Question

Write the reducing agents used to convert Fe\(_2\)O\(_3\) to ‘Fe’ in the reduction zone of blast furnace. Write chemical equations involved in : (i) Carbylamine reaction for ethylamine. (ii) Hoffmann Bromamide degradation for acetamide.

Hint:

The Carbylamine test is specific to primary amines (both aliphatic and aromatic) and is a reliable way to distinguish them from secondary and tertiary amines. The Hoffmann degradation is a step-down reaction, crucial for synthesis where the carbon chain needs to be shortened by one atom.

Answer 1

Reducing Agents in Blast Furnace
In the reduction zone of a blast furnace, the primary reducing agent for converting iron oxides (like Fe\(_2\)O\(_3\)) to molten iron (Fe) is carbon monoxide (CO). Carbon (in the form of coke) also acts as a reducing agent at higher temperatures.
Chemical Equations

[(i)] Carbylamine Reaction for Ethylamine: This is a test for primary amines. Ethylamine is heated with chloroform (CHCl\(_3\)) and alcoholic potassium hydroxide (KOH) to form ethyl isocyanide, which has a foul smell. \[ \underset{\text{Ethylamine}}{\text{C}_2\text{H}_5\text{NH}_2} + \text{CHCl}_3 + 3\text{KOH (alc.)} \xrightarrow{\Delta} \underset{\text{Ethyl isocyanide}}{\text{C}_2\text{H}_5\text{NC}} + 3\text{KCl} + 3\text{H}_2\text{O} \]
[(ii)] Hoffmann Bromamide Degradation for Acetamide: This reaction converts an amide to a primary amine with one less carbon atom. Acetamide is treated with bromine in an aqueous or ethanolic solution of sodium hydroxide.
\[ \underset{\text{Acetamide}}{\text{CH}_3\text{CONH}_2} + \text{Br}_2 + 4\text{NaOH} \rightarrow \underset{\text{Methylamine}}{\text{CH}_3\text{NH}_2} + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O} \]