Organic Help

[nc2tarheels]

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For the Organic section, what seems to be the main focus'? I watched all of Chad's Videos and took notes, all of which I'm studying. However, are there certain things that we can disregard (since Chad, himself, said that the mcat is more detailed). For example, should I know all of the RXN's that are named after people, or are there certain ones that I can disregard?

By the way, can someone explain #89 on the sample test to me (Organic Section)? Thanks
https://www.ada.org/oat/oat_sample_test.pdf

 

[BandanaGuy]

For the Organic section, what seems to be the main focus'? I watched all of Chad's Videos and took notes, all of which I'm studying. However, are there certain things that we can disregard (since Chad, himself, said that the mcat is more detailed). For example, should I know all of the RXN's that are named after people, or are there certain ones that I can disregard?

By the way, can someone explain #89 on the sample test to me (Organic Section)? Thanks
https://www.ada.org/oat/oat_sample_test.pdf

First of all, imagine deprotonating the imidazole. This will leave the N atom with 2 sigma bonds, and 2 lone pairs.

Aromatic compounds have ODD numbers of electron pairs, must be planar in nature (SP2), and must be a ring with conjugation.

The protonated imidazole has 2 pi bonds, with an EVEN number of electron pairs in conugation. When all other rules are followed, but with EVEN pairs rather than ODD, the compound is considered to be anti-aromatic. These are VERY unstable.

Now going back to the deprotonation, the N now has 2 lone pairs, however the new electron pair in the P orbital overlaps with the others in the ring. This now provides the compound with 3 (odd) electron pairs in conjugation. This turns the imidazole from an unstable anti-aromatic, into a very stable aromatic ring. This is why it is acidic, and conversely very very weakly basic, as it would not want to lose aromaticity.

 

[nc2tarheels]

Thanks a lot!!!!