Cu(II) carboxylate arene C─H functionalization: Tuning for nonradical pathways.

We report carbon-hydrogen acetoxylation of nondirected arenes benzene and toluene, as well as related functionalization with pivalate and 2-ethylhexanoate ester groups, using simple copper(II) [Cu(II)] salts with over 80% yield. By changing the ratio of benzene and Cu(II) salts, 2.4% conversion of benzene can be reached. Combined experimental and computational studies results indicate that the arene carbon-hydrogen functionalization likely occurs by a nonradical Cu(II)-mediated organometallic pathway. The Cu(II) salts used in the reaction can be isolated, recycled, and reused with little change in reactivity. In addition, the Cu(II) salts can be regenerated in situ using oxygen and, after the removal of the generated water, the arene carbon-hydrogen acetoxylation and related esterification reactions can be continued, which leads to a process that enables recycling of Cu(II).

Reduction of N2 to Ammonia by Phosphate Molten Salt and Li Electrode: Proof of Concept Using Quantum Mechanics.

Electrochemical routes provide an attractive alternative to the Haber-Bosch process for cheaper and more efficient ammonia (NH3) synthesis from N2 while avoiding the onerous environmental impact of the Haber-Bosch process. We prototype a strategy based on a eutectic mixture of phosphate molten salt. Using quantum-mechanics (QM)-based reactive molecular dynamics, we demonstrate that lithium nitride (Li3N) produced from the reduction of nitrogen gas (N2) by a lithium electrode can react with the phosphate molten salt to form ammonia. We extract reaction kinetics of the various steps from QM to identify conditions with favorable reaction rates for N2 reduction by a porous lithium electrode to form Li3N followed by protonation from phosphate molten salt (Li2HPO4-LiH2PO4 mixture) to selectively form NH3.