Berdugo-Díaz CE, Manetsch MT, Sik Yun Y, Lee J, Luo J, Chen X, Flaherty DW. Ester Reduction with H
2 on Bifunctional Metal-Acid Catalysts: Implications of Metal Identity on Rates and Selectivities.
Angew Chem Int Ed Engl 2023;
62:e202216165. [PMID:
36755505 DOI:
10.1002/anie.202216165]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/10/2023]
Abstract
Esters reduce to form ethers and alcohols on contact with metal nanoparticles supported on Brønsted acidic faujasite (M-FAU) that cleave C-O bonds by hydrogenation and hydrogenolysis pathways. Rates and selectivities for each pathway depend on the metal identity (M=Co, Ni, Cu, Ru, Rh, Pd, and Pt). Pt-FAU gives propyl acetate consumption rates up to 100 times greater than other M-FAU catalysts and provides an ethyl propyl ether selectivity of 34 %. Measured formation rates, kinetic isotope effects, and site titrations suggest that ester reduction involves a bifunctional mechanism that implicates the stepwise addition of H* atoms to the carbonyl to form hemiacetals on the metal sites, followed by hemiacetal diffusion to a nearby Brønsted acid site to dehydrate to ethers or decompose to alcohol and aldehyde. The rates of reduction of propyl acetate appear to be determined by the H* addition to the carbonyl and by the C-O cleavage of hemiacetal.
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