A Resin‐Supported Formate Catalyst for the Transformative Reduction of Carbon Dioxide with Hydrosilanes

Abstract

A heterogeneous formate anion catalyst for the transformative reduction of carbon dioxide (CO2) based on a polystyrene and divinylbenzene copolymer modified with alkylammonium formate was prepared from a widely available anion exchange resin. The catalyst preparation was easy and the characterization was carried out by using elemental analysis, Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and solid‐state 13C cross‐polarization/magic‐angle spinning nuclear magnetic resonance (13C CP/MAS NMR) spectroscopy. The catalyst displayed good catalytic activity for the direct reduction of CO2 with hydrosilanes, tunably yielding silylformate or methoxysilane products depending on the hydrosilanes used. The catalyst was also active for the reductive insertion of CO2 into both primary and secondary amines. The catalytic activity of the resin‐supported formate can be predicted from the FTIR spectra of the catalyst, probably because of the difference in the ionic interaction strength between the supported alkylammonium cations and formate anions. The ion pair density is thought to influence the catalytic activity, as shown by the elemental and solid‐state 13C NMR analyses.

Heterogeneous Organocatalysts for the Reduction of Carbon Dioxide with Silanes

“…As listed in Table 2, among various anionic homogeneous systems, the highest yield of silylformate product was obtained when formate was employed. A similar trend was observed for heterogeneous systems [82] . Further, resin‐supported formate catalysts were active in both the direct hydrosilylation of CO 2 and the reductive incorporation of CO 2 into amines with hydrosilanes (Scheme 22).…”

“…An alkylammonium formate from a widely available anion exchange resin was employed as the active species in heterogeneous catalysts developed by Motokura and co‐workers [82] . Historically, anion exchange resins have been used as the support for various anion‐catalyzed reactions, including Knoevenagel [83] and aldol [84] condensations.…”

“… Catalytic activity of heterogeneous Amberlite IRA400/formate catalyst for (A) direct hydrosilylation and (B) N ‐formylation of morpholine ( 2 a ) [82] …”

“…Although the active sites are identical, their distribution can affect the catalytic activity of the heterogeneous catalysts in the CO 2 reduction with silanes. Motokura and co‐workers [82] prepared polymer‐supported alkylammonium formate catalysts from anion exchange resins. In these catalysts, the employed cation (trimethylammonium) is the same as in the case of polystyrene‐co‐divinylbenzene supports.…”

“… Effect of ion pair density (represented by N/C ratio) towards formate catalytic activity for CO 2 hydrosilylation [82] …”