Phenylboronic acid
[CAS# 98-80-6]

Identification

• Classification: Chemical reagent >> Organic reagent >> Boric acid
• Name: Phenylboronic acid
• Synonyms: Benzeneboronic acid; Phenylboron dihydroxide
• Molecular Formula: C₆H₇BO₂
• Molecular Weight: 121.93
• CAS Registry Number: 98-80-6
• EC Number: 202-701-9
• SMILES: B(C1=CC=CC=C1)(O)O

Properties

• Water solubility: 10 g/L (20 °C)
• Density: 1.1±0.1 g/cm³, Calc.^*
• Melting point: 217-220 °C
• Index of Refraction: 1.534, Calc.^*
• Boiling Point: 265.9±23.0 °C (760 mmHg), Calc.^*
• Flash Point: 114.6±22.6 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302
• Safety Statements: P264-P270-P301+P317-P330-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	2	H300
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

Phenylboronic acid is an organoboron compound with the chemical formula C6H7BO2. It is characterized by the presence of a phenyl group attached to a boronic acid functional group, which contains a boron atom bonded to a hydroxyl group and an alkyl or aryl group. The compound was first synthesized in the early 20th century, with significant advancements in its preparation and applications occurring over subsequent decades. Its discovery is attributed to the growing interest in organoboron chemistry, which has gained considerable attention for its utility in organic synthesis and medicinal chemistry.

One of the most notable applications of phenylboronic acid lies in the field of organic synthesis. It serves as a versatile building block for the preparation of various organic compounds. The unique properties of boronic acids, including their ability to form reversible complexes with diols and other nucleophiles, make them valuable intermediates in a wide range of reactions. For instance, phenylboronic acid is widely used in Suzuki coupling reactions, a key cross-coupling technique that allows for the formation of carbon-carbon bonds. This reaction has become a cornerstone in the synthesis of pharmaceuticals, agrochemicals, and other fine chemicals.

In addition to its role in organic synthesis, phenylboronic acid has found applications in the development of fluorescent probes and sensors. The ability of phenylboronic acid to selectively bind to cis-diol-containing molecules has led to the design of various chemosensors that can detect biologically relevant compounds, such as sugars and nucleotides. These sensors are valuable tools in biochemical research and diagnostics, as they enable the sensitive and selective detection of analytes in complex biological samples. The incorporation of phenylboronic acid into sensor designs enhances the performance and specificity of these analytical tools.

Furthermore, phenylboronic acid has been investigated for its potential therapeutic applications. Research has shown that it can act as a ligand for certain proteins and enzymes, leading to the development of boron-based therapeutics. For example, phenylboronic acid derivatives have been studied for their potential use in cancer therapy, where they can interfere with specific biological pathways and inhibit tumor growth. The unique chemical properties of phenylboronic acid allow for the modulation of biological activity, making it a promising candidate for drug development.

The handling of phenylboronic acid requires careful consideration of safety protocols, as it can be hazardous if ingested or inhaled. Proper laboratory practices, including the use of personal protective equipment and appropriate waste disposal methods, are essential when working with this compound. Additionally, researchers are encouraged to stay informed about the potential risks and regulatory guidelines associated with the use of organoboron compounds.

In conclusion, phenylboronic acid is a significant chemical compound with a wide range of applications in organic synthesis, sensor development, and medicinal chemistry. Its unique properties enable its use as a versatile building block in various chemical reactions, contributing to advancements in multiple fields. As research continues to uncover new applications and safety considerations, the relevance of phenylboronic acid in both industrial and scientific contexts remains strong.

References

2016. PLGA-PEG-supported Pd Nanoparticles as Efficient Catalysts for Suzuki-Miyaura Coupling Reactions in Water. CHIMIA, 70(4).
DOI: 10.2533/chimia.2016.252

2008. Detonation Nanodiamond: An Organic Platform for the Suzuki Coupling of Organic Molecules. Langmuir : the ACS journal of surfaces and colloids, 24(23).
DOI: 10.1021/la8029787

2007. Heterogeneous Pd/C‐Catalyzed Ligand‐Free, Room‐Temperature Suzuki-Miyaura Coupling Reactions in Aqueous Media. Chemistry (Weinheim an der Bergstrasse, Germany), 13(15).
DOI: 10.1002/chem.200601795