Tangyen Niracha, Natongchai Wuttichai, Del Gobbo Silvano, D'Elia Valerio
Department of Materials Science and Engineering, VISTEC Advanced Laboratory for Environment-Related Inorganic and Organic Syntheses, Vidyasirimedhi Institute of Science and Technology (VISTEC), Payupnai, Wang Chan, 21210 Rayong, Thailand.
ACS Omega. 2024 Apr 20;9(17):19712-19722. doi: 10.1021/acsomega.4c02190. eCollection 2024 Apr 30.
The utilization of biobased feedstocks to prepare useful compounds is a pivotal trend in current chemical research. Among a varied portfolio of naturally available starting materials, fatty acids are abundant, versatile substrates with multiple applications. In this context, the ethenolysis of unsaturated fatty acid esters such as methyl oleate is an atom-economical way to prepare functional C10 olefins with a biobased footprint. Despite the existence of a variety of metathesis catalysts for the latter process, there is a lack of readily available, efficient, and inexpensive catalytic systems based on earth-abundant metals (Mo, W) whose preparation does not require sophisticated syntheses and manipulations. Here, a systematic exploration of homogeneous and heterogeneous inorganic Mo, W (oxy)halides shows that MoOCl, while inactive as a homogeneous species, forms active and selective silica-supported ethenolysis precatalysts able to reach equilibrium conversion of methyl oleate within a few minutes upon activation with SnMe. Such heterogeneous MoOCl-based precatalysts were easily accessed through mechanochemical solvent-free procedures and found to contain, upon characterization by elemental analysis and Raman spectroscopy, isolated (≡SiO)Mo(=O)Cl units or polymeric silica-supported [-O(≡SiO)MoClO-] ( = 1, 2) complexes depending on the molybdenum loading. The former isolated species exhibited a higher catalytic performance. The developed heterogeneous precatalysts could be applied to the ethenolysis of various substrates, including polyunsaturated fatty acid esters and industrial fatty acid methyl ester (FAME) mixtures from palm oil transesterification.
利用生物基原料制备有用化合物是当前化学研究的一个关键趋势。在各种各样天然可得的起始原料中，脂肪酸是丰富、用途广泛的底物，有多种应用。在这种背景下，不饱和脂肪酸酯（如油酸甲酯）的乙烯基化反应是一种原子经济的方法，可制备具有生物基足迹的功能性C10烯烃。尽管对于后一过程存在多种复分解催化剂，但缺乏基于储量丰富的金属（钼、钨）的现成、高效且廉价的催化体系，其制备不需要复杂的合成和操作。在此，对均相和非均相无机钼、钨（氧）卤化物的系统探索表明，MoOCl虽然作为均相物种无活性，但能形成活性和选择性的二氧化硅负载的乙烯基化反应预催化剂，在用二甲基锡活化后几分钟内就能使油酸甲酯达到平衡转化率。这种基于MoOCl的非均相预催化剂可通过机械化学无溶剂程序轻松获得，经元素分析和拉曼光谱表征发现 根据钼负载量的不同，含有孤立的(≡SiO)Mo(=O)Cl单元或聚合的二氧化硅负载的[-O(≡SiO)MoClO-]（ = 1, 2）配合物。前者孤立的物种表现出更高的催化性能。所开发的非均相预催化剂可应用于各种底物的乙烯基化反应，包括多不饱和脂肪酸酯和来自棕榈油酯交换反应的工业脂肪酸甲酯（FAME）混合物。
