Question

Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?
A. \[{H_2}(excess)/Pt\]
B. \[LiAl{H_4}\] in ether
C. \[Fe\] and \[HCl\]
D. \[Sn\] and \[HCl\]

Answer 1

Hint: The reduction of aryl nitro compounds produces many types of compounds like amines, azo compounds etc. From the compounds given in the above options three of them produce amine but one of them produces another compound and the one which produces another compound is our answer.

Complete step by step answer:
Nitro compounds are organic compounds that contain one or more Nitro functional group. They are one of the most common explosophores (functional groups making compounds explosive) used globally. The nitro group is strongly electron withdrawing group. And, because of the C-H bonds adjacent to the nitro group they can be acidic. They are rarely found in nature and are almost invariably produced.
Aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon by the removal of a hydrogen atom such as phenyl and naphthyl.
Amines are compounds that contain and are based on one or more atoms of nitrogen.
Now in this question we need to reduce aryl nitro compound to amine with appropriate reagents and find out which reagent would not be a good choice.
Following are the few ways in which Aryl Nitro can be reduced to amines:
->Catalytic hydrogenation using platinum oxide or raney nickel.
->Iron metal in refluxing acetic acid
->Samarium diiodide
->Raney nickel, platinum on carbon or zinc dust and formic acid
Now, given below are the way of reducing nitro to azo compounds
->Lithium aluminium hydride
->Zinc metal with sodium hydroxide
Now in the options we have Platinum with $H_2$, lithium in ether, iron with \[HCl\] and Samarium with \[HCl\] . But we have seen in the ways of reduction that platinum with \[{H_2}\] , iron with \[HCl\] and samarium with \[HCl\] produce amines but Lithium aluminium hydride with ether produce azo compounds namely azobenzene. Therefore, Lithium Aluminium hydride with ether is not feasible for production of amines.

So, the correct answer is option B.

Note:
Reduction of aryl nitro compounds in different ways produces many types of compounds like amines, azo compounds, hydroxylamines, hydrazino compounds, anilines and oximes. These different reactions are carried out with different reactants.