Mechano-Induced Synthesis of Polyethylene Glycols α,ω-DiSubstituted with 4-(PAH)-1H-1,2,3-Triazoles in Presence of In Situ-Generated Bronze Microparticles as Catalyst

TL;DR

A new green method for making PEG-based compounds using bronze microparticles as a catalyst is developed, offering high efficiency and low environmental impact.

Contribution

A solvent-free, catalyst-free mechanochemical CuAAC click reaction using in situ-generated bronze microparticles is introduced.

Findings

The compounds were synthesized in up to 96% yields at room temperature within 3 hours.

The method achieved E-factor values as low as 0.38, indicating high efficiency and low waste.

The synthesized PEGs can act as chemosensors for electron-deficient species.

Abstract

A method for the mechanochemical CuAAC click reaction (Cu+-promoted azido–alkyne cycloaddition) in the presence of bronze powder/copper beads without the use of a pre-introduced catalyst and ligands with greener prospect is presented. A new type of tri-, tetra-, and penta-ethylene glycols (PEGs) α,ω-disubstituted with 4-(PAH)-1H-1,2,3-triazole moieties has been synthesized by means of solvent-free click reaction in the planetary ball-milling in absence of a pre-introduced Cu(I) catalyst. The reaction afforded the above-mentioned compounds at room temperature in as short as 3 h in up to 96% yields and with E-factor values as low as 0.38. For the comparison, some of the key compounds were obtained by the conventional click synthesis in DMF solution. The compounds obtained were synthesized for the first time and can be considered as representative examples of bola-type chemosensors for the detection of electron-deficient species. This work presents a method for catalyzing a click reaction using bronze microparticles that are formed in situ during powder milling. This heterophase catalyst has been shown to be efficient and inexpensive and is suitable for green chemistry methods under solvent-free ball-milling conditions.

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