Activated-Carbon-Supported Calcium Oxide: A Selective and Efficient Catalyst for Nitrile-Containing Diaryl Ether Synthesis

Activated-carbon-supported calcium oxide (CaO@AC) was prepared from AC and a suspension derived from CaO and ammonium carbonate. After calcination under nitrogen, high purity CaO@AC was obtained. The nature of non-aggregation and high purity of CaO@AC enabled a clean and selective synthesis protocol for nitrile-containing diaryl ethers. Various functional groups including methoxyl, amino, carboxyl, allyl and nitro were well-tolerated, and products were obtained in excellent yields and purities. Asymmetric substitutions could be achieved via simple adjustment of reaction conditions, and transetherification was greatly suppressed to 10(-3)-10(-4) scale. In addition, a mechanism for suppression in transetherification was proposed and discussed.