Studies of the hydrolysis of ethyl and tert-butyl phosphonates covalently bonded to silica xerogels

Abstract

The mild cleavage of phosphonodiester groups supported on a silica matrix has been investigated. The use of TMSBr (bromotrimethylsilane) with diethyl phosphonates has been revisited, and interactions of phosphonoacids with silicon species are described. An alternative route utilising di-tert-butyl phosphonate group has also been studied and in this case cleavage has been demonstrated in very mild conditions.Scheme 1 Gelification of (diethoxyphosphorylethyl)triethoxysilane, hydrolysis of the phosphonate function.

Synthesis and characterization of phosphonic acid-substituted porphyrazines

“…The presence of P-O-R stretching peaks in the FT-IR also supports this result. The cleavage of phosphonate esters of porphyrazines was accomplished by the treatment of porphyrazine 2a with TMSBr (bromotrimethyl silane) [14][15][16][17].…”

Modification of proton conductive polymer membranes with phosphonated polysilsesquioxanes

“…Partially functionalized polysiloxanes with compositions ranging from 90/10 to 10/90 (mol of phosphonic functionalized/ mol of non functionalized segments) were synthesized by a procedure based on that described by Carbonneau et al [9]. The reagents Ph-TEOS and TEOS in the appropriate molar ratio (ca.…”

“…Three approaches were tested. In the first one, the membrane was treated with concentrated hydrochloric acid at 60 o C for 24 h. In the second treatment the membrane was kept under reflux at 110-120 o C in concentrated hydrochloric acid for 24 h. In the third approach the membrane was treated with trimethylbromosilane (TMBS) at 60 o C for 24 h and then with H 2 O for 24 h at 60 o C [9]. After the acid treatments the membranes, initially transparent, became opaque with a pearl brightness.…”

“…These processes allow adjusting the degree of interpenetration of organic and inorganic networks on an atomic scale. Polysilsesquioxanes can be synthesized using organoalkoxysilanes R´xSi(OR) 4-x (R´=alkyl, phenyl) as precursors, which lead to the formation of organic-inorganic hybrid compounds [9]. The ligand R acts as a network modifier in the resulting structure.…”

Nanostructured Materials

“…have been assembled using bifunctional spacers: [88][89][90][91][92][93][94][95][96] PO 3 R 2 (RO) 3 Si have been assembled using bifunctional spacers: [88][89][90][91][92][93][94][95][96] PO 3 R 2 (RO) 3 Si…”