Question

IIdentify the product in following order
$3,4,5 - Tribromoaniline \xrightarrow[\left ( ii \right )H_3PO_4]{\left ( i \right )Diazotisation}$?
A. 3,4,5-Tribromobenzene
B. 1,2,3-Tribromobenzene
C. 2,4,6-Tribromobenzene
D. 3,4,5-Tribromo nitro benzene
E. 3,4,5-Tribromo phenol

Answer 1

Hint: 3,4,5-Tribromoaniline is a compound containing primary aromatic amine with three bromine groups at 3, 4 and 5 positions of aniline. Here in the first step diazotization is performed and then acid is given which will provide its proton in the reaction. Diazotization reaction is a type of coupling reaction for primary amine compounds.

Complete Step by Step Solution:
In the first step, a diazotisation reaction will take place where sodium nitrite and hydrochloric acid at \[{0^ \circ }\]C condition react to give nitrous acid, \[HONO\] which attacks the primary aromatic amine to give diazonium salt i.e., 3,4,5-Tribromobenzene diazonium salt. This then reacts with hypo phosphorus acid reagent which gives its hydrogen to the carbon of benzene ring where diazonium group is attached. So, from the final product nitrogen group is removed and hydrogen is present in its place. The name of the final compound is 1,2,3-tribromobenzene which is option B.

Image: Diazotisation reaction and further treatment with acid of 3,4,5-Tribromoaniline.

So, option B is correct. 2

Note: Ethanimine are the organic compounds having imine functional group i.e.,\[ - C = N - \]. This reacts with water and forms a compound containing a carbonyl functional group such as ketone or aldehyde. In this question acetonitrile is given so it forms acetaldehyde. Here, the overall number of carbons remains the same.