Catalytic Activity of Proton Sponge: Application to Knoevenagel Condensation Reactions

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

“…The adsorption data observed, both from Ar and N 2 adsorption measurements, would indicate that the framework structure of ITQ-51 may contain 1D extra-large (14-or 16-ring) pores. 27 Al, 29 Si, and 31 P MAS NMR spectra of the calcined ITQ-51 material were recorded to obtain information on the local atomic environments, which also may be very useful for structure elucidation. The 31 P MAS NMR spectrum shows at least four welldefined, distinct crystallographic positions for P atoms (SI Appendix, Fig.…”

“…S8). Finally, the 29 Si MAS NMR spectrum illustrates a single peak at −110 ppm, assigned to the presence of silicon atoms forming silicon-rich domains (SI Appendix, Fig. S9) (38).…”

“…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.…”

Chemicals from Biomass: Synthesis of Biologically Active Furanochalcones by Claisen–Schmidt Condensation of Biomass-Derived 5-hydroxymethylfurfural (HMF) with Acetophenones

“…A possible reason of these results can be based on differences on activation energy of the solvated transition states. If the reaction is performed with a polar solvent, the transition state complex could be better solvated decreasing the activation free enthalpy, enhancing the reaction rate as the solvent polarity is increased [32]. Moreover, it is observed that in the presence of polar solvents the order of activity (initial reaction rates) of the catalysts changes with respect to the results obtained when the reaction was performed in absence of solvent (see Table 2), being HTr>MgO>HTc.…”