Issue 36, 2016

Towards understanding the kinetic behaviour and limitations in photo-induced copper(i) catalyzed azide–alkyne cycloaddition (CuAAC) reactions

Abstract

The kinetic behaviour of the photo-induced copper(I) catalyzed azide–alkyne cycloaddition (CuAAC) reaction was studied in detail using real-time Fourier transform infrared (FTIR) spectroscopy on both a solvent-based monofunctional and a neat polymer network forming system. The results in the solvent-based system showed near first-order kinetics on copper and photoinitiator concentrations up to a threshold value in which the kinetics switch to zeroth-order. This kinetic shift shows that the photo-CuAAC reaction is not susceptible from side reactions such as copper disproportionation, copper(I) reduction, and radical termination at the early stages of the reaction. The overall reaction rate and conversion is highly dependent on the initial concentrations of photoinitiator and copper(II) as well as their relative ratios. The conversion was decreased when an excess of photoinitiator was utilized compared to its threshold value. Interestingly, the reaction showed an induction period at relatively low intensities. The induction period is decreased by increasing light intensity and photoinitiator concentration. The reaction trends and limitations were further observed in a solventless polymer network forming system, exhibiting a similar copper and photoinitiator threshold behaviour.

Graphical abstract: Towards understanding the kinetic behaviour and limitations in photo-induced copper(i) catalyzed azide–alkyne cycloaddition (CuAAC) reactions

Supplementary files

Article information

Article type
Paper
Submitted
15 Jul 2016
Accepted
23 Aug 2016
First published
23 Aug 2016
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2016,18, 25504-25511

Towards understanding the kinetic behaviour and limitations in photo-induced copper(I) catalyzed azide–alkyne cycloaddition (CuAAC) reactions

B. M. El-Zaatari, A. U. Shete, B. J. Adzima and C. J. Kloxin, Phys. Chem. Chem. Phys., 2016, 18, 25504 DOI: 10.1039/C6CP04950H

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