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Upward Trend in Catalytic Efficiency of Rare‐Earth Triflate Catalysts in Friedel–Crafts Aromatic Sulfonylation Reactions
Author(s) -
Nguyen Vo Thu An,
Duus Fritz,
Le Thach Ngoc
Publication year - 2014
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201402067
Subject(s) - lanthanide , chemistry , catalysis , trifluoromethanesulfonate , yield (engineering) , ionic radius , ion , inorganic chemistry , medicinal chemistry , organic chemistry , materials science , metallurgy
A series of 14 lanthanide (Ln) triflates were investigated as sustainable catalysts for aromatic sulfonylation reactions under microwave irradiation. The catalytic efficiency of the early triflates La(OTf) 3 –Eu(OTf) 3 is good for long irradiation times. For the later lanthanides, yields reaching over 90 % were achieved for short irradiation periods. This was the case especially for Tm(OTf) 3 , Yb(OTf) 3 , and Lu(OTf) 3 , of which Yb(OTf) 3 was the most efficient. The upward trend in catalytic efficiency therefore correlates with the lanthanide sequence in the periodic table. The results can be explained by the decrease in the radii of the Ln 3+ ions, and the hydrolysis and water‐exchanges rate within the series. The results are in agreement with the first principal property value ( t 1 ) calculated by principal component analysis (PCA) published previously. A large drop in sulfonylation yield was obtained with Gd(OTf) 3, which matched the “gadolinium break”; the well‐known discontinuity in lanthanide properties.