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Account for the following (i)Primary ...

Account for the following
(i)Primary amines `(R-NH_(2))` have higher boiling point than tertiary amines `(R_(3)N)`
(ii) Aniline does not undergo friedel - crafts reaction
(iii) `(CH_(3))_(2)` NH is more basic than `(CH_(3))_(3)N` in an aquaous solution

Text Solution

Verified by Experts

The basicity of `(CH_(3))_(2)NH and (CH_(3))_(3)N` mainly depends upon the stability of the ammonium cation formed when each one of them accepts a proton. Since the ammonium cation derived from `(CH_(3))_(2)NH` is stabilized by H-bonding with only one H-atom, therefore, `(CH_(3))_(2)NH` is more basic than `(CH_(3))_(3)N`.

(ii) The boiling points of amines depnds upon the degree of association due to H-bonding which, in turn, depends upon the number of H-atoms on the N-atom. since `1^(@)` amines have two H-atoms linked to N-atom while `3^(@)` amines have no H-atom linked to N-atom, therefore, `1^@` amines exist as associated

Molecules (as shown above) while `3^(@)` amines exist as individual molecules. to break these H-bonds, large amount of nergy is needed. therefore, `1^(@)` amines have higher boiling point than `3^(@)` amines.
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Account for the following : (i) Primary amines (R-NH_(2)) have higher boiling points than tertiary amines (R_(3)N) . (ii) Aniline does not undergo Friedel-Crafts reaction. (iii) (CH_(3))_(2)NH is more basic than (CH_(3))_(3)N in an aqueous solution.

Give reasons (CH_3)_2 NH is more hasic than (CH_3)_3N in an aqueous solution.

Knowledge Check

  • A: Aniline does not undergo Friedel Craft's reaction. R: NH_(2) group of Aniline is deactivating group for all reactions

    A
    If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
    B
    If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
    C
    If Assertion is true statement but Reason is false, then mark (3)
    D
    If both Assertion and Reason are false statements, then mark (4)

  • Assertion: Aniline does not undergo Friedel-Crafts reactions. Reason: -NH_2 group of aniline reacts with AlCl_3 to give acid-base reaction.

    A
    A and R are true and R is the correct explanation of A
    B
    A and R are true and R is not the correct explanation of A
    C
    A is true R is false
    D
    A is false R is true

  • Assertion (A) : PH_(3) is more basic than NH_(3) Reason (R) : EN of N is more than that of P

    A
    Both (A) and (R) are true and (R) is the correct explanation of (A)
    B
    Both (A) and (R) are true and (R) is not the correct explanation of (A)
    C
    (A) is true and (R) is false
    D
    (A) is false but (R) is true

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    State reasons for the following: primary amines have higher boiling points than tertiary amines.

    Give reasons for the following : (i) Aniline does not undergo Friedal-Crafts reaction. (ii) (CH_(3))_(2)NH is more basic than (CH_(3))_(3)N in an aqueous solution. (iii) Primary amines have higher boiling point than tertiary amines.

    Give plausible explanation for each of the following : Why do primary amines have higher boiling points than tertiary amines ?

    (a) Why have primary amines higher boiling points than tertiary amines? (b) Write the products obtained in the nitration of aniline. (c) What is carbylamine reaction?

    (a) Give reasons : (i) Although- NH_(2) group is o/p directing in electrophilic substitution reactions, yet aniline, on nitration gives good yield of m-nitroaniline. (ii) (CH_(3))_(2)NH is more basic than (CH_(3))_(3)N in an aqueous solution. (iii) Ammonolysis of alkyl halides is not a good method to prepare pure primary amines. (b) Distinguish between the following : (i) CH_(3)CH_(2)NH_(2) and (CH_(3)CH_(2))_(2)NH (ii) Aniline and CH_(3)NH_(2)

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