Nucleophilic Substitution Flashcards
Alkyl Halide =
Organic molecules containing a halogen atom X, bonded to an sp2 or sp3 hybridized carbon atom
Mechanism =
A set of physical changes and atomic movements on a molecular level that occurs as a reaction goes from reactants to products.
A mechanism is made up of one or more elementary reactions
Why is backside attack favored?
Severe repulsion between lone pairs on nucleophile and leaving group
What 4 factors affect the rates of SN2 rxn
- The structure of the substrate (alkyl halide)
- The concentrations and reactivity of the nucleophile
- The effect of the solvent
- The nature of the leaving group
Steric hindrance of SN2 rxn
1°
Unhindered
SN2 favored
Steric hindrance of SN2 rxn
2°
Partially hindered
SN2 if groups are small
Steric hindrance of SN2 rxn
3°
Sterically hindered
SN2 not possible
Can SN2 occur on tertiary (3°) carbons?
No
Nucleophilicity decreases to the __ of the periodic table
Right
Nucleophilicity increases as you go ___ the periodic table
Down
Nucleophilicity increas with __ charge
Negative
Smaller anions are more tightly solvated than larger atoms.
How does this affect a nucleophile?
Solvation weakens a nucleophile because it impedes its ability to attack an electrophile
What is the preferred solvent for SN2 rxn
Aprotic
What does aprotic mean
Has no hydrogen bound to O,N,F
What is the result of using an aprotic solvent
Anions are freer to react because they are unencumbered by solvent molecules
