Solvolysis of Tris-p-nitrophenyl-phosphate in aqueous and reverse micelles

Costas-Costas, Ugo; Bravo‐Díaz, Carlos; Chaimovich, Hernán; Cuccovia, Iolanda M.

doi:10.1016/j.colsurfa.2004.04.084

Cited by 13 publications

(11 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This extends over a wide range, up to at least pH 8, for the most electrophilic triesters, such as the tris‐nitrophenyl phosphates (Figure 1 b). 7 Thirdly, no such region is apparent for the hydrolysis of 2‐pyridyl phosphate DEPP (Figure 1 b), in which the spontaneous reaction is too slow to contribute significantly. The spontaneous hydrolysis reactions of main interest for this work are generally slow, and difficult to measure accurately for the least reactive triesters we have studied, with one or two simple alkyl groups.…”

Section: Resultsmentioning

confidence: 96%

See 1 more Smart Citation

Activating Water: Important Effects of Non‐leaving Groups on the Hydrolysis of Phosphate Triesters

Kirby

Medeiros

Oliveira

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained by the activating effects of the non-leaving ("spectator") groups on P-OAr cleavage, and not by intramolecular catalysis. Previous work on phosphate-transfer reactions has concentrated on the contributions to reactivity of the nucleophile and the leaving group, but our results make clear that the effects of the non-leaving groups on phosphorus can be equally significant. Rate measurements for three series of phosphate triesters showed that sensitivities to the non-leaving groups are substantial for spontaneous hydrolysis reactions, although significantly smaller for reactions with good nucleophiles. There are clear differences between triaryl and dialkyl aryl triesters in sensitivities to leaving and non-leaving groups with the more reactive triaryl systems showing lower values for both β(LG) and β(NLG). Intramolecular catalysis of the hydrolysis of TPP by the neighbouring pyridine nitrogens is insignificant, primarily because of their low basicity.

show abstract

Section: Resultsmentioning

confidence: 96%

“…Misprinted as 1×10 −8 in Cox and Ramsay 8. A more recent Figure of 2×10 −3 is not corrected for buffer catalysis 7. [g] Estimate: from rate measured for diethyl‐2,4‐dinitrophenyl phosphate in water at 25° C9 by using βLG=−0.99.…”

Section: Resultsmentioning

confidence: 99%

Activating Water: Important Effects of Non‐leaving Groups on the Hydrolysis of Phosphate Triesters

Kirby

Medeiros

Oliveira

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Previously, CTAB was dissolved in n-hexanol/isooctane to make reverse micelles (Costas-Costas et al 2004). Because such organic solvents were unsuitable for the preparation of PLGA microspheres, new formulations using ethyl formate were developed in this study.…”

Section: Resultsmentioning

confidence: 99%

Reverse Micelle-Based Microencapsulation of Oxytetracycline Hydrochloride into Poly-d,l-Lactide-co-Glycolide Microspheres

2007

View full text Add to dashboard Cite

The objectives of this study were to solubilize oxytetracycline hydrochloride (HCl) in reverse micelles to prepare poly-d,l-lactide-co-glycolide (PLGA) microspheres and to explore parameters affecting its encapsulation efficiency. Oxytetracycline HCl was dissolved in the reverse micelles consisting of cetyltrimethylammonium bromide, water, and ethyl formate. A PLGA polymer was then dissolved in the reverse micellar solution, and a modified solvent quenching procedure was carried out to prepare PLGA microspheres. Encapsulation efficiencies of oxytetracycline HCl ranged from 2.3 +/- 0.2 to 24.9 +/- 4.6%, depending on experimental conditions. Important parameters affecting its encapsulation efficiency included the amounts of water used to prepare the reverse micelles and PLGA polymer. With regard to microsphere morphology, the reverse micellar process produced the microspheres with smooth and pore-free surfaces. In particular, their internal matrices did not possess hollow cavities that were frequently observed when a typical double emulsion technique was used to make microspheres. In summary, it was possible to encapsulate oxytetracycline HCl into PLGA microspheres via the ethyl formate-based reverse micellar technique. We also anticipate that the use of ethyl formate could avoid environmental and human toxicity issues associated with methylene chloride.

show abstract

“…Moss et al investigated the cleavage of paraoxon and parathion with a surfactant‐based iodosobenzoate (IBA) and observed that (CTA) IBA was more reactive than simple IBA. Cuccovia et al . reported solvolysis of tris‐ p ‐nitrophenyl phosphate in aqueous and reverse micelles.…”

Section: Introductionmentioning

confidence: 99%

Hydrolytic Cleavage of Paraoxon by Octanohydroxamate Ion in Cationic Microemulsions

Satnami

Dewangan

Nagwanshi³

2016

Int J of Chemical Kinetics

View full text Add to dashboard Cite

The hydrolysis reaction of O,O‐diethyl O‐p‐nitrophenylphosphate (Paraoxon) with the octanohydroxamate ion (OHA−) was studied in a cationic oil‐in‐water (O/W) microemulsion system over a pH range 7.5–12.0 at 300 K. The O/W systems are stabilized by using cationic surfactant, cetyltrimethylammonium bromide (CTAB), and n‐butanol as cosurfactants. In a microemulsion, the rate enhancement by OHA− is greater toward the cleavage of paraoxon than its spontaneous (2.1 × 107 s−1) hydrolysis. The kobs values for the reaction of paraoxon with OHA− were determined in different microemulsion compositions with varying chain length of alcohols (n‐butanol, n‐pentanol, n‐octanol, and n‐dodecanol) and alkanes (n‐hexane, n‐heptane, and n‐decane). The effects of water content, pH, and size of the oil pool have been discussed.

show abstract

Solvolysis of Tris-p-nitrophenyl-phosphate in aqueous and reverse micelles

Cited by 13 publications

References 46 publications

Activating Water: Important Effects of Non‐leaving Groups on the Hydrolysis of Phosphate Triesters

Activating Water: Important Effects of Non‐leaving Groups on the Hydrolysis of Phosphate Triesters

Reverse Micelle-Based Microencapsulation of Oxytetracycline Hydrochloride into Poly-d,l-Lactide-co-Glycolide Microspheres

Hydrolytic Cleavage of Paraoxon by Octanohydroxamate Ion in Cationic Microemulsions

Contact Info

Product

Resources

About