Catalyst Screening followed by TLC-MS for Reaction Progress Analysis using KitAlysis™
Sarah Trice, Thorsten vom Stein, Michael Schulz
Introduction
Catalyst screening is an important prerequisite in organic synthesis. KitAlysis™ High-Throughput Screening Kits showcase the most widely used catalytic methods of synthetic chemists, translated into an off-the-shelf screening system to quickly and efficiently identify or optimize suitable catalytic reaction conditions.
To evaluate the screening an analysis tool is needed. Thin layer chromatography (TLC) allows for a fast and cost-effective determination of the reaction progress by parallel analysis of the samples on one plate. This setup perfectly fits to the parallel synthesis utilizing KitAlysis™.
This application note displays the use of the KitAlysis™ High-Throughput Buchwald-Hartwig Amination Reaction Screening Kit for the optimization of the coupling of aryl bromide and diphenylamine combined with an evaluation of the result with TLC-MS analysis.

Figure 1.Schematic reaction showing the coupling of aryl bromide (1) and diphenylamine (2) to form biphenyl-4-yl-di-p-tolyl-amine (3), where the product has a molecular weight of 349.468 g/Mol.
Results and Discussion
The two reactants, aryl bromide and diphenylamine, were applied in addition to the samples. The samples were clearly visible under UV-light, therefore no derivatization was necessary. Figures 2a, 2b and 2c show the developed plate under white light, at 254 nm and at 366 nm.
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Figure 2a.Developed plate under white light
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Figure 2b.Developed plate at 254 nm
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Figure 2c.Developed plate at 366 nm
Confirmation of reaction product by mass spectrometry: Formation of ACN adduct via radical ionization
![Mass spectrum (ESI+) of product [M+ACN] Mass spectrum (ESI+) of product [M+ACN]](/deepweb/assets/sigmaaldrich/marketing/global/images/technical-documents/protocols/analytical-chemistry/thin-layer-chromatography/catalyst-screening-followed-by-tlc-ms/mass-spectrum/mass-spectrum.jpg)
Figure 3.Mass spectrum (ESI+) of product [M+ACN]
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Biphenyl-4-yl-di-p-tolyl-amine (M=349.568 g/Mol)
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