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1.
Gary W. Breton Lauren A. Hahn Kenneth L. Martin 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(9):1208-1212
Tetrahydrotetrazoles are five‐membered‐ring heterocycles containing four contiguous saturated nitrogen atoms. Very few examples of such compounds have been reported in the literature. Our previous attempt at the synthesis of a member of this class of compound suggested that the N—N bonds may be more labile than expected. This finding raised the question as to whether the structures of any of the previously reported tetrahydrotetrazoles had been properly assigned. We have reproduced the synthesis of a reported tetrahydrotetrazole, namely 1,2‐di‐tert‐butyl 3‐phenyl‐1H,2H,3H,10bH‐[1,2,3,4]tetrazolo[5,1‐a]isoquinoline‐1,2‐dicarboxylate, C25H30N4O4, and have now confidently confirmed its structure via X‐ray crystallography. However, while sufficiently stable in the crystal phase, we discovered that it remains very labile in solution (having a half‐life of only 15 min at 20 °C in CDCl3). A tentative reaction pathway for its dissociation based on 1H NMR spectral evidence is provided. 相似文献
2.
The European Physical Journal E - The isothermal gas adsorption of two hexane isomers (n-hexane and cyclohexane) in the mesopores of MCM-41 silica have been investigated by small angle neutron... 相似文献
3.
Theresa J. Hermel-Davidock H. Sean Tang Daniel J. Murray Stephen F. Hahn 《Journal of polymer science. Part A, Polymer chemistry》2007,45(24):3338-3348
It has been found that by the addition of low concentrations of an amphiphilic block copolymer to an epoxy resin, novel disordered morphologies can be formed and preserved through curing. This article will focus on characterizing the influence of the block copolymer and casting solvent on the templated morphology achieved in the thermoset sample. The ultimate goal of this work is to determine the parameters that would control the microphase morphology produced. Epoxy resins blended with a series of amphiphilic block copolymers based on hydrogenated polyisoprene (polyethylene-alt-propylene or PEP) and polyethylene oxide (PEO), specifically, were investigated. In this article, the cure-induced order–order phase transition from the spherical to wormlike micelle morphology will also be discussed. It is proposed that the formation of the wormlike micelle structure from the spherical micelle structure is similar to the phase transition behavior that occurs in dilute block copolymer solutions as a function of the influence of the solvent on micelle morphology. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3338–3348, 2007 相似文献
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LetX,X
1,X
2,... be i.i.d. random vectors in d. The limit laws that can arise by suitable affine normalizations of the partial sums,S
n=X
1+...+X
n, are calledoperator-stable laws. These laws are a natural extension to
d
of the stable laws on. Thegeneralized domain of attraction of [GDOA()] is comprised of all random vectorsX whose partial sums can be affinely normalized to converge to . If the linear part of the affine transformation is restricted to take the formn
–B for some exponent operatorB naturally associated to thenX is in thegeneralized domain of normal attraction of [GDONA()]. This paper extends the theory of operator-stable laws and their domains of attraction and normal attraction. 相似文献
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A new technique, called modulated thermogravimetry, is introduced as a tool for obtaining continuous kinetic information for
decomposition and volatilization reactions. The approach makes use of an oscillatory temperature program to obtain kinetic
parameters during a mass loss. MTGA™ may be used under quasi-isothermal conditions to observe a single mass loss or may be
combined with linear heating rate or Hi-Res™ controlled rate thermogravimetry to scan from one mass loss region to another.
Results obtained are in agreement with those obtained by other kinetic methods.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Hydroxylamido(1-)-O,N Complexes of Molybdenum(VI) Containing Terminal Oxo, Sulfido, and Selenido Ligands. Crystal Structures of [MoO2(C5H10NO)2] and of [MoS2(C5H10NO)2] Molecular complexes of cis-dioxo-bis(hydroxylamido(1-)-O,N)molybdenum(VI) containing O,N-coordinated, N,N-substituted hydroxylamine ligands react with H2S in toluene substituting one or both terminal oxo groups yielding cis-oxosulfido- and cis-disulfido-bis (hydroxylamido(1-)-O,N) molybdenum complexes, respectively. With H2Se the corresponding cis-oxoselenido complexes are formed. The crystal structures of the two title compounds containing piperidine-N-oxide as ligands are described: The cis-disulfido complex crystallizes tetragonal in the space group D—I 4 2 m with four formula units per unit cell; the corresponding cis-dioxo complex crystallizes orthorhombic (D—P 212121; Z = 4). The 1H—nmr spectra and the UV-visible absorption spectra are reported. 相似文献
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