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61.
The structures of the inclusion compounds formed by the host 9,9’-(ethyne-1,2-diyl)bis(fluoren-9-01) with pyridine and picolines are similar and display tubular topology. The host discriminates poorly between
these guests. The kinetics of desorption of the pyridine compound is governed by the Avrami-Erofe’ev equation A2, with an
activation energy of 111(7) kJ mol−1. 相似文献
62.
63.
Repeated temperature scanning method was applied to observe non-stoichiometry of YBa2Cu3O7-d, and interesting results were obtained. Two simultaneously occurring processes were separately observed in mass change;
one is a fast process and the other is slow, so that their responses to the temperature change are quite different from each
other. The fast process follows the cyclic temperature change, but the slow process is observed to be a gradual mass change.
Kinetic behaviors of these two processes are also made clear by plotting the mass vs. the temperature. Furthermore, a hysteresis
loop was observed in the plot of the mass vs. the temperature in a high temperature range presumably due to the third process,
and it depends on the heating and cooling rates.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
64.
65.
66.
Lothar Hennig Mario Alva-Astudillo Gerhard Mann Thomas Kappe 《Monatshefte für Chemie / Chemical Monthly》1992,123(6-7):571-579
Summary Treatment of substituted benzylidene anilines1 a – df with cyclic CH-acidic compounds2a–m in ethanol at room temperature yields in additon/elimination reactions the corresponding arylidene derivatives4 and the 2:1 adducts5. The addition products3, which are formed as intermediates, could not be isolated in any case. The donor/acceptor effect of the substituents on the benzylidene moiety influences to a significant extent the reactivity towards the azomethine carbon.
Neue Aspekte der Reaktion von Azomethinen mit cyclischen CH-aciden Verbindungen
Zusammenfassung Bei der Umsetzung der substituierten Benzylidenaniline1 a – f mit den cyclischen CH-aciden Verbindungen2 a – m in Ethanol bei Raumtemperatur erhält man in Additions/Eliminierungsreaktionen die Arylidenderivate4 und die 2:1-Addukte5. Die als Intermediat gebildeten Additionsprodukte3 konnten in keinem Fall isoliert werden. Die Donor-bzw. Acceptorwirkung der Substituenten am Benzylidenrest beeinflußt maßgebend die Reaktivität am Azomethinkohlenstoff.相似文献
67.
68.
The high-pressure behavior of Li2CO3 is studied up to 25 GPa with synchrotron angle-dispersive powder X-ray diffraction in diamond anvil cells and synthesis using a multi-anvil apparatus. A new non-quenchable hexagonal polymorph (P63/mcm, Z=2) occurs above 10 GPa with carbonate groups in a staggered configuration along the c-axis—a=4.4568(2) Å and c=5.1254(6) Å at 10 GPa. Two columns of face-shared distorted octahedra around the Li atoms are linked through octahedral edges. The oxygen atoms are coordinated to one carbon atom and four lithium atoms to form a distorted square pyramid. Splittings of X-ray reflections for the new polymorph observed above about 22 GPa under non-hydrostatic conditions arise from orthorhombic or monoclinic distortions of the hexagonal lattice. The results of this study are discussed in relation to the structural features found in other Me2CO3 carbonates (Me: Na, K, Rb, Cs) at atmospheric conditions. 相似文献
69.
The UV and visible spectra of six model compounds were studied. These compounds can be considered as models of polyaniline in the reduced, cation radical, partially oxidized and oxidized forms. After treatment of a mixture of equal molar quantities of the reduced form (DPPD) and the oxidized form (QDIM) with acid, the following reaction was observed: DPPD(I)+QDIM(III)+2H+=2DPPD+(II) After similar treatment of the partially oxidized form (V) with acid, the radical cation salt formed. The UV and visible spectra of polyaniline in the reduced form, oxidized form and conductive form are similar to the spectra of DPPD, QDIM and DPPD+ or radical cation salt of V respectively. We propose that the polyaniline synthesized by chemical oxidation of aniline consists of oxidized and reduced repeat units. Upon protonation a redox reaction (or electron rearrangement) occurs and forms delocalized radical cations (polarons) in the polymer chain which are highly conductive. 相似文献
70.
Zn3V3O8 two-dimensional micro sheets are successfully synthesized by combination of solvothermal method and heat treatment. The Zn3V3O8 has better electrochemical performances after calcinations. 相似文献