Kinetic and ESR studies of the CuII-halides mediated oxidation of promazine by dioxygen in acidic aqueous solutions

Wı́sniewska, Joanna; Kita, P.; Wrzeszcz, Grzegorz

doi:10.1007/s11243-007-0219-1

Cited by 6 publications

(11 citation statements)

References 31 publications

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“…+0.25 V, compared to a HZ only solution, again indicating possible interactions between the PZ and HZ. The area of the 1 mM PZ peak (∼21.7 µC) is smaller than that of the HZ peak (56.4 µC) by a factor of 2.6, which is reasonable given literature assumes a two electron transfer process 44, 45. A D for PZ was determined to be 2.65×10 −6 cm 2 s −1 assuming a two electron process, which is similar to reported values 46.…”

Section: Resultssupporting

confidence: 83%

Selective Detection of Hydrazine in the Presence of Excess Electrochemically Active Pharmaceutical Ingredients Using Boron Doped Diamond Metal Nanoparticle Functionalised Electrodes

et al. 2013

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Detection of the genotoxic impurity hydrazine (HZ) in the presence of active pharmaceutical ingredients (APIs) represents a significant challenge to the pharmaceutical industry. Here we show how the use of electrochemical strategies in conjunction with metal nanoparticle (NP) functionalised polycrystalline boron‐doped diamond (BDD) electrodes enables detection of HZ in the presence of two different electrochemically active APIs. By simply changing the chemical identity of the metal NP, which shifts the detection potential for HZ, it is possible to selectively screen out the API signature from the HZ current – voltage response. HZ detection limits of 11.1 µM (Au NP BDD) and 3.3 µM (Pt NP BDD) in the presence of excess acetaminophen and promazine respectively, were determined using differential pulse voltammetry in quiescent solution.

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Section: Resultssupporting

confidence: 83%

Selective Detection of Hydrazine in the Presence of Excess Electrochemically Active Pharmaceutical Ingredients Using Boron Doped Diamond Metal Nanoparticle Functionalised Electrodes

et al. 2013

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“…Compared to manganese(III)-pyrophosphate, the green oxidants, such as oxygen or hydrogen peroxide, react slowly and require the use of transition metal complexes as catalysts for the oxidation process [38,39].…”

Section: Resultsmentioning

confidence: 99%

A mechanistic study on the disproportionation and oxidative degradation of phenothiazine derivatives by manganese(III) complexes in phosphate acidic media

Wı́sniewska

Rześnicki

Topolski

2011

Transition Met Chem

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The oxidative degradation of phenothiazine derivatives (PTZ) by manganese(III) was studied in the presence of a large excess of manganese(III)-pyrophosphate (P 2 O 7 2-), phosphate (PO 4 3-), and H ? ions using UV-vis. spectroscopy. The first irreversible step is a fast reaction between phenothiazine and manganese pyrophosphate leading to the complete conversion to a stable phenothiazine radical. In the second step, the cation radical is oxidized by manganese to a dication, which subsequently hydrolyzes to phenothiazine 5-oxide. The reaction rate is controlled by the coordination and stability of manganese(III) ion influenced by the reduction potential of these ions and their strong ability to oxidize many reducing agents. The cation radical might also be transformed to the final product in another competing reaction. The final product, phenothiazine 5-oxide, is also formed via a disproportionation reaction. The kinetics of the second step of the oxidative degradation could be studied in acidic phosphate media due to the large difference in the rates of the first and further processes. Linear dependences of the pseudo-first-order rate constants (k obs ) on [Mn III ] with a significant non-zero intercept were established for the degradation of phenothiazine radicals. The rate is dependent on [H ? ] and independent of [PTZ] within the excess concentration range of the manganese(III) complexes used in the isolation method. The kinetics of the disproportionation of the phenothiazine radical have been studied independently from the further oxidative degradation process in acidic sulphate media.

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“…In an earlier article, we reported on the kinetics of the slow oxidation of promazine by dioxygen in solutions of aqueous copper(II) halides 12. In this reaction, the copper(II) halides oxidized promazine to a cation radical and copper(I) was reoxidized by dioxygen to copper(II).…”

Section: Introductionmentioning

confidence: 99%

Formation of a promazine radical and promazine 5‐oxide in the reaction of promazine with hydrogen peroxide: Mechanistic insight from kinetic and EPR measurements

Wı́sniewska

Wrzeszcz

Koter

2009

Int J of Chemical Kinetics

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The kinetics of the oxidation of promazine (PMZ) by hydrogen peroxide was studied in the presence of a large excess of H 2 O 2 in acidic chloride media using UV-vis spectroscopy. The reaction proceeds via two consecutive steps. In the first step, oxidation leads to formation of a promazine radical. In the second step, the promazine radical is oxidized to promazine 5-oxide. Electron paramagnetic resonance spectroscopy (EPR) results provide clear evidence for the formation of an intermediate promazine radical. Linear dependences of the pseudo-firstorder rate constants (k 1 and k 2 ) on [H 2 O 2 ] with a nonzero intercept were established for the first and the second process, respectively. The rate of the first stage of the reaction increased slightly with increasing concentration of O 2 , indicating the role of the OH • radicals on the redox process, which are transformed into the Cl −• 2 radicals. The mechanism of the overall reaction is discussed on the basis of all these kinetic measurements. C 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42:

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Kinetic and ESR studies of the CuII-halides mediated oxidation of promazine by dioxygen in acidic aqueous solutions

Cited by 6 publications

References 31 publications

Selective Detection of Hydrazine in the Presence of Excess Electrochemically Active Pharmaceutical Ingredients Using Boron Doped Diamond Metal Nanoparticle Functionalised Electrodes

Selective Detection of Hydrazine in the Presence of Excess Electrochemically Active Pharmaceutical Ingredients Using Boron Doped Diamond Metal Nanoparticle Functionalised Electrodes

A mechanistic study on the disproportionation and oxidative degradation of phenothiazine derivatives by manganese(III) complexes in phosphate acidic media

Formation of a promazine radical and promazine 5‐oxide in the reaction of promazine with hydrogen peroxide: Mechanistic insight from kinetic and EPR measurements

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