Question

How to convert methanol into ethanol? Write chemical equations only.

Answer 1

Hint: We can convert methanol into ethanol by an organic coupling reaction which is called Wurtz reaction. This is carried out with sodium metal in the presence of dry ether and forms higher alkanes.

Complete Solution :
Wurtz reaction is the classic coupling reaction in which halo-alkanes are created to higher alkanes in presence of sodium atoms and dry ether. Single electron transfer takes place from sodium metal to the alkyl halide dissociating to form the alkyl radical and sodium halide salt. It is one of the oldest coupling reactions.
Here, we can see the stepwise process to convert methanol into ethanol. They are-
- First, we will react to the methanol with $\text{PC}{{\text{l}}_{3}}$ or $\text{HCl}$. The ${{\text{H}}^{+}}$ will attack the OH bond to give chloromethane.
- Alkyl halide i.e. chloromethane which is obtained reacts with sodium metal in dry ether to give the final product ethane.
- Ethane obtained is then reacted with $\text{C}{{\text{l}}_{2}}$ in presence of sunlight to give chloroethane.
- Chloroethane thus obtained is then reacted with aq. KOH to give final product Ethanol.
- In this way, we can convert methanol into ethanol. The chemical reaction for the above is given below:
Chemical reaction:

\[C{{H}_{3}}OH\to C{{H}_{3}}Cl\xrightarrow[\text{dry ether}]{Na}C{{H}_{3}}C{{H}_{2}}\xrightarrow[h\nu ]{C{{l}_{2}}}C{{H}_{3}}C{{H}_{2}}Cl\xrightarrow{aq.KOH}C{{H}_{3}}C{{H}_{2}}OH\]
In this way, we can convert methanol into ethanol.

Note: Another method to convert methanol into ethanol is by using Grignard reagent. We can first add Grignard Reagent (RMgX) with PCC (Pyridinium Chlorochromate, also called Corey’s reagent) to give HCHO (Formaldehyde). The Grignard reagent further undergoes acid hydrolysis and reacts with HCHO formed results in ethanol. The chemical reaction is mentioned below:

\[C{{H}_{3}}OH\xrightarrow{HI}C{{H}_{3}}I\xrightarrow[\text{dry ether}]{Mg}C{{H}_{3}}MgI\xrightarrow[{{H}_{2}}O/{{H}^{+}}]{HCHO}C{{H}_{3}}C{{H}_{2}}OH\]