Tunable Hydro/Dicarboxylation of Ethylene with CO2 via a Barrierless Radiolytic Free-Radicals Pathway

The hydro/dicarboxylation of ethylene (C2H4) feedstock with CO2 to produce high-value carboxylic acids is an industrially relevant yet challenging reaction due to their extremely low reactivities. Herein, we present an effective strategy to synthesize propionic acid and succinic acid from a mixture of CO2 and C2H4 catalyzed by high-energy water radiolysis. The process involves the generation of CO2 radical anions via the barrierless attachment of hydrated electrons to CO2, facilitating an ambient, continuous carboxylation of C2H4 with an efficiency of 81.4%. Utilizing easily available electron beam irradiation, we achieved a combined production rate of 0.34 mmol L–1 min–1 for carboxylic acids, which is unattainable by the existing methods. Notably, product selectivity between hydro- and dicarboxylation was dose-rate/beam intensity-dependent: high-dose-rate irradiation favored succinic acid formation with a proportional yield of up to 65.4%, while milder conditions resulted in an 85.1% yield of propionic acid. We suggested that the simplicity and efficiency of the present carboxylation approach promote circular carbon in the sustainable chemical industry.