氯过氧化物酶修饰电极催化氧化肉桂醇的研究

将氯过氧化物酶(Chloroperoxidase,CPO)与双十二烷基溴化铵(DDAB)形成的类生物膜滴涂到Nation修饰的玻碳电极表面,再滴涂壳聚糖制得Chi/CPO-DDA B/Nafion/GC修饰电极.循环伏安曲线上可以观察到一对可逆的氧化还原电流峰,表明CPO与电极之间发生了直接的电子传递.该修饰电极可有效地催化O2还原为H2O2,产生的H2O2作为氧源与电极上的CPO结合进一步催化氧化肉桂醇,产物经气质联用色谱、以及红外光谱测试鉴定为肉桂醛,总的肉桂醛转化量达到80500mol/mol CPO,为高效专一获得末端醛提供了一种绿色合成方法.此外,还讨论了壳聚糖对提高修饰电极稳定性的作用.     

Crystal structures of dibenzo-14-crown-4 alcohol and diol monohydrates

Monohydrate complexes1–3 ofsym-hydroxydibenzo-14-crown-4,sym-cis-dihydroxydibenzo-14-crown-4 andsym-trans-dihydroxydibenzo-14-crown-4, respectively, have been prepared and their solid state structures determined. For all three complexes the space group wasCmc2₁. The crystal data are: for1,a=16.256(10),b=12.076(5),c=8.767(3) Å,V=1721.0 ų withZ=4; for2,a=16.437(3),b=11.997(4),c=8.640(3) Å,V=1703.8 ų withZ=4; for3,a=16.528(7),b=12.306(3),c=8.540(3) Å,V=1737.0 ų withZ=4. The structures were refined to [R, R _w, unique data withF<n (F)]: for1, 0.066, 0.055, 828, 2.5; for2, 0.034, 0.035, 1090, 3.0; for3, 0.047, 0.036, 1038, 3.0. The three crystal structures have a high degree of isomophism and the dibenzo-14-crown-4 units in the three host-guest complexes are nearly identical. Intramolecular hydrogen bonds link an alcohol oxygen atom of the host to the oxygen atom of the guest water molecule and the oxygen atom of the guest water molecule to ether oxygen atoms of the host in1–3. In2 and3, there is an intermolecular hydrogen bond between the hydrogen atom of an alcohol group of the host and the oxygen atom of a symmetry-related water molecule guest of another complex.     

Structural bases for the catalytic mechanism of Ni-containing carbon monoxide dehydrogenases

Significant progress has been made recently in our understanding of the structure/function relationships of the catalytic C-cluster of carbon monoxide dehydrogenases. Several structures of this enzyme have been reported, some of them at very high resolution. One recurrent problem, however, is the high degree of heterogeneity within each structure, as well as between the different X-ray models. Here, we have tried to relate the structural data with the wealth of spectroscopic and biochemical information gathered over many years. As a result, we propose a catalytic cycle that is consistent with both observations and stereochemistry. We also give alternatives to one of the most difficult aspects of the cycle, namely, the location of the two electrons in the most reduced state of the C-cluster.     

Crystal and molecular structures of 4-hydroxy-5-nitrophenyl cyclohexyl ketone

Technical Physics Institute, Tadzhik Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 1, pp. 195–198, January–February, 1990.     

Titanium and zirconium benzofuranoxides. Crystal structures and catalytic properties

Reactions of Ti(OiPr)4 or Zr(OEt)4 with 4 equivalents of 2,3-dihydro-2,2-dimethyl-7-benzofuranol (ddbfoH) in toluene gave neutral complexes that in the solid state are dimers of [Ti(micro-ddbfo)2(ddbfo)6] and [Zr(ddbfo)3(EtOH)(micro-EtO)]2 composition. The former could also be conveniently synthesized in a direct reaction of TiCl4 with ddbfoH. This air-stable aryloxo compound was found to initiate living ring-opening polymerization of lactides affording polyesters with narrow molecular weight distribution. It also catalyzed addition of terminal acetylenes to aryl aldehydes.     

Glycosides of cinnamyl alcohol from the rhizomes ofRhodiola rosea

Three new cinnamyl alcohol glycosides have been isolated for the first time from the rhizomes of roseroot stonecropRhodiola rosea L. (Sedum rosea). On the basis of chemical transformations and the results of UV, IR, PMR, and mass spectroscopy the following structures are proposed for the compounds isolated: rozin — trans-cinnamyl O-β-D-glucopyranoside; rozavin — transcinnamyl O-(6′-O-α-L-arabinopyranosyl-β-D-glucopyranoside); and rozarin — trans-cinnamyl O-(6′-O-α-L-arabinofuranosyl-β-glucopyranoside).     

Kinetics and mechanism of oxidation of allyl,crotyl and cinnamyl alcohol by chromium(V)

Summary The kinetics of oxidation of unsaturated alcoholsviz. allyl, crotyl and cinnamyl alcohol by sodium bis[2-ethyl-2-hydroxy butanoato (2–)] oxochromate(V) Cr^v, has been investigated in 25% (v/v) aq. HOAc:HClO₄. The order in [oxidant] and [substrate] was 1.0 and 0.7 respectively. The oxidation rate increased with increase in [2-ethyl-2-hydroxybutyric acid] (EHBA) and decreased with increase in the percentage of HOAc. The rate decreases slightly with increase in [H^_]. The unsaturated alcohols exhibited higher reactivity compared to their saturated analogues. A mechanism involving the formation of a complex between Cr^v and alcohol which in turn disproportionates into products in a slow step is advanced to explain the kinetic results.     

Crystal structures of two 4-phenylbenzophenones

Two 4-phenylbenzophenones (I) and (II) are synthesized via Friedel-Crafts reactions. There are four crystallographically independent molecules with different conformations in the crystal structure of [1,1′-biphenyl]-4-yl(2-chlorophenyl)methanone (I). Crystals are orthorhombic, Pca2₁, C₁₉H₁₃ClO, a = 13.699(3) Å, b = 8.9385(17) Å, c = 46.836(9) Å; V = 5735(2) ų, Z = 16, d _x = 1.356 g/cm³. Torsion angles between the biphenyl rings are between 28.5° and 30.8°. Several C-H…O and C-H…Cl hydrogen bonds and weak π-π stacking contacts consolidate the crystal. Crystals of [1,1′-biphenyl]-4-yl(3-methoxyphenyl)methanone (II) are orthorhombic, Pbca, C₂₀H₁₆O₂, a = 7.8179(15) Å, b = 16.003(3) Å, c = 23.345(5) Å; V = 2920.7(10) ų, Z = 8, d _x = 1.311 g/cm³. The torsion angle between the biphenyl rings is 28.1° and C-H…O hydrogen bonds are observed in compound (II).     

Crystal and magnetic structures of the layer Compound TlMnF4

The crystal structure and the magnetic properties of the fluoromanganate(III) TlMnF₄ have been investigated. The structure has been refined down to R/wR of 0.057/0.043 in the monoclinic I2/a space group with the unit cell constants a = 539.7(2) pm; b = 544.1(2) pm; c = 1248.4(5) pm; β = 90.19(3)° (Z = 4). TlMnF₄ is characterized by a layer structure formed of MnF₆ octahedra sharing their four equatorial corners. Within each octahedron the Mn? F distances range from 178 pm to 215 pm. The intralayer magnetic interaction (J/K) has been evaluated to be approximately ?0.45 K by fitting the experimental susceptibility in the 10–300 K range using the quadratic layer Heisenberg model. A 3 D-antiferromagnetic ordering occurs at T_n = 4.2(5) K. The magnetic cell corresponding to the nuclear one but with a primitive symmetry. The magnetic structure has been refined down to R = 0.0528 in the P2′/a′ magnetic group. The Mn^III moments are colinear to the b-axis and show antiparallel ordering within the layers.     

Preparation of polymer-protected Pt/Co bimetallic colloid and its catalytic properties in selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

A polymer-protected Pt/Co bimetallic colloid with a molar ratio of 3:1 has been prepared by a polyol process. Over the above Pt/Co bimetallic colloid catalyst, cinnamaldehyde can be selectively hydrogenated to cinnamyl alcohol with 99.8% selectivity at 96.2% conversion.     

纳米金催化肉桂醛选择加氢制肉桂醇

α,β-不饱和醛/酮选择加氢生成不饱和醇是化学工业中一类重要反应,在精细化工生产中具有广泛应用,近年来吸引了研究者的广泛关注.该类反应因涉及不饱和官能团和碳氧双键的选择加氢而颇具挑战性:以肉桂醛选择加氢生成肉桂醇反应为例,肉桂醛分子中同时含有共轭的C=C双键和C=O双键,从热力学角度上看,C=O双键键能比C=C双键键能...     

Crystal and moleclar structures of 5-allyl-25-methoxy-26,27,28-tribenzoylcalix[4]arene

The crystal and molecular structures of 5-allyl-25-methoxy-26,27,28-tribenzoylcalix[4]arene, an unsymmetrically substituted macrocycle, are reported. The space group is orthorhombic,P2₁2₁2₁, witha=13.4181(6),b=16.6652(10) andc=18.9936(14) Å andZ=4. Refinement by least-squares calculations converged with aR=0.060 for 4018 observed reflections. The molecule assumes a 1,3 alternate conformation with 2 benzoate rings and the disordered allyl side chain on one side and the third benzoate ring and the methoxy group on the opposite side of the mean plane of the methylene bridging groups. The four phenyl rings that comprise the macrocycle are approximately parallel in pairs; the members of a pair are 5.6 Å apart. The carbonyl oxygen atoms of the 3 benzoate groups are oriented away from the center of the cavity while the ester oxygen atoms and the methoxy oxygen atom are oriented toward the cavity center. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82033 (26 pages).     

Chemo-promiscuity of alcohol dehydrogenases: reduction of phenylacetaldoxime to the alcohol

The reduction of phenylacetaldoxime was catalysed by alcohol dehydrogenases in the presence of NAD(P)H yielding finally the primary alcohol via the imine and aldehyde intermediates. This suggests that the hydride of the cofactor NAD(P)H is transferred to the N-atom of the oxime moiety and not to the carbon atom, as usual stated. This reaction represents the first example of a catalytic chemo-promiscuity of alcohol dehydrogenases.     

Crystal structures of aroylhydrazones derived from 5-methoxysalicylaldehyde

Two new aroylhydrazones 3-bromo-N′-(2-hydroxy-5-methoxybenzylidene)benzohydrazide (1) and 4-hydroxy-3-methoxy-N′-(2-hydroxy-5-methoxybenzylidene)benzohydrazide (2), derived from 5-methoxysalicylaldehyde, are prepared and determined by means of infrared and ¹H NMR spectroscopy and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/n with a = 5.9406(7) Å, b = 31.833(3) Å, c = 7.6460(8) Å, β = 94.522(4)°, V = 1441.4(3) ų, Z = 4. Compound 2 crystallizes in the monoclinic space group P2₁/c with a = 14.3471(9) Å, b = 11.3893(7) Å, c = 9.6853(6) Å, β = 94.063(2)°, V = 1578.6(2) ų, Z = 4. Both molecules have very similar bond lengths and angles. The crystal structures of both compounds are stabilized by N-H...O and O-H...O hydrogen bonds as well as π...π interactions.     

Crystal structure,thermal decomposition mechanism and catalytic performance of hexaaquaaluminum methanesulfonate

Hexaaquaaluminum methanesulfonate crystals, [Al(H₂O)₆][CH₃SO₃]₃ were synthesized by a hydrothermal reaction of Al(OH)₃ with methanesulfonic acid. Single-crystal diffraction determination revealed that Al³⁺ was coordinated by six water molecules in octahedral geometry, while the CH₃SO₃^– anion connected with Al³⁺ through coordinated water molecules by hydrogen bonds. The six-coordinate environment of Al was also determined by ²⁷Al MAS NMR measurement. Thermogravimetric analysis and Fourier transform infrared spectroscopy showed that the decomposition intermediate at 265–365 °C was Al₂(μ-OH)(CH₃SO₃)₅ and the final product was amorphous Al₂O₃ residue with about 0.8 wt% SO₃ at 520–800 °C. A pure phase of [Al(H₂O)₆][CH₃SO₃]₃ was confirmed by powder X-ray diffraction analysis. Esterification of n-butyric acid with n-butanol and ketalization of cyclohexanone with glycol catalyzed by [Al(H₂O)₆][CH₃SO₃]₃ and Al₂(μ-OH)(CH₃SO₃)₅, respectively, proceeded in 100% yield by continuously removing the produced water. In the case of tetrahydropyranylation of n-butanol at room temperature in dichloromethane, the catalytic activity of [Al(H₂O)₆][CH₃SO₃]₃ was much lower than that of Al₂(μ-OH)(CH₃SO₃)₅. Furthermore, both [Al(H₂O)₆][CH₃SO₃]₃ precursor and Al₂(μ-OH)(CH₃SO₃)₅ catalysts could be recycled.     

The mechanism for palladium catalyzed carbonylation of cinnamyl chloride

In the palladium catalyzed alkoxycarbonylation of cinnamyl chloride two mechanisms play a role. An associative mechanism was observed at low pressure, while an insertion mechanism was observed at high pressure or when an excess of ligand was used. Several putative intermediates of the catalytic alkoxycarbonylation have been synthesized and characterized, such as 5c of which an X-ray crystal structure was obtained.     

Crystal structures of pyridine-4-aldehyde thiosemicarbazone perchlorate and trifluoromethane sulfonate

The new salts of pyridine-4-aldehyde thiosemicarbazone: perchlorate (I) and trifluoromethane sulfonate (II) HN⁺C₅H₄-CH=N-NH-C(S)-NH₂·X^? (X = ClO₄, CF₃SO₃) were synthesized and studied by IR and NMR spectroscopy and X-ray diffraction analysis. The compounds were synthesized by a reaction of pyridine-4-aldehyde thiosemicarbazone with chloric or trifluoromethane sulfonic acid, respectively. Compound I crystallized in the triclinic crystal system, space group P-1, a = 6.8691(2) Å, b = 9.5406(4) Å, c = 9.6348(4) Å, α = 78.838(1)°, β = 77.618(1)°, γ = 69.661(1)°, Z = 2. Compound II crystallized in the monoclinic crystal system, space group P2₁/c, a = 7.3149(8) Å, b = 11.9830(16) Å, c = 15.143(2) Å, β= 96.949(4)°, Z = 4. The structures are formed by hydrogen-bonded ions. Moreover, the cations are linked in “dimmers” due to the weak N-H...S hydrogen bonds.