- First Synthesis of Sulfoxides and Sulfones in the 3H-Phenothiazin-3-one and 5H-Benzophenothiazin-5-one Ring Systems. Addition Reactions with Nucleophiles
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We report the first synthesis of sulfoxides and sulfones in the 3H-phenothiazin-3-one and 5H-benzophenothiazin-5-one ring systems.The pronounced reactivity of the parent compounds 2a, 2b, 4a, and 4b does not allow their isolation, but they can be conveniently trapped, as various types of adducts, with nucleophiles such as water, alcohols, and amines.The monoadduct 16b of oxo-3H-phenothiazine 5,5-dioxide with n-propylamine rearranges into a derivative of the novel oxazolophenothiazine ring system (17).
- Girard, Yves,Hamel, Pierre,Therien, Michel,Springer, James P.,Hirshfield, Jordan
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- Spectrophotometric Determination of Loperamide Hydrochloride in Pure and Pharmaceutical Dosage Forms Using Oxidative Coupling Reaction
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Loperamide hydrochloride (LopH) has been determined by oxidative - coupling reaction using phenothiazine reagent in the presence of potassium dichromate as an oxidant to create a greenish-blue soluble complex measured at 625 nm., linearity range is from0.8 to 40 μg.ml-1 of LopH. The molar absorptivity is 0.3799×104 l.mol-1.cm-1, Sandell's sensitivity is 0.1351μg cm-2, limit of detection and limit of quantitation are 0.33918, and 1.1306 μg.ml-1 respectively. The method is new ,simple, sensitive and it has been applied successfully for determination of LopH in pharmaceutical preparation of three dosage forms of LopH; Loperamide 2 mg/tablets Medochemie Ltd, Limassol-Cyprus (Europe), Loperamide 2 mg/tablets Safa Co. - Diala (Iraq) and Loperamide 2 mg/capsules Janssen pharmaceuticals (Belgium).
- Shehab, Ahlam A.,Mohammed, Dawood H.,Mahmood, Hana Sh.
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p. 7271 - 7276
(2021/11/16)
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- Antioxidant activities of phenothiazines and related compounds: Correlation between the antioxidant activities and dissociation energies of O-H or N-H bonds
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The antioxidant activities of phenothiazines, carbazoles, and related diphenylamines were evaluated in the oxidation of tetralin at 60°C and linoleic acid micelles in aqueous dispersion at 37°C induced by an azo initiator. Phenothiazines were highly antioxidant in both systems. Although diphenylamine and carbazole were not good antioxidants, those having a hydroxy group as a substituent at the ortho or para position to the amino group were potently antioxidant. The antioxidant activity of o-hydroxydiphenylamine was much greater than that of other compounds in both systems due to a stabilization of the phenoxyl radical by delocalization of the unpaired electron to the p-type lone pair of the amino group. A semiempirical MNDO-AM1 calculation was applied to study hydrogen abstractions of antioxidants in the chain process of autoxidation. These results indicated that the rates of oxidation during the induction period correlated with the dissociation energies of the O-H or N-H bonds.
- Yamamura, Tatsuo,Suzuki, Kyouichi,Yamaguchi, Tatsuya,Nishiyama, Tomihiro
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p. 413 - 419
(2007/10/03)
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- Benzophenone-sensitized Photoreduction of N-Phenyl-p-benzoquinoneimine and Phenothiazine-3-one in Isopropyl Alcohol, Benzhydrol and Ethylene Glycol
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The results of the title investigation show that whereas N-phenyl-p-benzoquinoneimine (PBQ) and phenothiazine-3-one (PT) physically quench triplet benzophenone (3BP) in competition with hydrogen abstraction 3BP from alcohols, these substrates also undergo quantitative reduction to corresponding phenols via the ketyl radicals involving chemical sensitization.The reduced product also quenches the sensitizer through electron transfer at rates comparble to quenching rates by the substrates.The quantum yield data have been rationalised and a reaction scheme consistent with the observations and in close agreement with the kinetic expressions has been presented and various rate constants evaluated.Bulk of evidence is in support of the reduction taking place through hydrogen atom transfer to the carbonyl oxygen rather than to the azomethine nitrogen in these quinoneimines.
- Sidhu, K. S.,Bansal, W. R.,Malhotra, Kamini
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p. 747 - 752
(2007/10/02)
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