Learning Objectives –Chapter 7 and Chapter 8
CHAPTER 7 - Alkyl Halides: Nucleophilic Substitution and Elimination Reactions
Alkyl halide à carbon group + halide (F, Cl, I or Br)
1. Define substitution reaction and elimination reaction
Substitution rxnà Alkyl halide reacts with nucleophile. (leaving halide griup and
nuclephilic attack)
Elimination rxn à alkyl halide reacts w/ base, which takes a proton
Reasons why this happens:
1) Halogen is partially negative, creating a
partially + carbon (electrophilic) susceptible to
nucleophilic attack
2) Halogens acts as good leaving group
2. Distinguish between good leaving groups and
bad leaving groups
Good leaving groups are the conjugate bases of
strong
à stronger the acid the weaker the conjugate base
(more stable)
3. Classify alkyl halides as primary, secondary, or tertiary
à amount of
branching at the
alpha carbon affects
reaction mechanism
3 types:
4. Use IUPAC systematic nomenclature to name alkyl halides
• Identify and name the parent chain
• Identify the name of the substituents à halide group
I à Iodo Brà Bromo
Fà Flouro Clà chloro
• Assign a locant (number) to each substituents Assemble the name
alphabetically
• Add R/S if chiral centers (listed in numerical order)
, 5. Describe the details of an SN2 reaction, including its rate equation, mechanism, energy diagram, transition state, substrate effects,nucleophile
effects, solvent effects,and stereochemical outcome
Reaction Rate Mechanism E. Diagram Effect of:
equation
SN2 R= Solvent: (affects
concerted [nucleophile] nucleophilicity)
mechanism [A.Halide] medium in which rxn
involves à 1 nucleop. occurs
breaking of collides w/ 1 a-
the bond to halide - **Polar aprotic
the leaving Inversion of configuration: solvent à faster
group and rxn
making of
the bond to Transition state has to show partial charges (see L.O 6)
the & bonds that are breaking/forming con
nucleophile puntitos!
at the
same time. Kinetics: **
Stereochemical outcome: (substrate effects)
If ---Br on plane à attacking group on opposite side Less sterically hindered (crowdness)
If ---Br on dashed à attacking group on wedge electrophi. React better (less potential E.
If ---Br on wedge à attacking group on dashed needed to strat rxn)
à All dashes and wedges of atoms connected to the alpha
carbon undergo this inversion of configuration
Nucleophilicity:
Strong(polarizable atoms) nucleophile is
needed (faster)
CHAPTER 7 - Alkyl Halides: Nucleophilic Substitution and Elimination Reactions
Alkyl halide à carbon group + halide (F, Cl, I or Br)
1. Define substitution reaction and elimination reaction
Substitution rxnà Alkyl halide reacts with nucleophile. (leaving halide griup and
nuclephilic attack)
Elimination rxn à alkyl halide reacts w/ base, which takes a proton
Reasons why this happens:
1) Halogen is partially negative, creating a
partially + carbon (electrophilic) susceptible to
nucleophilic attack
2) Halogens acts as good leaving group
2. Distinguish between good leaving groups and
bad leaving groups
Good leaving groups are the conjugate bases of
strong
à stronger the acid the weaker the conjugate base
(more stable)
3. Classify alkyl halides as primary, secondary, or tertiary
à amount of
branching at the
alpha carbon affects
reaction mechanism
3 types:
4. Use IUPAC systematic nomenclature to name alkyl halides
• Identify and name the parent chain
• Identify the name of the substituents à halide group
I à Iodo Brà Bromo
Fà Flouro Clà chloro
• Assign a locant (number) to each substituents Assemble the name
alphabetically
• Add R/S if chiral centers (listed in numerical order)
, 5. Describe the details of an SN2 reaction, including its rate equation, mechanism, energy diagram, transition state, substrate effects,nucleophile
effects, solvent effects,and stereochemical outcome
Reaction Rate Mechanism E. Diagram Effect of:
equation
SN2 R= Solvent: (affects
concerted [nucleophile] nucleophilicity)
mechanism [A.Halide] medium in which rxn
involves à 1 nucleop. occurs
breaking of collides w/ 1 a-
the bond to halide - **Polar aprotic
the leaving Inversion of configuration: solvent à faster
group and rxn
making of
the bond to Transition state has to show partial charges (see L.O 6)
the & bonds that are breaking/forming con
nucleophile puntitos!
at the
same time. Kinetics: **
Stereochemical outcome: (substrate effects)
If ---Br on plane à attacking group on opposite side Less sterically hindered (crowdness)
If ---Br on dashed à attacking group on wedge electrophi. React better (less potential E.
If ---Br on wedge à attacking group on dashed needed to strat rxn)
à All dashes and wedges of atoms connected to the alpha
carbon undergo this inversion of configuration
Nucleophilicity:
Strong(polarizable atoms) nucleophile is
needed (faster)
