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1.
The flash pyrolysis of d-glucose was investigated by the use of 13C labeling, in conjunction with GC/MS. Co-pyrolysis of uniformly labeled and unlabeled d-glucose established the extent of unimolecular formation of each of the pyrolysis products. A complete set of singly labeled d-glucose isotopologs was used to determine the origin of specific carbons within each of the pyrolysis products. The results were compared with the expected labeling patterns that arise when the cyclic Grob 1,3-diol fragmentation and the tandem alkaline pinacol rearrangement/retro-aldol fragmentation (TAPRRAF) discovered from the pyrolysis of glycerin are used to initiate breakage of the six-carbon chain of d-glucose. The most promising rationalizations provided by this exercise are presented herein, for the formation of six C3 and eight C4 acyclic carbonyl-containing pyrolysis products, and for 3-cyclopentene-1,2-dione.  相似文献   

2.
Two chiral fluorescent chemosensors 1 and 2 were synthesized, and the structure characterized by IR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their recognition ability was studied in aqueous solution (Tris–HCl buffer pH 7.4, MeOH/H2O = 1:1) through fluorescence spectra. Receptors 1 and 2 showed a good binding ability to the copper ion. The host 1-Cu2+ complex showed a chiral recognition ability to mandelate anions with a preferable binding to l-mandelate than d-mandelate anions. The host 1-Cu2+ complex and l- or d-mandelate anions formed 1:1 stoichiometric complex. The binding constant for l-mandelate is 576 M−1, whereas that for d-mandelate is only 38 M−1, which can be distinguished by the different change of fluorescence intensity.  相似文献   

3.
丁霞  林中祥  邓慧敏 《有机化学》2007,26(2):252-254
拟利用枞酸分子中的非同环共轭二烯在氯化锌作用下异构化成具有同环共轭二烯的海松酸结构, 再与C60进行Diels-Alder加成反应, 预测可以得到Diels-Alder加成产物. C60、枞酸及氯化锌在邻二氯苯溶剂中, 在氮气保护下于175~180 ℃反应8 h, 将反应物洗涤后进行硅胶柱层析分离, 采用FT-IR, 13C NMR, 1H NMR和MALDI-TOF-MS等分析方法对反应主要产物进行结构测定, 却意外发现得到C60与枞酸的加成过程中发生了脱羧脱氢反应且产物含有芳环的化学结构.  相似文献   

4.
C2(a 3πu) disappearance rate constants of 1.44, 0.96, 0.0296, 0.0130 and < 10?6(x10?10cm3s?1) are reported for reactions with C2H4, C2H2, O2, C2H6, and CH4, respectively at 298 K. C2(a 3πu) fragments are generated by multiphoton ArF excimer laser photodissociation at C2H2, and monitored by dye laser induced fluorescence. Arguments are presented which favor chemical reactions over the C2(a 3πu) → (X 1σ+g) quenching channel. C2 + C2H2 represents the one possible exception to the reactive channel.  相似文献   

5.
Tris(dimethylamido) pentaphenylcyclopentadienyl zirconium (I) has been prepared and characterized by NMR spectroscopy and X-ray crystallography. The structure reflects the strong p-d amido donation with short Zr-N distances and Zr-C distances that are longer than those in the 16 electron C5Ph5(C5H5)ZrCl2. The reaction of I with (R)-(+)-sec-phenethyl alcohol to form the alkoxide complexes proceeds rapidly to the spectroscopically characterized tris((R)-(+)-sec-phenethyl alkoxide) complex, suggesting an activating effect upon alkoxide substitution.  相似文献   

6.
通过席夫碱配体N-(2-吡咯甲基)-1-苯基乙亚胺与三乙基铝按物质的量之比为1:1在无氧无水的条件下反应,合成了席夫碱铝的有机金属化合物N-(2-吡咯甲基)-1-苯基乙亚胺·二甲基铝。其结构分别用核磁氢谱、碳谱,元素分析和X射线单晶衍射技术进行了表征。铝化合物在催化外消旋丙交酯开环聚合反应中表现出了中等的活性并得到了以等规聚合为主的高聚物。  相似文献   

7.
通过席夫碱配体N-(2-吡咯甲基)-1-苯基乙亚胺与三乙基铝按物质的量之比为1:1在无氧无水的条件下反应,合成了席夫碱铝的有机金属化合物N-(2-吡咯甲基)-1-苯基乙亚胺·二甲基铝。其结构分别用核磁氢谱、碳谱,元素分析和X射线单晶衍射技术进行了表征。铝化合物在催化外消旋丙交酯开环聚合反应中表现出了中等的活性并得到了以等规聚合为主的高聚物。  相似文献   

8.
Heterogeneous electrocatalytic reduction of hydrogen peroxide (H2O2) by C60 is reported for the first time. C60 is embedded in tetraoctylammonium bromide (TOAB) film and is characterized by scanning electron microscopy and cyclic voltammetry. Electrocatalytic studies show that the trianion of C60 mediates the electrocatalytic reduction of H2O2 in aqueous solution containing 0.1 M KCl. Application of such film modified electrode as an amperometric sensor for H2O2 determination is also examined. The sensor shows a fast response within 1 s and a linear response is obtained (R = 0.9986) in the concentration range from 3.33 × 10−5 to 2.05 × 10−3 mol L−1 for H2O2, with the detection limit of 2 × 10−5 mol L−1 and the sensitivity of 1.65 μA mM−1. A good repeatability and stability is shown for the sensor during the experiment.  相似文献   

9.
A method of capillary electrophoresis with wall-jet amperometric detection (AD) has been developed for separation and determination of l-tyrosine (Tyr) and its metabolites, such as Tyramine (TA), p-hydroxyphenylpyruvic (pHPP), homogentisic acid (HGA) and some dipeptides containing Tyr, such as Tyr-Gly-Gly (YGG), Tyr-Arg (YR) and Tyr-d-Arg (Y-d-R). A carbon disk electrode was used as the working electrode and the optimal detection potential was 1.00 V (versus Ag/AgCl). At 18 kV of applied voltage, the seven compounds were completely separated within 20 min in 110 × 10−3 mol/L Na2HPO4–NaH2PO4 buffer (pH 7.10) containing 3 × 10−3 mol/L β-cyclodextrin (β-CD). Good linear relationship was obtained for all analytes and the detection limits of seven analytes were in the range of 0.95–4.25 ng/mL. The proposed method has been applied to examine the metabolic process of l-tyrosine in rabbit's urine.  相似文献   

10.
The 193 nm laser photodissociation of CH2H2 and CF3C2H has been studied. With the laser beam focused, C2(d3Πg) and CH(A2Δ) radicals were formed by multiphoton processes in both C2H2 and CF3C2H; however, the one-photon process forming C2H is still predominant in CF3C2H photolysis. The production of C2(d3Πg) and CH(A2Δ) emissions is prompt,and the emission intensities show similar (less than quadratic) dependence on laser power whether the radicals are produced from C2H2 or CF3C2H. In addition, the vibrational distribution of the Swan system is nearly the same in CF3C2H as in C2H2. The results indicate that the overall photolytic processes are similar in two molecules. Both the C2(d3Πg) and CH(A2Δ) emissions are quenched by Xe with rate constants of 4.8×10?11 and 1.8×10?11 cm3 molecule?1 s?1, respectively.  相似文献   

11.
The complexing ability of water-soluble calix[4]arene for l-tryptophan (l-try) was investigated by a variety of techniques. The spectrofluorometry titrations were performed at different temperatures to determine stability constants, as well as to evaluate the thermodynamic parameters of the obtained complex. The effect of pH on the complexation process was quantitatively assessed. Moreover, to obtain information about the binding mechanism of the interaction, 1H NMR studies were carried out. Molecular modeling showed that water-soluble calix[4]arene accommodated part of l-amino acid in its cavity meanwhile the aliphatic chain of l-tryptophan stuck out of the cavity. Based on the experiment data, the association process of complexes was established. The water-soluble calix[4]arene was found to be able to adjust its conformation to fit the size of aromatic l-tryptophan, and the benzene ring of amino acid penetrated into the hydrophobic cavity of calix[4]arene.  相似文献   

12.
The complexes C5H5CuPR3 (R = Me, Pri), C5H5AuPR3 (R = Me, Pri), C5Me5CuPR3 (R = Me, Pri, Ph) and C5Me5AuPR3 (R = Pri, Ph) are prepared from [ClCuPR3]n or ClAuPR3 and LiC5H5 (TlC5H5) or LiC5Me5, respectively. According to the 1H and 13C NMR spectra, the cyclopentadienyl and pentamethylcyclopentadienylgold compounds are fluxional in solution. The X-ray crystal structure of C5H5AuPPr3i has been determined at ?120°C. The gold atom is in a linear arrangement (PAuC(1) = 177.0(2)°) and primarily σ-bonded to the cyclopentadienyl ring which shows a weak “slip distortion” toward a η3-mode of coordination. The complexes C5R′5AuPR3 (R′ = H, Me) and C5Me5CuPPr3i react with 1-alkynes such as C2H2, HC2Ph and HC2CO2Me to form alkinylgold and copper compounds R″C2MPR3. They have been characterized by IR, UV and NMR (1H, 13C, 31P) spectroscopy.  相似文献   

13.
A series of fluorinated 2,5-disubstituted C60-pyrrolidine derivatives were synthesized via one-pot three-component reaction of C60, amino acid and fluorinated benzaldehyde under reflux in toluene or microwave irradiation. The cis- and trans-isomers could be isolated by chromatography and fully confirmed by 1H NMR.  相似文献   

14.
The diamagnetic susceptibilities of the C2H2 and HCN molecules have been calculated by use of the MO wave-functions with a minimal basis set by Palke and Lipscomb, and those with an extended basis set by McLean and Yoshimine. For the paramagnetic term of the susceptibility of C2H2, the value derived from the rotational magnetic moment is used, but for HCN the value interpolated from the paramagnetic terms of C2H2 and N2 is adopted. The magnetic anisotropies (Δχ = χ - χ) obtained are about −8 × 10−6 emu mole−1 for both C2H2 and HCN, and also nearly equal to the anisotropy of N2 established already. The results are discussed in connection with NMR chemical shifts.  相似文献   

15.
[C5Me5Rh(μ-co)]2 reacts with phosphines (PMe2H, PMe3) and trimethylphosphite to give the binuclear complexes C5Me5(L)Rh(μ-CO)2RhC5Me5 which have been characterised by elemental analyses, mass spectra,1H and 31P NMR data. They are surprisingly inert toward an excess of L and do not react to give the mononuclear compounds C5Me5Rh(CO)L. These are obtained in good yields from C5Me5Rh(CO)2 and L where L is PMe2H, P(OMe)3, PEt3, P(OEt)3 and PMe2Ph.  相似文献   

16.
The volatile fluorofullerene products of high-temperature reactions of C60 with the ternary manganese(III, IV) fluorides KMnF4, KMnF5, A2MnF6 (A+ = Li+, K+, Cs+), and K3MnF6 were monitored as a function of reaction temperature, reaction time, and stoichiometric ratio by in situ Knudsen-cell mass spectrometry. When combined with fluorofullerene product ratios from larger-scale (bulk) screening reactions with the same reagents, an optimized set of conditions was found that yielded the greatest amount of C60F8 (KMnF4/C60 mol ratio 28-30, 470 °C, 4-5 h). Two isomers of C60F8 were purified by HPLC, one of which has not been previously reported. Quantum chemical calculations at the DFT level combined with 1D and 2D 19F NMR, FTIR, and FT-Raman spectroscopy indicate that the C60F8 isomer previously reported to be 1,2,3,8,9,12,15,16-C60F8 is actually 1,2,3,6,9,12,15,18-C60F8, making it the first high-temperature fluorofullerene with non-contiguous fluorine atoms. The new isomer, which was found to be 1,2,7,8,9,12,13,14-C60F8, is predicted to be 5.5 kJ mol−1 more stable than 1,2,3,6,9,12,15,18-C60F8 at the DFT level. In addition, new DFT calculations and spectroscopic data indicate that the compound previously isolated from the high-temperature reaction of C60 and K2PtF6 and reported to be 16-CF3-1,2,3,8,9,12,15-C60F7 is actually 18-CF3-1,2,3,6,8,12,15-C60F7.  相似文献   

17.
Experimental differential cross sections for 40 keV electrons scattered by C2H2, C2H4 and C2H6 molecules were measured using the gas electron diffraction method in the range of the scattering variable s from s = 1 A?1 to s = 30 A?1. The differential cross sections for neon were also measured and compared with calculated differential cross sections to calibrate the diffractograph. Experimental differential cross sections show significant deviations with respect to theoretical differential cross sections calculated from the Debye-Ehrenfest model, mainly in the range of small scattering angles. The observed differences are connected to chemical binding effects. From the experimental data, an estimation of the binding energy was carried out. The deduced values: ?0.58 ± 0.20 au for C2H2, ?0.94 ± 0.30 au for C2H4 and ?1.23 ± 0.40 au for C2H6 are in agreement with those obtained by thermochemical methods.  相似文献   

18.
The 1H NMR spectra of C2H5InBr2 · tmen (1) C2H5InI2 · tmen (2) (tmen = N,N,N′,N′-tetramethylethanediamme) and [(C6H5)4P][C2H5InI3] (3) show only a broad singlet for the ethyl protons at 60 MHz. Spectra run at 400 MHz resolve these into a triplet + quartet for 1 and 3. The structure of each compound has been determined by X-ray crystallography; 1 and 2 are five-coordinate species, with InC2N2X (X = Br, I) nuclei, while 3 consists of [(C6H5)4P]+ cations and anions whose InCI3 nucleus has C3v, symmetry.  相似文献   

19.
The rate constants for the reactions C2O + H → products (1) and C2O + H2 → products (2) have been determined at room temperature by means of laser-induced fluorescence detection of C2O radicals, generated either by the KrF excimer laser photolysis Of C3O2, or by the reaction of C3O2 with O atoms. Values of k1 = (3.7 ± 1.0) × 10?11 cm3 s?1 and k2 = (7 ± 3) × 10?13 cm3 s?1 were obtained.  相似文献   

20.
The preparation, mass and 1H NMR spectra and the crystal structure of C4H4Fe2(CO)6 are described.The compound can be prepared in a simple way by reaction of Fe3(CO)12 with thiophene (yield 17%). It forms monoclinic crystals (space group P21/c) with four formula units in the unit cell. The positions of all atoms (except H atoms) have been determined and refined until an R value of 0.058 was reached. Within the practically planar ferracyclopentadiene ring, multiple bond orders must be assumed for all bonds. One of the six CO groups in the molecule is bent and represents a strongly unsymmetrical bridging carbonyl group (“semibridging carbonyl group”).  相似文献   

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