Mechanistic Insight into the Heterogeneous Hydrogenation of Furan Derivatives with the use of Parahydrogen

Oleg G. Salnikov, Larisa M. Kovtunova, Ivan V. Skovpin, Valerii I. Bukhtiyarov, Kirill V. Kovtunov, Igor V. Koptyug

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Parahydrogen-induced polarization (PHIP) was shown to be a useful and unique technique to study the mechanisms of catalytic reactions involving hydrogen. In this paper, PHIP was utilized for mechanistic investigation of the gas-phase hydrogenation of furan, 2,3-dihydrofuran, and 2,5-dihydrofuran over titania-supported Rh, Pd, and Pt catalysts. In the hydrogenation of all three substrates over the Rh/TiO2 catalyst, the PHIP technique revealed the possibility of pairwise addition of two H atoms from the same H2 molecule with the formation of tetrahydrofuran molecules while retaining spin correlation between the added protons. In the hydrogenation of 2,3-dihydrofuran over the Rh/TiO2 catalyst, PHIP effects were detected not only for tetrahydrofuran but also for the reactant (2,3-dihydrofuran) at positions 2 and 3 of the heterocyclic ring. Such unexpected results are direct evidence for the pairwise replacement of the hydrogen atoms in 2,3-dihydorfuran. A probable mechanism for this pairwise replacement includes sequential steps of addition and elimination of hydrogen atoms. In contrast, if the hydrogenation of 2,5-dihydrofuran was performed over Rh/TiO2, PHIP effects were detected for all protons of 2,3-dihydrofuran, implying that 2,3-dihydrofuran could be formed from 2,5-dihydrofuran not only through isomerization of the C=C bond but also through dehydrogenation of 2,5-dihydrofuran to furan with subsequent semihydrogenation.

Original languageEnglish
Pages (from-to)1178-1183
Number of pages6
JournalChemCatChem
Volume10
Issue number5
DOIs
Publication statusPublished - 7 Mar 2018

Keywords

  • hydrogenation
  • oxygen heterocycles
  • polarization
  • reaction mechanisms
  • supported catalysts

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