Kinetic and Mechanism of Oxidation of Methylaminopyrazole Formamidine by Alkaline Hexacyanoferrate(III) and the Effect of Divalent Transition Metal Ions
Ahmed Fawzy,
Ishaq Zaafarany,
Naeema Yarkandi,
Ameena Al-Bonayan,
Zakiya Almallah
Issue:
Volume 4, Issue 1, February 2016
Pages:
1-8
Received:
16 January 2016
Accepted:
25 January 2016
Published:
1 February 2016
Abstract: In aqueous alkaline medium, the kinetics of oxidation of methylaminopyrazole formamidine (MAPF) by hexacyanoferrate(III) (HCF)has been studied spectrophotometrically under the conditions, MAPF >> HCF at a constant ionic strength of 0.1 mol dm-3 and at 25°C. The reaction showed first order dependence on [HCF] while it exhibited fractional-first order kinetics with respect to [MAPF] and [OH-]. The oxidation rate increased with increasing ionic strength and dielectric constant of the reaction medium. Addition of small amounts of some divalent transition metal ions accelerates the oxidation rate and the order of catalytic efficiency was: Cu(II) > Ni(II) > Zn(II) > Co(II) > Cd(II). The suggested mechanism involves formation of a 1: 1 intermediate complex between HCF and the deprotonated MAPF species in a pre-equilibrium step. The final oxidation products were identified as methylaminopyrazole, dimethylamine and carbon dioxide. The appropriate rate law was deduced. The reaction constants involved in the mechanism were evaluated. The activation and thermodynamic parameters were determined and discussed.
Abstract: In aqueous alkaline medium, the kinetics of oxidation of methylaminopyrazole formamidine (MAPF) by hexacyanoferrate(III) (HCF)has been studied spectrophotometrically under the conditions, MAPF >> HCF at a constant ionic strength of 0.1 mol dm-3 and at 25°C. The reaction showed first order dependence on [HCF] while it exhibited fractional-first orde...
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Synthesis and Characterization of Non-linear 6, 8 and 9, 12-Dichloroazaphenothiazine Derivatives
Ayuk Eugene Lakem,
Nweke Cletus M.,
Agu Ifeoma S.
Issue:
Volume 4, Issue 1, February 2016
Pages:
9-13
Received:
25 November 2015
Accepted:
10 December 2015
Published:
2 March 2016
Abstract: The synthesis of non-linear diaza and tetraaza dichlorophenothiazine derivatives is reported in this article. This was achieved through the thiocyanation of 2,6-diamino-4-chloropyrimidine using potassium thiocyanate, bromine and glacial acetic acid at –5°C to give 2,6-diamino-3-thiocynatopyrimidine, which was hydrolyzed using 20% sodium hydroxide to furnish 2, 6-diamino-4-chloropyrimidin-3-thiol. Base catalyzed condensation reaction of 2, 6-diamino-4-chloropyrimidin-3-thiol and 2, 3-dichloro-1, 4-naphthoquinone gave the first derivative, 10-amino-6, 8-dichloro-9, 11-diazabenzo [a] phenthiazin-5-one, a reddish crystalline product. Similarly, another condensation reaction of 2, 6-diamino-4-chloropyrimidin-3-thiol with the first derivative, 10-amino-6, 8-dichloro-9, 11-diazabenzo[a]phenthiazin-5-one using the same reaction conditions, furnished the second derivative known as 7, 14-diamino-9,12-dichloro-6, 8, 13, 15-tetraazabenzo [a] [1,4] benzothiazino-[3,2-c] phenothiazine, a deep reddish crystalline compound. The synthesized compounds were characterized on the basis of UV-Visible, IR, 1HNMR and 13CNMR spectra data.
Abstract: The synthesis of non-linear diaza and tetraaza dichlorophenothiazine derivatives is reported in this article. This was achieved through the thiocyanation of 2,6-diamino-4-chloropyrimidine using potassium thiocyanate, bromine and glacial acetic acid at –5°C to give 2,6-diamino-3-thiocynatopyrimidine, which was hydrolyzed using 20% sodium hydroxide t...
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