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SBA‐15/POSS‐Imidazolium Hybrid as Catalytic Nanoreactor: the role of the Support in the Stabilization of Palladium Species for C−C Cross Coupling Reactions.
Author(s) -
Calabrese Carla,
Campisciano Vincenzo,
Siragusa Fabiana,
Liotta Leonarda F.,
Aprile Carmela,
Gruttadauria Michelangelo,
Giacalone Francesco
Publication year - 2019
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201900350
Subject(s) - chemistry , nanoreactor , catalysis , palladium , silsesquioxane , heck reaction , nanocages , coupling reaction , aryl , heterogeneous catalysis , mesoporous material , nanocomposite , polymer chemistry , chemical engineering , organic chemistry , polymer , alkyl , engineering
Supported imidazolium modified polyhedral oligomeric silsesquioxanes (POSS) on SBA‐15 have been used as platform for Pd(II) species. The so‐obtained material was firstly characterized by means of TGA, solid state NMR, TEM, XPS, SAXS, porosimetry and ICP‐OES and it was successfully tested as pre‐catalyst in C−C cross couplings, namely Suzuki‐Miyaura and Heck reactions. In both cases, the solid proved to be highly efficient and easily recoverable from the reaction mixture. The recyclability was verified for up to seven cycles without showing any activity decrease. Interestingly, only Pd(II) was detected in the reused catalyst in the Heck reaction. Therefore, the versatility of the material was investigated by using various aryl halides. Our palladium nanocomposite was able to promote both Suzuki and Heck reactions down to 0.0007 mol% showing outstanding turnover frequency (TOF) values of 114,286 and 32,381 h −1 , respectively. Comparison with the palladium catalyst on SiO 2 ‐POSS‐imidazolium support showed interesting differences in terms of stabilization of Pd species and recyclability. The excellent outcome of the reactions could be ascribed to the textural properties of the SBA‐15 support and the presence of the imidazolium‐POSS nanocage within the pores of SBA‐15, that worked as a sort of nanoreactor.