Insight into decomposition of formic acid to syngas required for Rh-catalyzed hydroformylation of olefins

Formic acid (FA) is one kind of important bulk chemicals, which is recognized as a sustainable and ecofriendly energy carrier to transport H-2 via dehydrogenation or CO via decarbonylation. Expectantly, FA upon decomposition into H-2 and CO could be used as the syngas alternative for hydroformylation. In this paper, the behaviors of FA to release H-2 as well as CO following the distinct pathways were carefully investigated for the first time, and then established a new hydroformylation protocol free of syngas. It was found that the atmospheric hydroformylation of olefins with formic acid (FA) as syngas alternative was smoothly fulfilled over Xantphos (L1) modified Rh-catalyst under mild conditions (80 degrees C, Rh concentration 1 mol %, 14 h), resulting in >90% conversion of the olefins along with the high selectivity to the target aldehydes (>93%). By using FA as syngas source, the side-reaction of olefin-hydrogenation was greatly depressed. The in situ FT-IR and the high-pressure H-1 NMR spectroscopic analyses were applied to reveal how FA behaves dually as CO surrogate and hydrogen source over L1-Rh(acac)(CO)(2) catalytic system, based on which the deeply insight into the catalytic mechanism of hydroformylation of olefins with FA as syngas alternative was offered. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

In this study, the behavior of formic acid (FA) in releasing H-2 and CO was carefully investigated, leading to the development of a new hydroformylation protocol without the need for syngas. The use of FA as a syngas source suppressed side reactions and enabled insight into the catalytic mechanism through spectroscopic analysis. This research provides a promising alternative for olefin hydroformylation with potential environmental benefits.