Ch. 7 - Substitution ReactionsSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Good Leaving Groups

See all sections
Sections
Nucleophilic Substitution
Good Leaving Groups
SN2 Reaction
SN1 reaction
Substitution Comparison
Additional Practice
Physical Properties of RX
Ion Pairing Effects
Additional Guides
Alkyl Halide

The favorability of many reactions depends on the ability of the leaving group to be stable after it gains a negative charge. Sounds familiar, yes?

That’s because this is the same exact way we determine conjugate base stability.  

Concept #1: How to use the factors affecting acidity to predict leaving group ability.  

We use factors affecting acidity to determine which leaving groups will be most stable after gaining a lone pair.

  • Recall that the element effect consists of two trends: 

Predict which of the following pairs of electrophiles possesses the best leaving group.

Example #1: Predict which of the following pairs of electrophiles possesses the best leaving group.

Predict which of the following pairs of electrophiles possesses the best leaving group.

Example #2: Predict which of the following pairs of electrophiles possesses the best leaving group.

Predict which of the following pairs of electrophiles possesses the best leaving group.

Example #3: Predict which of the following pairs of electrophiles possesses the best leaving group.

Predict which of the following pairs of electrophiles possesses the best leaving group.

Example #4: Predict which of the following pairs of electrophiles possesses the best leaving group.

Due to their high electronegativity, alkyl halides will be the primary leaving groups for this chapter.