Sustainable Catalytic Synthesis of Diethyl Carbonate

Abstract

New sustainable approaches should be developed to overcome equilibrium limitation of dialkyl carbonate synthesis from CO2 and alcohols. Using tetraethyl orthosilicate (TEOS) and CO2 with Zr catalysts, we report the first example of sustainable catalytic synthesis of diethyl carbonate (DEC). The disiloxane byproduct can be reverted to TEOS. Under the same conditions, DEC can be synthesized using a wide range of alkoxysilane substrates by investigating the effects of the number of ethoxy substituent in alkoxysilane substrates, alkyl chain, and unsaturated moiety on the fundamental property of this reaction. Mechanistic insights obtained by kinetic studies, labeling experiments, and spectroscopic investigations reveal that DEC is generated via nucleophilic ethoxylation of a CO2‐inserted Zr catalyst and catalyst regeneration by TEOS. The unprecedented transformation offers a new approach toward a cleaner route for DEC synthesis using recyclable alkoxysilane.

On-Demand Photochemical Synthesis of Hydrogen Peroxide from Alkylated Anthraquinones

“…It is possible that even though abstraction of H b results in a somewhat more stabilized organic radical, follow-up reactions with O 2 are less favored because the production of aldehyde from benzyl radical would be much faster (Figure ). Diethyl carbonate and ethyl isobutyrate were both active solvents for the production of H 2 O 2 but possessed calculated oxidation potentials that were highly thermodynamically unfavorable (>3 V vs SCE, Table S13). The calculated BDFEs of these solvents, while significantly uphill of p -cymene and toluene, would still be thermodynamically accessible from the excited state of 5* and significantly less strong than H 2 O (exptl., 117.9 kcal mol –1 , in H 2 O), , which suggests that PCET is the preferable abstraction mechanism in these solvents.…”

From SiO2 to Alkoxysilanes for the Synthesis of Useful Chemicals

“…An improved sustainable synthesis of DEC has been reported using TEOS and CO 2 as substrates. 24 In the presence of Zr(OEt) 4 catalysts, the maximum yield of DEC was ∼50% at 180 °C. No improvement in the yield was observed upon extending the reaction time from 15 to 40 h due to equilibration.…”

“…An improved sustainable synthesis of DEC has been reported using TEOS and CO 2 as substrates . In the presence of Zr­(OEt) 4 catalysts, the maximum yield of DEC was ∼50% at 180 °C.…”

En Route to CO2-Based (a)Cyclic Carbonates and Polycarbonates from Alcohols Substrates by Direct and Indirect Approaches

“…The highest DMC yield of 70% was obtained after 72 h at 180 • C, under 30 MPa of CO 2 pressure using the Bu 2 Sn(OMe) 2 /Bu 4 PI catalytic system, while lower DMC yields of 1.8-10.4% were obtained at 12 MPa after 34 h when 1,1,1-trimethyl orthoformiate was combined with ceriazirconia oxides. Recently, Fukaya revisited this conceptual route by using water-sensitive an alkoxysilane, i.e., tetraethyl orthosilicate, as the alcohol precursor and a Zr(OEt) 4 catalyst, which favors the ethoxylation of CO 2 [71]. The DEC yield reached 58% after 24 h at 180 • C under 5 MPa of CO 2 .…”