29314-22-5Relevant articles and documents
NUCLEOPHILIC SUBSTITUTION IN BIS(4-NITROPHENYL) ETHYL PHOSPHATE IN ALKALINE MICELLAR SOLUTIONS OF 2-HYDROXYETHYLDIMETHYLOCTADECYLAMMONIUM BROMIDE
Tishkova, E.P.,Fedorov, S.B.,Kudryavtseva, L.A.,Bel'skii, V.E.,Ivanov, B.E.
, p. 2302 - 2305 (1991)
A study was carried out on the mechanism of nucleophilic substitution in bis(4-nitrophenyl) ethyl phosphate (BNEP) in alkaline solutions of 2-hydroxyethyldimethyloctadecylammonium bromide.In the presence of a 2-hydroxyethyl surfactant (Sur), nucleophilic properties of the 2-hydroxyethyl group, which is dissociated in alkaline media, are evident in addition to alkaline hydrolysis of the substrate.The second pathway arises beginning in the region of premicellar surfactant aggregates and is predominant in micellar solutions.
Hydrolysis of bis(4-nitrophenyl) ethyl phosphate in micellar solutions of dicationic surfactants
Tishkova, E. P.,Kudryavtseva, L. A.,Shagidullina, R. A.,Ivanov, B. E.
, p. 1488 - 1492 (2007/10/02)
The effect of dicationic surfactants on the hydrolysis of bis(4-nitrophenyl) ethyl phosphate in a borate buffer is studied.The presence of long-chain surfactants results in a significant (up to 50-fold) increase in the observed rate constant (kobs) of the process.The catalytic effect of micelles increases with increasing alkyl chain length due to the strengthening of binding of the reagents by micelles.The presence of two cationic centers in the surfactant molecule enhances the catalytic properties of micelles.The dependence of kobs of hydrolysis of the substrate on the borate buffer concentration is studied.Alkaline hydrolysis is more sensitive to the added surfactant than the reaction involving borate ions. - Key words: micellar catalysis; hydrolysis; dicationic surfactants; buffer.
Reactivity of coordinated phosphate esters: Pentaamminecobalt(III) complexes
Hendry, Philip,Sargeson, Alan M.
, p. 92 - 97 (2008/10/08)
The reactivity of two phosphate ester complexes designed to test the efficacy of different modes of activation of phosphate esters by metal ions has been investigated. Ethyl 4-nitrophenyl phosphate coordinated to the pentaamminecobalt(III) moiety liberates nitrophenolate in basic solution 106-fold faster than the free phosphodiester. The reaction proceeds via attack of coordinated amido ion to yield a four-membered N,O chelate phosphoramidate ethyl ester. The four-membered chelate does not display the enhanced reactivity of the five-membered-ring cyclic ethylene phosphates but decays with cobalt-ligand bond rupture and yields finally free ethyl phosphoramidate. The aminolysis is accompanied by some loss of ethyl 4-nitrophenyl phosphate by the SN1(CB) mechanism. The binuclear complex (μ-nitrophenyl phosphato)decaamminedicobalt(4+) undergoes aminolysis in basic aqueous media, also by intramolecular attack of coordinated amido ion. The reaction proceeds some 102-fold faster than the analogous aminolysis of the mononuclear complex, (4-nitrophenyl phosphato)pentaamminecobalt(1+). The reaction is also accompanied by some SN1(CB) loss of the intact ligand; in this case, the ligand is the mononuclear complex. This study illuminates some of the modes by which metal ions can enhance the reactivity of phosphate esters. In agreement with other studies, the electrostatic and inductive effects are estimated to contribute ～102-fold to the rate enhancement, while the intramolecularity of the reaction is responsible for the remainder of the observed rate enhancement.
