Fischer Anna, Makowski Philippe, Müller Jens-Oliver, Antonietti Markus, Thomas Arne, Goettmann Frederic
Colloid Chemistry Department, Max-Planck Institute of Colloids and Interfaces, Research Campus Golm, 14542 Potsdam, Germany.
ChemSusChem. 2008;1(5):444-9. doi: 10.1002/cssc.200800019.
To design more sustainable processes for the alkylation of ketones, the use of both atom-ineffective leaving groups such as halides and boron as well as noble-metal-based catalysts should be avoided. For that purpose, high-surface-area titanium nitride was prepared from high-surface-area titanium dioxide using cyanamide as a transcription agent. The resulting nitride as well as the initial oxide proved to be effective and versatile catalysts for the alkylation of ketones with alcohols. Interestingly, the TiN catalyst yields unsaturated compounds, while the oxide-based catalyst mainly yields saturated coupling products. As a result of its metallic properties, TiN shows a strong tendency to catalyse the dehydrogenation of alcohols, which then undergo aldol condensation with ketones. In contrast, TiO(2) promotes the direct nucleophilic attack of ketones on alcohols.
为设计更可持续的酮烷基化工艺，应避免使用卤化物和硼等原子利用率低的离去基团以及基于贵金属的催化剂。为此，以氰胺为转化剂，由高比表面积二氧化钛制备了高比表面积氮化钛。结果表明，所得氮化物以及初始氧化物是酮与醇烷基化反应的有效且通用的催化剂。有趣的是，TiN催化剂生成不饱和化合物，而氧化物基催化剂主要生成饱和偶联产物。由于其金属特性，TiN表现出强烈的催化醇脱氢的倾向，脱氢后的醇再与酮发生羟醛缩合反应。相比之下，TiO₂促进酮对醇的直接亲核进攻。
