Read the passage carefully and answer the questions.
Many halogen containing organic compounds are present in nature and some of them are clinically useful. These classes of organic compounds find a wide range of applications in our daily life as well as in industries. Many of the polyhalogen compounds are useful too in agriculture. However, some of these compounds cannot be easily decomposed and are thus considered to be environmental hazards. These halo compounds are prepared via different synthetic routes where a variety of organic compounds can be used as substrates such as amines, hydrocarbons etc. They are used as solvents for relatively non-polar compounds. These compounds exhibit substitution and elimination reactions, in addition to their reactions with different metals, which leads to the formation of a versatile starting material for others organic compounds.
Alkyl halides react with sodium in dry ether and give hydrocarbon containing double the number of carbon atom present in the halides. The reaction is known as:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Wurtz Reaction
Sodium metal in dry ether removes the halogen atoms from organic halides as sodium halide, and the two organic groups left behind join to each other. The name of the reaction depends on which groups are joined: two alkyl groups (Wurtz), two aryl groups (Fittig) or one alkyl and one aryl group (Wurtz-Fittig). Dry ether is used because sodium reacts with water.
When two molecules of the same alkyl halide are joined, the alkane formed has twice as many carbon atoms as the halide. This is the Wurtz reaction. For example, bromoethane (2 C) gives butane (4 C):
\( \displaystyle \ce{2CH3CH2Br + 2Na} \xrightarrow{\text{dry ether}} \ce{CH3CH2-CH2CH3 + 2NaBr} \)
So the reaction described is the Wurtz reaction.
Why the other options are incorrect
Option (1) Wurtz Fittig reaction — Incorrect. It joins an alkyl halide with an aryl halide to give an alkylarene, for example toluene:
\( \displaystyle \ce{C6H5Cl + 2Na + CH3Cl} \xrightarrow{\text{dry ether}} \ce{C6H5-CH3 + 2NaCl} \)
Option (3) Fittig Reaction — Incorrect. It joins two aryl halides, giving a diaryl such as biphenyl:
\( \displaystyle \ce{2C6H5Cl + 2Na} \xrightarrow{\text{dry ether}} \ce{C6H5-C6H5 + 2NaCl} \)
Option (4) Swarts Reaction — Incorrect. It is a halogen exchange that makes alkyl fluorides: an alkyl chloride or bromide is heated with a metallic fluoride such as AgF, \( \ce{Hg2F2} \), \( \ce{CoF2} \) or \( \ce{SbF3} \). No carbon–carbon bond is formed:
\( \displaystyle \ce{CH3Br + AgF -> CH3F + AgBr} \)
NCERT (2026-27 edition):
Wurtz Reaction
