Lanthanide(III) tosylates as new acylation catalysts

Lanthanide(III) complexes of p-toluenesulfonic acid (Ln(TOS)3) were prepared, characterized, and examined as catalysts for the acetylation of various alcohols in acetic acid solution. Examination of a series of Ln(TOS)3 catalysts in the acetylation of 2-phenylethanol revealed a clear correlation between the ionic radius of the lanthanide(III) ion and the yield of the reaction, with the heavier lanthanides being more effective. In the presence of 5 mol-% of Yb(TOS)3, a quantitative conversion of phenethyl alcohol to phenethyl acetate was achieved within 18 hours at 50 ° C. Faster reaction was obtained under reflux conditions, in which case acetylation was complete within 30 minutes and in the presence of only 2 mol-% of the Yb(TOS)3 catalyst. The Yb(TOS)3 catalyst was effective for acetylation of a range of primary, secondary, and tertiary alcohols. The Yb(TOS)3 catalyst was also effective for acylation of phenethyl alcohol with propionic acid and cyclohexanecarboxylic acid. The catalysts could be easily recovered and reused for further acetylation, with no apparent change in selectivity or efficiency.status: publishe