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Neutral alternant hydrocarbons

The cyclooctatetraene ligand is generally introduced in one of two ways either as the neutral hydrocarbon or alternatively via initial reduction to the aromatic (10tc) dianion by treatment with a Group 1 metal (Figure 7.51). [Pg.179]

In a neutral, alternant hydrocarbon or hydrocarbon-radical, atomic charges on the various carbon-atoms which are involved in the conjugation are, in the ground state, all precisely unity . [Pg.53]

Callis PR, Scott TW and Albrecht AC (1983) Perturbation selection rules for multiphoton electronic spectroscopy of neutral alternant hydrocarbons. J Chem Phys 78 16-22... [Pg.186]

For the ground state of a neutral alternant hydrocarbon, all the Huckel tt-electron charges q are 1. (For the proof, see Lowe, Appendix 5.)... [Pg.645]

Theorem % The eigenvalues of an alternant are symmetrically distributed about the zero energy level. The corresponding eigenfunctions also show a mirror relationship, except for a difference of sign (only) in every other atomic orbital coefficient. The total charge density at any carbon atom in the neutral alternant hydrocarbon equals unity. [Pg.97]

For the ground state of a neutral alternant hydrocarbon, all the Hiickel rr-electron... [Pg.616]

A5-2 Demonstration That Electron Densities Are Unity in Ground States of Neutral Alternant Hydrocarbons... [Pg.602]

Not considered were the simple homodesmotic reactions which have been used here. The HSFs calculated from eq 14 for neutral alternant polynuclear hydrocarbons using only ethylene and butadiene as the reference species appear in Table 2. [Pg.11]

This last result is an example of an important general result. In a neutral alternate hydrocarbon (AH) the bond order between two atoms which are either both starred or both unstarred (referred to as being of like parity) is... [Pg.49]

Two techniques, electrochemical reduction (section IIl-C) and Clem-mensen reduction (section ITI-D), have previously been recommended for the direct reduction of isolated ketones to hydrocarbons. Since the applicability of these methods is limited to compounds which can withstand strongly acidic reaction conditions or to cases where isotope scrambling is not a problem, it is desirable to provide milder alternative procedures. Two of the methods discussed in this section, desulfurization of mercaptal derivatives with deuterated Raney nickel (section IV-A) and metal deuteride reduction of tosylhydrazone derivatives (section IV-B), permit the replacement of a carbonyl oxygen by deuterium under neutral or alkaline conditions. [Pg.171]

The apparent rate of hydrolysis and the relative abundance of reaction products is often a function of pH because alternative reaction pathways are preferred at different pH. In the case of halogenated hydrocarbons, base-catalyzed hydrolysis will result in elimination reactions while neutral hydrolysis will take place via nucleophilic displacement reactions. An example of the pH dependence of hydrolysis is illustrated by the base-catalyzed hydrolysis of the structurally similar insecticides DDT and methoxy-chlor. Under a common range of natural pH (5 to 8) the hydrolysis rate of methoxychlor is invariant while the hydrolysis of DDT is about 15-fold faster at pH 8 compared to pH 5. Only at higher pH (>8) does the hydrolysis rate of methoxychlor increase. In addition the major product of DDT hydrolysis throughout this pH range is the same (DDE), while the methoxychlor hydrolysis product shifts from the alcohol at pH 5-8 (nucleophilic substitution) to the dehydrochlorinated DMDE at pH > 8 (elimination). This illustrates the necessity to conduct detailed mechanistic experiments as a function of pH for hydrolytic reactions. [Pg.494]


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See also in sourсe #XX -- [ Pg.602 ]




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