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101.
Kaminskii A. A. Manomenova V. L. Rudneva E. B. Sorokina N. I. Grebenev V. V. Kozlova N. N. Angeluts A. A. Ozheredov I. A. Solyankin P. M. Denisyuk I. Yu. Fokina M. I. Zulina N. A. Shkurinov A. P. Voloshin A. E. 《Crystallography Reports》2019,64(4):669-677
Crystallography Reports - Aqueous solutions of guanylurea hydrogen phosphite (GUHP) have been synthesized. The temperature dependence of equilibrium GUHP concentration in water was obtained. The... 相似文献
102.
Russian Journal of General Chemistry - Reactions of 2-and 3-furoyl chlorides having chloromethyl or butylthiomethyl group in the adjacent position of the furan ring as well as of analogous... 相似文献
103.
Ian Drake Gregoire Cardoen Andrew Hughes Kebede Beshah Kenneth L. Kearns Tianlan Zhang John Reffner Casey Wolf Ralph Even 《Journal of polymer science. Part A, Polymer chemistry》2019,57(13):1373-1388
A polyurea macromer (PUM) was synthesized and dispersed in basic conditions to form self‐assembled nanoparticles (<20 nm dispersions, up to 30 wt % aq. soln.). These nanoparticles enabled surfactant‐free emulsion polymerization to form hybrid polyurea‐acrylic particles despite the absence of a measureable water‐soluble fraction. The Tg of the starting PUM material was a strong function of the PUM's extent of neutralization and hydration (varying between 100 °C and >175 °C) due to changes in hydrogen and ionic bonding. Two separate hybrid polyurea‐acrylic emulsion systems were prepared: one by direct polymerization of (meth)acrylic monomers in the presence of the nanodispersion and a second by a physical blend of PUM nanodispersion with an acrylic latex control. The direct polymerization method resulted in a hybrid emulsion particle size that developed by a mechanism resembling conventional emulsion polymerization and was unlike that described for seeded polyurethane dispersion systems. Film hardness was shown to increase with increasing coating thickness for the hybrid film prepared by direct polymerization. The resulting mechanical properties could be explained by applying mechanical models for a composite foam structure. These results were unprecedented for normal elastomer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1373–1388 相似文献
104.
Thomas Marmin Prof. Yves L. Dory 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(27):6707-6711
Cyclohexane and cyclotri-β-alanyl have been used as scaffolds for the design of new C3-symmetric rings incorporating conjugated alkenes and dienes. All three C3-symmetric lactams share the same triangular shape and their crystal system is trigonal. They all belong to the R3 space group, R3m, R3 and R3c, for the increasingly large 12-, 18- and 24-membered rigid rings, respectively. All lactams stack on top of each other, through H-bonds and van der Waals noncovalent interactions, leading to endless supramolecular cylinders and tubes. The largest member of the family leads to tubes, the central pores of which is wide enough to let water in. A common feature of all the lactams is their very large dipole, of around 9 D, according to DFT calculations. Surprisingly, all the resulting cylinders and tubes pack side by side in the crystals, with all the dipoles pointing to the same direction. As a result, all three crystals are anisotropic and appear to be the first members of a new kind of highly polar crystals. 相似文献
105.
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107.
David Tong Jackie Wu Nathan Bazinski Donghyun Koo Naresh Vemula Prof. Dr. Brian L. Pagenkopf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(67):15244-15247
Cycloadditions of strained carbocycles promoted by Lewis acids are powerful methods to construct heterocyclic frameworks. In fact, the formal [3+2] cycloadditions of donor–acceptor (DA) cyclopropanes with nitriles has seen particular success in synthesis. In this work, we report on the first [4+2] cycloaddition of nitriles with DA cyclobutanes by Lewis acid activation. Tetrahydropyridine derivatives were obtained in up to 91 % yield from various aryl-activated cyclobutane diesters and aliphatic or aromatic nitriles. 相似文献
108.
Dr. Samantha A. Orr Dr. Emily C. Border Prof. Philip C. Andrews Dr. Victoria L. Blair 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11876-11882
By exploring lithium–bromide exchange reactivity of aromatic Schiff's bases with tert-butyllithium (tBuLi), we have revealed unprecedented competitive intermolecular and intramolecular cascade annulation pathways, leading to valuable compounds, such as iso-indolinones and N-substituted anthracene derivatives. A series of reaction parameters were probed, including solvent, stoichiometry, sterics and organolithium reagent choice, in order to understand the influences that limit such ring-closing pathways. With two viable reactivity options for the organolithium on the imine; namely, nucleophilic addition or lithium–bromide exchange, a surprising competitive nature was observed, where nucleophilic addition dominated, even under cryogenic conditions. Considering the most commonly used solvents for lithium–bromide exchange, tetrahydrofuran (THF) and diethyl ether (Et2O), contrasting reactivity outcomes were revealed with nucleophilic addition promoted in THF, while Et2O yielded almost double the conversion of cyclic products than in THF. 相似文献
109.
P. Benetti F. Boffelli C. Marciano A. Piazzoli G.L. Raselli 《Physics letters. A》2019,383(18):2145-2148
A series of experimental tests, such as those of Carpinteri et al. (2013), have been performed. The aim was to check the emission of neutrons in the fracture of Luserna granite blocks under mechanical loading, as reported by the above mentioned authors. No neutrons have been detected and some doubts have emerged on the soundness of the previous measurements. 相似文献
110.
Nathamgari S. S. P. Dong S. Hosseinian E. Lauhon L. J. Espinosa H. D. 《Experimental Mechanics》2019,59(3):349-359
Experimental Mechanics - Nanoelectromechanical (NEMS) systems fabricated using atomically thin materials have low mass and high stiffness and are thus ideal candidates for force and mass sensing... 相似文献