Related Experiment Video
Updated: Jan 16, 2026

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
Silica surface modification via diazotization of p-phenylenediamine: a stationary phase for HPLC
Joseph R Ezzo1, Brandon L Salazar1, Raúl J Díaz-Santiago1
1Department of Chemistry, Natural Sciences Complex, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, USA. lacolon@buffalo.edu.
Abstract:
A phenylenediamine-derived layer was grafted onto superficially porous silica particles through the diazotization of p-phenylenediamine (p-PDA), circumventing traditional silica silanization reactions. The polyphenylene-type layer was characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and elemental analysis. XPS revealed a surface layer containing approximately one nitrogen atom for every three aryl rings. In addition, the layer on silica included azo-linkages of aryl groups and amine functionalities, with one amine group per four to five benzene rings. Elemental analysis indicated that surface coverage of the aryl groups could be modulated by adjusting the reaction conditions, thereby enabling control over surface loading while reducing potential pore obstruction. A p-PDA-derived layer having 2-4 rings per nm2 proved effective as a stationary phase for high-performance liquid chromatography (HPLC) and exhibited excellent hydrolytic stability under relatively harsh acidic conditions (0.5% TFA at 80 °C). Furthermore, beyond small molecules, the new phase showed promise for peptide separation.
More Related Videos
Related Concept Videos
Diazonium Group Substitution: –OH and –H
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
High-Performance Liquid Chromatography: Introduction
In HPLC, two phases play a critical role in the separation process:
Silica Gel Column Chromatography: Overview
Polar components tend to bind strongly to the silica gel, causing them to move slowly through the column. In contrast, nonpolar compounds...
Aryldiazonium Salts to Azo Dyes: Diazo Coupling

