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RuNi nanoparticles supported on a metal− organic framework (RuNi@MOF) and formed in situ from a ruthenium complex enclosed inside a nickel-based MOF act as a highly active catalyst for the Guerbet reaction of ethanol to 1-butanol, providing turnover numbers up to 725 000 Ru−1. Negligible activity of the RuNi@MOF ethanol upgrading catalyst system toward chemically similar 1-butanol makes it possible to synthesize the competent Guerbet substrate 1-butanol with >99% selectivity. A high selectivity for a desired product in a catalytic reaction is exceedingly challenging when the starting material and the product bear strong chemical resemblance, because the product itself can act as a substrate, leading to oligomerization and polymerization. Indeed, polymerization reactions rely on the fact that the catalyst continues to add monomers to a growing chain because the same functional group terminates the polymer after every addition of monomer. The synthesis of 1-butanol (n-BuOH) from ethanol (EtOH) via the Guerbet reaction, on the other hand, is an example of a reaction where the ideal catalyst would display very high activity for the conversion of EtOH, but be unreactive toward n-BuOH, which only differs from EtOH by the length of the primary alcohol’s carbon chain. Beyond the academic interest in achieving differential catalytic selectivity toward chemically similar compounds, the efficient conversion of EtOH to n-BuOH is desirable because n-BuOH is a promising drop-in alternative to gasoline. Although EtOH itself can replace a fraction of gasoline in transportation fuel, EtOH, unlike n-BuOH, cannot be transported via pipelines or fully replace gasoline for use in cars without special engine modifications. Due to its considerably lower corrosiveness, as well as physical and chemical properties that more closely resemble gasoline, nBuOH can serve as a drop-in biofuel if obtained from a renewable source such as bio-derived EtOH. The homogeneous and heterogeneous catalysts currently available for the Guerbet upgrading of EtOH to n-BuOH show distinct side product profiles: whereas homogeneous Guerbet catalysts commonly produce sodium acetate and C6+ alcohols as undesirable side products, heterogeneous catalysts tend to form undesirable olefins, ethers, alkanes, as well as C6+ alcohols. 6−23 Furthermore, although homogeneous Guerbet reactions can be conducted at 150−160 °C, heterogeneous Guerbet reactions typically require temperatures in excess of 250 °C for practical reaction rates. A more desirable catalyst is one that combines the process advantages of heterogeneous catalysts, but operates below 200 °C and produces minimal side products. One class of compounds that share characteristics of both homogeneous and heterogeneous catalysts and are therefore well positioned to answer this challenge is metal−organic Received: August 19, 2019 Published: October 22, 2019 Scheme 1. Proposed Mechanism of EtOH Upgrading to nBuOH Scheme 2. Synthetic Scheme for Accessing MOF-Derived Guerbet Pre-catalysts for EtOH Upgrading to n-BuOH Communication pubs.acs.org/JACS Cite This: J. Am. Chem. Soc. XXXX, XXX, XXX−XXX © XXXX American Chemical Society A DOI: 10.1021/jacs.9b08968 J. Am. Chem. Soc. XXXX, XXX, XXX−XXX D ow nl oa de d vi a M A SS A C H U SE T T S IN ST O F T E C H N O L O G Y o n N ov em be r 5, 2 01 9 at 1 3: 37 :1 7 (U T C ). Se e ht tp s: //p ub s. ac s. or g/ sh ar in gg ui de lin es f or o pt io ns o n ho w to le gi tim at el y sh ar e pu bl is he d ar tic le s.

Metal Organic Framework-Derived Guerbet Catalyst Effectively Differentiates between Ethanol and Butanol