4-Bromophenylboronic acid
[CAS# 5467-74-3]

Identification

• Classification: Chemical reagent >> Organic reagent >> Boric acid
• Name: 4-Bromophenylboronic acid
• Synonyms: 4-Bromobenzeneboronic acid
• Molecular Formula: C₆H₆BBrO₂
• Molecular Weight: 200.83
• CAS Registry Number: 5467-74-3
• EC Number: 226-779-9
• SMILES: B(C1=CC=C(C=C1)Br)(O)O

Properties

• Density: 1.7±0.1 g/cm³, Calc.^*
• Melting point: 284-288 °C (Expl.)
• Index of Refraction: 1.598, Calc.^*
• Boiling Point: 315.0±44.0 °C (760 mmHg), Calc.^*
• Flash Point: 144.3±28.4 °C, Calc.^*

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

4-Bromophenylboronic acid is an important organoboron compound with the chemical formula C6H6BBrO2. It consists of a phenyl group (C6H5) attached to a boronic acid group (-B(OH)2) and a bromine atom (Br) located at the para position relative to the boronic acid group on the phenyl ring. This compound is widely used in organic synthesis, particularly in Suzuki coupling reactions, which are a critical tool for the formation of carbon-carbon bonds.

The discovery of 4-bromophenylboronic acid can be traced to the development of boronic acid chemistry in the mid-20th century. Boronic acids, including 4-bromophenylboronic acid, gained significance after their applications were explored in the context of cross-coupling reactions, especially those promoted by palladium catalysts. The versatility and reactivity of boronic acids have made them indispensable in the synthesis of complex organic molecules, especially in the development of pharmaceuticals, agrochemicals, and materials.

The primary application of 4-bromophenylboronic acid is in Suzuki-Miyaura cross-coupling reactions, where it acts as a reagent for the formation of biaryl compounds. These compounds are widely used in the synthesis of various organic materials, including liquid crystals, pharmaceuticals, and dyes. The reaction involves the coupling of a boronic acid with an organohalide in the presence of a palladium catalyst and a base, allowing the creation of highly functionalized molecules with precision. This reaction has been critical in the synthesis of several bioactive molecules, including anticancer agents and other therapeutic compounds.

Beyond the Suzuki reaction, 4-bromophenylboronic acid is also employed in the development of sensors and in the field of material science. Its ability to form reversible covalent bonds with diols makes it useful for designing molecular sensors, particularly for detecting carbohydrates and other biological molecules. Additionally, boronic acids like 4-bromophenylboronic acid are used in the design of polymers and materials that respond to environmental changes, such as pH and temperature, due to their ability to undergo reversible reactions with small molecules.

The application of 4-bromophenylboronic acid is also evident in the development of agrochemicals, where it is used in the synthesis of molecules with herbicidal or fungicidal properties. By enabling the formation of complex organic structures, this compound plays a key role in improving the efficiency and effectiveness of agricultural products.

References

2022. Chemoselective borylation of bromoiodoarene in continuous flow: synthesis of bromoarylboronic acids. Journal of Flow Chemistry.
DOI: 10.1007/s41981-022-00246-w

2019. Recent Progress in the Synthesis of 4-Arylcoumarins. Chemistry of Natural Compounds, 55(2).
DOI: 10.1007/s10600-019-02705-8

1998. Structure-based enhancement of boronic acid-based inhibitors of AmpC beta-lactamase. Journal of Medicinal Chemistry, 41(21).
DOI: 10.1021/jm980343w