- Oxidative Cyclization of Lithium 4-Ethoxy-1,1,1-trifluoro-4-oxobut-2-en-2-olate
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Diethyl 2,5-dihydroxy-2,5-bis(trifluoromethyl)tetrahydrofuran-3,4-dicarboxylate has been synthesized for the first time by reaction of lithium 4-ethoxy-1,1,1-trifluoro-4-oxobut-2-en-2-olate with manganese(III) acetate. The structure of its (2S*3S*4S*5S*) stereoisomer has been confirmed by X-ray analysis.
- Boltacheva,Slepukhin,Filyakova,Charushin
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p. 883 - 885
(2019/08/02)
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- Kinetic stability of corrole complexes with manganese, copper, and zinc in environments based on acetic and sulfuric acids
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Complexes of some meso- and undeca-substituted corroles with manganese, copper, and zinc are synthesized. Their stability in protolytic dissociation processes studied using spectroscopy methods increases for meso-triphenylcorrole (I) complexes in the following series of metals: Zn 2SO4 environment increases after electron-donor substitution of molecules in the series: Cu(ms-Ph)3Cor (Ib) > Cu(ms-4-OCH3Ph)3Cor (IIb) ≈ Cu(β-Br)8(ms-Ph)3Cor (IVb) > Cu(ms-4-NO2Ph)3Cor (IIIb). Contrariwise, the dissociation rates of manganese corroles increase with increasing electron-donating properties of the substituents in the macrocycle: IVb IIIb Ia IIa. Dissociation of metallocorroles is accompanied by donor-acceptor and acid-base interactions, as well as by intramolecular redox processes, to result in low selectivity of dissociation and formation of side products. The dissociation scheme of corrole complexes with mixed-valence d metals was proposed for the first time.
- Berezin,Shukhto,Thao, Vu Thi,Karimov,Berezin
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p. 1522 - 1529
(2015/02/19)
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- Anomalous non-prussian blue structures and magnetic ordering of K 2MnII[MnII(CN)6] and Rb 2MnII[MnII(CN)6]
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The reaction of MnII and KCN in aqueous and non-aqueous media leads to the isolation of three-dimensional (3-D) Prussian blue analogues, K2Mn[Mn(CN)6] (1a-d, 1e, respectively). Use of RbCN forms Rb2Mn[Mn(CN)6] (2). 1 and 2 are isomorphic {monoclinic, P21/n: 1 [a = 10.1786(1) A, b = 7.4124(1) A, c = 6.9758(1) A, β = 90.206(1)°]; 2 [a = 10.4101(1) A, b = 7.4492(1) A, c = 7.2132(1) A, β = 90.072(1)°]}, with a small monoclinic distortion from the face centered cubic (fcc) structure that is typical of Prussian blue structured materials that was previously reported for K2Mn[Mn(CN)6]. Most notably the average Mn-N-C angles are 148.8° and 153.3° for 1 and 2, respectively, which are significantly reduced from linearity. This is attributed to the ionic nature of high spin MnII accommodating a reduced M-CN-M0 angle and minimizing void space. Compounds 1a, b have a sharp, strong.OH band at 3628 cm-1, while 1e lacks a v OH absorption. The vOH absorption in 1a, b is attributed to surface water, as use of D2O shifts the.OH absorption to 2677 cm-1, and that 1a-e are isostructural. Also, fcc Prussian blue-structured Cs2Mn[Mn(CN)6] (3) has been structurally [Fm3hm: a = 10.6061(1) A] and magnetically characterized. The magnetic ordering temperature, Tc, increases as K+ (41 K) + (34.6 K) + (21 K) for A2Mn[Mn(CN)6] in accord with the increasing deviation for linearity of the Mn-N-C linkages [148.8 (K+) +)], decreasing Mn(II) · · · Mn(II) separations [5.09 (K+) > 5.19 (Rb+) > 5.30 A° (Cs+)], and decreasing size of the cation (increasing electrostatic interactions). Hence, the bent cyanide bridges play a crucial role in the superexchange mechanism by increasing the coupling via shorter Mn(II) 3 3 3 Mn(II) separations, and perhaps enhanced overlap. In addition, the temperature dependent magnetic behavior of K4[MnII(CN) 6] · 3H2O is reported.
- Her, Jae-Hyuk,Stephens, Peter W.,Kareis, Christopher M.,Moore, Joshua G.,Min, Kil Sik,Park, Jong-Won,Bali, Garima,Kennon, Bretni S.,Miller, Joel S.
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p. 1524 - 1534
(2010/04/25)
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- Preparation and characterization of manganese(IV) in aqueous acetic acid
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Mn(iv) acetate was generated in acetic acid solutions and characterized by UV-vis spectroscopy, magnetic susceptibility, and chemical reactivity. All of the data are consistent with a mononuclear manganese(iv) species. Oxidation of several substrates was studied in glacial acetic acid (HOAc) and in 95 : 5 HOAc-H2O. The reaction with excess Mn(OAc)2 produces Mn(OAc)3 quantitatively with mixed second-order kinetics, k (25.0 °C) = 110 ± 4 M-1 s-1 in glacial acetic acid, and 149 ± 3 M-1 s-1 in 95% AcOH, ΔH ? = 55.0 ± 1.2 kJ mol-1, ΔS ? = -18.9 ± 4.1 J mol-1 K-1. Sodium bromide is oxidized to bromine with mixed second order kinetics in glacial acetic acid, k = 220 ± 3 M-1 s-1 at 25 °C. In 95% HOAc, saturation kinetics were observed. The Royal Society of Chemistry 2010.
- Jee, Joo-Eun,Pestovsky, Oleg,Bakac, Andreja
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p. 11636 - 11642
(2011/02/27)
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- Stabilizing Vegetable Oils And Methods Of Making Same
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A method for modifying ethylenic unsaturation in a triglyceride. One or more unsaturated fatty acyl moieties present in the triglyceride are substituted with a lactone or ketone moiety via a electron donor mediated reaction. The resulting reaction products are useful, for example, as formulations for lubricants, hydraulic fluids, dielectric fluids, and intermediates for polymer synthesis.
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Page/Page column 7
(2008/06/13)
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- Effect of octabromo substitution on the coordination properties of manganese(III) octaphenyltetraazaporphyrin
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Comparative studies of the kinetics of formation of manganese(III) complexes with octaphenyltetraazaporphyrin and its octabromo derivative, of their dissociation and axial ligand exchange were carried out. The effect of octabromo substitution on the coordination properties of the compounds is determined by the -I effect of bromine atoms. The different effects on the kinetic parameters of the reactions [increase in the rate and significant decrease in the activation energy upon complex formation, slowing down of dissociation, and acceleration of acido ligand exchange with nitrido(tetraphenyporphyrin)manganese(V) are caused by the involvement of different reaction centers in the limiting stages (different mechanisms of the processes).
- Klyueva,Repina,Chizhova
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p. 975 - 979
(2007/10/03)
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- Racemic and chiral expanded salen-type complexes derived from biphenol and binaphthol: Salbip and salbin
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The reaction of 2-fluoronitrobenzene with 2,2′-biphenol or (R)-binaphthol, followed by reduction and subsequent reaction of the resulting diamine with two equivalents of a salicylaldehyde, affords expanded salen-type ligands having backbones based on biphenol or binaphthol: salbipH2, (R)-salbinH2 and (R)-salbin(t-Bu)4H2. Deprotonation of these ligands with sodium methoxide or potassium hydride, followed by metallation with M(OAc)2 (M = Mn, Co, Ni, or Cu), affords the corresponding metal complexes in good yield (61-85%). The species containing Mn, Co, and Ni all have distorted octahedral geometry, as determined by X-ray crystallography. The ethereal oxygen atoms occupy two coordination sites with metal-oxygen distances ranging from 2.19 to 2.36 ?. The imine nitrogen atoms are trans to each other in the solid state, an impossible geometry in traditional salen-type complexes. The species containing Cu are distorted square planar and show much longer metal-ethereal oxygen distances ranging from 2.79 to 3.22 ?. The manganese complexes are competent catalysts for the epoxidation of olefins.
- Grill, Joseph M.,Reibenspies, Joseph H.,Miller, Stephen A.
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p. 3009 - 3017
(2007/10/03)
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- Cobalt(III)-d-metal triethanolamine complexes as catalysts of electrochemical reduction of oxygen
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Carbon-supported oxide catalysts of oxygen electroreduction were prepared from Co(III)-M(II) ethanolamine complexes. The electrochemical properties of these catalysts were studied. The apparent activation energies of the reduction were measured. 2001 MAIK
- Kublanovskii,Pirskii
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p. 1147 - 1150
(2007/10/03)
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- Thermal decomposition of freeze-dried μ-oxo-carboxylates of manganese and iron
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The decomposition of freeze-dried mixed carboxylates of manganese and iron was investigated by means of DTA, TG, mass spectroscopy and X-ray powder diffractometry. The three main steps of decomposition are characterized as release of (a) H2O, (b) carboxylic acid and CO2/CO, and (c) the corresponding carbonyl compound and CO2. In particular, the course of process (b) strongly depends on the stability of the metal-carboxylate link in the three investigated carboxylates. Well-crystallized single-phase manganese ferrites can be obtained on decomposition of formates of appropriate composition and thermal treatment of decomposition products at 600°C while maintaining a p(O2) within the coexistence field of manganese ferrite.
- Langbein,Christen,Bonsdorf
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p. 173 - 180
(2008/10/09)
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- Thermochemical reactivity of transition metal acetates and of a novel DMSO solvate of iron(II) acetate in molecular hydrogen
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The thermal decomposition of acetates of the transition metals Fe, Co, Ni, Mn and Cu in molecular hydrogen has been investigated by means of combined thermogravimetry/mass spectrometry, X-ray diffraction, and transmission as well as scanning electron microscopy. In the context of the reproducible preparation of the parent phases, i.e. the hydrated or anhydrous metal(II) acetates, single crystalline Fe3(CH3COO)6(DMSO)2, a novel DMSO solvate of iron(II) acetate, has been isolated and its crystal structure has been determined by means of X-ray diffraction. For the series of metal(II) acetates it has been found that the course of the thermal degradation in molecular hydrogen, in particular the formation of the gaseous products, strongly depends on the transition metal ion present in the parent compound. The detailed characterization of the solid products revealed, that phases exhibiting different catalytic activities and selectivities are formed as micro- or nanocrystalline metals and/or metal oxides.
- Ehrensberger,Schmalle,Oswald,Reller
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p. 139 - 149
(2008/10/09)
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- Process for glycol esters of an alkali metal salt of 5-sulfoisophthalic acid
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A process for preparing bis alkylene glycol esters of an alkali metal salt of 5-sulfoisophthalic acid. The subject compound is useful in preparing modified polyesters which can be dyed with basic or cationic dyes. The process is economical and low cost since intermediate reaction products are not purified.
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- Potentiometric Studies on Electron Transfer Reactions of Anodically generated Manganese(III) Sulphate in Aqueous H2SO4-HOAc and Manganese(III) Acetate in Aqueous Acetic Acid : Oxidation of Semicarbazide and Semicarbazones
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Manganese(III) sulphate in aqueous sulphuric acid and manganese(III) acetate in aqueous acetic acid have been prepared by electrolytic methods with high current efficiency. The nature of the manganese(III) formed is elucidated spectrophotometrically. Condition for potentiometric determination of semicarbazide and its derivatives under different reaction conditions have been investigated. Hydrazinium sulphate or hydroquinone is employed as back-titrant. The number of electrons in these oxidations differed, depending on the nature of the molecule and the reaction condition. The free radical nature of the reaction intermediate is demonstrated. Manganese(III) sulphate and manganese(III) acetate oxidation of semicarbazide and its derivatives in aqueous H2SO4 or aqueous HOAc yielded different results, probably because of the changes in the coordination environment of manganese(III).
- Pinto, Ivan,Sherigara,Bhat, K. Ishwara,Udupa
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- Characterization of the reaction of cobalt(II) acetate, dioxygen and acetic acid, and its significance in autoxidation reactions
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When cobalt(II) acetate is added to an oxygenated solution of acetic acid at reflux, a reaction occurs producing cobalt(II) acetate, carbon dioxide, carbon monoxide, methane, methyl acetate and water. Evidence is presented that this reaction is initiated by a trace amount of adventitious peroxide in acetic acid and is then is propagated via a free radical chain reaction. A balanced set of reactions is given which are consistent with the products observed. It is suggested that this is the initiation step in cobalt-catalyzed autoxidations in acetic acid. Of the first row metal acetates from calcium to zinc, only cobalt(II) acetate undergoes this reaction. It is shown that cobalt is, by far, the most active autoxidation catalyst toward p-toluic acid in acetic acid. The author concludes that the Co(OAc)2/O2/ HOAc reaction is one of the reasons for cobalt's unique character as an autoxidation catalyst in carboxylic solvents.
- Partenheimer
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- Kinetics of reaction of cyanoisopropylperoxy radicals with divalent manganese in acetic acid
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The kinetics of the reaction of cyanoisopropylperoxy radicals with Mn(II) acetate in acetic acid at a temperature of 70°C, leading to the formation of a hydroperoxide, was studied by the chemiluminescent method. It was found that the effective rate constant of this reaction decreases with increase in the concentration of Mn(II) approximately according to the relationship keff approximately [Mn(II)]-1 from 9.104 to 1.104 liter/mole·sec when [Mn(II)] increases from 10-4 to 10-3 mole/liter. A scheme was proposed for the reaction of RO2· with Mn(II) via the formation of an intermediate complex RO2 -Mn3+. The observed decrease in keff is explained by the inactivation of the complex by its reaction with a free Mn(II) ion.
- Adamyan,Geletii,Popova,Zakharov
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p. 1307 - 1310
(2008/10/08)
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- Iodimetric determinations in organic solvents: Determination of manganese oxidation states in methylene chloride solutions
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An iodimetric technique has been developed to quantitatively analyze the oxidants present in organic solutions.Addition of excess tetrabutylammonium iodide and excess glacial acetic acid results in the formation of tetrabutylammonium triiodide, whose concentration can be measured spectrophotometrically at 295 or 365 nm.Application of this technique to the determination of the final oxidation state of manganese in permanganate reaction in methylene chloride solutions is described.The equilibrium constant for formation of tetrabutylammonium triiodide in methylene chloride has been measured: K = (3.48 +/- 0.12)*1E4 at 25.0 deg C.
- Perez-Benito, Joaquin F.,Brillas, Enrique,Arias, Conchita
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- HOMOLYTIC AROMATIC ALKYLATION OF 1- AND 2-ALKOXYNAPHTHALENES BY Mn(III) OXIDATION OF METHANES OR ETHANES 1,1-DISUBSTITUTED WITH ELECTRON-WITHDRAWING GROUPS
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Thermal decomposition of anhydrous Mn(III) acetate in acetic acid in the presence of methanes or ethanes 1,1-disubstituted with electron-withdrawing groups (RCHXY; X,Y = COOR, COCH3, CN; R = H, CH3) and 1- or 2-alkoxynaphthalenes affords aromatic substitution products (in position 4 and 1, respectively) with good yield and selectivity by using stoicheiometric amounts of reagents.The reaction can be performed also with Mn(CRXY)3 complexes.
- Citterio, Attilio,Fancelli, Daniele,Santi, Roberto,Pagani, Anselmo,Bonsignore, Stefano
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p. 405 - 408
(2007/10/02)
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- State and Solubility of Mn(II) and Mn(III) Acetates in Binary Organic Solvents
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We have measured the solubility of Mn(II) and Mn(III) acetates in binary mixtures of acetic acid (HAc) with hexane, butan-1-ol (BuOH), and dimethylformamide (DMF) at 298.15 K.MnAc2 and MnAc3 are found to form octahedral solvato complexes: p*(HAc)6-p> (p = 2 or 3) in HAc-hexane mixtures, and p*(HAc)6-p-q(Solv)q> (Solv = DMF or BuOH) in HAc-DMF and HAc-BuOH mixtures.In saturated butanolic solutions containing a fraction of 1 percent of water MnAc2 and MnAc3 form hydroxo complexes, with a substantial increase in solubility.
- Golubchikov, O. A.,Kadykov, V. V.,Berezin, B. D.
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p. 148 - 152
(2007/10/02)
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- THE DIRECT ELECTROCHEMICAL SYNTHESIS OF SOME TRANSITION METAL CARBOXYLATES
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The transition metal carboxylates M(O2CR)n (M=Cr, R=C2H5, C6H5, n=3; M=Mn, Fe, Ni, R=CH3, C2H5, C6H5, n-C7H15, n=2, not all combinations) have been prepared by oxidising suitable metal anodes electrochemically in solutions of RCOOH in acetonitrile.With Co and Cu, a wide range of carboxylic acids (R=C2H5, c-C3H5, c-C5H9, C6H5, n-C4H9, n-C7H15, 2-ethylhexanoic, oleic, linoleic) has been used succesfully to give M(O2CR)2.The advantages of the method are discussed.The preparation of Cu(O2CR)2 involves the prior formation of CuO2CR at the anode, followed by oxidation by the solvent.
- Kumar, N.,Tuck, Dennis G.,Watson, Katherine D.
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p. 740 - 743
(2007/10/02)
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- 4-carbalkoxy-2-ethyl-2,3-dihydrofurans
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2,3-Dihydrofurans having highly desirable odor characteristics closely mimicking that of natural products are provided herein. The 2,3-dihydrofurans correspond to the formula STR1 wherein R' is an alkyl group having from 1 to 4 carbon atoms, R** is an alkyl group having from 1 to 5 carbon atoms, R1 is an alkyl group having from 1 to 4 carbon atoms, R2 is hydrogen or an alkyl group having from 1 to 6 carbon atoms, and R3 and R4 are hydrogen or a methyl group. The 2,3-dihydrofuran compounds are useful in the preparation of fragrance compositions and fragranced articles and can be employed in conjunction with known fragrance materials to augment or enhance the aromas thereof.
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- Manufacture of gamma halogen substituted adducts
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Halogen-substituted olefin addition compounds that contain a carbonyl group are formed by oxidatively adducting an olefin and a carbonyl compound such as a ketone, aldehyde, or ester. The method consists of reacting the olefin and the carbonyl component, in solution, with an oxidizing ion of manganese, cerium or vanadium in the presence of fluoride, chloride or bromide ion. This ionic component is incorporated in the adduct and appears on the olefin-derived carbon atom gamma to the carbonyl group. The gamma halogen substituted adducts are readily converted to cyclopropane derivatives, including pyrethroid intermediate compounds.
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