Efficient Catalysis of Phosphate Ester Hydrolysis by Bare Silica

Abstract

This work reports the catalysis of bare silica materials (MCM-41, SBA-15, and silica gel) for the complete hydrolyses of bis(2,4-nitrophenyl)phosphate (BDNPP) and bis(4nitrophenyl)phosphate (BNPP), which share the same phosphate diester chemical core with important biological molecules, DNA and RNA, and toxic substances like EA2192 and anatoxin-a(s). Catalytic effects above 7000-fold were observed for the hydrolysis of BNPP, which were consistent with a concerted S N 2(P) mechanism under the action of siloxide and silanol groups that provide water activation by general base catalysis and leavinggroup departure stabilization by general acid catalysis, respectively. We also observed that product formation follows a sigmoidal behavior as a result of catalytic effect enhancement following an induction period. This effect is discussed considering cooperative effects caused by silica hydration, which is unchanged upon material reuse affording strong catalytic effects for phosphate diester hydrolyses and no induction periods.

Lanthanum Materials Enable Catalytic Hydrolysis of Phosphate Esters: Implications for Water Treatment and Eutrophication Control

“…In summary, the Lewis acid activation might be the dominating mechanism for La(OH) 3 catalyzed hydrolysis of p -NPP, with the possible participation of nucleophilic activation by surface −OH and leaving group activition . The three mechanisms may play in synergy to catalyze the hydrolysis of phosphate esters . Future studies using advanced in situ probes and theoretical calculations using explicit hydration methods , are needed to further reveal the complex heterogeneous catalytic mechanisms.…”

“…50 The three mechanisms may play in synergy to catalyze the hydrolysis of phosphate esters. 51 Future studies using advanced in situ probes 52 and theoretical calculations using explicit hydration methods 47,53 are needed to further reveal the complex heterogeneous catalytic mechanisms.…”

Facile Synthesis of H-Phosphinates from P(OR)3 or ClP(OR)2 via SiO2-Promoted Hydrolysis

“…It should be noted that, for crude phosphonite in this procedure, only by column chromatography treatment could H-phosphinate be obtained with high purity and efficiency. According to the detailed study on silica-catalyzed hydrolysis of phosphates by Brandao et al, 12 silica materials share similar silanol densities of about 4.2−5.7 OH groups nm −2 , despite their source and structural characteristics. The exposed silanol groups on the amorphous silica gel surface can interact with the polar water molecules, as well as phosphonite diesters, at the solid−liquid interface with weak to strong hydrogen bonds.…”

The Dynamic Catalytic Activity of Phosphorus-containing Catalysts

“…2.3.5 Solid-state 31 P nuclear magnetic resonance. Room temperature 31 P solid-state nuclear magnetic resonance (NMR) experiments were performed at 11.7 T magnetic field, corresponding to a Larmor frequency of 323.85 MHz for 31 P spins. Given the hygroscopic nature of P-zeosils, all P-BEA-3 samples were purged in He at 513 K for 2 h post-activation to remove residual water and base molecules, sealed in glass vials under an inert He environment, and transferred into sealed 4.0-mm zirconia NMR rotors in a glovebox.…”

“…In all cases, a 7 µs 90 ° pulse was used to excite 31 P spins. 31 P chemical shifts are referenced to phosphoric acid solution (1 M).…”