Chapter 6 Properties and Reactions of Haloalkanes

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Chapter 6 Properties and Reactions of
Haloalkanes

• Lecture 3
• Sections 6.7-6.9
• Factors that Influence SN2 Reaction Rates

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Factors that Influence SN2 Reaction Rates
The rates of SN2 reactions depend upon Nature of
the leaving group Reactivity of the
nucleophile Structure of the alkyl portion of the
substrate
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SN2 Leaving Groups
Halogen Leaving Groups (best) I- gt Br- gt Cl- gt
F-(worst)
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Basicity and Leaving Group Ability
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Factors that Influence SN2 Reaction Rates
The rates of SN2 reactions depend upon Nature of
the leaving group Reactivity of the
nucleophile Structure of the alkyl portion of the
substrate
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Nucleophile Strength

• Nucleophilicity of the nucleophile depends upon
• Charge
• Basicity
• Solvent
• Polarizability
• Nature of substituents

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Charged Nucleophiles
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Nucleophilicity and Basicity
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Solvation and Nucleophilicity
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Solvation of Halogen Anions
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Solvent Effects and the SN2 Reaction
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Solvent Effects and the SN2 Reaction
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Steric Bulk and Nucleophilicity
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Factors that Influence SN2 Reaction Rates
The rates of SN2 reactions depend upon Nature of
the leaving group Reactivity of the
nucleophile Structure of the alkyl portion of the
substrate
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Reaction Rate and Haloalkane Sterics
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Reaction Rate and Haloalkane Sterics
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Chain Length and Branching
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Chain Length and Branching