Kinetic Study of the Thermal Polymerization Reactions between Diazide and Internal Diyne

Abstract

The reaction kinetics between diazide(4,4′‐biphenyl dibenzyl azide) and internal diyne(bis[2‐(phenyl)ethynyl]dimethylsilane) was studied in this study by means of differential scanning calorimetry (DSC) and nuclear magnetic resonance spectra (1H NMR). DSC was carried out to analyze the reaction in bulk polymerization condition, whereas 1H NMR for solution reaction polymerization. The apparent activation energy (eα) calculated by Kissinger's method was 90.83 kJ/mol, which was confirmed by Friedman's method, and 87.67 kJ/mol by 1H NMR, respectively. The polymerization between the diazide and internal diyne was the second‐order reaction based on calculation from both of DSC and 1H NMR.

Rate of a Click Chemistry reaction under catalysis by trace‐amounts of copper as evaluated by NMR spectroscopy

“…In the absence of any Cu + catalyst, it was established that a cycloaddition reaction between azide and alkyne groups may only occur by using high temperatures (>70 °C) which are capable of overcoming the relatively high‐energy activation barrier by increasing the collision energy between these groups. In such instances, second‐order kinetics are observed . Conversely, owing to the introduction of a Cu + catalyst, the cycloaddition step follows a different mechanism which requires a lower activation energy.…”

“…In such instances, second-order kinetics are observed. [5] Conversely, owing to the introduction of a Cu + catalyst, the cycloaddition step follows a different mechanism which requires a lower activation energy. Specifically, the Cu + catalyst binds with the alkyne group in the initial step and facilitates conjugation of the azido group to the Cu + -alkyne complex in the subsequent step.…”

“…This notwithstanding, many kinetic and thermodynamic aspects of the typical Cu + ‐catalysed [3 + 2] azide–alkyne cycloaddition (CuAAC) remain vaguely characterized at the present time. There are a number of studies focusing also on the kinetics of typical CuAAC reactions, showing how these follow first‐order or, in some chain reaction mechanisms, second‐order kinetics, and no regioselectivity is observed. In the absence of any Cu + catalyst, it was established that a cycloaddition reaction between azide and alkyne groups may only occur by using high temperatures (>70 °C) which are capable of overcoming the relatively high‐energy activation barrier by increasing the collision energy between these groups.…”