Question

In the reaction ${C_2}{H_5}OH \to X$ the molecular formula of X is,
A. ${C_4}{H_6}O$
B. ${C_4}{H_{10}}O$
C. ${C_2}{H_4}O$
D. ${C_2}{H_6}$

Answer 1

When alcohol is treated with copper catalyst at ${300^o}C$, then dehydrogenation will take place. There will be removal of hydrogen or oxidation will take place. This reagent is also used for the separation of the primary, secondary and tertiary alcohols.

Step by step answer: Let us see how Copper at ${300^o}C$ will react with different types of alcohol. In the primary alcohol, the carbon connecting to the hydroxyl group will be connected to only one carbon atom. While in case of secondary alcohol, the carbon connecting to the hydroxyl group will be further connected to two more carbon atoms. And in case of tertiary alcohols the carbon connecting to the hydroxyl group, will be further connected to three more carbon atoms.
Primary alcohol-The primary alcohols will react with copper vapours at ${300^o}C$ to form corresponding aldehyde.
Secondary alcohol-The secondary alcohol will react with copper vapours at ${300^o}C$ to form corresponding ketone.

Tertiary alcohol-The tertiary alcohol will react with copper vapours at ${300^o}C$ to undergo dehydrogenation and corresponding alkene will be formed.

The given alcohol given is an example of primary alcohols named as Ethanol which reacts with vapours of copper to form corresponding aldehydes named Acetaldehyde.

The molecular formula of Acetaldehyde is ${C_2}{H_4}O$.

Hence, option (C) ${C_2}{H_4}O$, is the correct option.

Note: There are various different reagents used for the oxidation of alcohols’ for example potassium dichromate, Collins reagent$Cr{O_3}$,Pyridinium chlorochromate, Dess Martin reagent, Dimethyl Sulphoxide (Swern Oxidation), Jones reagent aluminium isopropoxide/acetone (Oppenauer oxidation).