General Description

2-Phenylimidazole is a white crystalline powder or granular substance with a melting point of 142-148 °C, a boiling point of 340 °C, and a density of 0.6 g/cm3. It has various applications in the chemical, biomedical, and pharmaceutical industries due to its physical and chemical properties, including its ability to act as a ligand in coordination chemistry and its use as a precursor for the synthesis of pharmaceuticals. Furthermore, it has been applied in the synthesis of azo dyes for fiber dyeing, producing deep shades with excellent color fastness, and in the removal of p-nitrophenol from petrochemical wastewater by adsorption with 2-Phenylimidazole-modified ZIF-8. Overall, 2-Phenylimidazole is a versatile and valuable compound for various industrial applications.

Figure 1. 2-Phenylimidazole

Physical and Chemical Characteristics

2-Phenylimidazole is a white crystalline powder or granular substance with a melting point of 142-148 °C (lit.), a boiling point of 340 °C, a density of 0.6 g/cm3, and an estimated refractive index of 1.6025. It has a flash point of 200 °C and is soluble in methanol, where it appears almost transparent. The acid dissociation constant (pKa) of 2-Phenylimidazole is predicted to be 13.00±0.10. To maintain its integrity, this substance should be sealed in a dry environment and stored at room temperature. 2-Phenylimidazole has various applications, including its use as a ligand in coordination chemistry and as a precursor for the synthesis of pharmaceuticals. This compound's properties make it useful in many industries, including biomedical, chemical, and pharmaceutical sectors. Overall, 2-Phenylimidazole's physical and chemical properties make it a versatile and valuable compound for various applications. ¹

Versatile Applications

Synthesis of azo dyes

2-Phenylimidazole is a versatile compound that has found widespread application in the synthesis of azo dyes for fiber dyeing. 2-Phenylimidazole can react with various aromatic amine diazonium salts under alkaline conditions to produce azo dyes. Although imidazole-containing azo compounds were synthesized in the past, they were not used for fiber dyeing. However, recent studies have shown that nickel and zinc salt-modified fibers can be successfully dyed using these azo dyes. The resulting colors include deep shades of brown, yellow, olive, red, and purple, with excellent light fastness, wash fastness, dry cleaning fastness, and rubbing fastness. In contrast, unmodified fibers cannot be dyed with these dyes, and zinc-modified fibers exhibit poor light fastness. These differences in dyeing performance suggest that the dyes interact differently with metals and chelating agents in modified polypropylene fibers. Furthermore, due to the basic nitrogen atoms in imidazole rings, these dyes can also be used as cationic dyes for woolen fabrics. Double azo dyes have better dyeing properties than single azo dyes, and one of the double azo dyes exhibits excellent dyeing properties and high color fastness. Overall, 2-Phenylimidazole is a key compound for the development of high-performance azo dyes for fiber dyeing applications. ²

Removal of p-nitrophenol

2-Phenylimidazole has been applied in the removal of p-nitrophenol from petrochemical wastewater by adsorption with 2-Phenylimidazole-modified ZIF-8. Petrochemical wastewater is known to contain highly toxic, bioaccumulative and persistent pollutants such as p-nitrophenol which can cause harm to ecosystems and environmental sustainability. In a study, ZIF-8-Phenylimidazole was prepared using solvent-assisted ligand exchange (SALE) with 2-phenylimidazole for the purpose of removing p-nitrophenol from petrochemical wastewater. The composition and structure of ZIF-8-PhIm were characterized using various methods including XRD, SEM, FT-IR, 1H NMR, XPS, and BET. The adsorption effect of ZIF-8-PhIm on p-nitrophenol was investigated using the static adsorption method. Compared to ZIF-8 materials, ZIF-8-PhIm exhibited stronger π-π interactions, produced a multistage pore structure with larger pore capacity and size, and had increased hydrophilicity and exposure of adsorption sites. Overall, 2-Phenylimidazole has been successfully applied in the modification of ZIF-8 for the removal of p-nitrophenol from petrochemical wastewater. ³

Reference

1. 2-Phenylimidazole. National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 69591.

2. KIROKU K. Azo Dyes from 2-Phenylimidazole as Coupler. Nippon Kagaku Kaishi, 1970.

3. Zhao Y, Yuan P, Xu X, Yang J. Removal of p-Nitrophenol by Adsorption with 2-Phenylimidazole-Modified ZIF-8. Molecules. 2023;28(10):4195.