The given reaction can occur in the presence of: (a) Bromine water (b) \(\mathrm{Br}_{2}\) in \(\mathrm{CS}_{2}, 273 \mathrm{~K}\) (c) \(\mathrm{Br}_{2} / \mathrm{FeBr}_{3}\) (d) \(\mathrm{Br}_{2}\) in \(\mathrm{CHCl}_{3}, 273 \mathrm{~K}\) Choose the correct answer from the options given below:

JEE Main · 2021 · 25 Jul 2021 · Shift 1 · Hydrocarbons

The given reaction can occur in the presence of:
(a) Bromine water
(b)

Br_{2}

CS_{2}, 273 K

(c)

Br_{2} / FeBr_{3}

(d)

Br_{2}

CHCl_{3}, 273 K

Choose the correct answer from the options given below:

(A)(a) and (c) only
(B)(b), (c) and (d) only✓ Correct
(C)(b) and (d) only
(D)(a), (b) and (d) only

Answer: (B)

Solution

The reaction shown is the addition of bromine to an alkene (electrophilic addition). This occurs under conditions that favor addition rather than substitution:

Bromine water (a): Provides Br₂ in aqueous medium, favoring addition to C=C.
Br₂ in CS₂ at 273 K (b): Non-polar solvent at low temperature favors addition.
Br₂/FeBr₃ (c): This is for electrophilic aromatic substitution, not addition to alkenes.
Br₂ in CHCl₃ at 273 K (d): Non-polar solvent at low temperature favors addition.

Thus, conditions (a), (b), and (d) promote addition to the double bond. The correct answer is (D).

JEE Main · 2021 · 25 Jul 2021 · Shift 1 · Single correct option

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JEE Main · 2021 · 25 Jul 2021 · Shift 1 · Hydrocarbons

Solution

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