Hydrolysis of Aspirin Studied by Spectrophotometric and Fluorometric Variable-Temperature Kinetics

Alibrandi, Giuseppe; Micali, Norberto; Trusso, S.; Villari, A

doi:10.1021/js950506t

Cited by 31 publications

(42 citation statements)

References 16 publications

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“…A lot of effort has been put into studying the effect of self-organizing assemblies and its pharmaceutical formulation, solubilization, stability, etc. The hydrolysis of aspirin has been studied extensively to understand its stability in biological systems for pharmaceutical formulation [8][9][10][11][12][13][14]. The unique role of surfactants in solu- bilizing the drugs depends on numerous factors such as chemical structure of the surfactant, chemical structure of the drug, temperature, pH, and ionic strength [15].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of the cationic surfactants and their influence on the alkaline hydrolysis of acetylsalicylic acid

Kumar

Ghosh

Dafonte

2010

Int J of Chemical Kinetics

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A kinetic study of the reaction of acetylsalicylic acid (aspirin) with sodium hydroxide has been studied in the presence of some conventional and novel cationic surfactants. The pseudo-first-order rate constant increases with the surfactant concentration initially and then decreases. In comparison to conventional cationic surfactants, i.e., cetyltrimethylammonium bromide and cetylpyridinium bromide, novel alkyldiethylethanolammonium bromide (R = C 16 ) surfactant accelerated the alkaline hydrolysis significantly. The pseudophase ion-exchange model has been applied to fit the experimental results.

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Section: Introductionmentioning

confidence: 99%

Comparative study of the cationic surfactants and their influence on the alkaline hydrolysis of acetylsalicylic acid

Kumar

Ghosh

Dafonte

2010

Int J of Chemical Kinetics

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“…The parameter can change in a vessel being part of the analytical instrument, for example, an ultraviolet -visible (UV -Vis) spectrophotometric cell [39,41,45,14,47,48] , an infrared (IR) cell [42,46] , or a fl uorometer cell [45,51] , or a polarimetric tube [27,49] . It can change in a reactor vessel where the analytical signal can be read in some way, for example using an optical fi ber cell for spectrophotometry [52 -54] or a conductometric cell [16,34,40] .…”

Section: Devices To Obtain Variable -Parameter Conditionsmentioning

confidence: 99%

“…Infrared [42,46] , fl uorimeters [45,51] , and conductometers [16,34,40] have been used with success. Gas -liquid chromatography (GLC) and high -performance liquid chromatography (HPLC) are very much used in pharmaceutical studies, for both analytical investigations and kinetic studies.…”

Section: Analytical Instrumentsmentioning

confidence: 99%

Alternative Accelerated Methods for Studying Drug Stability: Variable‐Parameter Kinetics

Alibrandi

2010

Pharmaceutical Sciences Encyclopedia

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“…The kinetic profile obtained in a single scan automatically varying the pH with time (using an autoburette [7] or [1.1.1]cryptand [2] ) can be fitted to this equation to give the pHrate profile of the system studied. When the parameter is the temperature, it assumes the form of Equation (3) where the dependence function is the Eyring equation, [4] and the modulating function is an analytical or empirical equation relative to the conditions generated by a temperature programmer [6][7][8] or a VT-chemical device:…”

mentioning

confidence: 99%

“…When the parameter is the temperature, it assumes the form of Equation (3) where the dependence function is the Eyring equation, [4] and the modulating function is an analytical or empirical equation relative to the conditions generated by a temperature programmer [6][7][8] or a VT-chemical device:…”

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confidence: 99%

Towards Molecular Temperature Programmers for Variable‐Temperature Kinetic Experiments

2009

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[a] Molecular devices are conceived to be used for specific functions.[1] Some of them can be used to substitute physical devices (e.g. autoburettes [2,3] ) with chemical devices which operate in the same environment as a system which is being investigated. A small step in this direction is presented herein.In studying reaction mechanisms, a key step in the experimental work is the collection of kinetic data describing the dependence of the specific rate on the environmental parameters (temperature, pH, ionic strength, etc.).[4] For this reason we devised a computer-aided accelerated method where, by changing a parameter in a controlled way during the experiment, it is possible to obtain the entire dependence of the specific rate on that parameter in a single run. [5][6][7][8][9][10][11][12][13][14][15] Recently we thought of changing the physical methods (temperature programmers, autoburettes, etc.) used to create the variable parameter conditions inside the reaction vessel with chemical devices. We have carried out a variable-pH kinetic (VpHK) experiment using as a chemical device [1.1.1]cryptand, [16][17][18] a proton sponge that is able to capture hydrogen ions in a selective, slow and irreversible way.[2] Herein, for the first time, we show how it is possible, using a chemical device, to generate variable-temperature conditions inside a reaction vessel to carry out a variabletemperature kinetic (VTK) experiment and obtain the activation parameters of a reaction in a single run. The compound used herein is acetic anhydride.The mathematical model describing the variable-parameter kinetic (VPaK) experiment is given by Equation (1) where the specific rate is a function of the parameter, which is a function of time [k obs (Par i ) = dependence function, describing the dependence on the parameter; Par i (t) = modulating function, describing how the parameter changes with time]:[10]When the parameter is the pH it assumes the form of Equation (2):The kinetic profile obtained in a single scan automatically varying the pH with time (using an autoburette [7] or [1.1.1]cryptand [2] ) can be fitted to this equation to give the pHrate profile of the system studied. When the parameter is the temperature, it assumes the form of Equation (3) where the dependence function is the Eyring equation, [4] and the modulating function is an analytical or empirical equation relative to the conditions generated by a temperature programmer [6][7][8] or a VT-chemical device:Any chemical system able to change the temperature of the reaction environment without interfering with the main reacting system and with its instrumental monitoring can be used as a VT-device for VTK experiments.A simple way to increase the temperature inside a reaction vessel is to carry out an exothermic reaction. Because we decided to study an isomerization of an organometallic complex in methanol, we choose as a VT-chemical device acetic anhydride, which gives an acid-catalysed solvolysis in methanol [Eq. (4)] at a suitable rate and characterized by a good v...

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Hydrolysis of Aspirin Studied by Spectrophotometric and Fluorometric Variable-Temperature Kinetics

Cited by 31 publications

References 16 publications

Comparative study of the cationic surfactants and their influence on the alkaline hydrolysis of acetylsalicylic acid

Comparative study of the cationic surfactants and their influence on the alkaline hydrolysis of acetylsalicylic acid

Alternative Accelerated Methods for Studying Drug Stability: Variable‐Parameter Kinetics

Towards Molecular Temperature Programmers for Variable‐Temperature Kinetic Experiments

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