Hafnium zeolite stitches together itaconic acid analogs

Itaconic acid and its ester analogs have been identified by the Department of Energy as one of the top 12 biomass-derived chemical classes that can serve as substitutes for high-volume petroleum-derived feedstocks. The top 12 candidates are versatile building blocks for making polymers, lubricants, plasticizers, and more. A goal in creating this list is to prompt chemists and chemical engineers to develop cost-effective methods to produce the compounds on a large scale. For itaconic acid, which is a potential replacement for acrylic acid, maleic anhydride, and acetone cyanohydrin, a challenge has been to develop an affordable catalytic synthesis that selectively forms linear products rather than cyclic lactones and avoids catalyst deactivation issues that have plagued prior approaches. MIT’s Yuran Wang, Jennifer D. Lewis, and Yuriy Román-Leshkov have found a solution in the form of a hafnium zeolite that efficiently catalyzes the self-aldol condensation/hydrolysis of sugar-derived ethyl pyruvate to make itaconic acid ester analogs (ACS Catal. 2016, DOI: 10.1021/acscatal.6b00561). The team’s spectrochemical analysis suggests that the synthesis is made possible because the zeolite is endowed with unique dual functionality: Lewis acidic hafnium centers catalyze the aldol condensation and Brønsted acidic silanol groups catalyze hydrolysis (shown).