Atoms components

Heterocyclics of all sizes, as long as they are unsaturated, can serve as dipolarophiles and add to external 1,3-dipoles. Examples involving small rings are not numerous. Thiirene oxides add 1,3-dipoles, such as di azomethane, with subsequent loss of the sulfur moiety (Section 5.06.3.8). As one would expect, unsaturated large heterocyclics readily provide the two-atom component for 1,3-dipolar cycloadditions. Examples are found in the monograph chapters, such as those on azepines and thiepines (Sections 5.16.3.8.1 and 5.17.2.4.4). [Pg.28]

Nonstoichiometric Compounds Intrinsic defects are stoichiometric defects (i.e., they do not involve any change in overall composition). Defects can also be nonstoichiometric. In the case of extrinsic defects where the host crystal is doped with aliovalent impurities, the solid so formed is a nonstoichiometric compound because the ratio of the atomic components is no longer the simple integer. There is also... [Pg.420]

Ring syntheses of 1,2,4-oxadiazoles from a five-atom component 270... [Pg.243]

The cyclization of the five-atom component O-acylated amidoximes 204 leads to 1,2,4-oxadiazoles via C-N bond formation as shown in Scheme 30. The requisite O-acylated amidoximes 204 are accessed via the reaction of an amidoxime with an activated carboxylic acid or a carboxylic acid derivative. Often the O-acylated amidoxime 204 is not isolated and the cyclization is either spontaneous or occurs in a one-pot process, and these approaches are dealt with in Section 5.04.9.1.2 as syntheses from a one-atom component and a four-atom component. In this section, only those methods in which the O-acylated amidoxime 204 is isolated and cyclized in a separate step are dealt with. [Pg.271]

Ring syntheses of 1,2,4-oxadiazoles from a one-atom component and a four-atom component 5.04.9.1,2(i) Syntheses from amidoximes and carboxylic acids and their derivatives... [Pg.272]

The reaction of an amidoxime 206, the four-atom component N-C-N-O, with a carboxylic acid derivative constitutes the historically most used <1984CHEC(6)365, 1996CHEC-II(4)179> entry into the 1,2,4-oxadiazole nucleus, and this approach has continued to be popular since it was reviewed in CHEC-II(1996). The reactions discussed in this section proceed, as discussed in Section 5.04.9.l.l(iii) (see also Scheme 30), via a nonisolable acylated amidoxime. [Pg.272]

The intermediate acylamidine 244 functions as the three-atom component in reaction with hydroxylamine to give the [l,2,4-oxadiazol-5-yl]pyrazole 245, where the intermediate acylamidine 244 was obtained in good yield from reaction of the corresponding amide 243 with dimethylacetamide-dimethyl acetal (Scheme 37) <1999JME2218>. [Pg.281]

Cyclopropyl imines can be used as five-atom components in intermolecular [5 + 2]-cycloaddition reactions with dimethylacetylene dicarboxylate (DMAD) (Scheme 14).45 In this hetero-[5 + 2]-cycloaddition reaction, dihydroaze-pines are constructed from simple, readily available starting materials. The cyclopropyl imines can be preformed or made in situ by the condensation of cyclopropyl carboxaldehydes and amines. Although, thus far, DMAD is the only... [Pg.611]

The palladium-catalyzed trimethylenemethane reaction with tropanones was reported in 1987 by Trost and Seoane and is the first example of a [6 + 3]-cycloaddition.130 Chromium-mediated [6 + 3]-cycloadditions of two types have been described-one in which the chromium complex activates the six-carbon component and one in which the chromium complex activates the three-atom component. An example of the first type involves the reaction of a cycloheptatriene-Cr(CO)3 complex with azirines to give cyclic imines in moderate yields (Scheme 40).131... [Pg.624]

Many binary inorganic phases with a significant composition range can be listed1 (Table 4.3). Apart from binary compounds, ternary and other more complex materials may show nonstoichiometry in one or all atom components. [Pg.143]

J. R Anderson and C. Lebiere. The Atomic Components of Thought. Lawrence Erlbaum Associates, 1998. [Pg.364]

When the solution is formed in the places of atom-components contact, the unified electron density has to be established. The dissolving process is accompanied by the redistribution of this density between valence areas of both particles and transition of some electrons from external spheres to the neighboring ones. [Pg.95]

It is obvious that if electron densities in free atom-components of the solution at the distances of orbital radius r, are similar, the transition processes between boundary atoms of particles are minimal thus favoring the solution formation. [Pg.95]

Other data are not less important initial value of PE-parameter of 2S2-orbital of magnesium atom gives from PE-parameter (table 3) of radical (O-H) a=8.24 % and p 77-82 %. This p value can increase to even 100 % under the light action due to minor changes in dimensional characteristics of atoms-components. Absolute difference of these P-parameters equals 0.43 eV, thus corresponding to the changes in the scale of potentials during the synthesis of ATP. [Pg.96]

In particular, electron transfer results in that phosphoric acid molecules present in ATP, NADP and NADPN contain oxygen atoms in the form of O". Spatial-energy interactions (including isomorphic) are objectively expressed both at similar and opposite electrostatic charge of atoms-components. Such interactions can also take place between two heterogeneous atoms, if only their PE-parameters are roughly equal, and geometric shapes of orbitals are similar or alike. [Pg.98]

Such approximate equality of PE-parameters and geometric similarity of shapes of orbitals of atoms-components shows that actual degree of their interaction p= ()() %, thus... [Pg.98]

During the formation of solution and other structural interactions the same electron density must be formed in the areas of contact of atoms-components. This process is accompanied by the redistribution of electron density between valence zones of both particles and transition of a part of electrons from some outer spheres into neighboring ones. Apparently, spanning electrons of atoms do not participate in such an exchange. [Pg.109]

Apparently, with the closeness of electron densities in free atoms-components, the transition processes between boundary atoms of particles will be minimum, thus favoring the formation of new structure. So, the evaluation of the degree of structural interactions in many cases comes to the comparative evaluation of electron density of valence electrons in free atoms (on averaged orbitals) participating in the process. [Pg.109]

Following this methodology the mutual solubility of atoms-components was evaluated in many (over a thousand) simple and complex systems. The calculation results agree with reference and experimental data. [Pg.109]

Complete 100% isomorphism, complete isomorphous replacement of atoms-components ... [Pg.111]

The focus of our analyses and experimental procedures has been upon identification and quantitative determination of the atomizer component per se. Greater emphasis is placed upon the actual workplace dust level when the atomizer component has been removed by engineering controls or when it has been subtracted. [Pg.106]

In some cases, the workplace dust level is below the applicable PEL for cotton dust when the atomizer component is excluded. [Pg.106]

In some cases, the atomizer component is much larger than the workplace dust levels x. In this case it is necessary to establish that the applicable ERF s for normal and subtracted conditions are the same. [Pg.109]

Projection of the density matrix onto the internal basis, which is, due to the way the internal basis is constructed, no extra approximation, and build the full Coulomb matrix. A further approximation can be made by calculating only the intra-atomic components of this matrix, which is not expected to produce a serious loss in accuracy, since V l Ic is only large near the nuclei. We will refer to these alternatives as the full and atomic Coulomb ZORA option. Of course these two options are equivalent in the atomic calculations presented in the next section. [Pg.255]

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