Phenanthrene resonance energy

Benzene rings can also be fused in angular fashion, as in phenanthrene, chrysene, and picene. These compounds, while reactive toward additions in the center ring, retain most of the resonance energy per electron (REPE) stabilization of benzene and naphthalene. ... 

This treatment could be applied to anthracene and phenanthrene, with 429 linearly independent structures, and to still larger condensed systems, though not without considerable labor. It is probable that the empirical rule6 of approximate proportionality between the resonance energy and the number of benzene rings in the molecule would be substantiated. 

The resonance energies of fused systems increase as the number of principal canonical forms increases, as predicted by rule 6 (p. 35).75 Thus, for benzene, naphthalene, anthracene, and phenanthrene, for which we can draw, respectively, two, three, four, and five principal canonical forms, the resonance energies are, respectively, 36, 61, 84, and 92 kcal/mol (152, 255, 351, and 385 kJ/mol), calculated from heat-of-combustion data.76 Note that when phenanthrene, which has a total resonance energy of 92 kcal/mol (385 kJ/mol), loses the 9,10 bond by attack of a reagent such as ozone or bromine, two complete benzene rings remain, each with 36 kcal/mol (152 kJ/mol) that would be lost if benzene was similarly attacked. The fact that anthracene undergoes many reactions across the 9,10 positions can... 

Anthracene and phenanthrene are isomeric compounds with three fused benzene rings. Their resonance energies are calculated to be 84 kcal/niol (352 kJ/mol) and 92 kcal/mol (385 kJ/mol), respectively. Many other polycyclic aromatic hydrocarbons are known. Chrysene and benzo[a]pyrene are typical examples. 

Reaction of phenanthrene with Br2 produces C14HinBr2. This reaction occurs at the bond with the most double bond character. Show the structure of this product. Qualitatively compare the amount of resonance energy lost on formation of this product to the amount that would be lost if the addition were to occur at a different bond. 

Enantiopure epoxides (3/ ,4Y)-dibenz[ 7, ]anthracene 3,4-oxide and (3iJ,4Y)-phenanthrene 3,4-oxide were synthesized via involved routes and were observed to spontaneously racemize. This racemization of arene oxides is in accordance with perturbation molecular orbital predictions based on resonance energy considerations, and presumably occurs via an electrocyclic rearrangement to the corresponding (undetected) oxepine tautomer (Scheme 17) <2001J(P1)1091>. 

Phenanthrene is best represented as a hybrid of the five canonical forms 20-24. It has a resonance energy of 380 kJ mol and is more stable than anthracene. In four of the five resonance structures, the 9,10-bond is double and its length is about the same as an alkenic C=C bond. The numbering system for phenanthrene is shown in 20. Five different mono-substituted products are possible. 

ProMem 30.20 How much resonance energy would be sacrificed by oxidation or reduction of one of the outer rings of anthracene Of phenanthrene ... 

The phenanthrene and chrysene structures could be derived from cyclic terpenoids such as abietic acid, sterols, and hopanes (34). Although tri-phenylene, which has the highest resonance energy among the four-ring catacondensed PAHs (35), was not present in the SRC II HD at a significant level, this compound was found in the coal tar which is a higher temperature... 

Apply the SRT method to phenanthrene and to styrene in order to verify the resonance energies listed in Table 4.5. 

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