O-formals

Angle, S. R. Amaiz, D. O. Formal [3 + 2]cycloaddition of henzylic cations with alkenes. 

A number of Lewis base adducts of diorganosilylenes have been observed by electronic spectroscopy in frozen matrices (see Section V.A)115. The silylene-donor adducts of ethers, tertiary alcohols, tertiary amines and sulfides were found to revert to silylenes upon warming, but primary and secondary alcohol adducts underwent rearrangement to the H—O formal insertion products (equation 55). 

Charge neutrality is also responsible for the increased catalytic activity of some metal oxides. This is the case when MgO is substitutionally doped with lithium. Since the only possible ionic state for lithium is Li, an adjacent oxygen ion must be O (formally). Since it does not have a closed shell electronic configuration, O is much more chemically reactive than O, and it is believed that the unique catalytic properties of Li-doped MgO result from the presence of a Li O site [10]. This and other defects in MgO are discussed further in Chap. 3. 

Chem. Descrip. o-Formal with isothiazolinones and Mergal BCM Uses Preservative for rheology modifiers, inks, textile coatings and spinning baths, color concentrates, adhesives, fountain sol ns., and prods, with extended shelf life or exposed to environment Features In-can preservation stable to 100 C enhanced fungicidal and bactericidal activity Properties Amber clear liq. 

Chem. Desaip. o-Formal with isothiazolinones Uses Preservative for latex dispersions with residual redox agents, emulsion paints, caulks, sealants, adhesives, pigment pastes, rheology modifiers, stucco, and plasters... 

Object Management Group A UML profile for Modeling and Analysis of Real Time Embedded Systems (MARTE) (November 2009), vl.O, formal/2009-11-02... 

Nitrogen with 4 covalent bonds has a formal charge of+1 / O Formal charge 15-4-0-10 =+1... 

However, it is easily shown that if the mother wavelet is located in the frequency domain "around"/o (fig 8), then the wavelet a.b(t) is located around f(/a. That is to say, by the mean of the formal identification f = fata it is possible to interpret a time-scale representation as a time-frequency representation [4]. 

Jones R O 1987 Molecular calculations with the density functional formalism Advances in Chemicai Physics vol LXVIl, ed K P Lawley (New York Wiley-Interscience) pp 413-37... 

Gunnarsson O and B I Lundqvist 1976. Exchange and Correlation in Atoms, Molecules, and Solids by the Spin-density-functional Formalism. Physical Review B13.-4274-4298. 

There were two schools of thought concerning attempts to extend Hammett s treatment of substituent effects to electrophilic substitutions. It was felt by some that the effects of substituents in electrophilic aromatic substitutions were particularly susceptible to the specific demands of the reagent, and that the variability of the polarizibility effects, or direct resonance interactions, would render impossible any attempted correlation using a two-parameter equation. - o This view was not universally accepted, for Pearson, Baxter and Martin suggested that, by choosing a different model reaction, in which the direct resonance effects of substituents participated, an equation, formally similar to Hammett s equation, might be devised to correlate the rates of electrophilic aromatic and electrophilic side chain reactions. We shall now consider attempts which have been made to do this. 

This equation is formally similar to the p+(T+ relationship, Sf being related to p+, and b being a parameter whose value depends on the values of cr+ for meta- and ara-methyl groups b = o-+/(cr+ — o-+)]. 

Annelation increases the complexity of the spectra just as it does in the carbocyclic series, and the spectra are not unlike those of the aromatic carbocycle obtained by formally replacing the heteroatom by two aromatic carbon atoms (—CH=CH—). Although quantitatively less marked, the same trend for the longest wavelength band to undergo a bathochromic shift in the heteroatom sequence O < NH < S < Se < Te is discernible in the spectra of the benzo[Z>] heterocycles (Table 17). As might perhaps have been anticipated, the effect of the fusion of a second benzenoid ring on to these heterocycles is to reduce further the differences in their spectroscopic properties (cf. Table 18). The absorption of the benzo[c]... 

These compounds are usually written in the unionized form as in (8 Z = NH, NR, O, S). Canonical forms of types (9) or (10) are important, i.e. these compounds can also be considered as betaines formally derived from azolium ions. Many compounds of this type are tautomeric and such tautomerism is discussed in Section 4.01.5.2. 

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