84. Which of the compounds shown below would be the most likely product expected
from the reaction scheme shown?
HBr
ROOR ?
(CH3)2CHCH2C CH
Br
Br
Br
Br
Br Br
I II III IV
A) I and II
B) III and IV
C) II and III
D) II and IV
E) I and IV
85. Select the expected major product(s) from the treatment of 1-pentyne with
1 equivalent of HBr in the presence of peroxides.
A) 2-Bromo-1-pentene
B) (E)-1-Bromo-1-pentene
C) (Z)-1-Bromo-1-pentene
D) A and B
E) B and C
86. What mechanistic intermediate is used to explain the preference for addition of the
Br atom, of HBr, to the internal carbon of a terminal alkyne?
A) Formation of a more stable primary vinylic carbocation.
B) Formation of a more stable secondary vinylic carbocation.
C) Addition of the H atom to the carbon already with an H.
D) Addition of H, from HBr, to the least hindered carbon.
E) Steric hindrance for the approach of the Br atom to the primary carbon.