Hybrid organic–inorganic catalytic mesoporous materials with proton sponges as building blocks

Designing bifunctional acid–base mesoporous hybrid catalysts for cascade reactions

“…Synthesis of the silylated base precursor 1,8-bis(dimethylamino)naphthalene (DMAN) was functionalized with terminal silyl-alcoxide reactive groups, 34,35 (see Fig.1SI for NMR characterisation of the silyl derived DMAN), obtaining 50 mono and bi-silylated DMAN precursors. In fact, to graft DMAN onto the wall of mesoporous silica, a mono-silylated precursor (DMAN-1Sil) is necessary, whilst two terminal reactive silyl groups (DMAN-2Sil) are needed to integrate the base organocatalysts into the framework of mesoporous material 55 through one-pot synthesis with conventional monosilane precursors (TMOS or TEOS), used as additional silicon sources, through sol-gel or micellar routes.…”

Classical Keggin Intercalated into Layered Double Hydroxides: Facile Preparation and Catalytic Efficiency in Knoevenagel Condensation Reactions

“…It is worth noting that the Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate gave us a yield of >99.9% using a reaction mixture ratio of benzaldehyde : ethyl cyanoacetate : Mg3Al-PW12 = 47980 : 71970 : 1 at 60 o C in Vipropanol:Vwater = 2 : 1. Interestingly, the TON can reach as high as 47980 (Table 4, Entry 1), which is the highest reported so far in comparison with other reported catalysts such as VAp in water (TON = 39583, Entry 2), [44] DMAN/SiO2 in ethanol (TON = 10000, Entry 3), [45] polystyrene-supported poly(amidoamine)dendrimer in ethanol (TON = 198, Entry 4), [46] amine-grafted PE-MCM-41 in cyclohexane (TON = 198, Entry 5), [47] and others listed in Table 4. [48][49][50][51][52][53][54][55][56][57][58][59][60] In an effort to confirm the fact that the catalysis is truly heterogeneous, the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate has been selected as an example.…”

Synthesis of an extra-large molecular sieve using proton sponges as organic structure-directing agents

“…The 13 C MAS NMR cross-polarization spectrum was achieved with a spinning rate of 5 kHz. 29 Si, 27 Al, 31 P, and 13 C chemical shifts were referenced to tetramethylsilane, Al 3+ (H 2 O) 6 , 85% H 3 PO 4 , and adamantane, respectively. The 27 Al (triple-quantum) MAS NMR experiment was performed using z-filter pulse sequence.…”

“…These molecules present a highly unusual basicity because of the repulsion of the close electronic lone pairs (pK a ≈12.1) (28). They are used extensively in organic synthesis as very selective nonnucleophilic bases with very interesting catalytic properties when used in the homogeneous phase (29) or when prepared in the form of structured hybrid solid catalytic materials (30,31). Taking into account their basic properties, the C/N ratio, and molecular structures, we thought proton sponges might be suitable OSDAs for the synthesis of extra-large microporous molecular sieves.…”