An-Najah Staff

The kinetics of oxidation of L-cysteine by 3-di-2-pyridylketone-2-thiophenylhydrazone-iron(III), [Fe(DPKTH)2]3+ complex in acidic medium was studied spectrophotometrically at 36 C temperature. The molar ratios of DPKTH to iron(III) and iron(II) individually, were found to be [2:1] [DPKTH : iron(III)/(II)]. The reaction was stroked to be first-order with respect to iron(III) and L-cysteine, second-order with respected to DPKTH ligand and reversed second-order with respected to hydrogen ion concentration. Added salts did not affect the rate and no free radical was detected when radical detector was placed in the reaction mixture. Ethanol solvent ratio was found to effect both the initial rate and the maximum absorbance (ʎmax) of [Fe(DPKTH) 2]2+ complex. The initial rate rose when the temperature was increased which empowered to calculate the activation parameters. A suitable reaction mechanism was proposed.

The kinetics oxidation of L-cysteine by 3-di-2-pyridylketone-2-thiophenylhydrazone-iron(III)[Fe(DPKTH)2]3+complex in acidic medium was studied spectrophotometrically at 36Co temperature.The differential rate method (initial rate) was served in this investigation. The molar ratios of DPKTH to iron(III) and iron(II) individually, were found to be [2:1] [DPKTH :iron(III)/(II)]. The reaction was stroked to be first-order with respect to iron(III) and L-cysteine,second-order with respected to DPKTH ligand and reversed second-order with respected tohydrogen ion concentration. Added salts did not affect the rate and no free radical was detectedwhen radical detector was placed in the reaction mixture. Ethanol solvent ratio was found to effect both the initial rate and the maximum absorbance (λmax) of [Fe(DPKTH)2]2+complex. The initial raterose when the temperature was increased which empowered the activation parameters calculations.From the evaluation of the obtained linear data, a reaction mechanism is proposed which involves a pre-equilibrium of an adduct formation between L-cysteine and [Fe(DPKTH)2]3+complex.

The kinetics of oxidation of L-cysteine by 3-di-2-pyridylketone-2-thiophenylhydrazone-iron(III), [Fe(DPKTH) 2 ] 3+ complex in acidic medium was studied spectrophotometrically at 36 o C temperature. The molar ratios of DPKTH to iron(III) and iron(II) individually, were found to be [2:1] [DPKTH : iron(III)/(II)]. The reaction was stroked to be first-order with respect to iron(III) and L-cysteine, second-order with respected to DPKTH ligand and reversed second-order with respected to hydrogen ion concentration. Added salts did not affect the rate and no free radical was detected when radical detector was placed in the reaction mixture. Ethanol solvent ratio was found to effect both the initial rate and the maximum absorbance (λ max) of [Fe(DPKTH) 2 ] 2+ complex. The initial rate rose when the temperature was increased which empowered to calculate the activation parameters. A suitable reaction mechanism was proposed.

Kinetic oxidation of L-cysteine by [Fe(Fz)2] 1-  complex was carried out in acidic medium under  pseudo rate conditions. The molar ratios between iron(III), iron(II) and Ferrozine (HFz)  complexes in absence and presence of L-cysteine were individually determined using job's  method. The formation of [Fe2+-Fz] at lmax = 562nm was spectrophotometrically followed  during this kinetic study. The reaction is found to be first-order with respect to iron(III) and  L-cysteine, second-order with respect to HFz-1  ligand and reversed second-order with respect to  hydrogen ion concentrations. The salts effect was determined and no radical species have been  detected. The kobs rose when the temperature was increased which empowered the activation  parameters of the rate-determining step calculations. A reaction mechanism and rate law  derivation are proposed with a pre-equilibrium of an adduct formation between L-cysteine and  [Fe3+-Fz] complex.   

Kinetic oxidation of L-cysteine by [Fe(Fz)2]1- complex was carried out in acidic medium under pseudo rate conditions. The molar ratios between iron(III), iron(II) and Ferrozine (HFz) complexes in absence and presence of L-cysteine were individually determined using job's method. The formation of [Fe2+-Fz] at lmax = 562nm was spectrophotometrically followed during this kinetic study. The reaction is found to be first-order with respect to iron(III) and L-cysteine, second-order with respect to HFz-1 ligand and reversed second-order with respect to hydrogen ion concentrations. The salts effect was determined and no radical species have been detected. The kobs rose when the temperature was increased which empowered the activation parameters of the rate-determining step calculations. A reaction mechanism and rate law derivation are proposed with a pre-equilibrium of an adduct formation between L-cysteine and [Fe3+-Fz] complex.

The kinetics of oxidation of L-cysteine by 3-di-2-pyridylketone-2-thiophenylhydrazone-iron(III), [Fe(DPKTH)2]3+ complex in acidic medium was studied spectrophotometrically at 36 C temperature. The molar ratios of DPKTH to iron(III) and iron(II) individually, were found to be [2:1] [DPKTH : iron(III)/(II)]. The reaction was stroked to be first-order with respect to iron(III) and L-cysteine, second-order with respected to DPKTH ligand and reversed second-order with respected to hydrogen ion concentration. Added salts did not affect the rate and no free radical was detected when radical detector was placed in the reaction mixture. Ethanol solvent ratio was found to effect both the initial rate and the maximum absorbance (ʎmax) of [Fe(DPKTH) 2]2+ complex. The initial rate rose when the temperature was increased which empowered to calculate the activation parameters. A suitable reaction mechanism was proposed.