Polyphenylene-Based Solid Acid as an Efficient Catalyst for Activation and Hydration of Alkynes

Area of Science:

• Materials Science
• Catalysis
• Organic Chemistry

Background:

• Porous polymer catalysts offer combined benefits of heterogeneous and homogeneous catalysis.
• Easy catalyst recovery and high active site dispersion are key advantages.
• Traditional catalysts often involve toxic liquid phase acids.

Purpose of the Study:

• To design and synthesize a novel porous polymer catalyst for alkyne hydration.
• To investigate the catalytic activity and structural properties of the new material.
• To evaluate its potential as a replacement for hazardous liquid catalysts.

Main Methods:

• Synthesis of a sulfonic acid (-SO₃H) functionalized polyphenylene (PPhen) framework.
• Characterization of porosity, surface area (653 m²·g^-1), and acidic site density (2.12 mmol·g^-1).
• Evaluation of catalytic activity in alkyne hydration, including aliphatic substrates like 1-octyne.

Main Results:

• The PPhen-SO₃H framework exhibited high activity in alkyne hydration.
• High swellability and porosity were achieved due to covalent crosslinking and π-π stacking.
• Similar turnover frequencies (0.015 ± 0.001 min^-1) indicated high accessibility of active sites.
• Spectroscopic evidence (IR) confirmed CH/π interaction activating alkynes.

Conclusions:

• The designed PPhen-SO₃H is a highly active and accessible solid acid catalyst.
• Its structure facilitates efficient alkyne hydration, even for challenging substrates.
• This material presents a promising, environmentally benign alternative to toxic mercury salts and liquid acids.