993-02-2Relevant articles and documents
Oxidative Cyclization of Lithium 4-Ethoxy-1,1,1-trifluoro-4-oxobut-2-en-2-olate
Boltacheva,Slepukhin,Filyakova,Charushin
, p. 883 - 885 (2019/08/02)
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.
Kinetic stability of corrole complexes with manganese, copper, and zinc in environments based on acetic and sulfuric acids
Berezin,Shukhto,Thao, Vu Thi,Karimov,Berezin
, p. 1522 - 1529 (2015/02/19)
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.
Anomalous non-prussian blue structures and magnetic ordering of K 2MnII[MnII(CN)6] and Rb 2MnII[MnII(CN)6]
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.
, p. 1524 - 1534 (2010/04/25)
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.
Preparation and characterization of manganese(IV) in aqueous acetic acid
Jee, Joo-Eun,Pestovsky, Oleg,Bakac, Andreja
, p. 11636 - 11642 (2011/02/27)
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.
Stabilizing Vegetable Oils And Methods Of Making Same
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Page/Page column 7, (2008/06/13)
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.
Effect of octabromo substitution on the coordination properties of manganese(III) octaphenyltetraazaporphyrin
Klyueva,Repina,Chizhova
, p. 975 - 979 (2007/10/03)
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).
Racemic and chiral expanded salen-type complexes derived from biphenol and binaphthol: Salbip and salbin
Grill, Joseph M.,Reibenspies, Joseph H.,Miller, Stephen A.
, p. 3009 - 3017 (2007/10/03)
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.
Cobalt(III)-d-metal triethanolamine complexes as catalysts of electrochemical reduction of oxygen
Kublanovskii,Pirskii
, p. 1147 - 1150 (2007/10/03)
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
Thermal decomposition of freeze-dried μ-oxo-carboxylates of manganese and iron
Langbein,Christen,Bonsdorf
, p. 173 - 180 (2008/10/09)
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.
Thermochemical reactivity of transition metal acetates and of a novel DMSO solvate of iron(II) acetate in molecular hydrogen
Ehrensberger,Schmalle,Oswald,Reller
, p. 139 - 149 (2008/10/09)
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.
