Formation of 1-Bromoheptane from 1-Heptanol and Hydrogen Bromide

Formation of 1-Bromoheptane from 1-Heptanol and Hydrogen Bromide THE OVERALL REACTION  

Step 1 Protonation of 1-heptanol to give the corresponding alkyloxonium ion  

It is attacked by bromide ion, which acts as a nucleophile. We can represent step 2 and its transition state as  

Bromide ion forms a bond to the primary carbon by pushing off a water molecule. This step is bimolecular because it involves both bromide and heptyloxonium ion. Step 2 is slower than the proton transfer in step 1, so it is rate-determining. Using Ingold s terminology, we classify nucleophilic substitutions that have a bimolecular rate-determining step by the mechanistic symbol Sn2. 

Sketch a potential energy diagram for the reaction of 1-heptanol with hydrogen bromide, paying careful attention to the positioning and structures of the intermediates and transition states. 

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FIGURE 4 18 The mechanism of formation of 1 bromoheptane from 1 heptanol and hydrogen bromide... 

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