What is the value of x(% yield of product) ? | TestHub

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Halogenation is a substitution reaction, where halogen replaces one or more hydrogens of hydrocarbon.

$R - H + X_{2} h ν R - X + H X$

Chlorine free radicals form 1°, 2°, and 3° radicals with almost equal ease, whereas bromine free radicals show a clear preference for the formation of tertiary free radicals. Therefore, bromine is less reactive and more selective, while chlorine is more reactive and less selective.

The relative rate of abstraction of hydrogen by Br• is:

3° > 2° > 1°

(1600) (82) (1)

The relative rate of abstraction of hydrogen by Cl• is:

3° > 2° > 1°

(5) (3.8) (1)

What is the value of x(% yield of product) ?

Options:

Answer:

B

Solution:

Question Explanation: Calculate the percentage yield of the major product formed during free-radical bromination using relative hydrogen abstraction rates.

Concept: This question is based on free-radical halogenation selectivity in bromination and quantitative yield calculation.

Solution:

The relative rate of abstraction of hydrogen by $Br^{∙}$ is

$3^{\circ} > 2^{\circ} > 1^{\circ}$

(1600) (82) (1)

$x = \frac{1600 \times 1}{1600 \times 1 + 15 \times 1 + 4 \times 82} \times 100 = \frac{1600}{1600 + 15 + 328} \times 100 = 82.34%$

Final Answer: Option (B)

Stream:JEESubject:ChemistryTopic:HydrocarbonSubtopic:Miscellaneous/Mixed

⏱ 2mℹ️ Source: QB

Chemistry - Hydrocarbon Question with Solution | TestHub

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