline-2-carboxylic acid. Researchers should consult the Safety Data Sheet (SDS) provided by Aladdin Scientific (B195794) for authoritative hazard classification, first-aid measures, and disposal guidance prior to use.

General precautions for this compound class include the use of personal protective equipment (PPE) such as nitrile gloves, a laboratory coat, and safety glasses. Work in a well-ventilated area or fume hood is recommended when weighing or handling the solid to minimize inhalation of fine particulates.

For storage, quinoline carboxylic acid derivatives are typically maintained in a cool, dry, well-ventilated location, away from incompatible materials such as strong oxidizers and strong bases. The container should be kept tightly sealed to prevent moisture uptake and degradation. Specific storage temperature requirements for B195794 should be confirmed on the product label and CoA.

Frequently asked questions

What makes 8-Bromoquinoline-2-carboxylic acid a useful building block in medicinal chemistry?

Its bifunctional nature—an aryl bromide amenable to palladium-catalyzed cross-coupling at C-8 and a carboxylic acid available for amide or ester coupling at C-2—allows chemists to independently modify both positions, enabling rapid construction of structurally diverse quinoline-based drug candidates from a single scaffold.

Can 8-Bromoquinoline-2-carboxylic acid act as a ligand for metal complexes?

Yes. The quinoline nitrogen and the adjacent C-2 carboxylate together form a bidentate N,O-chelating motif that readily coordinates to a variety of transition metals, yielding stable five-membered chelate rings. The C-8 bromine further modulates the electronic and steric profile of the resulting complex.

How should I store 8-Bromoquinoline-2-carboxylic acid (B195794) to maintain its integrity?

Store the compound in a tightly sealed container in a cool, dry, and well-ventilated location, away from strong oxidizers and moisture. Always refer to the Aladdin Scientific product label and Certificate of Analysis for lot-specific storage temperature recommendations.

What cross-coupling reactions are compatible with the C-8 bromo group?

The aryl bromide at C-8 is compatible with several palladium-catalyzed transformations including Suzuki–Miyaura (with arylboronic acids), Sonogashira (with terminal alkynes), and Buchwald–Hartwig (for C–N bond formation) couplings. Reaction conditions should be optimized empirically, as the electron-deficient quinoline ring and the proximal carboxylic acid may influence catalyst selection and yield.

References

1. March, J.; Smith, M. B. March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 7th ed.; Wiley: Hoboken, NJ, 2013. (General cross-coupling and carboxylic acid chemistry)
2. Anastas, P. T.; Warner, J. C. Green Chemistry: Theory and Practice; Oxford University Press: New York, 1998. (Referenced for context on sustainable synthetic intermediates)
3. Aladdin Scientific. Product Information: 8-Bromoquinoline-2-carboxylic acid, SKU B195794. (Supplier product page and Certificate of Analysis)

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