Question

How may the following be obtained?

Hint:

Alkene reactions with HX (like HBr) follow Markovnikov's rule where the halide adds to the carbon with the greater number of hydrogen atoms.

Answer 1

(A) Ethane from methyl iodide:
Ethane can be obtained from methyl iodide via a reduction reaction: \[ \text{CH}_3\text{I} + \text{H}_2 \xrightarrow{\text{Ni}} \text{C}_2\text{H}_6 + \text{HI} \] Here, methyl iodide reacts with hydrogen in the presence of nickel catalyst to form ethane. (B) Allyl chloride from propene:
Allyl chloride can be obtained by chlorination of propene: \[ \text{CH}_2=\text{CHCH}_3 + \text{Cl}_2 \rightarrow \text{CH}_2\text{CHCH}_2\text{Cl} \] Here, propene reacts with chlorine to form allyl chloride. (C) Isopropyl bromide from propene:
Isopropyl bromide can be obtained from propene by reacting with hydrogen bromide: \[ \text{CH}_2=\text{CHCH}_3 + \text{HBr} \rightarrow \text{CH}_3\text{CH(Br)CH}_3 \] Here, propene reacts with HBr to form isopropyl bromide. (D) 1-Bromobutane from butene-1:
1-Bromobutane can be obtained by the addition of hydrogen bromide to butene-1: \[ \text{CH}_2=\text{CHCH}_2\text{CH}_3 + \text{HBr} \rightarrow \text{CH}_3\text{CH}_2\text{CH(Br)}\text{CH}_3 \] Here, butene-1 reacts with HBr to form 1-bromobutane. v) Propene from propene:
Propene is already present and no further reaction is needed. Final Answer: (A) Ethane from methyl iodide: Reduction with hydrogen
(B) Allyl chloride from propene: Chlorination with chlorine
(C) Isopropyl bromide from propene: Addition of HBr
(D) 1-Bromobutane from butene-1: Addition of HBr
v) Propene from propene: No reaction needed