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Chapter 4: Alcohols and Alkyl Halides



Summary | Alcohols | Alky halides | Nucleophilic Substitution Reactions | Radical Substitution Reactions | Preparations of Alkyl Halides | Self Assessment | Quiz |


Preparations of Alkyl Halides

Chapter 4: Alcohols and Alkyl Halides

 

Reaction of Alcohols with Hydrogen Halides

 

Substitution of alcohols using HX

Reaction type: Nucleophilic Substitution (SN1 or SN2)

Summary:

SN1 MECHANISM FOR REACTION OF ALCOHOLS WITH HBr

Step 1:
An acid/base reaction. Protonation of the alcoholic oxygen to make a better leaving group. This step is very fast and reversible.  The lone pairs on the oxygen make it a Lewis base.
 
 
 

Step 2:
Cleavage of the C-O bond allows the loss of the good leaving group, a neutral water molecule, to give a carbocation intermediate. This is the rate determining step (bond breaking is endothermic)
 
 
 
 

Step 3:
Attack of the nucleophilic bromide ion on the electrophilic carbcation creates the alkyl bromide.
 
 
 
 

 


 

Reaction of Alcohols with other Halogenating agents (SOCl2, PX3)

Substitution of ROH using SOCl2
Substitution of ROH using PCl3
Substitution of ROH using PBr3

Reaction type: Nucleophilic Substitution (SN1 or SN2)

Summary:

 

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