Reactions of antioxidants with molecular oxygen. Part I. 2,2′-methylene-bis(4-methyl-6-tert-butylphenol) in silicone matrix

The reaction of 2,2′-methylene-bis(4-methyl-6-tert-butylphenol) stabiliser with oxygen was studied in an inert substrate at 80-120 °C temperature under 0.02-3.0 MPa oxygen pressure ranges. UV/VIS spectrophotometry and Gel Permeation Chromatography were used to follow the antioxidant consumption and the formation of oxidation products. A simplified mechanistic model of stabiliser oxidative transformation was proposed and corresponding kinetic parameters were determined and compared with the kinetic values obtained by other authors.     

Reactions of antioxidants with molecular oxygen. Part III: Influence of phenolic stabiliser structures on their oxidation in an inert matrix

The oxidation of five different phenolic antioxidants in inert substrates has been investigated varying the temperature and oxygen pressure conditions. The stabiliser consumption in this reaction has been quantified by steric exclusion chromatography. The tendency of the variation of the residual antioxidant concentration with exposure time in the presence of oxygen shows a simple apparent first order process in all cases. The kinetic parameters were determined applying this simple kinetic model. The influence of structural characteristics of stabilisers under study on kinetic parameters of the direct reaction with the oxygen has been analysed. On the other hand, the information obtained about reaction products generated for each antioxidant helped us to explain the results obtained.     

Synthesis and properties of 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-nitroindazole

N-(2-Azido-5-nitrobenzylidene)-3,5-di-tert-butyl-4-hydroxyaniline (3a) and N-(2-azido-5-nitrobenzilidene) aniline (3b), when heated in dimethylformamide yielded 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-5-nitroindazole (4a) and 2-phenyl-5-nitroindazole (4b), respectively. The structure of4b was confirmed by X-ray analysis. A stable phenoxyl radical was shown to originate from the oxidation of4a with lead (IV) dioxide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1095–1097, June, 1994.     

Photochemical reactions of pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and dicumyl peroxide in hexane solution and polystyrene films

The photochemical reactions of pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010; IH) and dicumyl peroxide (DCP) initiated by long-wavelength radiation with λ>300 nm in hexane solutions and polystyrene films were studied. It was found that the rate of formation of acetophenone (APH) in the photolysis of DCP in hexane solution is lowered in the presence of IH and the rate constant for the reaction between alkoxyl radical RO^? and IH is about 10³ times greater than the sum of the rate constants for APH formation and hydrogen abstraction from solvent molecules by RO^?.The consumption of IH was confirmed during the irradiation of PS films containing DCP and IH. The decrease in the rate of APH formation and the inhibiting effect on the photodegradation of the polymer were observed.     

Transesterification of methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate with tetrakis(hydroxymethyl)methane. The properties of the reaction products

The transesterification of methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate with tetrakis(hydroxymethyl)methane depends on the equilibrium constants of the reversible reactions; for the final step, the equilibrium constant is K ? 1. The molecular geometries and the enthalpies and entropies of the equilibrium reactions were calculated by the semiempirical PM6 quantum chemical method. The thermodynamic equilibrium constants of the reversible reactions were calculated by the Boltzmann equation from the Gibbs energies G _f ^○. For tris-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoyloxymethyl](hydroxymethyl)methane, the dipole moment is μ = 0.97 D and the energy of the O-H homolysis is D _OH = 347.3 kJ mol^?1. For tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoyloxymethyl]methane, μ is 5.6 D and D _OH is 321 kJ mol^?1. The geometry of the structure affects the H-O homolysis energy and the chain termination coefficient under the conditions of inhibited cumene oxidation.     

Crystallography and magnetism of radicals with hindered hydroxyl groups: 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl and 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl

Radicals form networks of OH...ON and OH...Me(nitroxide) interactions. In 2, a frustrated network forms with insufficient N-O units to form extended chain interactions. The magnetism of 1 fits a 1-D Heisenberg model with J/k=-25 J mol(-1), while 2 shows more complex exchange behaviour consistent with its disordered crystal lattice.     

(S)-2-乙氧基-3-(4-羟基苯基)丙酸乙酯的合成

(S)-2-乙氧基-3-(4-羟基苯基)丙酸乙酯的合成;二乙氧基乙酸乙酯;Horner Wadswordth Emmons反应;催化氢化;化学拆分;（S） 乙氧基（羟基苯基）     

The Synthesis of (3,5-DI-tert-butyl-4-hydroxyphenyl)methyl-(3-pyridylalkyl)-ethers via 1-(3,5-Di-tert-butyl-4-hydroxyphenyl)methyl Pyridinium Salts.

The rearrangement of 1-(3,5-di-tert-butyl-4-hydroxyphenyl)methyl pyridinium salts under basic conditions is described. A method for the synthesis of (3,5-di-tert-butyl-4-hydroxyphenyl)methyl-(3-pyridylalkyl)-ethers is elaborated.     

Multi-frequency ESR study of the polycrystalline phenoxyl radical of alpha-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-tert-butylnitrone in the diamagnetic matrix

Multifrequency (X-, Q-, and W-band) electron spin resonance (ESR) spectroscopy has been used to characterize the phenoxyl radical produced from alpha-(3,5-di-tert-butyl-4-hydroxyphenyl)-N-tert-butylnitrone, which is a new spin-trapping reagent. The X-band measurement did not resolve the powder-pattern ESR spectrum. Because of its higher resolution with g value, the Q-band ESR study revealed that the g factor has an axial-like symmetry and that the observed hyperfine structure in the Z-direction is caused by the nitrogen nucleus at the para-position. Furthermore, the results of the W-band ESR experiment more clearly distinguished the perpendicular components from the parallel component, resolving the perpendicular components into x and y components. The X-band powder spectrum was similar to the X-band ESR spectrum of the radical in a frozen solution of toluene. The computer simulation spectra performed using the obtained parameters fitted the experimental spectra well. A comparison of the amplitude of g( perpendicular)(gx, gy) with that of gz showed that the unpaired electron is delocalized over the pi-conjugated framework. Considering the hyperfine coupling constant, it was concluded that about 16% of the unpaired electron distributed over the nitrogen nucleus at the para-position. This study thus showed the significant potential of a multifrequency ESR approach to a powder sample radical in terms of its high resolution with g value.     

Alkylation of cobalt and lutetium tetra(3,5-di-tert-butyl-4-hydroxyphenyl)dodecachlorophthalocyanine complexes initiated with current

Electrochemical properties of tetra(3,5-di-tert-butyl-4-hydroxyphenyl)dodecachlorophthalocyanine complexes of cobalt(II) and lutetium(III) in DMF solutions have been studied. It was suggested that in the presence ofn-butyl bromide, the electrochemically generated monoanionic complexes undergo alkylation at the metal atom. The geometries of the neutral and anionic complexes were calculated by the ZINDO/I semiempirical method. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 289–293, February, 1998.     

Reactions of 4-alkylidene (arylidene)-1-phenylpyrazolidine-3,5-dione

Reactions of 4-alkylidene(arylidene)-1-phenylpyrazolidine-3,5-dione with oxidizing (chromium trioxide/acetic acid) as well as with reducing (sodium borohydride/methanol) agents were carried out. Phenylhydrazine reacted with 4-arylidene-1-phenylpyrazolidine-3,5-diones via fission of exo C=C bond to give 1-phenylpyrazolidine-3,5-dione and the corresponding aryl hydrazones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1335–1341, September, 2007.     

汞(II)与牛血红蛋白相互作用的研究

本文采用紫外光谱(UV/VIS)、荧光光谱和圆二色谱等方法,对汞(II)与牛血红蛋白(BHb)的相互作用进行了研究。结果表明:Hg2 处理导致BHb紫外吸收的增加,出现LMCT带,并随Hg2 浓度的增加LMCT带强度显著增强。BHb分子中Soret带的吸收随着Hg2 作用时间的增加而持续降低,表明Hg2 使部分血红素辅基从BHb中脱离出来。蛋白内源荧光光谱显示,Hg2 与BHb的结合会影响蛋白质的三级结构和四级结构。远紫外圆二色谱表明,Hg2 处理会导致BHb蛋白的α-螺旋含量减少。     

Reactions of 5-aryl-4-acyl-1-(4-hydroxyphenyl)-3-hydroxy-3-pyrrolin-2-ones with arylamines

The reaction of 5-(4-chlorophenyl)-4-benzoyl-1-(4-hydroxyphenyl)-3-hydroxy-3-pyrrolin-2-one with aromatic amines affords the corresponding 3-arylamino derivatives, and the reactions of 5-aryl-4-acetyl-1-(4-hydroxyphenyl)-3-hydroxy-3-pyrrolin-2-ones with p-toluidine yield 5-aryl-4-(1-p-tolylamino)ethylene-1-(4-hydroxyphenyl)pyrrolidin-2,3-diones.     

4-(3-羟基苯基)-2,6-二甲基-1,4-二氢吡啶-3,5-二羧酸乙酯的合成和晶体结构

标题化合物C19H23NO5由间羟基苯甲醛、碳酸氢铵、乙酰乙酸乙酯在乙醇溶剂中回流制备.结构通过单晶X-射线衍射法测定,其晶体属三斜晶系,空间群Pi,a=7.4550(15),b=8.9780(18),c=14.099(3)(A),α=80.22(3),β=86.72(3),γ=68.62(3)°, V=865.9(3)(A)3, Z=2, Mr=345.38, Dc=1.325g/cm3, F(000)=368. 晶体结构用直接法解出,经全矩阵最小二乘法对原子参数进行修正,最终的偏离因子为R1=0.0633,wR2=0.1709[I＞2σ(I)].在晶体结构中,二氢吡啶环与苯环之间的二面角为90.0(2)°,分子通过氢键形成有隧道的一维超分子结构.     

Synthesis and characterization of copper(II) complexes with 3-methylpicolinic acid. Crystal and molecular structure of bis (3-methylpicolinato- N,O )(4-picoline)copper(II)

Copper(II) complexes of 3-methylpicolinic acid (3-MepicH), namely [Cu(3-Mepic)₂] · 2H₂O (1) and [Cu(3-Mepic)₂(4-pic)] (2) were prepared and characterized by IR spectroscopy and thermal analysis (TGA/DTA). Crystal structure for 2 was determined by X-ray crystal structure analysis. 1 was prepared by reaction of copper(II) sulfate pentahydrate and 3-methylpicolinic acid in aqueous solution, while 2 was prepared by recrystallization of 1 from 4-picoline solution. Structure analysis revealed square-pyramidal copper(II) coordination and N,O-chelating mode of 3-methylpicolinic acid in 2. Copper(II) is coordinated by two 3-Mepic ligands in the basal plane of a square pyramid and by 4-picoline in the apical position. Crystal packing of 2 is dominated by weak intermolecular C–H ··· O hydrogen bonds and π ··· π stacking interactions forming a complex three-dimensional supramolecular architecture.     

Mixed ligand complexes of nickel(II) and cerium(III) ions with 4-(-3-methoxy-4-hydroxybenzylideneamino)-1, 3-dimethyl-2,6-pyrimidine-dione and some nitrogen/oxygen donor ligands

Mononuclear mixed ligand complexes of Ni(II) and Ce(III) with 4-(-3-methoxy-4-hydroxybenzylideneamino)-1,3-dimethyl-2,6-pyrimidine-dione, 2-aminopyridine and 8-hydroxyquinoline have been prepared. The elemental analysis, molar conductance, spectral (IR, mass and solid reflectance), magnetic moment measurements and thermal study were utilized to investigate the coordination behavior. All metal complexes have metal-to-ligand ratios of 1:1:1 and the modes of bonding are consistent with N- and O-donation suggesting monomeric octahedral and square planar structures. The thermal behavior of these complexes was investigated and the thermal decomposition pathways postulated. The activation thermodynamic parameters, E*, ΔH*, ΔS* and ΔG* for the different thermal decomposition steps of the complexes were calculated using the Coats-Redfern equation. Antibacterial and antifungal properties of the metal complexes have also been examined against Staphylococcus aureus (ATCC 25923), Streptococcus pyogenes (ATCC 19615), Pseudomonas fluorescens (S 97), Pseudomonas phaseolicola (GSPB 2828), Fusarium oxysporum and Aspergillus fumigatus. The highest antimicrobial activity was observed for the Ce(III) complex, [CeL(8-Oqu)(NO₃)₂]·1½H₂O.     

Photo-stabilization of styrene-butadiene copolymer: The effect of 2,2′-thiodiethylbis-[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate] on the photo-sensitized oxidation of styrene-butadiene copolymer

The effect of 2,2′-thiodiethylbis-[3-(3,5-di-tert-butyl-4-hydroxy-phenyl) propionate] (Irganox 1035) on the 9-methylanthracene sensitized photo-oxidation of styrene-butadiene copolymer (SBR) has been examined. It was found that the photo-oxidation of SBR is considerably inhibited by the Irganox. Irganox was found to be able to quench singlet oxygen as well as to scavenge alkoxyl radicals.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.