Related Experiment Video
Updated: Feb 17, 2026

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
Differentiation of isomeric methylanilines by imidization and gas chromatography/mass spectrometry analysis
Mengmeng Chen1, Guohua Zhu2, Jiaxiang Xu1
1Key Laboratory of Organosilicon Chemistry and Material Technology, Hangzhou Normal University, Hangzhou, 311121, China.
Rationale:
Carcinogenic o-methylaniline is one of the banned aromatic amines in azo dyes, but it is very difficult to distinguish it from its noncarcinogenic isomers due to their identical retention time on chromatography and similar mass spectra.
Methods:
Imidization of the isomeric methylanilines was carried out by treatment with benzaldehyde under mild conditions. The formed derivatives were analyzed by gas chromatography/mass spectrometry (GC/MS). Theoretical calculations were carried out on the Gaussian 03 program by using the density functional theory method at the B3LYP/6-311+G(d,p) level.
Results:
Imidization of methylanilines occurred easily and gave rise to the corresponding N-methylbenzylidene benzenamines. The isomeric derivatives were completely separated by GC, and thus the three isomeric methylanilines could be determined simultaneously. Due to the ortho effect, the derivative from o-methylaniline has a characteristic fragment ion at m/z 118 with a stable bicyclic structure, and it could be easily differentiated from the meta- and para-isomers in electron ionization mass spectrometry.
Conclusions:
These results provided a promising solution for simultaneous determination of isomeric methylanilines.
More Related Videos
08:22Nitrogen Compound Characterization in Fuels by Multidimensional Gas Chromatography
Published on: May 15, 2020
09:54Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes
Published on: September 12, 2018
Related Concept Videos
Mass Spectrometry of Amines
Chemical Ionization (CI) Mass Spectrometry
Mass Spectrometry: Amine Fragmentation
In amines, the number of nitrogen atoms affects the mass of the molecular ion, which is described by the nitrogen rule of mass spectrometry. This rule states that a compound containing a single...
Basicity of Heterocyclic Aromatic Amines
Mass Spectrum: Interpretation
High-Resolution Mass Spectrometry (HRMS)