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CHAPTER 16 585 
 
of the two double bonds, and the stereodescriptor (Z) 
indicates the configuration of the C=C bond between C3 
and C4. 
 
 
(d) The parent (“hept”) indicates a seven-carbon chain, 
and the suffix (“diene”) indicates the presence of two 
C=C bonds. The locants (2 and 4) indicate the positions 
of the two double bonds, and the stereodescriptors 
indicate the configurations of the double bonds. 
 
 
 
(e) The parent (“but”) indicates a four-carbon chain, and 
the suffix (“diene”) indicates the presence of two C=C 
bonds. The locants (1 and 3) indicate the positions of the 
two double bonds. There are two methyl substituents, at 
positions C2 and C3. 
 
 
16.31. Each of the highlighted compounds possesses a 
conjugated  system, which is shown with darker bonds. 
 
 
 
 
16.32. Potassium tert-butoxide is a strong, sterically 
hindered base, and the starting material will react with 
two equivalents of this base to undergo two successive 
elimination (E2) reactions, producing a conjugated, 
homoannular diene, as shown. 
 
 
 
 
16.33. 
(a) The non-conjugated isomer (shown below) will be 
higher in energy than the conjugated isomer. 
 
 
 
As a result, this compound will liberate more heat upon 
hydrogenation. 
 
(b) The non-conjugated isomer (shown below) will be 
higher in energy than the conjugated isomer. 
 
 
 
As a result, this compound will liberate more heat upon 
hydrogenation. 
 
 
16.34. Treatment of 1,3-cyclohexadiene with HBr 
produces only one product (because 1,2 addition and 1,4 
addition give the same product). 
 
 
 
16.35. The diene is protonated to give a resonance 
stabilized cation, which can then be attacked in one of 
two locations, leading to the 1,2-adduct and the 1,4-
adduct. At low temperature, the kinetic product (the 1,2-
adduct) dominates. 
 
 
 
16.36. The diene is protonated to give a resonance 
stabilized cation, which can then be attacked in one of 
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