Effect of β-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives.

The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives.

Investigation of the inclusion complex of β-cyclodextrin with mycophenolate mofetil.

The acid-base equilibrium of mycophenolate mofetil is studied in the absence and presence of β-cyclodextrin (β-CD). The conditional acidity constants are obtained by rank annihilation factor analysis (RAFA) as a function of β-CD concentrations. Also the stability constants for inclusion complexes of β-CD with both acidic and basic forms are calculated.

Effect of inclusion complex on nitrous acid reaction with flavonoids.

The kinetic of the nitrous acid reactions with quercetin and catechin has been studied using spectrophotometric method in aqueous solution. The results show that these antioxidants participate in oxidation reactions with nitrous acid which is derived from protonation of nitrite ion in mild acidic conditions. Corresponding o-quinones as relatively stable products were detected by spectrophotometric techniques.

Kinetic study of the oxidation and nitration of catechols in the presence of nitrous acid ionization equilibria.

Conversion of catechols to corresponding nitro derivatives in the presence of nitrous acid dissociation is studied using voltammetry and UV-vis spectrophotometry. The results indicate that the quinones derived from oxidation of catechols by nitrous acid participate in Michael addition reaction with nitrite ion in very mild acidic solutions. Rank annihilation factor analysis RAFA is applied to resolve the two-way kinetic spectra data measured from spectroscopic reactions.

Spectrophotometric investigation of the effect of beta-cyclodextrin on the intramolecular cyclization reaction of catecholamines using rank annihilation factor analysis.

The catalytic effect of beta-cyclodextrin (beta-CD) on the intramolecular cyclization reaction of catecholamines dopamine, methyldopa and levodopa after their oxidation with periodate was investigated spectrophotometrically using rank annihilation factor analysis (RAFA). The method was based on the effect of beta-CD concentration on the intramolecular cyclization reaction of the investigated catecholamines after their oxidation with potassium periodate. In order to perform RAFA, concentration profiles were calculated by optimizing the value of formation constant.

Spectrophotometric determination of fluoxetine by batch and flow injection methods.

A rapid, simple, and accurate spectrophotometric method is presented for the determination of fluoxetine by batch and flow injection analysis methods. The method is based on fluoxetine competitive complexation reaction with phenolphthalein-beta-cyclodextrin (PHP-beta-CD) inclusion complex. The increase in the absorbance of the solution at 554 nm by the addition of fluoxetine was measured.