Straightforward Immobilization of Phosphonic Acids and Phosphoric Acid Esters on Mesoporous Silica and Their Application in an Asymmetric Aldol Reaction
Christian Weinberger,
Tatjana Heckel,
Patrick Schnippering,
Markus Schmitz,
Anpeng Guo,
Waldemar Keil,
Heinrich C. Marsmann,
Claudia Schmidt,
Michael Tiemann,
René Wilhelm
Affiliations
Christian Weinberger
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Tatjana Heckel
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Patrick Schnippering
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Markus Schmitz
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Anpeng Guo
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Waldemar Keil
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Heinrich C. Marsmann
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Claudia Schmidt
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
Michael Tiemann
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
René Wilhelm
Department of Chemistry, Paderborn University, Warburger Str. 100, D-33098 Paderborn, Germany
The combined benefits of moisture-stable phosphonic acids and mesoporous silica materials (SBA-15 and MCM-41) as large-surface-area solid supports offer new opportunities for several applications, such as catalysis or drug delivery. We present a comprehensive study of a straightforward synthesis method via direct immobilization of several phosphonic acids and phosphoric acid esters on various mesoporous silicas in a Dean⁻Stark apparatus with toluene as the solvent. Due to the utilization of azeotropic distillation, there was no need to dry phosphonic acids, phosphoric acid esters, solvents, or silicas prior to synthesis. In addition to modeling phosphonic acids, immobilization of the important biomolecule adenosine monophosphate (AMP) on the porous supports was also investigated. Due to the high surface area of the mesoporous silicas, a possible catalytic application based on immobilization of an organocatalyst for an asymmetric aldol reaction is discussed.
