Upward Trend in Catalytic Efficiency of Rare-Earth Triflate Catalysts in Friedel-Crafts Aromatic Sulfonylation Reactions

Fritz Duus, Thach Ngoc Le, Vo Thu An Nguyen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    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 Ln3+ ions, and the hydrolysis and water-exchanges rate within the series. The results are in agreement with the first principal property value (t1) 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
    Original languageEnglish
    JournalAsian Journal of Organic Chemistry
    Volume3
    Issue number9
    Pages (from-to)963-968
    Number of pages6
    ISSN2193-5807
    DOIs
    Publication statusPublished - 2014

    Cite this