Abstract

Mesoporous titania–ceria mixed oxide (MTCMO) was synthesised in a sol–gel method using cerium chloride and titanium isopropoxide (TTIP) as CeO₂ as well as TiO₂ precursors and sodium dodecyl sulphate (SDS) as a structure-directing agent and its application was evaluated in the synthesis of aromatic β-phosphonomalonate derivatives via cascade Knoevenagel–phospha-Michael addition reaction. The catalyst characterised by various techniques like FT-IR spectroscopy, XRD, SEM, EDS, TEM and N₂ adsorption-desorption. Partial substitution of Ti⁴⁺ cations with Ce⁴⁺ improved the BET surface area because TiO₂ crystallites were suppressed to be grown. Furthermore, as a consequence of charge imbalance in the obtained Ti-O-Ce solid solution, some oxygen vacancies have generated that act as Lewis base sites while cations (Ti and Ce) around the oxygen vacancies act as Lewis acid sites. Reusability up to eight consecutive runs without significant decrease in reactivity, Mild reaction conditions, environmentally benign and compatibility with various functional groups are some of the advantages of this work.

摘要

以溶胶-凝胶法合成了介孔二氧化钛-二氧化铈混合氧化物（MTCMO），使用氯化铈和异丙氧基钛（TTIP）作为CeO ₂，并使用TiO ₂前驱体和十二烷基硫酸钠（SDS）作为结构导向剂及其通过级联Knoevenagel-phospha-Michael加成反应合成芳族β-膦酰基丙酸酯衍生物的应用进行了评估。该催化剂具有多种技术特征，如FT-IR光谱，XRD，SEM，EDS，TEM和N ₂吸附-脱附。由于TiO _2，用Ce ⁴⁺部分取代Ti ⁴⁺阳离子改善了BET表面积。微晶被抑制生长。此外，由于所获得的Ti-O-Ce固溶体中电荷不平衡的结果，产生了一些氧空位，其充当路易斯碱位，而围绕氧空位的阳离子（Ti和Ce）充当路易斯酸位。这项工作的优点包括：最多可连续使用八次，而不会显着降低反应性，温和的反应条件，对环境无害以及与各种官能团的相容性。