Hyper‐Cross‐Linked Polyacetylene‐Type Microporous Networks Decorated with Terminal Ethynyl Groups as Heterogeneous Acid Catalysts for Acetalization and Esterification Reactions

Abstract

Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area S of up to 1000 m g active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g . The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.

Sulfonated Hyper‐cross‐linked Porous Polyacetylene Networks as Versatile Heterogeneous Acid Catalysts

“…The development of heterogeneous catalysts with permanent and well‐defined porosity is one of the main goals of research in the field of catalysis. The Porous Polymer Catalysts, PPCs, represent a new, interesting and promising subclass of such heterogeneous catalysts . The PPCs are insoluble and non‐swellable polymers containing permanent pores in the size range of micropores and in some cases also mesopores and the catalytically active centers as the part of the micro/mesoporous surface.…”

“…The Porous Polymer Catalysts, PPCs, represent a new, interesting and promising subclass of such heterogeneous catalysts. [1][2][3][4][5][6][7][8] The PPCs are insoluble and nonswellable polymers containing permanent pores in the size range of micropores and in some cases also mesopores and the catalytically active centers as the part of the micro/mesoporous surface. In terms of polymer architecture, the PPCs are highly aromatic polymer networks the permanent porosity of which results from the rigidity of the network segments and extensive cross-linking.…”

“…Recently we reported the chain‐growth polymerization of diethynylarenes as a powerful tool for template‐free preparation of texturally hierarchized micro/mesoporous hyper‐cross‐linked networks . In this article we report (i) the networks of this type prepared from commercially available 1,3‐diethynylbenzene (1,3‐DEB) and 1,4‐diethynylbenzene (1,4‐DEB) monomers, (ii) the smooth post‐polymerization sulfonation of parent networks into acid PPCs proceeding under preservation of micro/mesoporous texture and (iii) the catalytic activity of sulfonated PPCs in esterification of fatty acids and Prins cyclization reactions.…”

Microporous Hyper‐Cross‐Linked Polymers with High and Tuneable Content of Pyridine Units: Synthesis and Application for Reversible Sorption of Water and Carbon Dioxide

“…[ 44,45 ] The monomers were various aromatics substituted with two to four terminal ethynyl groups. [ 46 ] The resulting POPs consisted of polyacetylene (polyene) main chains that were hyper‐cross‐linked by arene‐type cross‐links. [ 22 ] Polyacetylene POPs were active as heterogeneous catalysts, [ 47 ] sorbents, [ 10 ] and porous fluorescent materials.…”

Carbazole-functionalized hyper-cross-linked polymers for CO2 uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

“…HCPs get more attention in recent years due to their high BET specific surface area [1], made under mild reaction conditions [2], used nonprecious materials as catalyst [3] and wide applications [4–9], etc. The synthesis methods of HCPs include solvent knitting methods [10], Scholl coupling reaction [11], the knitting method with formaldehyde dimethyl acetal (FDA) [12], functional group reactions [2,13] and so on. Among these methods, the knitting method with FDA as external cross-linker is the most time-efficient approach [14].…”