Modelling drug release from hydrophobic matrices by use of thermodynamic activation parameters

1990 ◽  
Vol 60 (3) ◽  
pp. 229-234 ◽  
Author(s):  
M EFENTAKIS ◽  
G BUCKTON
Keyword(s):  
Drug Release ◽  
Activation Parameters ◽  
Thermodynamic Activation Parameters ◽  
Hydrophobic Matrices

Kinetic Studies of [4n+2]π-Thermal Cyclodimerization of 1-(3-Pyridazinyl)-3-oxidopyridinium Betaines

1992 ◽  
Vol 57 (9) ◽  
pp. 1951-1959 ◽  
Author(s):  
Madlene L. Iskander ◽  
Samia A. El-Abbady ◽  
Alyaa A. Shalaby ◽  
Ahmed H. Moustafa
Keyword(s):  
Energy Gap ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Cyclic Transition ◽  
Concerted Mechanism ◽  
First Order ◽  
Thermodynamic Activation Parameters ◽  
Cyclic Transition State ◽  
Complete Dissociation ◽  
Homo Lumo

The reactivity of the base induced cyclodimerization of 1-(6-arylpyridazin-3-yl)-3-oxidopyridinium chlorides in a pericyclic process have been investigated kinetically at λ 380 nm. The reaction was found to be second order with respect to the liberated betaine and zero order with respect to the base. On the other hand dedimerization (monomer formation) was found to be first order. It was shown that dimerization is favoured at low temperature, whereas dedimerization process is favoured at relatively high temperature (ca 70 °C). Solvent effects on the reaction rate have been found to follow the order ethanol > chloroform ≈ 1,2-dichloroethane. Complete dissociation was accomplished only in 1,2-dichloroethane at ca 70 °C. The thermodynamic activation parameters have been calculated by a standard method. Thus, ∆G# has been found to be independent on substituents and solvents. The high negative values of ∆S# supports the cyclic transition state which is in favour with the concerted mechanism. MO calculations using SCF-PPP approximation method indicated low HOMO-LUMO energy gap of the investigated betaines.

Alkyl pectin: Hydrophobic matrices for controlled drug release

2014 ◽  
Vol 132 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Xue-Fang Zheng ◽  
Qi Lian ◽  
Hua Yang ◽  
Hong Zhu
Keyword(s):  
Drug Release ◽  
Controlled Drug Release ◽  
Hydrophobic Matrices

N-acylated chitosan: hydrophobic matrices for controlled drug release

2003 ◽  
Vol 93 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Canh Le Tien ◽  
Monique Lacroix ◽  
Pompilia Ispas-Szabo ◽  
Mircea-Alexandru Mateescu
Keyword(s):  
Drug Release ◽  
Controlled Drug Release ◽  
Hydrophobic Matrices

Kinetic Study of the Oxidation of Alcohols with Quaternary Ammonium Permanganates

1993 ◽  
Vol 58 (8) ◽  
pp. 1777-1781 ◽  
Author(s):  
Robert Šumichrast ◽  
Vladislav Holba
Keyword(s):  
Kinetic Study ◽  
Catalytic Reaction ◽  
Rate Constants ◽  
Quaternary Ammonium ◽  
Iterative Procedure ◽  
Activation Parameters ◽  
Reaction Products ◽  
Thermodynamic Activation Parameters ◽  
Oxidation Of Alcohols ◽  
Kinetics Of

Kinetics of the oxidation of 2-propanol, 1-butanol, and 1-pentanol with tetraalkylammonium permanganates have been investigated as function of temperature. The studied reactions are partly autocatalytic, colloidal manganese dioxide as one of the reaction products has been identified as the autocatalyst.A computerized iterative procedure has been used in order to obtained the rate constants of both non-catalytic and catalytic reaction steps together with the thermodynamic activation parameters.

scholarly journals Kinetics and Mechanism of Oxidation of Diethanolamine and Triethanolamine by Potassium Ferrate

2011 ◽  
Vol 8 (2) ◽  
pp. 903-909 ◽  
Author(s):  
Shan Jinhuan ◽  
Zhang Jiying
Keyword(s):  
Activation Parameters ◽  
Rate Equations ◽  
Potassium Ferrate ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Dependence ◽  
Rate Determining Step ◽  
Thermodynamic Activation Parameters ◽  
Plausible Mechanism ◽  
Kinetics Of

The kinetics of oxidation of diethanolamine and triethanolamine by potassium ferrate(VI)in alkaline liquids at a constant ionic strength has been studied spectrophotometrically in the temperature range of 278.2K-293.2K. The reaction shows first order dependence on potassium ferrate(VI), first order dependence on each reductant, The observed rate constant (kobs) decreases with the increase in [OH-], the reaction is negative fraction order with respect to [OH-]. A plausible mechanism is proposed and the rate equations derived from the mechanism can explain all the experimental results. The rate constants of the rate-determining step and the thermodynamic activation parameters are calculated.

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