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)₄Cr-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 mol_Anhydride·mol_Co ^-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.