Benzene can be converted to 1,3,5-tribromobenzene in five reaction steps and four intermediate compounds. Select the appropriate reagent from the followings.

Br2, R2O2

CH3Cl, AlCl3

CH3COCl, AlCl3

NaNO2, HCl

HNO3, H2SO4

H3PO2

H3PO4

KMnO4

The appropriate reagent is: H3PO2.

Explanation:

H3PO2 is in charge of eliminating the amino group by diazotization, remember that the amino group had previously achieved bromination at positions m; that is to say that it achieved in the beginning that the three bromine atoms of 1,2,4 tribromobenzene were introduced in the meta positions among themselves, which finally corresponds as part of the last reaction to the 1,3,5-tribromobenzene position.