Real-Time Detection of Intermediates in Rhodium Catalyzed Hydrogenation of Alkynes and Alkenes by Dissolution DNP

Peter Andreas Boeg, Jens Øllgaard Duus, Jan Henrik Ardenkjær-Larsen, Magnus Karlsson, Susanne Mossin*

*Corresponding author for this work

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Abstract

The hydrogenation of alkynes and alkenes using a Shrock-Osborn catalysts was followed in-situ with dissolution dynamic nuclear polarization (dDNP) NMR. Natural abundance and 13C labeled dimethyl acetylenedicarboxylate was hyperpolarized prior to hydrogenation using (1,4-bis{diphenylphosphino}butane)(2,5-norbornadiene) rhodium(I) perchlorate, [Rh(NBD)(DPPB)]ClO4. The increased signal-to-noise ratio of dDNP compared to conventional 13C NMR allowed real-time detection of substrate and products as well as the modeling of the hydrogenation kinetics. The build-up of an intermediate was observed during interruption in hydrogen flow, substantiating the current view of the reaction mechanism. Selective inversion of the carbonyl NMR signal of the substrate was applied to demonstrate unequivocally that the new peak appearing in the spectrum originates from a reaction intermediate. The scope of the dDNP method for following reaction dynamics in real time was further demonstrated by substrate competition experiments.
Original languageEnglish
JournalThe Journal of Physical Chemistry Part C
Volume123
Issue number15
Pages (from-to)9949-9956
Number of pages8
ISSN1932-7447
DOIs
Publication statusPublished - 2019

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