Answer:
See explanation
Explanation:
In this question, we can have <u>several possibilities</u> for the bromodichlorobenzene that depends on the position of the Br and Cl in the benzene. Our options are:
<u>a) 2-bromo-1,3-dichlorobenzene</u>
<u>b) 1-bromo-2,4-dichlorobenzene</u>
<u>c) 1-bromo-2,3-dichlorobenzene</u>
<u>d) 1-bromo-2,3-dichlorobenzene</u>
<u>e) 4-bromo-1,2-dichlorobenzene</u>
See figure 1
Now, if only have 4 signals, we will have only 4 different types of carbons. In benzene we have 6 carbons, therefore, we will have <u>symmetry</u> in the molecule and some of the carbons would be equivalent. The only molecule that has symmetry is "<u>2-bromo-1,3-dichlorobenzene</u>" because we have several carbons with the same neighbors (<u>see figure 2</u>).
Finally, to check the molecule we can check the 13C NMR for 2-bromo-1,3-dichlorobenzene and we will see that only have 4 signals (<u>see figure 3</u>)
