title: Physicochemical properties and supernucleophilicity of oxime-functionalized surfactants: hydrolytic catalysts toward dephosphorylation of di- and triphosphate esters.
abstract: Aggregation and kinetic studies have been performed to understand the hydrolytic potencies of the series of oxime-functionalized surfactants, viz., 3- hydroxyiminomethyl-1-alkylpyridinium bromide (alkyl = CnH2n+1, n = 10, 12, 14, 16, 18) in the cleavage of phosphate esters, p-nitrophenyl diphenyl phosphate (PNPDPP) and bis(2,4-dinitrophenyl) phosphate (BNDPP), in mixed micelles with cetylpyridinium bromide (CPB). Micellization and surface properties of mixed micelles functional surfactants with CPB were studied by conductivity and surface tension measurements. Acid dissociation constants (pKa) were determined, the effect of functional surfactant alkyl chain length and pH on the observed rate constant (kobs) for phosphate ester cleavage has been discussed, and the effect of substrate on the supernucleophilicities of the studied oximes was monitored. Functionalized oxime-based surfactants were proved to be supernucleophiles to attack on the P═O center of tri- and diphosphate esters. Oximes with hexadecyl alkyl chain length (3-C16) showed maximum micellar effect on the rate constants toward PNPDPP. Micellar effects were analyzed in terms of the pseudophase model.
authors.affiliation: School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh, India.
authors.forename: Namrata
authors.initials: N
authors.lastname: Singh
authors.forename: Yevgen
authors.initials: Y
authors.lastname: Karpichev
authors.forename: Bhanushree
authors.initials: B
authors.lastname: Gupta
authors.forename: Manmohan L
authors.initials: ML
authors.lastname: Satnami
authors.forename: Jan
authors.initials: J
authors.lastname: Marek
authors.forename: Kamil
authors.initials: K
authors.lastname: Kuca
authors.forename: Kallol K
authors.initials: KK
authors.lastname: Ghosh
mesh_terms: D002384:Catalysis; D002594:Cetylpyridinium / Q000737:chemistry*; D055664:Electrochemical Techniques; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008823:Micelles; D009574:Nitro Compounds / Q000737:chemistry*; D010755:Organophosphates / Q000737:chemistry*; D010091:Oximes / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D011726:Pyridinium Compounds / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D008823:Micelles; D009574:Nitro Compounds; D010755:Organophosphates; D010091:Oximes; D010710:Phosphates; D011726:Pyridinium Compounds; D013501:Surface-Active Agents; C546103:bis(2,4-dinitrophenyl) phosphate; C518259:p-nitrophenyl diphenyl phosphate; D002594:Cetylpyridinium