Outback1850
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Alright looking for insight
Im quite comfortable manipulating oubjects in 3d space. I would like to know how expirenced seasoned chemists actually work, take benzene for example
a planer eqilateral hexagon sp2 hybridized now all the orbitals are superimposed and this is where i get into trouble I imagine this but is this
actually a worth wild and consctructive way to think any responce would be appreciated im just trying to develope an intuitive sence for things thanks
in advance
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j_sum1
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Not sure what your question is. Nor why two of your cabons have 5 electron clouds.
This stuff is well understood and fully described in good organic chem textbooks. You might look in the forum library.
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12thealchemist
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I think the "5" electron clouds are supposed to be three sp2 hybridised orbitals, and one pure p orbital perpendicular to the
sp2 orbitals.
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stamasd
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I tend to mentally represent the benzene structure as a ring covered on both sides by fuzzy discs. The ring is the carbon backbone, and the fuzzy
discs the shared electrons.
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Sulaiman
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some nice explanations and diagrams
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Che
mical_Bonding/Fundamentals_of_Chemical_Bonding/Electrostatic_Potential_maps
CAUTION : Hobby Chemist, not Professional or even Amateur
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Tsjerk
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From what I understand the shared orbitals are fully delocalized and truly form two (here blue and yellow) donuts.
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Outback1850
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Thanks for the quick replys. My question is, what should i imagine when thinking of molecules; spacefilling diagrams, molecular orbitals or does a
pragmatist despence with this sort of thing and go with a more 2dimensional style?
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j_sum1
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You think of an aromatic ring as a planar, remarkably stable structure.
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Tsjerk
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Quote: Originally posted by Outback1850  | | Thanks for the quick replys. My question is, what should i imagine when thinking of molecules; spacefilling diagrams, molecular orbitals or does a
pragmatist despence with this sort of thing and go with a more 2dimensional style? |
As a pragmatist, I would say the 2D model is fine most of the time, as long as you remember a benzene ring doesn't have three double and three single
bonds, but more a donut as in the figure. Or you could even see them separately as when drawing reaction mechanisms involving these electrons. For
example :
[Edited on 24-12-2018 by Tsjerk]
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andy1988
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This 2D/3D model talk reminds me of an interesting article I read a while ago:
| Quote: | "Chemists have long had to choose between these two stalwart reaction classes, both presenting marked advantages, but also shortcomings," say Baran,
holder of the Darlene Shiley Chair in Chemistry at Scripps Research. "Combining these two reactions solves this dichotomy by leveraging the strengths
of both to provide a reliable and versatile strategy for producing complex molecules."
C-C cross coupling, a bond-forming method that is highly reliable and controllable, has long been the method of choice in the pharmaceutical industry
for synthesizing the skeletons of drug candidates. However, the method is limited in its ability to construct complex three-dimensional architectures,
resulting in a disproportionate number of flat drug molecules—a characteristic that potentially presents a hurdle to creating new drugs for
increasingly difficult biological targets. Cycloaddition reactions, in contrast, offer the ability to build highly complex 3-D shapes in a single
step, but different types cycloaddition reactions required highly customized preparation, which limited their utility. [1]
[Edited on 24-12-2018 by andy1988] |
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stamasd
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I prefer the benzene ring representation without double links:
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Dr.Bob
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In simple benzene, I do think of the carbons as all equivalent, and the electrons as a donut on both sides of the ring. To really understand
chemistry, you then need to think of each carbon based on the electron density on it. So for carbon with a "H" on it, there is an "average" amount
of electron density on the carbon. If the carbon has an alkyl chain or methoxy, that will donate more electrons to the carbon, so the donut is
thicker on that carbon. If the carbon has a nitro on it, or another element that is more electronegative than carbon, it will suck electrons away
from it, and the carbon will have a small donut of electrons near it. So that controls which carbons will react with various other reagents.
No matter what reactions you memorize, the key to organic chemistry is to remember that like charges repel and opposites attract. That, and sterics
control most reactivity and where molecules react. And I always liken bulky sterics to fat people trying to procreate. The bigger you are, the
less easy it is to do that. A tert-butyl group works the same way, crowding out any courting reagents from coming close to the carbon it is on.
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CharlieA
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I always said that sex could be an analogy for anything and everything!
Merry Christmas
Charlie
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