Valence Indices Research Articles

Relations between free valence index, stabilization energy of atom and total ?-electron energy in unsaturated molecules

Linear relations were established between the free valence index and the stabilization energy of the atom.

Photocyclization reactions of aryl polyenes—VI: The photocyclization of 1,4-diaryl-1,3-butadienes

Calculations by the Simple Hückel Molecular Orbital (SHMO) method of the sum of the free valence indices in the first excited state (ΣF*) of the terminal atoms concerned in the photocyclizations of 1,4-diaryl-1,3-butadienes give values which are accurate guides in predicting the photoproducts obtained in the photocyclization-oxidation reactions of 1,4-diaryl-1,3-butadienes. Irradiation of 1,4-di-α-naphthyl-1,3-butadiene gave 1-α-naphthylphenanthrene. The photocyclization-oxidation of 1,4-di-β-naphthyl-1,3-butadiene gave a mixture of 4-β-naphthylphenanthrene and naphtho[1,2-e]pyrene. It was shown that the naphtho[1,2-e]pyrene arose from a subsequent photocyclization-oxidation reaction of the first-formed 4-β-naphthylphenanthrene. Irradiation of 1-α-naphthyl-4-β-naphthyl-1,3-butadiene gave 4-α-naphthylphenanthrene. The structures of the photoproducts were confirmed by independent syntheses. All the photoproducts obtained from the irradiation of 1,4-diaryl-1,3-butadienes were the ones predicted by the SHMO calculations.

Free valence indices of carbon in heterocyclic compounds

Free valence indices of carbon in heterocyclic compounds

Les facteurs électroniques dans la réaction de formylation des hydrocarbures aromatiques condensés

A study of the formylation of several condensed aromatic hydrocarbons shows that within each class of such hydrocarbons, the reactivity increases with the free valence index of the position to be substituted. This rule makes it possible to predict not only the behaviour of the hydrocarbons themselves, but also that of the various positions inside each molecule. These considerations are applied to tribenzo[a,c,j]naphthacene and phenanthro[2,3-a]pyrene, each of which gave a single aldehyde, in accordance with the theory, the formylation site predicted being position 17 in the first case, and position 6 in the second.

An Infrared Spectroscopic Study of the Carbonyl Stretching Frequency in a Group of Ortho and Para Quinones

This paper reports on an experimental study of the C=O stretching vibration frequency in a large number of quinonoid compounds, both substituted and unsubstituted. For nonsubstituted ortho and para quinones, relationships between the carbonyl frequency and (a) the number of fused rings, (b) the oxidation-reduction potential, and (c) the index of free valence on the parent hydrocarbon are pointed out and discussed. It is shown that for a six-atom quinonoid ring the C=O frequency is, to a first approximation, a function of the C=O bond order. For substituted quinones, the variation in the carbonyl frequency is related to the induction effect of the substituent in the same way as is the variation in oxidation-reduction potential. Certain hydroxy-substituted quinones show spectral anomalies which do not seem to fit into the usual category of hydrogen bonded compounds.

Molecular Orbital Treatment of Tropolone

Abstract The molecular orbital treatment was carried out on tropolone. The π -electron distribution, interatomic distances, free valence indices and dipole moment were derived. It was found that the dipole moment is very high (second approximation value of π -electron moment = 4.4 D) owing to resonance and lies along a line from the center of the ring to the middle point between two O-atoms with its positive end at the ring and that the resonance energy amounts to about 1.5 times that of benzene in general agreement with experimental results. It was shown that the substitution by electrophilic atoms and groups are most liable to occur at C-atoms 7, 3 and 5.

Addition of osmium tetroxide to dinaphthylethylenes.

IT has been claimed by Pullman1 that the extent of conjugation of a given substituent with an aromatic ring system is determined by the electron density (index of free valence) at the position of substitution. Using the customary resonance terminology, this conclusion may be illustrated by the fact that for 1-substituted naphthalenes there are seven possible structures in which the substituent is linked to the ring by a double bond, but that for 2-substituted naphthalenes there are only six such structures. If X is a substituent, the C—X bond in 1-substituted naphthalenes should therefore have greater double-bond character than the corresponding bond in 2-substituted naphthalenes, and examination of the dipole moments of the halogenated naphthalenes confirms that this is the case2. Furthermore, examination of the ultra-violet absorption spectra of suitable substituted compounds shows that there is a correlation between the magnitude of the bathochromic shift, the extent of conjugation, and the index of free valency at the position of substitution3. The experimental evidence supporting Pullman's generalization is not, however, extensive, and the present work was undertaken to provide further information of interest.