Continuous-Flow Production of Succinic Anhydrides via Catalytic β-Lactone Carbonylation by Co(CO)4⊂Cr-MIL-101

Industrial synthesis of succinic acid relies on hydrocarbon oxidation or biomass fermentation routes that suffer from energy-costly separation processes. Here we demonstrate an alternate route to succinic anhydrides via β-lactone carbonylation by heterogeneous bimetallic ion-pair catalysis in Co(CO)4–-incorporated Cr-MIL-101 (Co(CO)4⊂Cr-MIL-101, Cr-MIL-101 = Cr3O(BDC)3F, H2BDC = 1,4-benzenedicarboxylic acid). Postsynthetically introduced Co(CO)4– facilitates CO insertion to β-lactone substrates activated by the Lewis acidic Cr(III) centers of the metal–organic framework (MOF), leading to catalytic carbonylation with activity and selectivity profiles that compare favorably to those reported for homogeneous ion-pair catalysts. Moreover, the heterogeneous nature of the MOF catalyst enables continuous production of succinic anhydride through a packed bed reactor, with room temperature β-propiolactone carbonylation activity of 1300 molAnhydride·molCo–1 over 6 h on stream. Simple evaporation of the fully converted product stream yields the desired anhydride as isolated solids, highlighting the unique processing advantages conferred by this first example of heterogeneous β-lactone carbonylation pathway.