Alkanes Flashcards
SN1 Reactions: Steps: Solvent: Priority: Rate: Products: Nucleophile:
2 Steps Favoured in Polar Protic Solvents tertiary>secondary>primary>methyl rate= k[RL] Racemic products Solvent is often the nucleophile (weak)
SN2 Reactions Steps: Solvent: Priority: Rate: Products: Nucleophile:
1 Step Favoured in polar aprotic solvents methyl>primary>secondary>tertiary rate=k[Nu][RL] inverted stereochemistry and optically active Favoured with strong nucleophile
Nucleophiles
“nucleus loving”
tend to have lone pairs or pi bonds that can form new bonds to electrophiles, nucleophilicity increases with increasing electron density/charge
Effect of Charge on Nucleophilicity
increases with more negative charge
Effect of Electronegativity on Nucleophilicity
decreases as En increases because thee atoms are less likely to share electron density
Effect of Steric Hindrance on Nucleophilicity
Bulkier molecules are less nucleophilic
Effect of Solvent on Nucleophilicity
Protic solvents can inhibit nucleophilicity by protonating the nucleophile or through hydrogen bonding
Electrophiles
“electron loving”
tend to have a positive charge or positively polarized atom that accepts an electron pair from a nucleophile, electrophilicity is increased by increasing the positive charge
Leaving Groups
molecular fragments that retain the electrons after heterolysis
most common: weak bases, large groups with resonance, large groups with electron withdrawing atoms