What are \(X, Y, Z\) in the following reactions? \(\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OH} \xrightarrow{Y}…

What are \(X, Y, Z\) in the following reactions?
\(\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OH} \xrightarrow{Y} \mathrm{CH}_2=\mathrm{CH}_2+\mathrm{H}_2 \mathrm{O}\)

1. \(\begin{array}{|c|c|c|} \hline X & Y & Z \\ \hline \mathrm{H}_2 \mathrm{SO}_4, 443 \mathrm{~K} & \begin{array}{l} 85 \% \mathrm{H}_3 \mathrm{PO}_4 \\ 440 \mathrm{~K} \end{array} & \begin{array}{l} 20 \% \mathrm{H}_3 \mathrm{PO}_4, \\ 358 \mathrm{~K} \end{array} \\ \hline \end{array}\)
2. \(\begin{array}{|c|c|c|} \hline X & Y & Z \\ \hline \begin{array}{l} 85 \% \mathrm{H}_3 \mathrm{PO}_4 \\ 440 \mathrm{~K} \end{array} & \mathrm{H}_2 \mathrm{SO}_4, 443 \mathrm{~K} & \begin{array}{l} 20 \% \mathrm{H}_3 \mathrm{PO}_4 \\ 358 \mathrm{~K} \end{array} \\ \hline \end{array}\)
3. \(\begin{array}{|c|c|c|} \hline X & Y & Z \\ \hline \begin{array}{l} 20 \% \mathrm{H}_3 \mathrm{PO}_4, \\ 358 \mathrm{~K} \end{array} & \mathrm{H}_2 \mathrm{SO}_4, 443 \mathrm{~K} & \begin{array}{l} 85 \% \mathrm{H}_3 \mathrm{PO}_4, \\ 440 \mathrm{~K} \end{array} \\ \hline \end{array}\)
4. \(\begin{array}{|c|c|c|} \hline X & Y & Z \\ \hline \mathrm{H}_2 \mathrm{SO}_4, 443 \mathrm{~K} & \begin{array}{l} 20 \% \mathrm{H}_3 \mathrm{PO}_4, \\ 358 \mathrm{~K} \end{array} & \begin{array}{l} 85 \% \mathrm{H}_3 \mathrm{PO}_4 \text {, } \\ 440 \mathrm{~K} \end{array} \\ \hline \end{array}\)

Solution

These reactions are known as dehydration reactions where \(\mathrm{H}_3 \mathrm{PO}_4\) and \(\mathrm{H}_2 \mathrm{SO}_4\) are dehydrating agents. Ethanol undergo dehydration by heating with conc. \(\mathrm{H}_2 \mathrm{SO}_4\) at \(443 \mathrm{~K}\) whereas \(2^{\circ}\) alcohols by \(85 \% \mathrm{H}_3 \mathrm{PO}_4\) at \(440 \mathrm{~K}\) and \(3^{\circ}\) alcohols by \(20 \% \mathrm{H}_3 \mathrm{PO}_4\) at \(358 \mathrm{~K}\).

Asked in: AP EAMCET 2019 (23 Apr Shift 1)

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