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Unprecedented Reductive Esterification of Carboxylic Acids under Hydrogen by Reusable Heterogeneous Platinum Catalysts
Author(s) -
Touchy Abeda S.,
Kon Kenichi,
Onodera Wataru,
Shimizu Kenichi
Publication year - 2015
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.201401172
Subject(s) - chemistry , catalysis , lewis acids and bases , formic acid , tin , carboxylic acid , metal , platinum , tin oxide , inorganic chemistry , yield (engineering) , oxide , organic chemistry , materials science , metallurgy
Supported metal catalysts have been tested for an unprecedented reductive dimerization of carboxylic acids to esters under 8 bar hydrogen in solvent‐free conditions. Among various metal‐loaded tin oxide catalysts, platinum‐loaded tin dioxide (Pt/SnO 2 ) shows the highest ester yield for the reaction of dodecanoic acid. Among Pt catalysts on various supports, Lewis acidic oxides, especially SnO 2 , show high activity. The most active catalyst, 5 wt% Pt/SnO 2 reduced at 100 °C, is effective for the reductive esterification of various carboxylic acids, and the catalyst is reusable for nine cycles, demonstrating the first successful example for the title reaction. Infrared (IR) studies of a model compound (formic acid) on some metal oxides indicate a strong Lewis acid‐base interaction between SnO 2 and the carbonyl oxygen. For Pt/SnO 2 catalysts with different Pt particle sizes, the activity increases with decreasing size of Pt metal. A cooperative catalysis of the Pt metal nanoparticles and the Sn 4+ Lewis acid sites is proposed.