These monolayers have measurable polar order
For molecules that self-associate well, the opposite orientation is observed. These films are comprised of isolated stacks of molecules parallel to the Synthesis of low-generation, aryl-/alkyl-type, nonpolar dendrons carrying protected hydroxyalkyl groups in the periphery.An efficient convergent synthesis of first- and second-generation aryl-/alkyl-type nonpolar dendrons via Suzuki cross-coupling is described. The dendrons carry either one or two benzyl-protected hydroxyalkyl groups/terminus. Iododesilylation reactions of aryltrimethylsilanes with iodo chloride are used as a tool for the incorporation of iodo, an important functionality for transition-metal-catalyzed cross-coupling reactions. In the case of sensitive aromatics, the addition of some donor solvent like diethyl ether proved effective in suppressing side reactions through electrophilic aromatic Surface patterning of (bio)molecules onto the inner wall of fused-silica Joseph Fourier, BP 53, 38041, Grenoble Cedex 9, France.
An efficient photochemical method for the site-specific immobilization and patterning of (bio)molecules inside glass capillary tubes is reported. The strategy involves the photodeprotection of reactive aminooxy groups on surfaces and subsequent reaction with aldehyde containing (bio)molecules.Control of extremely fast competitive consecutive reactions using micromixing. Applications of 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid in Cross-Coupling Reactions -Crafts aminoalkylation.of Engineering, Kyoto University, Katsura, Kyoto 615-8510.Friedel-Crafts reactions of aromatic and heteroaromatic compounds with an N-acyliminium ion pool were studied. The reaction of 1,3,5-trimethylbenzene in a batch reactor gave rise to the selective formation of a monoalkylation product (69%).
Presumably, 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid in Medicinal Chemistry is slower than the first alkylation because of the protonation of the monoalkylation product that decreases its reactivity. The reaction of 1,3,5-trimethoxybenzene, however, gave rise to the formation of both monoalkylation (37%) and dialkylation (32%) products. Disguised chemical selectivity due to faster reaction than mixing seems to be responsible for the lack of selectivity. The use of micromixing was found to be quite effective to solve this problem to increase the selectivity. The monoalkylation product was obtained in 92% yield together with a small amount of the dialkylation product (4%). The reaction with various aromatic and heteroaromatic compounds revealed that the low mono/dialkylation selectivity was observed only for highly reactive aromatics. In such cases, the use of micromixing was quite effective to improve the selectivity.
On the basis of micromixing, the selective sequential dialkylation using two different N-acyliminium ions was achieved. CFD simulations using a laminar flow and finite-rate model are consistent with the experimental observations and clearly The experimental and calculational thermochemistry of 1,2,4,5-benzenetetracarboxylic dianhydride: is this 10 pi multiring species Ciências da Universidade do Porto, Rua do Campo Alegre 687, P-4169-007 Porto, The standard (p degrees = 0 MPa) molar enthalpy of formation of 1,2,4,5-benzenetetracarboxylic dianhydride in the gaseous phase, -826 +/- 3 kJ mol-1, was derived from the standard molar enthalpy of combustion, in oxygen, at T = 2985 K, measured by static bomb combustion calorimetry and the standard molar enthalpy of sublimation, at T = 2985 K, measured by Calvet microcalorimetry. In addition, density functional theory calculations have been performed with the B3LYP, MPW1B95, and B3PW91 density functionals and the cc-pVTZ basis set for 1,2,4,5-benzenetetracarboxylic dianhydride and 1,2,4,5-benzenetetracarboxylic diimide. Nucleus-independent chemical shifts calculations show that the aromaticity is restricted to the benzenic ring in both compounds even though they are formally 10 pi polynuclear species.Alkanethiol-functionalized organosilicon monoliths for nano-reversed-phase Organosilicon monoliths carrying chromatographic ligands with different alkyl chain lengths were obtained by thiol-methacrylate photopolymerization. The use of thiol-ene chemistry in the presence of a main monomer with a series of methacrylate functionality (i.e.
, methacrylate substituted polyhedral oligomeric silsesquioxane) allowed the synthesis of organosilicon monoliths with high cross-linking density and carrying hydrophobic alkyl-chain ligands by a one-pot process. In the synthesis runs, 1-butanethiol, 1-octanethiol, and 1-octadecanethiol were used as the hydrophobic thiol ligands with the number of methylene units between 4 and 18. The selectivity analysis performed using cytosine/uracil retention ratio showed that alkanethiol-attached organosilicon monoliths exhibited hydrophobicity close to octadecyl-attached silica-based RP columns. In the RP, chromatographic runs performed in nano-liquid chromatography, phenols, alkylbenzenes, and PAHs were used as the analytes. Among the synthesized monoliths, retention-independent plate height behavior and the smallest plate heights were obtained with 1-octadecanethiol-attached organosilicon monolith for the analytes in a wide polarity range.
