Ch 9 Notes

Ch 9 Notes - R C LG R R Nuc R C LG R R Nuc Electron rich...

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Unformatted text preview: R C LG R R ! + !- Nuc + R C LG R R + Nuc Electron rich reactant Nucleophile base Electron poor reactant Electrophile acid A group leaves in both, the more stable, the more readily it leaves B N : N B- + : Acid/Base and Substitution Reactions H O + + O H H O CH 3 O H H H O O CH 3 ! + !- H C Br H H ! + !- + H C Br H H + C N C N H O + + O H H O CH 3 O H H H O O CH 3 Acid-Base Reactions: H + Transfer from Acid to Base. Leaving Group Leaves as New Bond to H Forms Substitution Reactions: Nucleophile Attacks Electrophilic Center (C-X or C+). S N 2 or S N 1, Leaving Group Leaves while (or Before) Nucleohile Attacks Elimination Reactions: Loss of HX To Create π System. E 1 or E 2 , Leaving Group Leaves while (or Before) Base Attacks. KOtBu Br H H H Me Me H H Me Me OtBu + + + H KBr catalyst + H H H H H H H H H H H H Hydrogenation: Addition of Hydrogen Across a π Bond H C Br H H ! + !- + H C Br H H + C N C N Bronsted acid-base reaction: electron rich base attacks electron poor H Substitution reaction: electron rich nucleophile attacks electron poor carbon Addition reaction: electrons of π bond attacks electron poor H C C H H H H H Br + C C H H H H H + Br ! + !- ! + !- H Br + + O H H O H H H Br Old Knowledge New Knowledge Analogy Addition Reactions While a new reaction class, this section is largely a review of acid-base reactions, substitution reactions, elimination reactions, and stereochemistry. We start with a model of the π system of an alkene and the reverse of a reaction already discussed, a dehydration reaction, the elimination of water from a molecule. X and Y add to same side X and Y add to opposite sides top bottom Y R 1 R 2 R 3 R 4 R 1 R 2 R 3 R 4 + X Y X and/or Y R 1 R 2 R 3 R 4 X R 1 R 3 R 2 R 4 SYN ANTI Me Me H H H Me Me H H HO H OH + (cat) (cat) H-OH 2 H-OH 2 addition, acid cat. alkene hydration elimination, acid cat. alcohol dehydration Addition of water Addition of HBr Me Me H H H Me Me H H Br H Br + General Example: H Me H H H OH 2 + addition elimination H Br + addition elimination H Me H H H H Me H H + H H Me H H OH 2 H H Me H H + H H Me H H Br X Y X Y OH 2 Br Extension to Other Additions Br Br + Me Me H H H Me Me Br H Br X Y H Me Me Br H l r H Me Me Br H Br Br ! + !- l r :OH 2 H Me Me Br H OH 2 H Me Me Br H H 2 O + + H Me Me Br H OH H Me Me Br H HO :OH 2 1 1' 2 2'-H+-H+ PREVIOUSLY: What if Water is Present? parallel (lower energy) μ = +1/2 antiparallel (higher energy) μ = -1/2 Energy B o external magnetic field ! E ! E is the difference in energy between the two nuclear spin states. The Origin of the Nuclear Resonance Classical Physics: Resonance happens when you drive a harmonic oscillator at it’s fundamental frequency. In this case, amplitude can become (arbitrarily) large....
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This note was uploaded on 03/04/2010 for the course CHEM 322AL at USC.

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Ch 9 Notes - R C LG R R Nuc R C LG R R Nuc Electron rich...

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