Sample 1Medium
What is the correct order of basic strength of the following in aqueous solution?
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The answer is B.
In water, basicity depends on the +I effect, solvation of the ammonium ion by hydrogen bonding and steric hindrance together. For ethyl-substituted amines these combine to give (C2H5)2NH > (C2H5)3N > C2H5NH2 > NH3.
- A.
This is the gas-phase order based on +I effect alone; in water, solvation and steric factors put the secondary amine first.
- C.
Alkyl groups increase electron density on nitrogen, so ammonia is the weakest base, not the strongest.
- D.
Ethylamine is weaker than diethylamine and triethylamine in water because of fewer electron-releasing groups.
NCERT: Class 12 Chemistry, Chapter 9, 9.6