Complete the reactions:
(i) 2 (CH₃)₂CHCl + 2Na \xrightarrow{dry ether} ?
(ii) 2 CH₃-CH(Cl)-CH₂-CH₃ + 2Na \xrightarrow{dry ether} ?
Answer (1)
The reactions given in the question involve an organic chemistry concept known as the Wurtz reaction. This reaction is used to couple two alkyl halides to form a larger alkane, using sodium metal in dry ether as the medium.
Let's complete the reactions step-by-step:
(i) Reaction:
2 (CH 3 ) 2 CHCl + 2 Na dry ether ?
In this reaction, the reactant is isopropyl chloride ( (CH 3 ) 2 CHCl ) . The sodium metal helps to couple the two isopropyl groups, forming the following product:
(CH 3 ) 2 CH-CH(CH 3 ) 2 + 2 NaCl
Therefore, the product of the reaction is isobutane.
(ii) Reaction:
2 CH 3 -CH(Cl)-CH 2 -CH 3 + 2 Na dry ether ?
Here, the reactant is sec-butyl chloride ( CH 3 -CH(Cl)-CH 2 -CH 3 ) . Following the same Wurtz reaction steps, sodium will couple the sec-butyl groups to form:
CH 3 -CH(CH 2 )-CH 2 -CH(CH 2 ) -CH 3 + 2 NaCl
So, the final product is 2,5-dimethylhexane.
In summary, the Wurtz reaction is a useful reaction for synthesizing higher alkanes from alkyl halides, especially when simple coupling of the same alkyl groups is desired. The key here is to ensure that dry ether is used as the solvent, which avoids unwanted side reactions and supports the coupling process.
