Abstract Synthesis, separation and X-ray crystal structures of E and Z isomers of 3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl)acrylic acid are reported. Separation of E and Z isomers from a 1:1 mixture has been carried out by selective acidification of their sodium salts carefully controlling the
pH of the solution. The structures of E and Z isomers were confirmed by determining crystal structures of these isomers using single crystal X-ray diffraction. The E isomer crystallizes in the P21/c space group with a = 11.493(2) ?, b = 5.5456(11) ?, c = 24.900(5) ?, α = 90°, β = 92.36(3)°, γ = 90°, Z = 4. The Z isomer crystallizes in the P21/c space group with a = 10.192(2) ?, b = 12.893(3) ?, c = 13.948(3) ?, α = 90°, β = 92.18(3)°, γ = 90°, Z = 4. Details of the synthesis and structural characterization and X-ray crystal structure determination of the title compounds
are presented.
Index Abstract
Synthesis, Separation and Crystal Structures of E and Z Isomers of 3-(2,5-Dimethoxyphenyl)-2-(4-Methoxyphenyl)Acrylic AcidBalachandra Chenna, Bidhan A. Shinkre, Shweta Patel, Samuel B. Owens Jr., Gary M. Gray, Sadanandan E. Velu*
Separation of E and Z isomers of 3-(2,5-dimethoxyphenyl)-2-(4-methoxyphenyl)acrylic acid from a 1:1 mixture has been carried out by selective acidification
of their sodium salts and the structures of the individual isomers have been determined by X-ray single crystal diffraction.
相似文献
We have investigated the thermodynamic properties of perovskite manganite LaMnO3, the parent compound of colossal magnetoresistive manganites, with the Ca2+ doping at the A-site. As strong electron-phonon interactions are present in these compounds, the lattice part of the specific heat deserves proper attention. We have described the temperature dependence of the lattice contribution to the specific heat at constant volume (Cv(lattice)) of La1−xCaxMnO3 (x=0.125, 0.175, 0.25, 0.35, 0.50, 0.67, 0.75) as a function of temperature (1 K–20 K) by means of a rigid ion model (RIM).The trends of specific heat variations with temperature are almost similar at all the composition. The Debye temperatures obtained from the lattice contributions are found to be in somewhat closer agreement with the experimental data. The specific heat values revealed by using RIM are in closer agreement with the available experimental data, particularly at low temperatures for some concentrations (x) of La1−xCaxMnO3. The theoretical results at higher temperatures can be improved by including the effects of the charge ordering, van der Waals attraction and anharmonicity in the framework of RIM. 相似文献
Composite films of poly(3,4‐ethylenedioxythiophene) (PEDOT)‐coated over functionalized multiwalled coiled and linear carbon nanotubes (CNTs) have been fabricated by a simple oxidative electropolymerization route. The nanotubular morphology of the polymer–CNT composite is responsible for the lower charge transfer impedance, lower internal resistance, and superior capacitive response in comparison to that shown by the control PEDOT film doped by trifluoromethanesulfonate ions. This facile electrochemistry exhibited by the PEDOT–CNT composite film ensues in a remarkably high coloration efficiency of 367 cm2 · C−1 at 550 nm, hitherto unrealized for PEDOT; thus demonstrating the huge potential the PEDOT–CNT composite film has as cathode for the entire spectrum of electrochromic devices.
We present here an efficient method for the hydroboration of aldimines (-C=N-) with pinacolborane (HBpin) using an alkali metal catalyst, potassium benzyl. The reaction was accomplished with unprecedented catalytic efficiency under mild and solvent-free conditions to afford the high yield of the corresponding N-boryl amines up to 97%. Various functionalities on aldimines were incorporated for hydroboration. The corresponding boryl amines were subjected to further hydrolysis to yield the corresponding secondary amines with good yields up to 89%. This protocol for the reaction demonstrates an atom-economic and green method with diverse imines that bears excellent functional group tolerance. Chemoselective reduction of imines was also attained, with good yields of 74–89%. We also propose the most plausible mechanism involving the formation of metal hydride as the active pre-catalyst. 相似文献
A new simple, economical, rapid, precise and accurate method for simultaneous determination of rabeprazole sodium and itopride hydrochloride in capsule dosage form has been developed. The method is based on ratio spectra derivative spectrophotometry. The amplitudes in the first derivative of the corresponding ratio spectra at 231nm (minima) and 260nm were selected to determine rabeprazole sodium and itopride hydrochloride, respectively. The method was validated with respect to linearity, precision and accuracy. 相似文献
A new, simple high-performance thin-layer chromatographic method has been established and validated for simultaneous determination
of escitalopram oxalate and clonazepam in a combined tablet dosage form. The drugs were separated on aluminum plates precoated
with silica gel 60 F254; toluene–ethyl acetate–triethylamine 7:3.5:3 (v/v) was used as mobile phase. Quantitative analysis was performed by densitometric scanning at 258 nm. The method was validated
for linearity, accuracy, precision, and robustness. The calibration plot was linear over the ranges 250–2,500 and 50–500 ng band−1 for escitalopram oxalate and clonazepam, respectively. The method was successfully applied to the analysis of drugs in a
pharmaceutical formulation. 相似文献
ABSTRACTThe solid solutions of Bi0.8Gd0.1Pb0.1Fe0.9Ti0.1O3 have been prepared by the solid-state reaction method. The preliminary structural studies were carried out by X-ray diffraction technique showing the formation of polycrystalline sample with ABO3 type of perovskite structure with hexagonal symmetry for the Bi0.8Gd0.1Pb0.1Fe0.9Ti0.1O3 ceramic system at room temperature. Dielectric properties and impedance study of this ceramic have been characterized in the temperature range room temperature to 375 °C and frequency range 100 Hz–1 MHz. The maximum ferroelectric transition temperature (Tc) of this system was in the range 200 °C–260 °C with the dielectric constant of peak to be ~30,170 at 1 kHz. The complex impedance plot exhibited one impedance semicircle observed at low temperature, whereas two semicircles above 80 °C and the centres of the semicircles lie below the real axis, which indicates that the material is non-Debye type. Single semicircle is explained by the grain effect of the bulk and double semicircle is due to the bulk and grain boundary effect. The bulk resistance and grain boundary resistance of the materials decrease with the increasing temperature, showing negative temperature and a typical semiconducting property, i.e. negative temperature coefficient of resistance behaviour. 相似文献