from my understanding mr jonathan orsay has never taken these classes... also, through some research that my friends and i did, we found that 1,3,5,-hexatriene is NOT benzene, there are some subtleties. orsay is trying to make a point about benzene and its aromaticity but its not worded very well. also, in EK ochem, they have a rule for determining aromaticity, but they leave out some important stuff that i remembered from my ochem lecture ie, every ring atom must be sp2 hybridized. leaving that particular information out makes me feel VERY weary about EK. i'd say ~95% of their stuff is really good review, but they leave you feeling uncertain and that's not a feeling you want going into the MCAT. with that said, i immediately sent my money order in yesterday, i'm excited for TBR books and hope they live up to the hype.
I think the EK author often didn't really have an in depth knowledge about the material, which explains the short answers and missing points here and there.
As for 1,3,5-cyclohexatriene, it doesn't exist. It is a theoretical molecule used to compared to benzene. It's basically a calculated structure based on heats of hydrogenation of what benzene would generate if it were not aromatic. Basically it's
benzene, if benzene wasn't aromatic. I think that is one of those typical BS things you see with EK. Maybe it's the author trying to show how smart he is or maybe it's just the author pilfering a cool topic and changing the wording to make it his own, without really getting the concept completely. Either way, I still like EK for some things.
Here's what I found on line for it:
"The geometry and energy of 1,3,5-cyclohexatriene,
the reference molecule for the determination of the extra stabilization of benzene, have been calculated using an
Ab Initio Valence Bond method. The theoretical resonance energy, according to Dewar, calculated as the energy difference between two-structure benzene and single-structure 1,3,5-cyclohexatriene, both with completely optimized geometries and orbitals, is only −12.05 kcal/mol. Resonance energies of −25.37 (local orbitals), −19.82 (delocal orbitals) and −44.13 (breathing orbitals) kcal/mol are found using the Pauling definition. The concept of the vertical resonance energy, however, is proven to be not tenable beyond a minimal basis."
Ab Initio = make believe so some computer geek can get a chemistry degree.