Q7P Propose a mechanism for each rea... [FREE SOLUTION]

Chapter 15: Q7P (page 761)

Propose a mechanism for each reaction, showing explicitly how the observed mixtures of products are formed.
a) $3 - methyl - but - 2 - en - 1 - ol + HBr 鈫� 1 - bromo - 2 - ene + 3 - bromo - 3 - methyl - 1 - ene$
b) $2 - methyl - but - 3 - en - 2 a - ol + HBr 鈫� 1 - bromo - 2 - ene + 3 - bromo - 3 - methyl - 1 - ene$ c) $cyclopenta - 1, 3 - diene + {Br}_{2} 鈫� 3, 4 - dibromocyclopent - 1 - ene + 3, 5 - dibromocyclopent - 1 - ene$
d) $1 - cholorobut - 2 - ene + {AgNO}_{3} + H_{2} O 鈫� but - 2 - en - 1 - ol + but - 3 - en - 2 - ol$
e) $3 - cholorobut - 1 - ene + {AgNO}_{3} + H_{2} O 鈫� but - 2 - en - 1 - ol + but - 3 - en - 2 - ol$

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Allylic carbocations

Allylic carbocations are resonance-stabilized, and there are two forms of resonance with a +1 charge on an allylic carbon.The nucleophile can attack either one.

Mechanism of the reaction

When is $3 - methyl - but - 2 - en - 1 - ol$ reacted with HBr, two allylic cations are formed, and the nucleophile can attack either one. The mechanism of the reaction is shown as follows:

Mechanism of the reaction

When $2 - methyl - but - 3 - en - 2 a - ol$ is reacted with HBr, two allylic cations are formed, and the nucleophile can attack either one. The mechanism of the reaction is shown as follows

Mechanism of the reaction

When $cyclopenta - 1, 3 - diene$ isreacted with and ${Br}_{2}$ , two allylic carbocations are formed, and the nucleophile can attack either one. The mechanism of the reaction is shown as follows:

Mechanism of the reaction

When is $1 - cholorobut - 2 - ene$ reacted with ${AgNO}_{3}$ and $H_{2} O$ , the same allylic carbocations as in are formed. The nucleophile can attack either one. The mechanism of the reaction is shown as follows:

Mechanism of the reaction

When $3 - cholorobut - 2 - ene$ is reacted with ${AgNO}_{3}$ and $H_{2} O$ , the same allylic carbocations as in are formed. The nucleophile can attack either one. The mechanism of the reaction is shown as follows: