Self-aldol condensation of unmodified aldehydes catalysed by secondary-amine immobilised in FSM-16 silica

Sustainable Self-Aldol Condensationof Unmodified Aldehyde: A Combination of Ionic Liquid and HeterogeneousSecondary-Amine Grafted on Silica

“…The catalyst, NMAP-SiO 2 exhibited higher reactivity in [bmim]PF 6 than in any other solvents. 16 The system can be recycled several times simply after evacuation without appreciable loss of reactivity. Simplicity of operation as well as the mild and environmentally benign nature of the reaction would enable expansion to a wide variety of functionalised substrates, even to a larger-scale reaction.…”

“…Washing the system with alkaline solution was not required, which is more efficient than our previous NMAP-FSM16/toluene system. 16 Marked loss of reactivity of the system was not observed until the eighth recycle. Aldehydes 1 having an acid or a base-sensitive protecting group also provided enals 2 without any decomposition, which exemplified the mild nature of the present procedure ( Table 2, entries 8-11).…”

“…Our previous investigation on self-aldol condensation corroborated the finding that a conventional inorganic solid base such as MgO or hydrotalcite did not give satisfactory result. 16 To this end, two kinds of heterogeneous secondary amine catalysts, an Nmethylaminopropyl group grafted on FSM-16 mesoporous silica (NMAP-FSM16) 17 and on amorphous silica (NMAP-SiO 2 , Figure 1), 16,18,19 were prepared, according to the post-modification procedure, 16,17 and their catalytic reactivities were investigated towards self-aldol condensation of an unmodified aldehyde 1 in [bmim]PF 6 . Nitrogen loading in each catalyst was 0.74 or 0.75 mmol/g, respectively.…”

Nanostructured Catalysts for the Aldol, Knoevenagel, and Henry Reactions

“…This produced three different catalysts, abbreviated as NH 2 -FSM, NHMe-FSM, and NMe 2 -FSM, respectively. 68 By using these materials as solid catalysts, the aldol condensation of n-hexanal into the corresponding enal product with moderate-to-high yield was achieved. The catalytic activity of the reaction was found to be strongly dependent on the type of amine groups supported on the mesoporous material, with the catalytic activity decreasing in order of secondary amine Ͼ primary amine Ͼ tertiary amine.…”

Ordered Mesoporous Silica Derived from Layered Silicates

“…Conjugate addition and self-aldol condensation of aldehydes effectively proceed over FSM-16 with N-methyl-3-aminopropyl groups. [148,149] Surface Si-OH groups of FSM-16 are converted to Si-NH 2 groups in a flow of NH 3 . [150] As described above, strained siloxane bridges are present at the surface of FSM-16 by preheating at higher temperatures.…”