Hydrocarbon, xvii

Inspection of Table 2 reveals that all those molecules that suffer a molecular-symmetry reduction in the ground state possess (E2 — E1) values considerably larger than the critical value, so that they should have a fully-symmetrical nuclear configuration in their first excited states. On the other hand, there are cases where a molecule has an ( , — Eg) value significantly higher than the critical value, but has a relatively smaller (Ej— i) value. The ( 2 i) value of the pentalene dianion (I ) is of the same order of magnitude as the critical value and those for the peri-condensed nonalternant hydrocarbon, XVII, the fulvalenes, XXI, XXII and XXIII, and the dianions, IVand VII are significantly smaller than the critical value ( 0.6eV). 

A typical failure of the Hiickel method in the case of non-alternant systems is its prediction that all the hydrocarbons XVII-XXIII should be aromatic of these only azulene (XXII) shows aromatic properties. 

PHYSICAL PROPERTIES OF HYDROCARBONS. XVII. C4-C5 BRANCHED HYDROCARBONS. 

Using the same method as described in II.B, Binsch and Heil-bronner have examined the second-order bond distortion in the lowest excited states of nonalternant hydrocarbons (I, IV—VII, X, XI, XIII — XV and XVII), and have shown that, of the molecules examined, only VI and XVII suffer a molecular-symmetry reduction in the lowest... 

The reaction product XVII on decomposition with water exchanges the boron atom for hydrogen and gives a saturated hydrocarbon XVIII and on oxidation by H202 in alkaline medium forms an alcohol XIX. 

Carpenter CP et al Petroleum hydrocarbon toxicity studies. XVII animal response to nonane. Toxicol Appl Pharmacol 53, 1978... 

Whereas the parent difluoro-vinylcyclopropane isomerizes to difluorocyclopentene under pyrolysis conditions, the corresponding alkyl compounds also lead to acyclic dienes. The activation energy for the difluoro-vinylcyclopropane isomerization is practically identical with that observed for the unsubstituted hydrocarbon [211, 212], If the alkyl group is oriented cis to the vinyl substituent, only dienes are isolated, and the process occurs at much lower, temperatures. Presumably these stereoisomers rearrange by a different mechanism (a 1,5-homodienyl hydrogen shift [213]). When the dichlorocyclopropane XVII is subjected to flash vacuum pyrolysis it isomerizes to 9,9-dichloro-bicyclo[5.3.0]dec-l(7)-ene [214],... 

Stage 1, if assumed to be irreversible and taking place on a nearly free surface, explains the reaction kinetics [Eq. (274)] in the high temperature range (82). Stages 2 and 3 correspond to the notions of Eidus and Zelinskii (86,87) on the mechanism of catalytic synthesis of hydrocarbons from CO and H2. Stages 5 and 6 reproduce the mechanism of reaction (273) that will be discussed in detail in Section XVII. 

The it energy of a non-classical conjugated hydrocarbon can be compared directly with that of a classical analogue by the PMO method.14 Consider an even monocyclic polyene. This can be formed by fusion of methyl with an odd AH with one atom less. These components can also be fused to form an acyclic polyene. Comparison gives the aromatic energy of the cyclic system by difference. In this way we find that rings with An + 2 atoms are more stable, and those with An atoms less stable, than analogous acyclic compounds. The same method can be used for the bicyclic systems XVII, XIX, XXI, XXII, XXIII. The procedure is indicated below... 

Associated compounds conduct heat better than do non-H bonded substances, and Table 2-XVII illustrates some trends and magnitudes. The alcohol series probably reflects the interference of longer hydrocarbon chains and the increasing difficulty of rotation for larger molecules. Water is compared with GS2 because compounds nearer its molecular weight (e.g., methane) are gases at 30 G. 

Dehydrogenation of the lactone acid (XVII) with palladium-charcoal yielded 2-ethylnaphthalene and under the same conditions the acid X afforded 2-ethyl-3-methylnaphthalene. The formation of these two hydrocarbons disproved the earlier hypotheses that the carbonyl group of himbacine was attached to a tertiary carbon atom and that the ethyl groups of 2-ethyl-6-methylpyridine and 2-ethyl-3-methylnaphthalene, isolated from the selenium dehydrogenation of himbacine, were derived from the same structure in the alkaloid. Moreover, since the results of the Hofmann degradation and the oxidation experiments had shown that the 6-(l,2-dimethylpiperidyl)-vinyl group was attached to a decalin residue by reason of the formation of the C-13 ketones, it only remained to establish the point of attachment. For this purpose the carboxyl group... 

Balaban, A.T. (1972) Chemical graphs. XVII (Aromaticity. X). Cata-condensed polycydic hydrocarbons which fulfil the Hiickel rule but lack closed electronic shells. Rev. Roum. Chim., 17, 1531-1543. 

Liquid fuels equivalent to existing commerical products (kerosine, diesel, jet fuel, high octane gasoline) can be produced using biomass type feedstocks. A summary of potential products and operating conditions is shown in Figure XII and Table XVI. The present status of the project is indicated in Table XVII. Liquid hydrocarbon yields of 50-100 gal/ton of feedstock (dry, ash free) are to be expected. The process is characterized by ... 

Figure 8-19 ESR hyperfine splitting constants in gauss versus for the highest occupied MO of the radical. All data are from hydrocarbon radical anions or cations of alternant or nonaltemant type. ( ) Anion radical (x) cation radical. Uncertain assignments (o) anion ((g)) cation. The two correlation lines are merely sight fitted to the anion and cation points separately and suggest that Q for cations should be larger than for anions. Points thought to result from negative spin density are underlined. [See Tables I, III, VIII, XII, XIII, XIV, XV, XVI, XVII, XVIII of Gerson and Hammons [9], and Table 6.2 of Streitwieser [7] for data plotted here.]...

---