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131.
An efficient procedure for the synthesis of N‐alkyl‐2,5‐diaryl‐1,3‐dioxol‐4‐amines 3 via a one‐pot reaction of aromatic aldehydes 2 and alkyl isocyanides 1 at room temperature in good yields is described (Scheme 1, Table). 相似文献
132.
Satyawati S. Joshi Prajakta R. Patil Madhav S. Nimase P.P. Bakare 《Journal of nanoparticle research》2006,8(5):635-643
The electrochemical synthesis of alpha Fe2O3 nanoparticles was performed using quaternary ammonium salts viz. TPAB, TBAB and TOAB in an organic medium by optimizing current density and molar concentration of the ligand. The role of ligands in the formation of α phase, structure and magnetic properties was investigated in details. The effect of increasing chain length on the particle size confirmed that as the chain length increases from propyl to octyl, the particle size decreases. X-ray diffraction spectra of as prepared samples and TEM analysis confirmed the amorphous nature of iron oxide. TEM showed beads of iron oxide joined together with a size distribution in the range of 6–30 nm. The Mossbauer studies also support this observation that for the lowest particle size, the line width is broader which successively reduces with increase in particle size. Iron oxide capped with TOAB indicated superparamagnetic nature at room temperature. The resultant internal magnetic field of 506 mm/s due to hyperfine splitting clearly established the formation of α-Fe2O3 The infrared spectroscopy and pH measurements revealed the binding of tetra alkyl ligand with iron oxide. The IR spectra and the increase in basicity of as prepared samples confirmed the formation of hydrated iron oxide. Above 800°C the spectra indicated only iron oxide. Surface area obtained by BET method was 205 m2/g. 相似文献
133.
The reactive intermediate generated by the addition of alkyl isocyanides to dimethyl acetylenedicarboxylate was trapped by phenols such as resorcinol, catechol, hydroquinone, pyrogallol, 2,4-dihydroxybenzaldehyde, or 8-hydroxyquinoline to produce highly functionalized 4H-chromenes in fairly good yields. 相似文献
134.
A. N. Pudovik R. R. Shagidullin V. K. Khairullin I. I. Vandyukova 《Russian Chemical Bulletin》1994,43(9):1584-1586
The reaction of dialkyl H-phosphonates with pyridine-3-carbaldehyde gives alkyl (3-pyridyl)hydroxymethylphosphonates. In liquid systems, the hydrogen atom is localized at the oxygen atom of the hydroxyl group; in crystals, the existence of a zwitter-ionic form could not be excluded. In CHCl3 solutions, isolated molecules and cyclic dimeric H-complexes exist in an equilibrium.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1674–1676, September, 1994. 相似文献
135.
本文讨论了求解密集型线性方程组的两种并行算法。这两种算法都在下上单元(LU)分解。法的基础上使用了前向和后向置换进行的。这些算法在数值上是稳定的,并在顺序平衡机上用各种处理程序进行试验,都得到良好效果。 相似文献
136.
137.
Zoltán Varga Jen Hancsók Dénes Kalló árpád Stumpfc 《Reaction Kinetics and Catalysis Letters》2006,88(1):19-26
Summary The hydrodesulfurization (HDS) of dibenzothiophene (DBT), 4-methyl-dibenzothiophene (4 M-DBT), 4,6-dimethyldibenzothiophene
(4,6 DM-DBT) and 4,6-diethyldibenzothiophene (4,6 DE-DBT) as real gas oil components on NiMo/Al2O3 catalyst was investigated. On the basis of the first order rate constants of HDS of the individual sulfur compounds calculated
by both integral and differential evaluations the reactivities of the investigated compounds decreased in the order DBT >>
4 M-DBT > 4,6 DE-DBT ? 4,6 DM-DBT. Additionally, results showed that product inhibition during HDS does not take place. 相似文献
138.
Eiji Ihara Shingo Honjyo Tomomichi Itoh Mitsufumi Nodono 《Journal of polymer science. Part A, Polymer chemistry》2007,45(20):4597-4605
Radical copolymerization of alkyl 2‐norbornene‐2‐carboxylates (alkyl = Me 1a , nBu 1b ) with alkyl acrylates (alkyl = ethyl, methyl, and n‐butyl) was investigated. Copolymerization of 1a,b with the alkyl acrylates initiated by 1,1′‐azobis (cyclohexane‐1‐carbonitrile) at 85 °C proceeded to give random copolymers, although the homopolymerization of 1a,b did not proceed efficiently under the same conditions. Typically, bulk copolymerization of 1a with ethyl acrylate in a feed ratio of 1:3 ([ 1a ]:[EA]) afforded a copolymer with Mn = 33,300 containing 19.4 mol % of 1a unit in the composition. An increase of Tg derived from the incorporation of the rigid norbornane framework was observed, although the extent of the temperature rise was rather moderate. The ternary radical copolymerization of 1a,b /alkyl acrylate/N‐phenylmaleimide proceeded to give copolymers with the three repeating units in the main chain. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4597–4605, 2007 相似文献
139.
140.
L. A. J. M. Sliedregt G. A. Van Der Marel J. H. Van Boom 《Journal of Chemical Sciences》1994,106(5):1213-1224
Condensation of 4-nitrophenylthioD-glycosyl acceptors with ethylthioD-glycosyl donors in the presence of thiophilic promoters IDCP and NIS/TfOH, according to the “latent-active” principle proposed
by Royet al, did not proceed in all cases as expected. On the other hand, replacement of the ethylthio function by an n-pentenyloxy group
shows promise for the future chemoselective assembly of oligosaccharides. 相似文献