Q. 34.7( 4 Votes )

Amongst the following, the strongest base in aqueous medium is ____________.
A. CH3NH2

B. NCCH2NH2

C. (CH3)2 NH

D. C6H5NHCH3

Answer :

Basicity of amines depends on its structure and the classification (electron releasing/withdrawing) other groups attached to the adjacent carbon atoms which determine ease of formation of the cation by accepting protons from the acid.


(iii) (CH3)2 NH is the strongest base due to the efficient +I effect(electron releasing effect ) of alkyl(here –CH3). This effect of alkyl group pushes the unshared electron pair(lone pair) more towards the N atoms and thus make them more available for protonation by acid.


• For the same reason (i) CH3NH2 will be less basic than (iii) because it has less of the effect.


• In case of (ii) NCCH2NH2, CN(cyanide CN:) is an electron-withdrawing group i.e. it pulls electrons towards itself from the N atom hence making the lone pairs less available for protonation, therefore it is not a strong base.


• In comparison between alkyl and aryl amines, the former is always more basic than the latter because in case of aryl amines:


the -NH2 (amine) group is attached directly to the benzene(aryl) ring. hence the unshared electron pair on nitrogen atom undergoes conjugation (resonance) with the benzene ring and thus it becomes almost unavailable for protonation.


thus (iv) C6H5NHCH3 might be theweakestamongst the given amines.

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Chemical reaction of AminesChemical reaction of AminesChemical reaction of Amines45 mins
Recap of Amines | A Thorough RevisionRecap of Amines | A Thorough RevisionRecap of Amines | A Thorough Revision46 mins
Preparation of AminesPreparation of AminesPreparation of Amines45 mins
Introduction to Diazonium SaltsIntroduction to Diazonium SaltsIntroduction to Diazonium SaltsFREE Class
Quiz on amines | Check Important ConceptsQuiz on amines | Check Important ConceptsQuiz on amines | Check Important Concepts47 mins
General introduction of AminesGeneral introduction of AminesGeneral introduction of Amines54 mins
Complete revision of amines| Concepts at fingertipsComplete revision of amines| Concepts at fingertipsComplete revision of amines| Concepts at fingertips43 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses