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Imidazole (at right) has two nitrogens, ...

Imidazole (at right) has two nitrogens, N3 is relatively basic (like the nitroge of pyridine). N1 is relatively non-basic (like the nitrogen of pyrrole). Explain the different basicities of these two nitrogens.

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When imidazole accepts a proton at N3 the electron pair that accepts the proton is not a part of the `pi` system of six electrons that makes imidazole aromatic. Consequently, the conjugate base that is formed is still aromatic (it is an aromatic cation) and retains its resonance energy of stabilization.

On the other hand, if imidazole were to accept a proton at N1 the resulting ion (which is not formed) would not be aromatic and would have much greater potential energy (its resonance stabilization would be lost). Hence, N1 is not appreciably basic.
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Nitrogen (N_(2)) is relatively unreactive, because

A: Pyrrole is less basic than pyridine. R: Lone pair electron of nitrogen in pyrrole participate in conjugation to gain aromatic character.

Amines are basic compounds They act as Lewis base due to the presence of lone pair electrons at nitrogen Amines also behave as base as well as Bronsted inductive effect, steric hindrance and resosnance. CH_(3)-NH_(2)+HOH hArr CH_(3)-NH_(3)^(+)+OH^(-) CH_(3)-NH_(2)+H^(+)Cl^(-)hArr CH_(3)-NH_(3)^(+)+Cl^(-) Alkyl groups and electron groups hence these groups increases the electron density at nitrogen as well as the basic amines character of amines. Basic character of teritary amines is reduced due to the steric hindrance of three alkyl groups. Experimentally it is observed that stronger bases have smaller values of pK_(b) greater value of K_(b) . Which among the following is the most basic in aqueous medium?

Amines are basic compounds They act as Lewis base due to the presence of lone pair electrons at nitrogen Amines aho behave as base as well as Bronsted inductive effect, steric hindrance and resosnance. CH_(3)-NH_(2)+HOH hArr CH_(3)-NH_(3)^(+)+OH^(-) CH_(3)-NH_(2)+H^(+)Cl^(-)hArr CH_(3)-NH_(3)^(+)+Cl^(-) Alkyl groups and electron groups hence these groups increases the electron density at nitrogen as well as the basic amines character of amines. Basic character of teritary amines is reduced due to the steric hindrance of three alkyl groups. Experimentally it is observed that stronger bases have smaller values of pK_(b) greater value of K_(b) . Which among hte following is the most basic in aqueous medium?

Amines are basic compounds They act as Lewis base due to the presence of lone pair electrons at nitrogen Amines aho behave as base as well as Bronsted inductive effect, steric hindrance and resosnance. CH_(3)-NH_(2)+HOH hArr CH_(3)-NH_(3)^(+)+OH^(-) CH_(3)-NH_(2)+H^(+)Cl^(-)hArr CH_(3)-NH_(3)^(+)+Cl^(-) Alkyl groups and electron groups hence these groups increases the electron density at nitrogen as well as the basic amines character of amines. Basic character of teritary amines is reduced due to the steric hindrance of three alkyl groups. Experimentally it is observed that stronger bases have smaller values of pK_(b) greater value of K_(b) . Which of the following is the most basic?

(A) Pyrrole is more basic than pyridine. (R) In pyrrole, nitrogen is sp^(2) -hybridized.

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