5-甲基吲哚的合成

5 甲基吲哚是一种重要的化学中间体,在合成医药、染料等方面具有重要的作用[1]。传统合成方法路线较长、收率低、催化剂价格贵[2-5]。本文以对甲苯胺和环氧乙烷为原料,在铜系催化剂上一步合成5 甲基吲哚。反应方程式为:1　实验1 1　催化剂制备将硅胶放入箱式电炉中,以100℃/h的速度程序升温至900℃,恒温12h,自然冷却至室温进行扩孔。将扩孔硅胶置入0 2mol·L-1的Cu(NO3)2、0 05mol·L-1KNO3混合溶液中,浸渍24h取出,以120～130℃氮气流干燥,置入箱式电炉,500℃下煅烧2h取出,在氮气保护下冷却。将制得的催化剂装入Φ25mm的单管固定床…     

Presence of a low-lying “Rydberg” band in the vapour phase absorption spectra of indole and 1-methyl indole

The changes observed in the ultraviolet absorption spectra of indole and 1-methyl indole between the gaseous state and the solution, suggest the existence of a low-lying molecular Rydberg state.     

Polarized absorption spectroscopy of trans-azobenzene and trans-stilbene in stretched polyethylene films

The linear dichroism spectra of trans-azobenzene and trans-stilbene aligned in stretched polyethylene films are reported for the u.v.-vis region. On the basis of the results the u.v. transition moment directions with respect to the long molecular axis are determined. Infrared data indicate that trans-azobenzene has a non-planar geometry while trans-stilbene is more planar in the polyethylene matrix. The polarization direction of the nπ* transition in azobenzene is different from that of the first ππ* absorption band, which indicates a vibrational borrowing mechanism corresponding to a nonplanar geometry.     

Vibronic fine structure in the absorption spectrum of oligothiophene thin films

A multimode Holstein Hamiltonian is used to describe optical excitations in quaterthiophene pinwheel aggregates. The Hamiltonian includes the coupling of excitons originating from the 1A(g)-->1B(u) electronic transition to phonons originating from the five intramolecular vibrational modes known from oligothiophene solution absorption/emission spectroscopy. The resulting eigenstates with lowest energy are best described as hybrid polaron phonons. The polarons are formed by coupling excitons with the higher frequency (688, 1235, and 1551 cm(-1)) vibrational modes, while the (optical) phonons arise from the lower frequency (161 and 333 cm(-1)) modes. The polaron phonons are responsible for the fine structure defining the A(1) band in the low-energy region of the absorption spectrum, ranging from the band origin to approximately 1500 cm(-1) beyond. The calculated A(1) band of quaterthiophene aggregates agrees favorably with that observed from thin films.     

The polarized infrared spectrum of crystalline dimethyl oxalate

The polarized infrared spectra of oriented crystal films of dimethyl oxalate have been recorded at approximately 20 K. The symmetry species of the intramolecular modes have been determined on the basis of the polarization behavior of the observed bands and compared to the assignments made by previous workers by indirect methods. The Davydov components in some of the bands are observed and assigned to the infrared active factor group symmetry species A_u and B_u.     

Vibrational spectrum of 3-methyl and 4-methylpyridine

The assignments of the vibrational spectra of the 3-methyl and 4-methylpyridine molecules have been carried out following the SQMFF methodology (scaled quantum mechanical force field). The theoretical frequencies have been obtained by calculating the RHF/3-21G force field, using the scale factors for pyridine and 2-methylpyridine and are correlated in a satisfactory manner with the frequencies recorded in the IR and Raman of these methyl derivatives.     

The microwave absorption spectrum of MgO

The microwave absorption spectrum of ²⁴MgO, ²⁵MgO and ²⁶MgO has been observed in the frequency range between 67 and 275 GHz. Quadrupole hyperfine structure of ²⁵MgO was partially resolved. The molecular constants derived from these measurements are two orders of magnitude more accurate than previous MODR results.     

Vibrational and electronic absorption spectra of 4-chloro 2-methyl, 4-chloro 3-methyl and 6-chloro 3-methyl phenols

The infrared spectra of 4-Cl 2-Me, 4-Cl 3-Me and 6-Cl 3-Me phenols have been recorded. The vibrational spectrum has been analysed assuming that the molecules belong toC _s point group and a tentative assignment of the observed frequencies to various modes of vibration has been proposed. The near ultraviolet absorption spectrum of these compounds has also been recorded. Assuming the transition to be electronically allowed the strongest band on the longer wavelength side has been assigned as the (0, 0) band in each case. The spectrum has been analysed in terms of several excited state frequencies which have been correlated with the ground state frequencies observed in the infrared spectrum.     

Stark absorption spectroscopy of indole and 3-methylindole

Indole and 3-methylindole (3-MI) doped into a polymethylmethacrylate (PMMA) film are studied by the Stark absorption (electroabsorption) spectroscopy. The 1La and 1Lb absorption bands are distinguished and the change in permanent dipole moment on 1La excitation is determined by a model fit to the measured absorption and electroabsorption spectra. Analysis of the spectra, measured at normal incidence and magic angle conditions, proved the essential role of the electric-field-induced orientation/alignment effects for polar indole and 3-MI molecules in the PMMA environment at room temperature.     

Fluorination of polyethylene films

Fluorination of HDPE films (100 and 1800 μm thick) and LDPE films (100 μm thick) with elemental fluorine is described. The films were fluorinated at temperatures between 40°C and 100°C. The degree of fluorination was increased by increasing the concentration of fluorine in the F₂/N₂ gas mixture. A diffusion-controlled process was indicated by plotting the measured depth of fluorination against the square root of fluorination time. The chemistry of the process was studied by ESCA measurements or by energy dispersive analyses in the scanning electron microscope.     

Hole burning in the absorption spectrum of chlorin in polymer films: stark effect and temperature dependence

Optical hole-burning experiments at 2 K with chlorin in polymethylmethacrylate (PMMA), polystyrene (PST) and polyvinylbutanal (PVB) gave hole widths of 1.2, 1.6 and 0.75 GHz. Preliminary temperature-dependent measurements in PVB suggest that the linewidth at 0 K approximates the lifetime-limited value. Due to the Stark effect on the randomly distributed molecules, a significant reversible broadening was observed when an electric field of 6000 V/cm was applied to the sample.     

The absorption spectrum and dissociation constants of 4-hydroxybenzthiazole

The absorption spectra of 4-hydroxybenzthiazole and the parent compound, benzthiazole, have been determined in acidic, basic and neutral solutions, and compared with the corresponding absorption spectra of 8-hydroxyquinoline and quinoline. The dissociation constants of 4-hydroxybenzthiazole obtained by a spectrophotometric method as well as a potentiometric method, show that it is a stronger acid and a weaker base than 8-hydroxyquinoline.     

The microwave spectrum of the unsymmetrical conformation of 1-chloro-2-methyl propane

The microwave spectrum of 1-chloro-2-methyl propane has been recorded and lines assigned to ³⁵Cl and ³⁷Cl species in the unsymmetrical conformation. The rotational and distortion constants in MHz are: C₄H₉³⁵Cl, A = 7527.05, B = 2146.21, C = 1793.59, Δ_JK = 4.15 × 10^?3, δ_j = ?8.0 × 10^?5; C₄H₉³⁷Cl, A = 7524.40. B = 2091.73, C = 1755.54, Δ_JK = 2.5 × 10^?3, δ_j = 2.0 × 10^?4.     

The electronic absorption spectrum of the CrMo molecule

An absorption spectrum near 4800 Å was observed from flash photolysis of a mixture of Cr(CO)₆ + Mo(CO)₆ vapours, which is tentatively assigned to the CrMo molecule.     

The absorption spectrum of the pyrene excimer in different solvents

The absorption of the pyrene excimer obtained using modulation excitation spectrophotometry in different solvents is shown to be solvent dependent.     

Molecular and lamellar orientation in polyethylene thin films

Summary A combined wide (WA) and small angle X-ray diffraction (SAXS) study of melt compressed low density PE samples into the form of very thin films is reported. The WAXD patterns show an uniaxialb axis orientation normal to the film surface which can be interpreted in terms of a row structure in the plane of the film. The analysis of SAXS data indicates, in addition, a preferential orientation of bundles of stacked lamellae parallel to the film surface separated by longitudinal microvoids.With 3 figures     

Optical properties and orientation in polyethylene blown films

We report structural factors affecting the optical properties of blown polyethylene films. Two types of blown polyethylene films of similar degrees of crystallinity were made from (1) single‐site‐catalyst high‐density polyethylene (HDPE; STAR α) and (2) Ziegler–Natta‐catalyst HDPE (ZN) resins. The STAR α film exhibited high clarity and gloss, whereas the ZN film was turbid. Small‐angle X‐ray scattering (SAXS), small‐angle light scattering (SALS), and optical microscopy gave quantitative and qualitative information regarding structure and orientation in the films. A new approach is described for determining the three‐dimensional lamellar normal orientation from SAXS. Both the clear STAR α and turbid ZN films had similar lamellar crystalline structures and long periods but displayed different degrees of orientation. It is demonstrated that optical haze is related to surface features that seem to be linked to the bulk morphology. The relationship between haze and structural orientation is described. The lamellar orientation is linked to rodlike structures seen in optical microscopy and SALS through a stacked lamellar or cylindrite morphology on a nanometer scale and through a fiberlike morphology on a micrometer scale. The micrometer‐scale, rodlike structures seem directly related to surface roughness in a comparison of index‐matched immersion and surface micrographs. The higher haze and lower gloss of the ZN film was caused by extensive surface roughness not observed in the STAR α film. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2923–2936, 2001     

Electronically excited rubidium atom in helium clusters and films. II. Second excited state and absorption spectrum

Following our work on the study of helium droplets and film doped with one electronically excited rubidium atom Rb(?) ((2)P) [M. Leino, A. Viel, and R. E. Zillich, J. Chem. Phys. 129, 184308 (2008)], we focus in this paper on the second excited state. We present theoretical studies of such droplets and films using quantum Monte Carlo approaches. Diffusion and path integral Monte Carlo algorithms combined with a diatomics-in-molecule scheme to model the nonpair additive potential energy surface are used to investigate the energetics and the structure of Rb(?)He(n) clusters. Helium films as a model for the limit of large clusters are also considered. As in our work on the first electronic excited state, our present calculations find stable Rb(?)He(n) clusters. The structures obtained are however different with a He-Rb(?)-He exciplex core to which more helium atoms are weakly attached, preferentially on one end of the core exciplex. The electronic absorption spectrum is also presented for increasing cluster sizes as well as for the film.