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A Waste‐Minimized Approach to Cassar‐Heck Reaction Based on POLITAG‐Pd 0 Heterogeneous Catalyst and Recoverable Acetonitrile Azeotrope
Author(s) -
Valentini Federica,
Ferlin Francesco,
Tomarelli Elena,
Mahmoudi Hamed,
Bagherzadeh Mojtaba,
Calamante Massimo,
Vaccaro Luigi
Publication year - 2021
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.202101052
Subject(s) - catalysis , chemistry , azeotrope , heck reaction , acetonitrile , sonogashira coupling , heterogeneous catalysis , palladium , ionic liquid , combinatorial chemistry , chemical engineering , organic chemistry , distillation , engineering
Three different Pd 0 ‐based heterogeneous catalysts were developed and tested in the Cassar–Heck reaction (i. e., copper‐free Sonogashira reaction) aiming at the definition of a waste minimized protocol. The cross‐linked polymeric supports used in this investigation were designed to be adequate for different reaction media and were decorated with different pincer‐type ionic ligands having the role of stabilizing the formation and dimension of palladium nanoparticles. Among the ionic tags tested, bis‐imidazolium showed the best performances in terms of efficiency and durability of the metal catalytic system. Eventually, aqueous acetonitrile azeotrope was selected as the reaction medium as it allowed the best catalytic efficiency combined with easy recovery and reuse. Finally, the synergy between the selected catalyst and reaction medium allowed to obtain highly satisfactory isolated yields of a variety of substrates while using a low amount of metal catalyst. The high performance of the designed POLymeric Ionic TAG (POLITAG)‐Pd 0 , along with its good selectivity achieved in a copper‐free process, also led to a simplified purification procedure allowing the minimization of the waste generated as also proven by the very low E‐factor values (1.4–5) associated.