Tertiary Butyl Hydroperoxide Research Articles

Heteronuclear coordination polymers with imidazole ligand: Synthesis, characterization and alcohol oxidation activities

Two new heteronuclear Cd(II)/Pd(II) coordination polymers, [Cd2(µ-im)2(Him)4Pd(µ-CN)4]n (1) and [Cd(Him)2Pd(µ-CN)4]n (2) (Him: imidazole), have been synthesized under different conditions and characterized using elemental analysis, thermal analysis, FT-IR and Raman spectroscopy, single-crystal and powder X-ray diffraction techniques.. In 1, the Cd(II) ions are bridged by imidazolate ligands to generate 1D chain structure. Neighbouring 1D chains were linked by [Pd(CN)4]2- ions to form 3D framework. In 2, the metal ions are bridged by cyanide ligands to generate 2D [Cd2Pd2(µ-CN)4]n network. Furthermore, catalytic peroxidative oxidation activity of catalysts 1 and 2 was examined on the oxidation of benzyl alcohol using tertiary-butyl hydroperoxide (t-BuOOH) as the oxygen source. The compound 1 exhibited over 90 % product conversion at 80 °C in 24-hour reaction time. In addition, the catalyst exhibited high selectivity towards benzaldehyde and no over-oxidation product (benzoic acid) was detected.

NADPH-dependent peroxidase activity of antibodies in patients with schizophrenia

IntroductionThe development of oxidative stress in patients with schizophrenia is associated with changes in the level of activity of antioxidant enzymes. It is likely that catalytically active antibodies (abzymes) can take on these functions. Abzymes are antibodies with enzymatic activity. Catalase and SOD activity of abzymes was previously detected in patients with schizophrenia. But NADPH-dependent peroxidase activity has not been studied. The present work discusses the protective role of abzymes against reactive oxygen species within the pathogenesis of schizophrenia.ObjectivesThe aim of the study was to investigate the NADPH-dependent peroxidase activity of IgG in patients with paranoid schizophrenia in the exacerbation phase and in the remission phase.MethodsA total of 124 patients were examined during the work. Of them, 82 patients with paranoid schizophrenia (F20.0) had a mean age of 33.6±5.12 years (52 males, 30 females), disease duration averaged 8.9± 4.62 years. Patients with schizophrenia included 42 patients with acute schizophrenia and 40 patients with schizophrenia in therapeutic remission. The control group included 42 sex- and age-matched patients. IgG was purified by affinity chromatography on columns with proteinsepharose on an AKTA purifier chromatograph (GE). The homogeneity of isolated IgG preparations was checked by Lemilly electrophoresis in a gradient of 4-18% PAAG. Gel filtration under pH-shock conditions was performed on a Superdex-200 HR 10/30 column. NADPH-dependent peroxidase activity of IgG was determined on a SPECORD M-40 spectrophotometer (Carl Zeiss) at 340 nm by NADPH oxidation in the conjugated glutathione reductase reaction of tertiary butyl hydroperoxide reduction. Statistical processing of data was performed in Statistica 12.0 program.ResultsIt was proved that IgG from patients with schizophrenia had NADPH-dependent peroxidase activity, and this activity is an intrinsic property of the investigated antibodies. The NADPH-dependent peroxidase activity in IgG patients in the exacerbation stage was increased 3-fold (p=0.0001) compared to the studied activity in the group of healthy individuals, and it was increased 2-fold (p=0.017) in the group of patients in therapeutic remission compared to the activity in healthy individuals. Also NADPH-dependent IgG peroxidase activity in patients in remission was 1.7 times lower than in patients during the exacerbation period (p=0.012).ConclusionsIt was established for the first time that abzymes from patients with schizophrenia and healthy individuals have NADPH-dependent peroxidase activity and can decompose lipo and hydroperoxides. We hypothesize that these abzymes help cope with generalized oxidative stress. Under the influence of neuroleptic therapy in patients in remission, the level of oxidative stress and NADPH-dependent peroxidase activity of abzymes decrease.Disclosure of InterestNone Declared

Синтез и строение бис[3,4-дифторбензоата] трис(2-метоксифенил)сурьмы [(2-MeO)C6H4]3Sb[OC(O)C6H3(F2-3,4)]2 и бис[бензолсульфоната] трис(2-метоксифенил)сурьмы [(2-MeO)C6H4]3Sb[OSO2C6H5

Tris(2-methoxyphenyl)antimony bis[3,4-difluorobenzoate] (1) and tris(2-methoxyphenyl)antimony bis[benzenesulfonate] (2) were obtained by oxidative addition reaction from triarylantimony and 3,4-difluorobenzoic/benzenesulfonic acid in the presence of tertiary bu-tyl hydroperoxide in ether. The structure of 1 and 2 was established with the use of IR spectrosco-py and X-ray diffraction analysis (XRD). Crystals 1 [C35H27O7F4Sb, M 757.32; triclinic syngony, symmetry group P–1; cell parameters: a = 9.219(4), b = 9.507(6), c = 20.240(11) Å; a = 99.43(3)°, β = 95.756(16)°, g = 107.90(3)°; V = 1643.6(16) Å3; Z = 2; rcalc = 1.530 g/cm3; 2q 6.68-54.98 de-grees; total reflections 31858; independent reflections 7153; number of specified parameters 427; Rint = 0.0429; GOOF 1.051; R1 = 0.0265, wR2 = 0.0551; residual electron density (max/min); 0.30/-0.44 e/Å3], 2 [C33H31O9S2Sb, M 757.46; monoclinic system, symmetry group C2/c; cell parame-ters: a = 21.157(9), b = 10.363(4), c = 18.285(7) Å; β = 126.590(13) deg., V = 3219(2) Å3, Z = 1; rcalk = 1.563 g/cm3; 2q 6.012-54.234 degrees; total reflections 32454; independent reflections 3541; number of specified parameters 231; Rint = 0.0283; GOOF 1.161; R1 = 0.0283, wR2 = 0.0659; residual electron density (max/min); 0.74/-0.83 e/Å3] consist of trigonal bipyramidal molecules with electronegative ligands in axial positions. The Sb–C bond lengths vary in the range 2.093(2)−2.125(3) Å, The OSbO bond angles take values 176.63(6)° and 174.52(10)°, respective-ly. The Sb–O distances in 1 (2.1106(17) and 2.1149(17) Å) are shorter than in 2 (2.128(2) and 2.128(2) Å). Intramolecular Sb∙∙∙O contacts in 1 (3.162(2) and 3.257(2) Å) are significantly smaller than in 2 (3.617(2) and 3.617(2) Å) and do not exceed the sum of their van der Waals radii (3.7 Å). Complete tables of atomic coordinates, bond lengths and bond angles for structures have been de-posited in the Cambridge Structural Data Bank (No. 2123247 (1), No. 2116583 (2), depos-it@ccdc.cam.ac.uk; http://www.ccdc cam.ac.uk).

Синтез и строение сольвата бис[3,5-динитробензоата] трис(2-метокси)(5-бром)фенилсурьмы [C6H3(2-OMe)(5-Br)]3Sb[OC(O)C6H3(NO2)2-3,5]2 ∙ PhH ∙ ½ C8H18

Tris(2-methoxy)(5-bromo)phenylantimony bis[3,5-dinitrobenzoate] (1) was obtained from 3,5-dinitrobenzoic acid by oxidative addition to triarylantimony in the presence of tertiary butyl hy-droperoxide in ether, and was isolated by recrystallization from a benzene-octane mixture in the form of a crystal solvate with benzene and octane molecules in its crystal lattice. The structure of solvate 1 was established by the IR spectroscopy and X-ray diffraction analysis (XRD). In the IR spectrum of complex 1, in addition to the absorption bands related to the stretching vibrations of the Sb–C, СAr–О–Ме, and carbonyl groups, there are bands corresponding to the stretching vibra-tions of the C–Br bonds (524 and 555 cm–1). The X-ray diffraction data show that the antimony at-oms in complex 1 have a distorted trigonal bipyramid coordination with carboxylate ligands in the axial position. The antimony atom and two oxygen atoms do not lie on the same straight line and are located in such a way that the OSbO angle is 170.79°. The O…Sb distances (2.134(4) and 2.110(5) Å) are close to the sum of the covalent radii of antimony and oxygen. In addition, accord-ing to the X-ray diffraction data, compound 1 crystallizes in the monoclinic crystal system, space group P21/n. The structural organization in the crystal is formed due to short contacts of oxygen atoms in the nitro groups of the carboxylate ligands with carbon and bromine atoms of the aryl lig-ands of neighboring molecules, as well as hydrogen O...H (2.524–2.715 Å) bonds. In addition, a certain contribution to the formation of the crystal structure is made by the p-p stacking between the aromatic rings of crystallization benzene and the methoxy-bromo-phenyl ligands. The aro-matic rings are displaced in relation to each other and the distance between them is 3.367 Å. Melt-ing point of solvate 1 is 172.6 °C, according to the thermal analysis data. However, further in-crease in temperature is accompanied by decomposition of compound 1, and therefore an exo-thermic peak is observed on the DSC curve at 255.7 °C, corresponding to a mass loss of 31 % ac-cording to the TGA data. Complete tables of atom coordinates, bond lengths, and valence angles are deposited at the Cambridge Crystallographic Data Center (No. 2060562, depos-it@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/cif)

Direct Tertiary Butyl Alcohol Formation via Catalytic Liquid Phase Isobutane Oxidation with Molecular Oxygen

A safe one-pot catalytic process for directly producing tertiary butyl alcohol (TBA) from liquid-phase isobutane oxidation with oxygen is demonstrated. This is achieved by operating outside the vapor phase flammability envelope and catalytically decomposing tertiary butyl hydroperoxide (TBHP), the main product of homogeneous isobutane oxidation, at 125 °C and 35 bar. Among a dozen heterogeneous metal-based catalysts tested, amorphous MnO2 (AMO) was found to be roughly an order of magnitude more active than supported Pd, Co, Au, and Nb-based catalysts for TBHP decomposition to TBA. As a result, high TBA/TBHP (up to 20.4) selectivity was achieved during isobutane oxidation in the presence of the AMO catalyst. The yield of gas phase C1 products was <1% and only a minor amount of acetone was produced as a β-scission byproduct. The use of n-hydroxy phthalimide (NHPI) as an initiator was found to enhance the TBA yield. This process provides a possible low energy pathway for making isobutylene from isobutane, avoiding the energy-intensive dehydrogenation and isobutane/isobutylene separation steps.

Аддукты арильных соединений сурьмы и висмута с карбоновыми кислотами, фенолами и оксимами

When the reaction products of triarylantimony or -bismuth with carboxylic acids, phenol, or oxime in the presence of tertiary butyl hydroperoxide (molar ratio 1:2:1, diethyl ether, 24 °C, 24 h) were recrystallized brom benzene or toluene, the adducts of antimony or bismuth aryl compounds with carboxylic acids, phenol, and oxime of the Ar3MX2 type were isolated as minor products. According to X-ray structural analysis performed at 293 K on a D8 Quest Bruker automatic four-circle diffractometer (two-coordinate CCD detector, Mo Kα radiation, λ = 0.71073 Å, graphite monochromator), metal atoms in crystals m-Tol3Sb[OC(O)C6H3F2-2,5]2 ∙ HOC(O)C6H3F2-2,5 (1) [C42H31O6F6Sb, M 867.42; triclinic syngony, symmetry group P1 ̅; cell parameters: a = 8.78(5), b = 13.10(6), c = 16.64(8) Å;  = 102.86(19), β = 99.3(2),  = 98.0(3) degrees; V = 1813(16) Å3; Z 2; reflection index intervals –7 ≤ h ≤ 7, –11 ≤ k ≤ 11, –14 ≤ l ≤ 14; total reflections 14149; independent reflections 2603; Rint 0.0284; GOOF 1.049; R1 = 0.0348, wR2 = 0.0938; residual electron density 0.55/0.42 e/Å3]; p-Tol3Bi[OC(O)C6HF4]2∙HOC(O)C6HF4 (2) [C42H25O6F12Bi, M 1062.60; triclinic syngony, symmetry group P1 ̅; cell parameters: a = 12.246(11), b = 12.976(18), c = 14.391(13) Å;  = 68.27(4), β = 69.89(3),  = 86.11(5) degrees; V = 1990(4) Å3; Z 2; reflection index intervals –15 ≤ h ≤ 15, –16 ≤ k ≤ 16, –18 ≤ l ≤ 18; total reflections 48542; independent reflections 9207; Rint 0.0321; GOOF 1,136; R1 = 0.0322, wR2 = 0.0648; residual electron density 1.81/1.08 e/Å3]; [(2-MeO-5-BrC6H3)3SbOC6H4Br-4]2O∙2HOC6H4Br-4 (3) [C66H54Br10O11Sb2, M 2065.69; monoclinic syngony, symmetry group C21/c; cell parameters: a = 12.017(14), b = 25.54(3), c = 13.181(18) Å; β = 116.71(5) degrees; V = 3613(8) Å3; Z 2; reflection index intervals –13 ≤ h ≤ 13, –27 ≤ k ≤ 27, –12 ≤ l ≤ 12; total reflections 29461; independent reflections 4545; Rint 0.0656; GOOF 1.062; R1 = 0.0565 wR2 = 0.1200; residual electron density 1.59/1.31 e/Å3]; [(2-MeO)C6H4]3Sb[ON=CHC4H2O(NO2-2)]2 ∙ 2HON=CHC4H2O(NO2-2) ∙ ½PhH (4) [C44H38N8O19Sb, M 1104.57; triclinic syngony, symmetry group P1 ̅; cell parameters: a = 10.240(5), b = 14.480(8), c = 18.093(11) Å;  = 103.43(3), β = 104.50(2),  = 98.876(17) degrees; V = 2461(2) Å3; Z 2; reflection index intervals –13 ≤ h ≤ 13, –18 ≤ k ≤ 18, –23 ≤ l ≤ 23; total reflections 58643; independent reflections 10886; Rint 0.0558; GOOF 1.061; R1 = 0.0429, wR2 = 0.1095; residual electron density 1.91/0.51 e/Å3] have a distorted trigonal-bipyramidal coordination with the oxygen atoms in axial positions. Complete tables of atomic coordinates, bond lengths, and bond angles for the structures were deposited at the Cambridge Crystallographic Data Center (no. 2050322 for 1, no. 2045173 for 2, no. 2070387 for 3, no. 2119790 for 4; deposit@ccdc.cam.ac.uk; https www.ccdc.cam.ac.uk).

FEATURES OF KINETICS POLYMERIZATION OF METHYL METHACRYLATE INITIATED BY HYDROPEROXIDES -N, N-DIETHYLDITHIOCARBAMATES OF COPPER (II) SYSTEMS

Kinetic studies have shown that the use of systems based on secondary and tertiary hydroperoxides with N, N-diethyldithiocarbamate copper (II) can be used as effective sources of free radicals in the polymerization of methyl methacrylate in moderately low temperatures region (323–343 K). The introduction of an aromatic ring in molecules of hydroperoxides (ethylbenzene hydroperoxide and cumene hydroperoxide) increases the reactivity of the initiating system «hydroperoxide – complex» in comparison with tertiary butyl hydroperoxide. The shift of the gel effect to the region of high conversions during the polymerization of methyl methacrylate was noted. Such systems allow not only to accelerate the polymerization of the monomer, but also to conduct it in a controlled mode. H1 NMR spectroscopy showed that the formed polymers contained end dithiocarbamate fragments. Such groups are labile. It has been shown that the obtained and isolated in the presence of the initiating system tertiary hydroperoxide – N,N-diethyldithiocarbamate of copper(II) polymers are macroinitiators that can initiate a new portion of the monomer.

Окисление трис(2-метокси-5-бромфенил)сурьмы трет-бутилгидропероксидом в присутствии соединений, содержащих подвижный атом водорода

Oxidation of tris(2-methoxy-5-bromophenyl)antimony with tertiary butylhydroperoxide in the presence of water, benzoic acid, 2,6-dihydroxybenzoic acid and 2-chloro-4-fluorophenol in diethyl ether leads to formation of tris(2-methoxy-5-bromophenyl)antimony oxide (1), tris(2-methoxy-5-bromophenyl)antimony dibenzoate (2), -oxo[hexakis(2-methoxy-5-bromophenyl)-bis(2,6-dihydroxybenzoato)diantimony] (3), -oxo[hexakis(2-methoxy-5-bromophenyl)-bis(2-chloro-4-fluorophenoxo)diantimony] (4), respectively. The compounds have been identified by X-ray diffraction analysis. According to the X-ray diffraction data, the crystal of solvate 1 with chloroform consists of centrosymmetric binuclear molecules containing the Sb2O2 cycle with tetragonal coordination of the antimony atoms (the Sb–O bond lengths are 1.961(4) and 2.041(5) Å, the Sb–C distances are 2.114(6)–2.153(6) Å). In solvate 2 with benzene the antimony atoms have a distorted trigonal-bipyramidal coordination with the oxygen atoms of carboxylate ligands in axial positions (Sb–O 2.075(4), 2.105(4) Å), the carbonyl oxygen atoms are coordinated with the central metal atom (Sb∙∙∙O=C 3.023(6), 3.077(8) Å), the Sb–C bond lengths (2.104(5)–2.112(5) Å) are significantly less than in 1. The ranges of variation in the Sb–C bond lengths in the practically linear binuclear molecule of solvate 3 with acetonitrile are 2.101(5)–2.106(5) and 2.100(5)–2.104(5) Å (the SbOSb angle equals 178.05(18)). The bond lengths of antimony atoms with the bridging oxygen atom (1.925(4), 1.936(4) Å) are less than the sum of the covalent radii of antimony and oxygen, as well as the distances between the antimony atom and the terminal carboxyl ligand (Sb–O 2.263(4), 2.214(4) Å). The carbonyl oxygen atoms are coordinated with the central metal atom (Sb∙∙∙O=C 3.484(8), 3.512(9) Å) to a lesser extent than in 2. The crystal of solvate 4 with benzene contains two types of crystallographically independent corner molecules (the SbOSb angles are 163.75(18), 164.27(19)), the difference in lengths of the Sb–Obridge (1.939(11)–1.981(13) Å) and Sb–Oterm (2.096(11)–2.208(11) Å) is not as sharp as in the case of complex 3. Complete tables of atom coordinates, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Center (No. 2070383 (1); No. 2074511 (2); No. 1970910 (3); No. 2064392 (4); deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/cif).

Nitric oxide protects against ferroptosis by aborting the lipid peroxidation chain reaction

Ferroptosis is a type of iron-dependent necrotic cell death, which is typically triggered by the depletion of intracellular glutathione (GSH), which is associated with increased lipid peroxidation. Nitric oxide (NO) is a highly reactive gaseous radical mediator with anti-oxidation properties that terminates lipid peroxidation reactions. In the current study, we report the anti-ferroptotic action of NOC18, an NO donor that spontaneously releases NO, in cells under various ferroptotic conditions in vitro. Our results indicate that, when mouse hepatoma Hepa 1–6 cells are incubated with NOC18, cell death induced by various ferroptotic stimuli such as cysteine (Cys) starvation, the inhibition of glutathione peroxidase 4 (GPX4) and treatment with tertiary-butyl hydroperoxide (TBHP) is significantly reduced. Treatment with NOC18 failed to improve the decrease in the levels of Cys or GSH and the accumulation of ferrous iron upon ferroptotic stimuli. The fluorescent intensity of C11-BODIPY581/591, a probe that is used to detect lipid peroxidation products, was increased somewhat by treatment with NOC18 under conditions of Cys starvation, and the accumulation of lipid peroxidation end-products, as evidenced by the levels of 4-hydroxynonenal, were effectively suppressed. The pre-incubation of TBHP with NOC7, a short-lived NO donor completely eliminated its ability to trigger ferroptosis. These collective results indicate that NO exerts a cytoprotective action against various ferroptotic stimuli by aborting the lipid peroxidation chain reaction.

Molybdate Stabilized Magnesium‐Iron Hydrotalcite Materials: Potential Catalysts for Isoeugenol to Vanillin and Olefin Epoxidation

A series of molybdate-intercalated and stabilized magnesium‐iron hydrotalcite (HMFeMo) materials with different molybdate loadings were successfully prepared by an in-situ hydrothermal method. The prepared HMFeMo materials were systematically characterized using Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), Ultraviolet-visible spectroscopy, scanning electron microscopy, thermo-gravimetric analysis, nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS) experiments. The XRD results demonstrated the successful intercalation of molybdate ions in the interlayer space of magnesium-iron hydrotalcite and the stabilization of the layered structure. In addition, the XPS spectra of the HMFeMo materials revealed the presence of molybdenum in a higher-valent oxidation state. The calcination of HMFeMo materials led to the formation of solid solution of mixed metal oxides. Both the as-prepared and calcined HMFeMo catalysts showed promising activity for the epoxidation of cyclooctene, as a model reaction. Furthermore, the performance of the as-prepared and calcined HMFeMo catalysts for the oxidation of a biomass model compound, namely isoeugenol to vanillin, was evaluated. The isoeugenol conversion over the as-prepared HMFeMo catalysts under solvent-free conditions and using tertiary-butyl hydroperoxide in decane as the oxidant was good. Moreover, the isoeugenol conversion and selectivity toward vanillin of HMFeMo0.1, with a molybdate loading of 0.1 mol %, were the highest (86.2% and 83.1%, respectively) of all HMFeMo catalysts in this study at 80 °C for 5 hr. HMFeMo0.1 presented the best catalytic activity for both the epoxidation of cyclooctene and oxidation of isoeugenol to vanillin, and its activity remained unchanged after several runs.

Синтез и строение бис(2,5-дифторбензоата) трис(2-метоксифенил)сурьмы

Tris(2-methoxyphenyl)antimony bis(2,5-difluorobenzoate) (1) has been obtained by the oxidative addition reaction between tris(2-methoxyphenyl)antimony, 2,5-difluorocarboxylic acid and tertiary butyl hydroperoxide in diethyl ether with the 72% yield. The compound has been identified by IR spectroscopy and X-ray diffraction analysis. According to the X-ray diffraction data, the crystal of compound 1 contains two types of crystallographically independent molecules a and b, the geometric parameters of which are slightly different. In molecules a and b the antimony atoms have a distorted trigonal-bipyramidal coordination with the oxygen atoms of the carboxylate ligands in the axial positions. The crystal also contains a solvate molecule of diethyl ether, disordered in two positions. The updated ratios of position contributions are 0.50/0.50. The sums of the CSbC angles in the equatorial plane of molecules 1a and 1b are 359.9(3)° and 359.8(3)°, respectively. The OSbO axial angles are 174.60(16)° (1a) and 175.51(17)° (1b). The antimony atom departs from the equatorial plane [C3] by 0.040 Å for both molecules. The conformation of the aryl ligands with respect to the equatorial plane [C3] is propeller-like. The SbC bond lengths have close values: 2.097(7)2.127(6) Å in 1a, 2.107(7)2.115(6) Å in 1b. The SbO distances (2.112(5), 2.131(5) Å in 1a, 2.107(5), 2.128(5) Å in 1b) are commensurate with the covalent SbO bond lengths. Bidentate carboxylate ligands are coordinated to the metal atom less symmetrically in molecule 1а, while the SbO(=С) intramolecular distances are 3.116(7), 3.063(7) Å in 1a, and 3.120(6) Å, 3.126(7) Å in 1b, which is less than the sum of the van der Waals radii of the Sb and O atoms. In molecules 1a and 1b short distances are observed between the oxygen atoms of the methoxy groups and the antimony atoms (3.080(6), 3.138(7), 3.164(4) Å for 1a, 3.023(6), 3.085(5), 3.194(7) Å for 1b), which increases the coordination number of the antimony atom. The structure of the crystal is presented in such a way that the solvate molecules of diethyl ether, arranged in one chain of the form (∙∙∙СH3CH2OCH2CH3∙∙∙F∙∙∙)n, are surrounded by molecules of tris(2-methoxyphenyl)antimony bis(2,5-difluorobenzoate), forming a shell of sorts for a chain of ether molecules. This interaction is due to hydrogen bonds: –ОСH(СH3)–H∙∙∙F, Et2O∙∙∙HMeO–, –ОСH2CH2–H∙∙∙F. Molecules of the a and b types contact each other through hydrogen bonds С=О∙∙∙HMeO–, F∙∙∙HMeO–, F∙∙∙HAr, and Sb–O∙∙∙HAr. Also, the СН∙∙∙π interactions and the stacking effect are observed in the packing of molecules. Complete tables of atom coordinates, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Center (No. 2077192 (1), deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/cif).

Role of Ba(O2)1−xOx species in improvement of selective oxidation activity of CoOx/CeO2−y

A series of Ba-doped CoOx/CeO2−y catalysts was prepared by co-precipitation followed by the deposition–precipitation method. The catalysts were investigated for selective oxidation (selox) of benzyl alcohol (B-ol) using tertiary butyl hydroperoxide (TBHP) without solvent and activity was compared with Co0.5/Ce0.5. The Ba loading has been optimized with time and temperature for selox reaction. The catalyst was characterized by various surface and bulk characterization techniques. The characterization study indicates that the synergistic interaction between Ba and CoCe could form more oxygen vacancies and peroxide species responsible for the activation of B-ol and TBHP. The formation of Ba(O2)1−xOx oxide (peroxide) was observed and could be responsible for the activation of B-ol. The optimum Ba doping enhances selectivity and yields benzaldehyde. However, the increase in Ba concentration on CoOx/CeO2−y could lead to the over-oxidation of B-ol to by-products.

Asymmetric oxidation of sulfides catalyzed by (R)-6,6'-dibromo-BINOL derived titanium complex

An efficient asymmetric oxidation of sulfides was achieved using (R)-6,6'-dibromo-BINOL as chiral ligand in combination with Ti(OiPr)4 using 70% aqueous tertiary butyl hydroperoxide as oxidant. The resulting sulfoxides had high enantiopurities and good yields. A range of aryl alkyl and aryl benzyl sulfides were oxidized to the corresponding sulfoxides with 78–95% ee in 72–80% yields.

Impact of drying processes on Bryophyllum pinnatum phenolic constituents and its anti-inflammatory and antioxidative activities in human erythrocytes.

The effect of drying on the phytoconstituents, antioxidative, and anti-inflammatory properties of Bryophyllum pinnatum leaves was investigated. The phenolic constituents were characterized using HPLC-DAD. The aqueous extraction was done and various assays (Inhibition of membrane stabilization, albumin Denaturation and heat-induced hemolysis, malondialdehyde (MDA), and reduced glutathione (GSH) contents, as well as superoxide dismutase (SOD) activity), were carried out on human erythrocytes. The fresh portion (89.12µg/ml) exhibited the highest potential to inhibit heat-induced hemolysis compared to the standard drug-Diclofenac (91.51µg/ml). Freeze-dried sample showed the highest inhibitory potential on albumin denaturation ([Freeze-dried-330.72µg/ml], [Diclofenac-318.63µg/ml]) and membrane destabilization ([Freeze-dried-331.93µg/ml], [Diclofenac-289.57µg/ml]) when compared with Diclofenac. Similarly, the freeze-dried sample showed the highest GSH and SOD level and lowest MDA level when human erythrocytes challenged with tertiary butyl hydroperoxide (tBHP) were treated with the extract. This study confirms the retention of a considerable quantity of bioactive constituents of plants when freeze-dried. PRACTICAL APPLICATIONS: The ideal method of drying Bryophyllum pinnatum and possible anti-inflammatory potential was investigated. This work may apply to the development of anti-inflammatory agents from a natural source with little or no side effect in managing inflammation.

ROS-induced oxidative damage in lymphocytes ex vivo/in vitro from healthy individuals and MGUS patients: protection by myricetin bulk and nanoforms

We investigated the protective role of myricetin bulk and nanoforms, against reactive oxygen species (ROS)-induced oxidative stress caused by hydrogen peroxide and tertiary-butyl hydro peroxide in lymphocytes in vitro from healthy individuals and those from pre-cancerous patients suffering with monoclonal gammopathy of undetermined significance (MGUS). The change in intracellular reactive oxygen species was measured once cells were treated with myricetin bulk forms and nanoforms with and without either hydrogen peroxide or tertiary-butyl hydro peroxide co-supplementation. The direct and indirect antioxidant activity of myricetin was spectrofluometrically measured using the fluorescent dye 2′,7′-dichlorofluorescin diacetate and using the Comet assay, respectively. Hydrogen peroxide (50 µM) and tertiary-butyl hydro peroxide (300 µM) induced a higher level of reactive oxygen species-related DNA damage and strand breaks. Addition of myricetin nanoform (20 µM) and bulk (10 µM) form could, however, significantly prevent hydrogen peroxide- and tertiary-butyl hydro peroxide-induced oxidative imbalances and the nanoform was more effective. Glutathione levels were also quantified using a non-fluorescent dye. Results suggest that myricetin treatment had no significant effect on the cellular antioxidant enzyme, glutathione. The current study also investigates the effect of myricetin on the induction of double-strand breaks by staining the gamma-H2AX foci immunocytochemically. It was observed that myricetin does not induce double-strand breaks at basal levels rather demonstrated a protective effect.

Fabrication of Bimetal CuFe2O4 Oxide Redox-Active Nanocatalyst for Oxidation of Pinene to Renewable Aroma Oxygenates.

This study report on the synthesis of spinel CuFe2O4 nanostructures by surfactant-assisted method. The catalysts were characterized by X-ray diffraction (XRD), laser Raman, transition electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), hydrogen temperature programmed reduction (H2-TPR), and Brunauer-Teller-Emmett-Teller (BET) surface area techniques. CuFe2O4 was active for pinene oxidation using tertiary butyl hydroperoxide (TBHP) to pinene oxide, verbenol, and verbenone aroma oxygenates. Under optimized reaction conditions, the spinel CuFe2O4 catalyst could afford 80% pinene conversion at a combined verbenol/verbenone selectivity of 76% within the reaction time of 20 h. The changes in catalyst synthesis solvent composition ratios induced significantly varying redox, phases, and textural structure features, which resulted in various catalytic enhancement effect. Characterization results showed the spinel CuFe2O4 catalyst possessing less than 5 wt% impurity phases, Cu(OH)2, and CuO to afford the best catalytic performance. The CuFe2O4 catalyst was recyclable to up to five reaction cycles without loss of its activity. The recyclability of the bimetal CuFe2O4 oxide catalyst was simply rendered by use of an external magnet to separate it from the liquid solution.

Azoimine Chelated Ruthenium(II)- and Osmium(II)-Carbonyl Complex Catalyzed Alcohol Oxidation Reaction

Arylazoimidazole brings azoimine (-N=N-C=N-) chelating N(azo), N(imine) (abbreviated - N, N/) centres and forms Ru(II) and Os(II) carbonyl complexes. These complexes act as catalysts for the oxidation of alcohols to aldehydes/ketones by tertiary butyl hydro peroxide (ButOOH), hydrogen peroxide (H2O2) and N-methylmorpholine-N-oxide (NMO) as oxygen sources. Different substituted arylazoimidazoles such as 1-alkyl-2-(arylazo)imidazoles (RaaiR/), 1-alkyl-2-(naphthyl-α/β- azo)imidazoles (α/β-NaiR) and (1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole, SRaaiNR/) are used to prepare Ru/Os-CO complexes. Ancillary ligands like hydride (H-), chloride (Cl-), triphenylphosphine (PPh3) are used to monitor the catalytic efficiency of the complexes. Aromatic and aliphatic alcohols like benzyl alcohol, 2-butanol, cyclopentanol, cyclohexanol, 1-phenylethanol, cinnamyl alcohol, diphenylmethanol, are oxidized to the corresponding benzaldehyde, 2-butanone, cyclopentanone, cyclohexanone, phenylacetone, cinamaldehyde, cyclopentanone, benzophenone, respectively. Different physicochemical analyses (FT-IR, UV-Vis, Mass, NMR) suggest that the complexes react with an oxidant to yield high valent ruthenium/osmium-oxo species (RuIV=O; OsIV=O), which is capable of transferring the oxygen atom to alcohols. GC analysis accounts that percentage conversion order is as follows : Cinnamyl alcohol &gt; Cyclohexanol ~ 1-Phenylethanol &gt; Diphenylmethanol &gt; Cyclopentanol &gt; 2-Butanol &gt; Benzyl alcohol. The oxidation efficiency of the oxidant follows the order : NMO &gt; ButOOH &gt; H2O2. RuII complexes are more potent catalysts than OsII complexes. Out of three series of RuII complexes, [RuCl(CO)(SMeaaiNEt)]ClO4 and [RuCl(CO)(SEtaaiNMe)]ClO4 showed highest catalytic efficiency amongst 32 catalysts.

Microreactor studies for efficient organic oxidation processes

Abstract Industrially important partial oxidations of hydrocarbons are frequently characterized by low conversions and yields, which are mostly related to mass and heat transfer problems. Due to the reaction conditions, such processes include also important safety risks and are still not sufficiently understood. To study the influence of the process parameters on the product selectivity, a lab facility including a silicon-coated micro reactor of stainless steel has been developed and constructed. Due to its modular construction (e.g. replaceable capillary), it permits for the first time to perform catalysed and non-catalysed oxidations of hydrocarbons with oxygen as a two-phase process in a capillary reactor in wide ranges of residence times (some minutes to 24 h), temperatures and pressures. As an example, the oxidation of isobutane to tertiary butyl hydroperoxide (TBHP) has been studied. The reaction has been investigated for the first time as a Taylor-Flow process in a micro reactor at different reaction conditions as a prerequisite to enhance the space-time yield of the process. The advantages of micro reactors are the high surface-to-volume ratio ensuring efficient heat transfer and the improved, nearly inherent, safety. These permit investigating yet unexplored process windows, for instance within the explosive region of a reaction mixture. The reaction has been studied for varying flow rates, temperature, pressure and the molar ratio of the starting products using two different initiators, namely TBHP and di-t-butyl peroxide (DTBP). For all experiments, the selectivity of the reaction products and the conversion of the reaction have been studied by sampling and analysing the reaction by GC/ MS. The use of TBHP as initiator increased the selectivity of the reaction for the target product TBHP. TBHP as initiator yields a better selectivity since at high temperatures, which are common for DTBP, the formation of propanone already becomes important and favours the decomposition of TBHP. The replacement of the initiator diluent water by decane resulted in a faster reaction and the highest autocatalytic isobutane conversion (˜18%) obtained ever for this reaction in a micro reactor.

Cell-cell contacts protect against t-BuOOH-induced cellular damage and ferroptosis in vitro.

Ferroptosis is a recently discovered pathway of regulated necrosis dependent on iron and lipid peroxidation. It has gained broad attention since it is a promising approach to overcome resistance to apoptosis in cancer chemotherapy. We have recently identified tertiary-butyl hydroperoxide (t-BuOOH) as a novel inducer of ferroptosis. t-BuOOH is a widely used compound to induce oxidative stress in vitro. t-BuOOH induces lipid peroxidation and consequently ferroptosis in murine and human cell lines. t-BuOOH additionally results in a loss of mitochondrial membrane potential, formation of DNA double-strand breaks, and replication block. Here, we specifically address the question whether cell-cell contacts regulate t-BuOOH-induced ferroptosis and cellular damage. To this end, murine NIH3T3 or human HaCaT cells were seeded to confluence, but below their saturation density to allow the establishment of cell-cell contacts without inducing quiescence. Cells were then treated with t-BuOOH (50 or 200 µM, respectively). We revealed that cell-cell contacts reduce basal and t-BuOOH-triggered lipid peroxidation and consequently block ferroptosis. Similar results were obtained with the specific ferroptosis inducer erastin. Cell-cell contacts further protect against t-BuOOH-induced loss of mitochondrial membrane potential, and formation of DNA double-strand breaks. Interestingly, cell-cell contacts failed to prevent t-BuOOH-mediated replication block or formation of the oxidative base lesion 8-oxo-dG. Since evidence of protection against cell death was both (i) observed after treatment with hydrogen peroxide, methyl methanesulfonate or UV-C, and (ii) seen in several cell lines, we conclude that protection by cell-cell contacts is a widespread phenomenon. The impact of cell-cell contacts on toxicity might have important implications in cancer chemotherapy.

Green synthesis of nano silver on TiO2 catalyst for application in oxidation of thiophene

The present research work describes the preparation of silver nanoparticles from silver nitrate, and Tulsi (Ocimum tenuiflorum) leaf extract, impregnation on titanium dioxide (TiO2) and evaluation of the catalytic activity of this nano silver impregnated TiO2 in the oxidation reaction of thiophene. Tertiary-butyl hydroperoxide was used as an oxidant in the reaction. The catalyst was characterized by BET, SEM, XRF, TEM, UV–Vis spectroscopy, XPS and TPR. The effect of process parameters such as speed of agitation, catalyst weight, oxidant to sulfur mole ratio, silver loading in the catalyst and temperature on the oxidation reaction was studied. Both pseudo-homogeneous and heterogeneous kinetic models were considered and applied for the result. The pseudo-homogeneous form of rate equation shows the reaction follows second order kinetics and is endothermic. Langmuir-Hinshelwood kinetic model is proposed, considering the reaction as a heterogeneous one with solid catalyst and found that surface reaction is the rate controlling step. This model is well fitted with experimental data.