The correct order in aqueous medium of basic strength in case of methyl substituted amines is :
- $NH _3> Me _3 N > MeNH _2> Me _2 NH$
- $Me _2 NH > Me _3 N > MeNH _2> NH _3$
- $Me _2 NH > MeNH _2> Me _3 N > NH _3$
- $Me _3 N > Me _2 NH > MeNH _2> NH _3$
The Correct Option is C
Solution and Explanation
In aqueous medium, the basic strength of amines depends on:
1. Electron density on the nitrogen atom (due to inductive effect of methyl groups).
2. Solvation effect, which stabilizes the conjugate acid after accepting a proton.
- Dimethylamine (Me$_2$NH): The best combination of inductive effect and solvation, making it the most basic.
- Methylamine (MeNH$_2$): Slightly less basic due to less inductive effect but better solvation.
- Trimethylamine (Me$_3$N): Weaker basicity because bulky groups hinder solvation.
- Ammonia (NH$_3$): Lowest basicity due to the absence of inductive effect.
Thus, the basic strength order is Me$_2$NH $>$ MeNH$_2$ $>$ Me$_3$N $>$ NH$_3$. Basicity in aqueous medium is influenced by both inductive effects and solvation. Dimethylamine balances these effects best, while trimethylamine suffers from steric hindrance.
Top Questions on Amines
- How will you convert nitrobenzene to 2, 4, 6-Tribromo aniline?
- (i) The reaction in which an amide is converted into a primary amine by the action of Br2 and alcoholic NaOH is known as ________.
(ii) How is a primary amine distinguished from a secondary amine using the Hinsberg test? - Write the structures of (A), (B), and (C) in the following reaction:
\[ C_6H_5NO_2 \xrightarrow{Fe/HCl} (A) \xrightarrow[\text{273 K}]{NaNO_2 + HCl} (B) \xrightarrow[\Delta]{H_2O/H^+} (C) \] - What happens when aniline reacts with the following:
(A) Bromine water
(B) $(CH_3CO)_2O$ / Pyridine
(C) $HNO_2 + HCl (0^\circ - 5^\circ C)$ - Why is \(-NH_2\) group of aniline acetylated before carrying out nitration?
Questions Asked in JEE Main exam
MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K.
MX(s) $\rightleftharpoons M^{+(aq) }+ X^{-}(aq)$; $K_{sp} = 10^{-10}$
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Concepts Used:
Amines
Amine is a type of compound which is derived from ammonia (NH3). According to Organic chemistry, they are basically classified as the functional groups of the organic nitrogen compounds that contain nitrogen atoms with a lone pair.
Amine - Types
Primary Amines:
It is formed when one hydrogen atom in ammonia is substituted by an alkyl or aromatic group. Amino acids and methyl amine are the best examples that why aromatic amines include aniline.
Secondary Amines:
Amines that have two organic substitutes either alkyl or aryl ones or both and are bound to the nitrogen together with one hydrogen are termed as secondary amines. For Example, Dimethylamine.
Tertiary Amines:
Tertiary Amines are the amines where the nitrogen consists of three organic substitutes. For example, Trimethylamine and EDTA.