10. HALOGEN DERIVATIVES Textbook Solution

    i. The correct order of increasing reactivity of C-X bond towards nucleophile in the following
    compounds is

    The correct order of increasing reactivity of C-X bond towards nucleophile in the following compounds is

    a. I < II < III < IV
    b. II < I < III < IV
    c. III < IV < II < I
    d. IV < III < I < II

    Solution
    2) \[\ce{CH3 – CH = CH2 ->[HI][Peroxide]}\] The major product of the above reaction is, _______. Options

    I – CH2 – CH = CH2

    CH3 – CH2 – CH2I

    \[\begin{array}{cc} \ce{CH3-CH-CH3}\\ |\\ \ce{I}\end{array}\] \[\begin{array}{cc} \ce{CH3-CH-CH2}\\ \phantom{…..}|\phantom{…..}|\\ \phantom{…….}\ce{I}\phantom{….}\ce{OH} \end{array}\]
    Solution

    iii. Which of the following is likely to undergo racemization during alkaline hydrolysis ?

    Which of the following is likely to undergo racemization during alkaline hydrolysis
    Solution

    iv. The best method for preparation of alkyl fluorides is
    a. Finkelstein reaction
    b. Swartz reaction
    c. Free radical fluorination
    d. Sandmeyer’s reaction

    Solution

    v. Identify the chiral molecule from the following.
    a. 1-Bromobutane
    b. 1,1- Dibromobutane
    c. 2,3- Dibromobutane
    d. 2-Bromobutane

    Solution

    vi. An alkyl chloride on Wurtz reaction gives 2,2,5,5-tetramethylhexane. The same alkyl chloride on reduction with zinc-copper couple in alchol give hydrocarbon with molecular formula C5H12. What is the structure of alkyl chloride

    \[\begin{array}{cc}
    \ce{CH3}\\
    |\phantom{...}\\
    \ce{CH3-C-CH2Cl}\\
    |\phantom{...}\\
    \ce{CH3}
    \end{array}\]

  • \[\begin{array}{cc}
    \ce{CH3\phantom{..}}\\
    |\phantom{.....}\\
    \ce{CH3-C-CH2CH3}\\
    |\phantom{.....}\\
    \ce{Cl\phantom{....}}
    \end{array}\]

  • \[\begin{array}{cc}
    \ce{CH3-CH2-CH-Cl}\\
    \phantom{......}|\\
    \ce{\phantom{.........}CH3}
    \end{array}\]

  • \[\begin{array}{cc}
    \ce{CH3-CH-CH-CHCl}\\
    |\phantom{.....}|\phantom{...}\\
    \ce{\phantom{..}CH3} \ce{\phantom{..}CH3\phantom{..}}
    \end{array}\]

    • Solution

    vii. Butanenitrile may be prepared by heating
    a. propanol with KCN
    b. butanol with KCN
    c. n-butyl chloride with KCN
    d. n-propyl chloride with KCN

    Solution

    viii. Choose the compound from the following that will react fastest by SN1 mechanism.
    a. 1-iodobutane
    b. 1-iodopropane
    c. 2-iodo-2 methylbutane
    d. 2-iodo-3-methylbutane

    Solution

    ix. 

    Solution

    x. Which of the following is used as source of dichlorocarbene
    a. tetrachloromethane
    b. chloroform
    c. iodoform
    d. DDT

    Solution

    i. Write IUPAC name of the following compounds

    Write IUPAC name of the following
    Solution

    ii. Write structure and IUPAC name of the major product in each of the following reaction.

    Write structure and IUPAC name
    of the major product in each of the
    Solution

    iii. Identify chiral molecule/s from the following.

    a. 

    \[\begin{array}{cc}\ce{CH3 - CH - CH2 - CH3}\\|\phantom{.........}\\\ce{OH\phantom{.......}}\end{array}\]

    b.

    \[\begin{array}{cc}\ce{CH3 - CH2 - CH - CH2 - CH3}\\
    |\\\ce{Br}\end{array}\]

    c. CH3 - CH - CH2 - CH2Br

    d. 

    \[\begin{array}{cc}\ce{CH3 - CH - CH2 - CH3}\\
    |\phantom{.........}\\\ce{CH3\phantom{......}}\end{array}\]

    Solution

    iv. Which one compound from the following pairs would undergo SN2 faster from the?

    iv. Which one compound from the following pairs would undergo SN2 faster from the
    Solution
    v. Complete the following reactions giving major product.

    1. \[\ce{CH3 – CH = CH2 ->[HBr][peroxide] A ->[alc. KOH] B}\]

    2. \[\begin{array}{cc}\ce{CH3 – CH = CH2 ->[Red P/Br2] A ->[Ag2O/H2O]B}\\|\phantom{…………………….}\\
    \ce{OH\phantom{…………………..}}\end{array}\]

    3. \[\begin{array}{cc}\ce{CH3\phantom{…..}}\\
    |\phantom{…….}\\
    \ce{CH3 – C – CH2 – Cl ->[Na/dry ether]}\\
    |\phantom{…….}\\
    \ce{CH3\phantom{…..}}
    \end{array}\]

    complete the following reaction
    Solution

    vi. Name the reagent used to bring about the following conversions.
    a. Bromoethane to ethoxyethane
    b.1-Chloropropane to 1 nitropropane
    c. Ethyl bromide to ethyl isocyanide
    d. Chlorobenzene to biphenyl

    Solution

    vii. Arrange the following in the increase order of boiling points
    a. 1-Bromopropane
    b. 2- Bromopropane
    c. 1- Bromobutane
    d. 1-Bromo-2-methylpropane

    Solution

    Match the following

    Column I  Column II
    \[\begin{array}{cc}\ce{CH3CH – CH3}\\|\phantom{….}\\ \ce{X\phantom{….}}\end{array}\] vinyl halide
    CH2 = CH – CH2X alkyl halide
    CH2 = CH – X allyl halide
    benzyl halide
    aryl halide
    Solution

    i. Haloarenes are less reactive than halo alkanes.

    Solution

    ii. Alkyl halides though polar are immiscible with water.

    Solution

    iii. Reactions involving Grignard reagent must be carried out under anhydrous condition.

    Solution

    iv. Alkyl halides are generally not prepared by free radical halogenation of alkanes.

    Solution

    4. Distinguish between – SN1 and SN2 mechanism of substitution reaction ?

    Solution

    5. Explain – Optical isomerism in 2-chlorobutane.

    Solution

    6. Convert the following.
    i. Propene to propan-1-ol
    ii. Benzyl alcohol to benzyl cyanide
    iii. Ethanol to propane nitrile

    iv. But-1-ene to n-butyl iodide
    v. 2-Chloropropane to propan-1-ol
    vi. tert-Butyl bromide to isobutyl bromide
    vii. p-Nitrochlorobenzene to p-nitrophenol
    viii. Propene to 1-nitropropane

    Solution

    i. HCl is added to a hydrocarbon ‘A’ (C4H8) to give a compound ‘B’ which on hydrolysis with aqueous alkali forms tertiary alcohol ‘C’ (C4H10O). Identify ‘A’ , ‘B’ and ‘C’.

    Solution
    ii. Complete the following reaction sequences by writing the structural formulae of the organic compounds ‘A’, ‘B’ and ‘C’ . a)
    \[\ce{2-Bromobutane->[Alc.KOH]A->[][Br2]B->[][NaNH2]C}\]
    b) \[\ce{Isopropyl alcohol ->[\triangle][PBr3] A ->[][NH3 excess] B}\]
    Solution

    iii. Observe the following and answer the questions given below.

    a. Name the type of halogen derivative
    b. Comment on the bond length of C-X bond in it
    c. Can react by SN1 mechanism? Justify your answer.

    Solution