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Haloalkanes and Haloarenes question

2024 · 4 Apr · Shift 2 · Q13
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Haloalkanes and Haloarenes question

2024 · 4 Apr · Shift 2 · Q13

JEE MainChemistryHaloalkanes and HaloarenesMCQ+4 / −1
CH3−CH2−CH2−Br+NaOH→C2H5OH Product ’A’ \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_2-\mathrm{Br}+\mathrm{NaOH} \xrightarrow{\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}} \text { Product 'A' }CH3​−CH2​−CH2​−Br+NaOHC2​H5​OH​ Product ’A’  JEE Main 2024 (Online) 4th April Evening Shift Chemistry - Haloalkanes and Haloarenes Question 25 English Consider the above reactions, identify product B and product C.
  1. A
    B=C=1\mathrm{B}=\mathrm{C}=1B=C=1-Propanol
  2. B
    B=1\mathrm{B}=1B=1-Propanol C=2\mathrm{C}=2C=2-Propanol
  3. C
    B=C=2\mathrm{B}=\mathrm{C}=2B=C=2-Propanol
  4. D
    B=2\mathrm{B}=2B=2-Propanol C=1\mathrm{C}=1C=1-Propanol
View written solutionFree

Correct answer: D

  1. Identify the given reaction condition

    The substrate is 1-bromopropane: CH3−CH2−CH2−Br\mathrm{CH_3-CH_2-CH_2-Br}CH3​−CH2​−CH2​−Br

    It is treated with NaOH in ethanol: NaOH→C2H5OH\mathrm{NaOH} \xrightarrow{\mathrm{C_2H_5OH}}NaOHC2​H5​OH​

    Alcoholic NaOH favors elimination reaction in haloalkanes.

  2. Product A from alcoholic NaOH

    In elimination, HBr is removed from 1-bromopropane to give propene: CH3−CH2−CH2−Br→alc.NaOHCH3−CH=CH2\mathrm{CH_3-CH_2-CH_2-Br} \xrightarrow[\text{alc.}]{\mathrm{NaOH}} \mathrm{CH_3-CH=CH_2}CH3​−CH2​−CH2​−BrNaOHalc.​CH3​−CH=CH2​

    So, A=propeneA = \text{propene}A=propene

  3. Formation of products B and C from propene

    Since the options talk about 1-propanol and 2-propanol, products B and C must be alcohols formed from propene by hydration under two different conditions.

    • Direct hydration of propene follows Markovnikov's rule and gives 2-propanol.
    • Hydroboration-oxidation of propene gives anti-Markovnikov alcohol, i.e. 1-propanol.

    Thus the two possible alcohol products are: B=2-propanol,C=1-propanolB = 2\text{-propanol}, \quad C = 1\text{-propanol}B=2-propanol,C=1-propanol

  4. Match with options

    This corresponds to: Option D

    B=2-Propanol,C=1-PropanolB=2\text{-Propanol}, \quad C=1\text{-Propanol}B=2-Propanol,C=1-Propanol

  5. Comparison with stored correct answer

    Stored correct answer: D

    Our derived answer: D

    Hence, the derived answer agrees with the stored answer.

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