What is the expected product from the following reaction sequence?
A)I
B)II
C)III
D)IV

Question

What is the expected product from the following reaction sequence? 
A)I 
B)II 
C)III 
D)IV

Quizplus · Accepted Answer

The first step involves an SN2 reaction of sodium iodide with 3-bromo-1-butene to give 3-iodo-1-butene (I). 
In the second step, acidic conditions lead to the elimination of HBr from I to give 1-iodo-2-butene (II). 
In the third step, hydrogenation of II using H2 and Lindlar's catalyst leads to the formation of (Z)-2-butene (III). 
In the fourth step, reaction with bromine will result in electrophilic addition to give meso-2,3-dibromobutane (IV) and (E)-2,3-dibromobutane (V). However, since the starting material used is (Z)-2-butene, only meso-2,3-dibromobutane (IV) will be formed. 
Therefore, the expected product is meso-2,3-dibromobutane, which is answer choice A.

What Is the Expected Product from the Following Reaction Sequence