Conversion of Phenothiazine Derivatives to the Corresponding Sulphoxides on Thin-Layer Plates

Kofoed, Jacob; Korczak-Fabierkiewicz, C.; Lucas, George H. W.

doi:10.1038/211147a0

Cited by 19 publications

(5 citation statements)

References 1 publication

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“…The UV absorption spectra of F and VI in water were identical, with maxima a t 334, 293, 268, and 234 nm, in agreement with the values of Kofoed et al (31). The IR spectra of both compounds were identical as well, with a maximum a t 1020 cm-' due to the SO group (29).…”

Section: Resultssupporting

confidence: 77%

Oxidative Degradation of Pharmaceutically Important Phenothiazines I: Isolation and Identification of Oxidation Products of Promethazine

Underberg

1978

Journal of Pharmaceutical Sciences

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Section: Resultssupporting

confidence: 77%

Oxidative Degradation of Pharmaceutically Important Phenothiazines I: Isolation and Identification of Oxidation Products of Promethazine

Underberg

1978

Journal of Pharmaceutical Sciences

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“…The latter process is consistent with the decrease in absorbance in the n-p* band at 500-525 nm and is accompanied by the subsequent increase in absorbance in the p-p* band in the range 300-400 nm. The final product was characterized on the basis of the known positions of the electronic transition band at 340 nm, characteristic for chlorpromazine oxide, and at 347 nm, for trifluoperazine oxide [34].…”

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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“…Those containing different concentrations of O 2 were prepared by mixing, in different ratios, two solutions, one of which was argon saturated and the other was O 2 saturated, using a syringe technique. The reaction was initiated by an injection of 0.025 cm 3 of the promazine solution into a 1 cm path length cuvette containing the other reagents and the increase in absorbance of promazine 5-oxide at 345 nm [34] (see Figure 1) was monitored. A large excess of Cu II and O 2 over promazine was used to convert the reaction into a pseudo-first-order process.…”

Section: Kinetic Measurementsmentioning

confidence: 99%

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

Wı́sniewska

Kita

Wrzeszcz

2007

Transition Met Chem

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The Cu II -mediated oxidation of promazine by dioxygen to form promazine 5-oxide was studied in the presence of a large excess of dioxygen, Cu II -halides (Cl ) , Br ) ) and H + ions using u.v.-vis and ESR spectroscopies. The first step is a fast reaction between promazine and Cu II -halides leading to the production of a stable promazine radical with much higher yield in bromide than chloride media. ESR results provide clear evidence for the formation of this radical. In the second step the cation radical is oxidized by dioxygen to a dication hydrolyzing to promazine 5-oxide. The promazine-superoxide complex, concentration of which is determined by steady-state approximation, is postulated as a significant intermediate resulting from the reduction of dioxygen by the cation radical. The final product, promazine 5-oxide, is formed via a spontaneous and a Cu II -assisted reaction path way. Cu II controls the reaction rate through: (i) oxidation of promazine to the promazine radical, (ii) acting as a scavenger of superoxide, and (iii) slow oxidation of the promazine radical in the parallel reaction. The rate is independent of [H + ], linearly dependent on [O 2 ] and only slightly dependent on [Cu II ] within the excess concentration range of the Cu II complexes used. Mechanistic consequences of all these results are discussed.

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Conversion of Phenothiazine Derivatives to the Corresponding Sulphoxides on Thin-Layer Plates

Cited by 19 publications

References 1 publication

Oxidative Degradation of Pharmaceutically Important Phenothiazines I: Isolation and Identification of Oxidation Products of Promethazine

Oxidative Degradation of Pharmaceutically Important Phenothiazines I: Isolation and Identification of Oxidation Products of Promethazine

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

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

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