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201.
Chemical and electrochemical oxidation of different catechols were carried out in the presence of N,N′-dibenzylethylenediamine (DBEDA) in a phosphate buffer/acetonitrile solution for the synthesis of different new dibenzyltetrahydroquinoxalinedione derivatives. The oxidation of catechol (1a), 2,3-dihydroxybenzoic acid (1e), and 3,4-dihydroxybenzoic acid (1d) led to the same product, probably due to the decarboxylation reaction of intermediates. An oxidative decarboxylation reaction of 3,4-dihydroxybenzoic acid (1d) has been reported before, while an unexpected oxidative decarboxylation reaction of 2,3-dihydroxybenzoic acid (1e) in the presence of DBEDA is reported for the first time. 相似文献
202.
203.
An efficient method for preparation of the arylaminotetrazoles derivatives is reported using aluminium chloride as an effective Lewis acid. Generally, 5-arylamino-1H-tetrazole isomer can be obtained from arylcyanamides carrying electron-withdrawing substituents on the aryl ring. As the electropositivity of the substituent is increased, the product is shifted toward the formation of 1-aryl-5-amino-1H-tetrazole isomer. 相似文献
204.
This paper reports the preparation of a nano-Co(II)-catalyst (NCC) by anchoring of Co ions on immobilized bipyridylketone over the nano-sized SiO2/Al2O3 mixed oxides. The nano-Co(II)-catalyst has been characterized by elemental analysis, BET, FT-IR, DR UV–vis and SEM. The catalytic activity of the catalyst towards the oxidation of ethylbenzene, cyclohexene, and benzylalcohol to different chemically and pharmaceutically important products were evaluated with tert-butyl hydroperoxide (TBHP) in the absence of solvent. Under optimized conditions, the nano-catalyst proved highly selective towards the acetophenone, 2-cyclohexene-1-one and benzaldehyde as reaction products, with excellent conversion rates. 相似文献
205.
Abstract
Electrochemical oxidation of hydroquinone was studied in the presence of pyridine and 4-methylpyridine as nucleophiles in aqueous solution. The results indicate the participation of electrochemically generated p-benzoquinone in Michael addition reaction with pyridine and 4-methylpyridine, converting it to pyridinated compounds. 相似文献206.
Ataollah Asgharian Davood D. Ganji Soheil Soleimani Sina Asgharian Nima Sedaghaty zade Behzad Mohammadi 《Mathematical Methods in the Applied Sciences》2011,34(18):2209-2217
An analytical study is performed on heat and mass transfer in MHD‐free convection from a moving permeable vertical surface and the results are compared with previous works on this phenomenon to test the validity. The coupled equations of boundary layer are transformed from their non‐linear form to ordinary form using similarity transformation and then are solved by a newly developed method, homotopy analysis method. Having different base functions, homotopy analysis method provides us with great freedom in choosing the solution of a nonlinear problem. Solving the boundry layer equations, the effects of different parameters such as magnetic field strength parameter (M), Prandtl number (Pr), Schmidt number (Sc), buoyancy ratio and suction/blowing parameter (fw) on velocity, temperature, and concentration profiles are taken into consideration. Obtained results show that increment of magnetic field strength parameter (M) leads to decrease in velocity profile. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
207.
Davood?FathiEmail author Behjat?Forouzandeh Reza?Sarvari 《Applied Physics A: Materials Science & Processing》2011,102(1):231-238
A new method for the analysis of electron transmission property in single-walled carbon nanotubes (SWCNTs) using Green’s function
is presented in this paper for the first time. Using the proposed method, a new relation for the transmission function through
a deformed SWCNT is obtained, which depends on the energy variations and the coupling matrices related to the mechanical deformations
applied to the structure of CNT. The obtained new relation is explained by the presented results in the literature. 相似文献
208.
S. Davood Sadatian 《International Journal of Theoretical Physics》2014,53(2):675-684
We choose a modified Chaplygin Gas Dark energy model for considering some its cosmological behaviors. In this regards, we study different Rip singularity scenarios and bouncing model of the universe in context of this model. We show that by using suitable parameters can explain some cosmological aspects of the model. 相似文献
209.
The conformational behaviors of trans‐2,3‐dihalo‐1,4‐dithiane [halo = F ( 1 ), Cl ( 2 ), Br ( 3 )] and trans‐2,5‐dihalo‐1,4‐dithiane [halo = F ( 4 ), Cl ( 5 ), Br ( 6 )] have been analyzed by means of complete basis set CBS‐4, hybrid‐density functional theory (B3LYP/6‐311 + G**//B3LYP/6‐311 + G**) based methods, and natural bond orbital (NBO) interpretation. Both methods showed that the axial conformations of compounds 1–5 are more stable than their equatorial conformations but CBS‐4 resulted in an equatorial preference for compound 6 . The Gibbs free energy difference (Geq?Gax) values (i.e., ΔGeq–ax) at 298.15 K and 1 atm between the axial and equatorial conformations decrease from compound 1 to compound 2 but increase from compound 2 to compound 3 . Also, the calculated ΔGeq–ax values decrease from compound 4 to compound 6 . The NBO analysis of donor–acceptor (LP → σ*) interactions showed that the anomeric effect (AE) increase from compound 1 to compound 3 and also from compound 4 to compound 6 . On the other hand, the calculated dipole moment values between the axial and equatorial conformations [Δ(µeq?µax)] decrease from compound 1 to compound 3 . The conflict between the increase of AE and the decrease of Δ(µeq?µax) values could explain the variation of the calculated ΔGeq–ax for compounds 1–3 . The Gibbs free energy difference values between the axial and equatorial conformations (i.e., ΔGax–ax and ΔGeq–eq) of compounds 1 and 4 , 2 and 5 and also 3 and 6 have been calculated. The correlations between the AE, bond orders, pairwise steric exchange energies (PSEE), ΔGeq–ax, ΔGax–ax, ΔGeq–eq, dipole–dipole interactions, structural parameters, and conformational behaviors of compounds 1–6 have been investigated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
210.
In this paper we analyze the effects of material characteristics (metallic behavior) and the periodicity of dielectric function, on the reflection peaks in a defected two-dimensional multiwall carbon nanotube (MWCNT) photonic crystal, for photon frequencies up to 10 THz. The simulation results show that, the second peak amplitude depends on both material and periodicity changes of the structure, whereas the previous report shows the mentioned dependence only on the material characteristics of structure. It should be noted that, the first and third (Bragg) peaks are dependent only on the material characteristics and the dielectric periodicity, respectively. 相似文献