Question

In the reactions given below, identify A and B.
$A\xrightarrow{{aq.NaOH/\Delta }}{C_2}{H_5}OH\xleftarrow{{AgOH}}B$
A.${C_2}{H_2}$ and ${C_2}{H_6}$
B.${C_2}{H_5}Cl$ and ${C_2}{H_4}$
C.${C_2}{H_4}$ and ${C_2}{H_5}Cl$
D.${C_2}{H_5}Cl$ and ${C_2}{H_5}Cl$

Answer 1

We know that alcohols are compounds that one or more hydroxyl (-OH) groups are directly attached to a carbon chain. Some of the methods to prepare alcohol are by hydrolysis of halides, hydration of alkanes, alkenes Hydroformylation, and Grignard reagents.

Complete step by step solution:
The given equation,
$A\xrightarrow{{aq.NaOH/\Delta }}{C_2}{H_5}OH\xleftarrow{{AgOH}}B$
In the above given reaction, we can see that ethanol is formed from alkali. We can prepare ethanol by alkyl halides hydrolysis.
In the given options, the alkyl halide is ${C_2}{H_5}Cl$. ${C_2}{H_2}$ is an alkene and ${C_2}{H_6}$ is an alkane.
So, alkyl halides when heated with an aqueous solution of an alkali hydroxide produce alcohol. The reaction undergoes nucleophilic substitution mechanism. The general reaction for the preparation of alcohol from alkyl halide is given as,
$R - X + KOH \to R - OH + KX$
The hydrolysis reaction of alkyl halides gives primary as well as secondary alcohols. We can also prepare glycerol from propylene by order of reactions including the halide hydrolysis as one phase in the process.
So, we have identified the alkyl halide as ${C_2}{H_5}Cl$. ${C_2}{H_5}Cl$ on reaction with aqueous sodium hydroxide gives ethanol. ${C_2}{H_5}Cl$ on reaction with $AgOH$ produces ethanol.
We can write the reaction as,
${C_2}{H_5}Cl\xrightarrow{{aq.NaOH/\Delta }}{C_2}{H_5}OH\xleftarrow{{AgOH}}{C_2}{H_5}Cl$
So, the reactant A is ${C_2}{H_5}Cl$ and reactant B is ${C_2}{H_5}Cl$.
Therefore, the option (D) is correct.

Note: The compound ${C_2}{H_6}$ undergoes a hydration reaction to form ethanol. Direct hydration happens when we add water in the presence of a catalyst. We have to first convert ethane to ethene. Ethene then passed through vapours through water in presence of sulfuric acid. Sulfuric acid plays the role of catalyst. We can write the chemical equation as,
$C{H_2} = C{H_2} + {H_2}O\xrightarrow{{{H_2}S{O_4}}}C{H_3}C{H_2}OH$
The compound ${C_2}{H_4}$ undergoes a Hydroformylation reaction to form ethanol. Ethene is reacted with carbon monoxide and hydrogen in presence of cobalt to form aldehyde, the aldehyde is then hydrogenated to form alcohol. Hydroboration of ${C_2}{H_4}$ also forms ethanol.