Question

How many atoms of hydrogen are required for the reduction of one molecule of nitroethane to ethylamine?
A. 2
B. 4
C. 6
D. 8

Answer 1

Hint: Amines are the alkyl or aryl-substituted derivatives of ammonia. The number of possible amines is very large as there are three replaceable hydrogen atoms in ammonia which can be replaced by alkyl or aryl groups. Amines are classified as primary, secondary, and tertiary amines depending on whether one, two, or three alkyl or aryl groups are respectively attached to the nitrogen atom.

$N{H_3}\xrightarrow[{ + R}]{{ - H}}RN{H_2}\xrightarrow[{ + R}]{{ - H}}{R_2}NH\xrightarrow[{ + R}]{{ - H}}{R_3}N$

If the R is alkyl then the amine is an aliphatic amine. If the r is aryl then the amine is aromatic. An amine in both alkyl and aryl groups are present is called a mixed amine. Tetra-alkyl or Tetra-aryl ammonium salts are called quaternary salts.

Complete step by step answer:
By catalytic reduction, nitro alkane can be reduced with hydrogen in presence of Ni, Pt, or Pd. The reaction involved in the process is written below:
$C{H_3}C{H_2}N{O_2} + 3{H_2}\xrightarrow{{Pd}}C{H_3}C{H_2}N{H_2} + 2{H_2}O$
In the above reaction, we can see that six hydrogen atoms are required for the reduction of one molecule of nitroethane to ethylamine.

Thus, the correct option is C.

Additional Information:
Oxidation is the process that occurs in an atom, ion, or molecule when there is a loss of electrons.
Oxidation number in an atom of a molecule is defined as the residual charge which an atom has or appears to have when all other atoms in a molecule or ion are removed as ions. The oxidation number in an atom may be negative, positive, or zero.
A substance which supplies oxygen or removes hydrogen is called an oxidizing agent.
A substance which supplies hydrogen and removes oxygen is called a reducing agent.
According to the electron concept, a chemical reaction during which there is a transference of electrons from one substance (atom, ion, or molecule) to another substance is called an oxidation-reduction reaction or redox reaction.

Note: Structure of amines: - We know that ammonia has a pyramidal structure and its nitrogen atom is $s{p^3}$ hybridized. Like ammonia, all amines (primary, secondary or tertiary) are pyramidal in shape. Also since lp-bp repulsions are greater than bp-bp, the bond angle between any two H- atoms or alkyl groups decreases from ${109^ \circ }{28^/}$ to ${107^ \circ }$ in primary and secondary amines. But in tertiary amines, due to steric hindrance between the three bulky alkyl groups, the bond angle increases from ${107^ \circ }$ in ammonia to ${108^ \circ }$ in trimethylamine.