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The foremost objective of the present study was to develop and validate a new LC-QTOF-MS/MS method for the identification and quantitative determination of 4,6-dichloro-5-nitro-2-(propylthio)pyrimidine (DPP) genotoxic impurity through the derivatization process in ticagrelor active pharmaceutical ingredient (API). Owing to the low response of DPP at the specification level, DPP was converted to 4,6-dibenzylamino-5-nitro-2-(propylthio)pyrimidine (DPP derivative) by addition of benzyl amine, then analyzed using mass spectrometry with a time-of-flight analyzer, and good separation was accomplished under the experimental conditions described. The effective separation of DPP derivative was achieved using an Acquity UPLC BEH C

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This study describes the solvent-dependent conversion of an oxime under identical reaction conditions ([Cu(bipy)Cl2]/NaN3/5-Br-H2salox/TEA=1:2:1:2 molar ratio; bipy=2,2′-bipyridyl, 5-Br-H2salox=5-bromosalicylaldoxime, TEA=triethylamine), but in different solvents. In DMSO/CH2Cl2 (2:1 v/v) only tetrazole is formed, whereas iminoacylation in MeCN and simple complexation takes place in MeOH. The formed tetrazole and iminoacylated ligands further undergo complexation with metal ions, as evidenced from single-crystal X-ray diffraction studies and ESI-MS analyses. Mechanistic models have been proposed in which coordination-assisted bonding of sodium azide across the CNOH double bond occurs to form a tetrazole and oxime–MeCN coupling forms an iminoacylated ligand. The former is a catalytic reaction, as evidenced from a turnover number of approximately 50, whereas the latter is stoichiometric in nature. This is the first report to demonstrate the dependence of solvent polarity on oxime transformation reactions through structural elucidation.

A new rhodamine-based dual signaling probe (L3) has been found to display quick responses through visible colorimetric changes as well as fluorogenic properties on selective 1:1 binding to Hg2+, as delineated by absorption and fluorescence titrations as well as by Job′s method and ESI-MS+ studies. The fluorescent probe L3 displays a 252-fold fluorescence enhancement on binding to Hg2+. A Benesi–Hilderband fit of the absorption titration data gives Kd = (32.01 ± 0.74) μM and a 1:1 binding stoichiometry. Owing to its solubility in mixed organic/aqueous solvents as well as its cell permeability, L3 could be used for in vitro/in vivo cell imaging of Hg2+ with no or negligible cytotoxicity. The detection limit of Hg2+ was calculated by the 3σ method to be 9.28 ng L–1. Moreover, the fluorescence of the L3–Hg2+ system was turned off and its red colour disappeared when KI was added. Thus, the “OFF–ON–OFF” fluorescence sensing behaviour of L3 observed in the presence of Hg2+ and I– may find applications in devices with logic gate functions.

Dinuclear CuII-CuII (1) and CuI-CuII (2) complexes were derived from a new N4O2 donor compartmental ligand (H2L) by changing the nature of the Cu precursors used. Single-crystal X-ray diffraction studies revealed that the Cu1 site in 1 has octahedral geometry and is in the inner compartment of the ligand axially coordinated by two ClO4 - anions, whereas the outer Cu2 ion has square-pyramidal geometry. In 2, there are two copper dinuclear complexes (A and B) in the asymmetric unit; the inner core is occupied by Cu1/Cu3 in the +2 oxidation state in a square-planar geometry.....

A mixed-valent manganese tricapped Keggin polyoxometalate (3) has been designed by insertion of three Mn atoms from [MnIIMn III 2(μ3-O)(2-Cl-benzoato) 6(py)3] (1) into the vacant sites of the trilacunary precursor Na10[A-α-SiW9O34] (2). This compound exhibits strong antiferromagnetic interaction between the spin carriers of the Mn mixed-valent trinuclear moiety, which suggests an S = 5/2 ground state. A Keggin polyoxometalate α-[MnIIMnIII 2(H2O)3SiW9O37] 8- (3) has been designed by insertion of three Mn atoms from [Mn IIMnIII 2(μ3-O)(2-Cl-benzoato) 6(py)3] (1) into the vacant sites of Na 10[A-α-SiW9O34] (2). Compound 3 exhibits antiferromagnetic interaction between the Mn centres, which leads to an S = 5/2 ground state. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel hexacoordinating non-Schiff base ligand (H4L) with N2O4 donor atoms has been synthesized by simple Mannich reactions. The use of this ligand with Cu(ClO4)2·6H2O in different molar ratios as well as pH leads to the formation of a mononuclear species and a tetranuclear CuII complex possessing a cubane [Cu4L2] core with almost equal Cu···Cu separation. In the presence of an excess amount of copper(II) ions and triethylamine at reflux, the mononuclear [CuH2L] species can be converted into the tetranuclear one, whereas the reverse process was not observed even after prolonged reaction time. Both the complexes have been characterized by single-crystal X-ray diffraction and magnetic measurements. Magnetic studies reveal that complex 1 displays a paramagnetic Curie-type behavior whereas 2 displays a singlet- spin ground state induced by strong intramolecular antiferromagnetic interactions.

A new solvent-free, reusable catalytic combination consisting of WO3/70 % TBHP/aqueous NaOH has been described for the direct oxidation of methylarenes and acetophenones to the corresponding benzoic acids in high yields. Alkylarenes are oxidized to the corresponding aromatic ketones or benzylic alcohols depending upon whether NaOH is used or not.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A kinetic study of the aminolysis of substituted (methylthio)benzylidene Meldrum's acids, 2-SMe-Z with the aliphatic primary amines, n-butylamine, glycinamide, methoxyethylamine, and aminoacetonitrile, in aqueous DMSO at 20 °C is reported. With all amines the reaction is strictly second-order, that is, first-order in 2-SMe-Z and first-order in the amine. A three steps mechanism has been proposed. The first step is a rate-limiting attachment of the amine to form the tetrahedral intermediate (T), and the subsequent steps are a fast acid–base equilibrium followed by a fast R‴CH2NH or H2O catalyzed expulsion of the leaving group. The Bronsted plot for k1 for the reaction of 2-SMe-H with four primary amines showed a good correlation between log k1 and pK with βnuc = 0.32 ± 0.02, a slightly lower value than that for the reactions of secondary amines (βnuc = 0.41 ± 0.01). The Hammett plot for n-butylamine yields ρ(k1) = 0.40 ± 0.05 which is smaller than that for the reaction of piperidine with the same substrates (ρ(k1) = 0.72 ± 0.07) and also for the reactions of HOCH2CH2S− (ρ(k1) = 1.18), CF3CH2O− (ρ(k1) = 1.14) and OH− (ρ(k1) = 1.11) addition to 2-H-H (ρ(k1) = 1.11). All these observations are consistent with the suggested mechanism. Copyright © 2006 John Wiley & Sons, Ltd.

The iron(II) complex of H2L (H2L=3, 14-dimethyl-4, 7, 10, 13-tetraazahexadeca-3,13-diene-2,15-dione dioxime, Coord. Chem. Rev., 33, 87 (1980)) is oxidized by periodate very rapidly in the range pH 2.0–7.0, and the kinetics of the reaction has been followed by stopped-flow spectrophotometry at 30°C and ionic strength I=0.20 mol L−1 (NaClO4). The reaction is found to follow a simple second-order kinetics as −d/dt [FeII(H2L)2+]=k [FeII(H2L)2+] [I(VII)], giving [FeIII(L)]+ and IO3− as the final products. The reaction has been proposed to occur through a H-bonded transition state formed probably between the protonated oxime group of the ligand and the oxygen atom on the periodate species, followed by an electron transfer from FeII centre to IVII in a rate-determining step. The IVI species thus generated reacts in a fast step with another FeII complex. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 23–28, 1999

An efficient, mild, and simple protocol is presented for the oxidation of aldehydes and diols to carboxylic acids utilizing 70% aq TBHP as oxidant and t-BuOK as additive. The oxidation of aldehydes could be achieved by two methods under aqueous medium. Excellent yields of products were obtained in short reaction times. Notably, the products were isolated by simple filtration technique and do not involve chromatographic separation. These reactions may prove to be valuable alternatives to traditional metal-mediated oxidations. Oxidation does not require any transition metals or organic solvents in reaction, making this protocol green.

The kinetics of the oxidation of thiosulfate ion by [Mn(Y)]− (H4Y = trans-cyclohezane-1,2-dimine-N,N,N′,N′-tetraacetic acid) and [Ni(L1)]2+ (HL1 = 15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-en-2-one oxime) have been investigated at 20.0, 30.0, and 40.0°C in aqueous solution and found to follow the general rate law −d/dt [complex] = kox[S2O32−] [complex]. The large negative entropy (ΔS‡) of activation for the reactions and the results of Marcus calculation provide support for inner-sphere mechanism to be operative. © 1995 John Wiley & Sons, Inc.

The new MnII/MnIII mixed tricapped Keggin polyoxometalate (IV) crystallizes in the trigonal space group R with Z = 3 (single crystal XRD).

A. Introduction B. Electron exchange in dodecatungstocobaltate(II/III) and dodecatungstocuprate(I/II) C. Electron transfer reactions of dodecatungstocobaltate(II1) (i) Reactions with inorganic reagents (ii) Reactions with thiols and related species (iii) Reactions with carboxylates, cc-hydroxycarboxylates and amine-N-polycarboxylates (iv) Reactions with carbonyl compounds and esters (v) Reactions with carbohydrates (vi) Reactions with substituted alkyl aromatic compounds (vii) Miscellaneous reactions D. Electron transfer reactions of dodecatungstocobaltate(I1) (i) Reactions of [CO”W,,O,,]~with peroxodisulphate and periodate (ii) Reactions of [Co”W,,O,,]‘~ and [CO”W,,O,,]~with polyhalogenated alkanes E. Electron transfer reactions of dodecamolybdocerate(IV) F. Electron transfer reactions of nonamolybdonickelate(IV) and nonamolybdomanganate(IV) G. Conclusions Note added in proof References . . . .._..._ _........__._.......__.....

This review encompasses the oxidation reactions of various manganese(III) coordinated molecules. The reactions have been categorized primarily with respect to the type of manganese(III) complexes. Emphasis has been given to the reactivity of the manganese(III) complexes derived from aminopolycarboxylic acids, acetylacetone, porphyrins, bipyridine and pyrophosphoric acid with various organic, inorganic and biochemical electron donors. Kinetic and mechanistic features associated with the interactions have been highlighted and analysed critically. The utility and scope of the catalytic oxidation of hydrocarbons and secondary amines by manganese(III) porphyrins are discussed at length.

The kinetics of the oxidation of thioglycolic and thiomalic acids by [Ni III L 1 ] 2+ (where HL 1 =15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-en- 2-one oxime) have been investigated at 30.0 °C; an inner-sphere mechanism for both the reactions has been proposed except for the fully deprotonated species of thiomalic acid which follows an outer-sphere route.

A new solvent-free, reusable catalytic combination consisting of WO3/70 % TBHP/aqueous NaOH has been described for the direct oxidation of methylarenes and acetophenones to the corresponding benzoic acids in high yields. Alkylarenes are oxidized to the corresponding aromatic ketones or benzylic alcohols depending upon whether NaOH is used or not.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The kinetics of the reactions of manganese(III) complexes of trans-cyclohexane-1,2-diamine-NNN'N'-tetraacetic acid (H 4 cydta) and 2,2'-bipyridyl (bpy) have been investigated in the acid range [H + ]=1.00×10 −5 −3.16×10 −3 M and [H + ]=0.10−1.00 M, respectively, at different temperatures and at a constant ionic strength. Both the molecular and mono-anionic forms of ascorbic acid have been found to be reactive in the experimental acid ranges. The monoanionic species has been found to be more reactive than the molecular form. Attempts have been made to correlate the kinetic results in terms of the Marcus relationship for outer-sphere electron transfer reaction. Differences between the calculated rates (k 0.s ) and experimental rates (k) by approximately four and seven orders of magnitude (k 0.s k) suggest an innersphere pathway for the reaction of Mn(cydta)(H 2 O) − . Inner-sphere reaction is also believed to be operative for the other reaction. The activation parameters have been evaluated and compared with other reported systems

[reaction: see text] LiBr catalyzes efficiently the dihydroxylation of alkenes to afford syn and anti diols with excellent diastereoselectivity depending upon the use of NaIO(4) (30 mol %) or PhI(OAc)(2) (1 equiv), respectively, as the oxidants. The oxidation of non-benzylic halides has been achieved for the first time to afford the corresponding diols in excellent yields.