Esterification of Tertiary Amides by Alcohols Through C−N Bond Cleavage over CeO2

• Published in: ChemCatChem Vol. 11; no. 1; pp. 449 - 456
• Main Authors: Toyao, Takashi, Nurnobi Rashed, Md, Morita, Yoshitsugu, Kamachi, Takashi, Hakim Siddiki, S. M. A., Ali, Md. A., Touchy, A. S., Kon, Kenichi, Maeno, Zen, Yoshizawa, Kazunari, Shimizu, Ken‐ichi
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 09.01.2019
• Subjects: Acid and base cooperation; Additives; Alcohols; Amide alcoholysis; Amides; Carbonyl groups; Carbonyls; Catalysis; CeO2; Cerium oxides; Cleavage; C−N bond cleavage; Density functional theory; Esterification; Infrared radiation; Substrates
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201801098

CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93 % isolated yield). Results of a density functional theory (DFT) study combined with in situ FT‐IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT‐IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C−N bond cleavage reaction. C−N bond breaking! Alcoholysis of tertiary amide, a C−N bond cleavage reaction, was achieved by a heterogeneous CeO2 catalyst. The present catalytic system has the advantage of being facile and not requiring any additives. The catalyst is moreover recyclable and shows wide substrate scope toward the ester forming process. A possible catalytic mechanism is proposed on the basis of results from density functional theory (DFT) and in situ FT‐IR studies.