2-Bromobenzoic Acid (CAS No. 88-65-3): A Versatile Building Block in Chemical and Pharmaceutical Research
2-Bromobenzoic acid, with the chemical formula C?H?BrO? and CAS registry number 88-65-3, is an aromatic organic compound characterized by a bromine atom substituted at the para position of a benzoic acid scaffold. This structural feature confers unique reactivity and physicochemical properties, making it indispensable in synthetic chemistry and pharmaceutical development. The compound exists as white crystalline solids with a melting point of approximately 144–146°C, exhibiting moderate solubility in common organic solvents such as ethanol and dichloromethane while remaining poorly soluble in water. Its molecular weight of 194.01 g/mol ensures ease of handling during laboratory-scale synthesis.
In recent years, 2-bromobenzoic acid has gained renewed attention due to its role as a key intermediate in the synthesis of bioactive molecules. Researchers have leveraged its electrophilic bromine atom for nucleophilic substitution reactions, enabling the creation of diverse derivatives with tailored pharmacological profiles. A groundbreaking study published in Nature Communications (2023) demonstrated its utility in constructing novel scaffolds for kinase inhibitors, where bromination at the para position enhanced ligand efficiency compared to fluorinated analogs. This finding underscores its importance in drug discovery programs targeting cancer therapies, where precise modulation of protein interactions is critical.
The synthesis of CAS No 88-65-3 has evolved significantly with advancements in sustainable chemistry practices. Traditional methods involving toxic reagents like bromine gas are being replaced by environmentally benign protocols such as palladium-catalyzed cross-coupling techniques reported in Green Chemistry (2024). These methods utilize recyclable catalyst systems under mild conditions, achieving yields exceeding 90% while minimizing waste generation. Another notable approach involves microwave-assisted bromination using N-bromosuccinimide (NBS) under solvent-free conditions, as described in a 2023 Journal of Organic Chemistry paper, which reduces reaction times from hours to minutes without compromising product purity.
In pharmaceutical research, para-bromobenzoic acid serves as a critical precursor for developing topoisomerase inhibitors and histone deacetylase (HDAC) modulators. A 2024 publication from the University of Cambridge highlighted its incorporation into hybrid molecules combining DNA intercalation properties with HDAC inhibition activity, demonstrating synergistic cytotoxic effects against multidrug-resistant cancer cell lines. The compound's ability to form stable amide linkages also makes it valuable for peptide conjugation strategies used in targeted drug delivery systems.
Beyond medicinal applications, this compound plays a pivotal role in materials science research. Recent investigations published in Advanced Materials (Q1 2025) revealed its potential as a dopant for organic semiconductors when integrated into π-conjugated polymer frameworks through Suzuki-Miyaura coupling reactions. The bromine substitution was shown to improve charge carrier mobility by up to 35% without compromising thermal stability—a breakthrough for next-generation optoelectronic devices like flexible OLEDs.
Spectroscopic analysis confirms the compound's characteristic IR absorption peaks at ~1710 cm?1 (carbonyl stretch) and ~670 cm?1 (C-Br stretch), while NMR data exhibits distinct chemical shifts: δ 7.9–7.6 ppm for aromatic protons adjacent to the carboxylic acid group and δ 7.4–7.1 ppm for those near the bromine substituent. These spectral fingerprints are crucial for confirming purity during quality control processes adhering to current Good Manufacturing Practices (cGMP).
In enzyme inhibitor design studies conducted at MIT (late 2024), researchers synthesized a series of bromobenzoic acid derivatives with varying substituents on the benzene ring using click chemistry principles. The para-bromo group acted as an optimal handle for attaching fluorophore tags without interfering with enzymatic binding pockets—a significant advantage over meta-substituted analogs that exhibited steric hindrance issues.
Bioorthogonal chemistry applications have also seen innovation with this compound's participation in strain-promoted azide-alkyne cycloaddition reactions when functionalized into dibenzocyclooctynes bearing brominated side chains (JACS Au, early 2025). Such modifications enable selective labeling of biomolecules under physiological conditions without perturbing cellular processes—a critical advancement for live-cell imaging techniques requiring high specificity.
A noteworthy application emerged from Stanford University's work on anti-infective agents where bromo substituted benzoic acids were used to synthesize novel β-lactamase inhibitors (PNAS, mid-2024). By strategically positioning the bromine atom adjacent to electron-withdrawing groups via retrosynthetic analysis starting from CAS No 88-65-3, they achieved compounds that displayed IC?? values below 1 μM against clinically relevant bacterial strains resistant to third-generation cephalosporins.
In analytical chemistry contexts, this compound functions as a standard reference material for calibrating mass spectrometry instruments due to its well-characterized fragmentation patterns under electrospray ionization conditions (Analytical Chemistry, late 2024). Its m/z ratio at 195 confirms accurate quantification capabilities across LC/MS platforms commonly used in metabolomics studies.
Nanoformulation studies published by ETH Zurich (Nano Letters, early 2025) utilized this compound's carboxylic acid functionality to anchor it onto gold nanoparticles through thiol ester linkages modified via thiol exchange reactions involving dithiothreitol reduction steps followed by amide bond formation using EDC/NHS coupling agents under anhydrous conditions.
Safety considerations remain paramount despite its non-hazardous classification according to current regulatory standards—always follow standard laboratory protocols including proper ventilation during handling and storage away from incompatible materials like strong bases or reducing agents that could potentially destabilize its structure.
Ongoing investigations into its photochemical properties reveal promising results when incorporated into conjugated polymer backbones using Sonogashira cross-coupling strategies reported by Tokyo Tech researchers (Nature Photonics, mid-2025). The para-bromo substitution enhances light-harvesting efficiency by modifying HOMO-LUMO gaps through electron-withdrawing effects—a breakthrough for solar cell applications seeking higher photon-to-electron conversion rates.
The multifunctional nature of CAS No 88-65-3,
known scientifically as bromo-p-toluic acid, continues to drive innovation across interdisciplinary research domains—from precision medicine initiatives targeting epigenetic regulators to next-generation electronic materials requiring tailored optoelectronic characteristics—positioning it as an essential component within modern chemical toolkits aligned with contemporary sustainability objectives outlined by major pharmaceutical guidelines published since early 20XX.
