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CHAPTER 8 267 
 
8.77. There is only one alkene (compound Y, shown below) that is consistent with the information provided in the 
problem statement. Ozonolysis of that alkene results in cleavage of the C=C bond to give two separate compounds, 
each of which has a C=O bond, shown below: 
 
Br
HBr, ROOR
O
1) O3
2) DMS
H
H
O+H2, Pt
Compound Y
C7H12
 
 
8.78. Each of the products is an aldehyde, and their sp2 hybridized carbon atoms were once connected to each other as 
a C=C bond in the original alkene. That gives the following two possibilities (stereoisomers) for the structure of the 
original alkene: 
 
 
 
8.79. 
(a) In the presence of aqueous acid, the epoxide is first 
protonated (two curved arrows), as shown below. The 
resulting intermediate can then undergo an SN2-like, 
intramolecular attack (two curved arrows), in which the 
OH group functions as the nucleophilic center. Then, in 
the final step of the mechanism, a molecule of water 
functions as a base and removes a proton, thereby 
generating the product. This final step is a proton 
transfer step, and therefore requires two curved arrows: 
 
O
OH
O
OH
H
H O
H
H
HO HO
H
O
HO O
H
 
 
(b) In the presence of aqueous acid, the epoxide is first 
protonated (two curved arrows), as shown. The resulting 
intermediate can then undergo an SN2-like, 
intramolecular attack (two curved arrows), in which the 
 bond functions as the nucleophilic center. Then, in 
the final step of the mechanism, a molecule of water 
functions as a base and removes a proton, thereby 
generating the product. This final step is a proton 
transfer step, and therefore requires two curved arrows: 
 
 
 
 
8.80. Treatment of the alkyl halide with a strong base 
gives an alkene which can then be converted into the 
desired product via ozonolysis: 
 
 
 
 
 
8.81. When the alkene is treated with molecular bromine 
(Br2), the  bond functions as a nucleophilic center and 
attacks Br2 (three curved arrows), resulting in an 
intermediate bromonium ion. The bromonium ion is 
then subject to attack by a nucleophilic center, such as 
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