定向催化氨解木质素衍生芳香化合物的C(sp2)–OMe键一步合成芳香胺的研究

木质素C(sp2)–OMe键的一步定向催化氨解是非化石资源制芳香胺的一条绿色经济的新路线，但胺化试剂与C(sp2)–OMe在催化剂上的竞争吸附将影响C(sp2)–OMe的活化氨解，因此构建氨解条件下高选择性活化C(sp2)–OMe键的催化剂是木质素定向氨解的关键。我们前期的研究发现，配位不饱和的NbOx具有优异的C–O活化能力，为此本项目拟通过改变铌材料的形貌组成、掺杂具有空轨道金属M（易与N的孤对电子成键）来调控铌的配位状态、电子价态及Nb–M间距离，从而增强铌对C–O的活化并抑制其对胺的吸附，合适的Nb–M距离使M活化的胺进一步氨解活化后的C(sp2)δ+–Oδ−成为可能；另一方面，选择不同的胺化试剂，优化反应条件，明确氨解反应速控步，理清氨解机理；并结合原位表征和理论计算，制备出定向氨解C(sp2)–OMe的高效铌基催化剂，实现木质素衍生芳香化合物一步定向催化氨解制芳香胺的过程。

One-step and site-directed catalytic amination of C(sp2)–OMe in lignin can provide a new green and economical route from non-fossil energy sources to anilines. However, there is the competitive adsorption between C(sp2)–OMe and amination reagents on the catalyst surface for the amination of lignin. The selective activation of C(sp2)–OMe bond in the presence of amination reagents is the key to solve it. It has been found in our previous research that NbOx with high unsaturated coordination has a good ability of C–O bond activation. In this project, we intend to start to study from the design and preparation of Nb based materials. Coordination and electronic valence of niobium and the distance between Nb and metal M will be controlled in a certain range by altering the morphology and composition of Nb based materials and doping the metals (M) with empty orbits (easy to bond N with lone pair electrons from N of amination reagents) to enhance the activation of O and inhibit the adsorption of amine on Nb. Suitable distance between Nb and metal M makes further amination of the active C(sp2)δ+–Oδ− possible; on the other hand, various amination reagents with different substituents will be assembled in the amination of C(sp2)–OMe. The reaction conditions will be optimized and the rate-determining step and the mechanism of the amination of C(sp2)–OMe will be clarified. Correlated with in situ characterization and calculation theory, the Nb based catalysts for the site-directed and efficient amination of C(sp2)–OMe will be constructed and one-step catalytic synthesis of anilines from lignin-derived aromatic compounds via site-directed C(sp2)–OMe amination will be realized.