Two students Rehan and Ananya were given the same compound, alkyl halide ( ) by their chemistry…
Two students Rehan and Ananya were given the same compound, alkyl halide ($\text{C}_2\text{H}_5\text{Cl}$) by their chemistry teacher and asked to perform different reactions.
• Rehan was instructed to use alcoholic KCN as a reagent and Ananya was instructed to use alcoholic AgCN.
• Rehan observed a compound was formed that could be converted to a carboxylic acid on hydrolysis but Ananya could not get the same compound.
(i)
Write the chemical reactions carried out by Rehan and Ananya respectively.
(ii)
Justify the reason for obtaining different products by Rehan and Ananya.
Answer
Answer (i)
AIWritten by AI (gemini) - it can contain mistakes.
Rehan's reaction:
$\text{C}_2\text{H}_5\text{Cl} + \text{KCN}(\text{alc}) \rightarrow \text{C}_2\text{H}_5\text{CN} + \text{KCl}$ (Propane nitrile)
Ananya's reaction:
$\text{C}_2\text{H}_5\text{Cl} + \text{AgCN}(\text{alc}) \rightarrow \text{C}_2\text{H}_5\text{NC} + \text{AgCl}$ (Ethyl isocyanide)
Answer (ii)
AIWritten by AI (gemini) - it can contain mistakes.
Justification: $\text{KCN}$ is predominantly ionic and provides cyanide ions ($\text{CN}^-$). The ambidentate cyanide nucleophile attacks through carbon because C-C bond is stronger than C-N bond, forming alkyl cyanide (which hydrolyses to carboxylic acid). In contrast, $\text{AgCN}$ is predominantly covalent, and nitrogen with its lone pair is free to donate electrons, forming alkyl isocyanide.
From ISC 2027 Specimen Chemistry Paper 1, question 12.