Mechanisms of Methylenecyclobutane Hydrogenation over Supported Metal Catalysts Studied by Parahydrogen‐Induced Polarization Technique

In this work the mechanism of methylenecyclobutane hydrogenation over titania‐supported Rh, Pt and Pd catalysts was investigated using parahydrogen‐induced polarization (PHIP) technique. It was found that methylenecyclobutane hydrogenation leads to formation of a mixture of reaction products includi...

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Bibliographic Details
Published in:Chemphyschem 2022-04, Vol.23 (7), p.e202200072-n/a
Main Authors: Salnikov, Oleg G., Burueva, Dudari B., Kovtunova, Larisa M., Bukhtiyarov, Valerii I., Kovtunov, Kirill V., Koptyug, Igor V.
Format: Article
Language:English
Subjects:
Catalysis
Catalysts
heterogeneous catalysis
Hydrogen - chemistry
Hydrogenation
hyperpolarization
Induced polarization
Isoprene
Magnetic Resonance Spectroscopy
methylenecyclobutane
NMR spectroscopy
Palladium
parahydrogen
Reaction products
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Summary:In this work the mechanism of methylenecyclobutane hydrogenation over titania‐supported Rh, Pt and Pd catalysts was investigated using parahydrogen‐induced polarization (PHIP) technique. It was found that methylenecyclobutane hydrogenation leads to formation of a mixture of reaction products including cyclic (1‐methylcyclobutene, methylcyclobutane), linear (1‐pentene, cis‐2‐pentene, trans‐2‐pentene, pentane) and branched (isoprene, 2‐methyl‐1‐butene, 2‐methyl‐2‐butene, isopentane) compounds. Generally, at lower temperatures (150–350 °C) the major reaction product was methylcyclobutane while higher temperature of 450 °C favors the formation of branched products isoprene, 2‐methyl‐1‐butene and 2‐methyl‐2‐butene. PHIP effects were detected for all reaction products except methylenecyclobutane isomers 1‐methylcyclobutene and isoprene implying that the corresponding compounds can incorporate two atoms from the same parahydrogen molecule in a pairwise manner in the course of the reaction in particular positions. The mechanisms were proposed for the formation of these products based on PHIP results. Methylenecyclobutane hydrogenation over TiO2‐supported Rh, Pt and Pd catalysts is investigated using parahydrogen‐induced polarization (PHIP) technique. Formation of up to 12 reaction products is observed including cyclic, linear, and branched acyclic compounds. The temperature dependence of reaction selectivity is studied. Based on the observed parahydrogen‐induced polarization effects the mechanisms of products formation are proposed.
ISSN:1439-4235
1439-7641
DOI:10.1002/cphc.202200072