4532-05-2Relevant academic research and scientific papers
Kinetic study on the interactions of cyclodextrins with organic phosphates and thiophosphates
Nagata, Takuya,Yamamoto, Kenta,Yoshikiyo, Keisuke,Matsui, Yoshihisa,Yamamoto, Tatsuyuki
experimental part, p. 76 - 80 (2009/04/10)
α-Cyclodextrin (α-CD) and 6-O-α-D-glucopyranosyl-β- cyclodextrin (G1-β-CD) affected the rates of phenol release from a few dimethyl(nitrophenyl) phosphates and the corresponding thiophosphates in aqueous alkaline solutions. Curvefitting analysis of change
Leaving group assistance in the La3+-catalyzed cleavage of dimethyl (o-methoxycarbonyl)aryl phosphate triesters in methanol
Edwards, David R.,Liu, C. Tony,Garrett, Graham E.,Neverov, Alexei A.,Brown, R. Stan
supporting information; experimental part, p. 13738 - 13748 (2010/01/06)
The catalytic methanolysis of a series of dimethyl aryl phosphate triesters where the aryl groups contain an o-methoxycarbonyl (o-CO2Me) substituent (4a-i) was studied at 25°C in methanol containing La 3+ at various concentrations and sspH. Determination of the second-order rate constant for La3+ 2-catalyzed cleavage of substrate 4a (dimethyl (o-methoxycarbonyl) phenyl phosphate) as a function of sspH was assessed in terms of a speciation diagram that showed that the process was catalyzed by La3+ 2(-OCH3)x dimers, where x = 1-5, that exhibit only a 5-fold difference in activity between all the species. The second-order catalytic rate constants (k2La) for the catalyzed methanolysis of 4a-i at sspH 8.7 fit a Bronsted relationship of log k2La= (-0.82 ± 0.11)sspKalg + (11.61 ± 1.48), where the gradient is shallower than that determined for a series of dimethyl aryl phosphates that do not contain the o-CO2Me substituent, log k2La = (-1.25 ± 0.06)s spKalg + (16.23 ± 0.75). Two main observations are that (1) the o-CO2Me group preferentially accelerates the cleavage of the phosphate triesters with poor leaving groups relative to those with good leaving groups and (2) it provides an increase in cleavage rate relative to those of comparable substrates that do not have that functional group, e.g., k2La(dimethyl o-(methoxycarbonyl) phenyl phosphate)/k2La(dimethyl phenyl phosphate) = 60. Activation parameters for the La3+2-catalyzed methanolysis of 4a and dimethyl 4-nitrophenyl phosphate show respective ΔH? (ΔS?) values of 3.3 kcal/mol (-47 cal/mol·K) and 0.7 kcal/mol (-46.5 cal/mol·K). The data are analyzed in terms of a concerted reaction where the catalytic complex (La3+2( -OCH3)x-1) binds to the three components of a rather loose transition state composed of a nucleophile CH3O -, a nucleofuge -OAr, and a central (RO)2P 2+-O- in a way that provides leaving group assistance to the departing aryloxy group.
Mononuclear Co(III)-complex promoted phosphate diester hydrolysis: Dependence of reactivity on the leaving group
Padovani, Michela,Williams, Nicholas H.,Wyman, Paul
, p. 472 - 477 (2007/10/03)
The TrpnCo(III)(OH)(OH2)-promoted hydrolysis of a range of methyl aryl phosphate diesters was investigated at 37°C and I = 0.1 M (NaClO4). The pH-rate profile confirms that the aqua-hydroxy form of the complex is the only kinetically
