Skip to main content
Ch. 19 - Amines
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Non è quello che usi tu?Cambia libro di testo
Capitolo 19, Problema 33e

Rank the amines in each set in order of increasing basicity.
(e)

Guida verificata passo dopo passo
1
Step 1: Identify the functional groups attached to the benzene ring in each compound. The first compound has an amino group (-NH2), the second compound has a methylamino group (-CH2NH2), and the third compound has an amide group (-CONH2).
Step 2: Understand the basicity of each functional group. Amines (-NH2 and -CH2NH2) are generally basic because the nitrogen atom has a lone pair of electrons that can accept a proton. Amides (-CONH2), on the other hand, are less basic because the lone pair on the nitrogen is delocalized into the carbonyl group, reducing its availability to accept a proton.
Step 3: Consider the effect of the benzene ring on basicity. In the first compound, the amino group (-NH2) is directly attached to the benzene ring, which can reduce its basicity due to resonance effects. The lone pair on the nitrogen can delocalize into the aromatic ring, making it less available for protonation. In the second compound, the methylamino group (-CH2NH2) is not directly attached to the benzene ring, so resonance effects are absent, and the nitrogen remains more basic.
Step 4: Compare the basicity of the amide group (-CONH2) in the third compound. The amide group is the least basic because the nitrogen's lone pair is delocalized into the carbonyl group, making it significantly less available for protonation compared to the amino groups in the first and second compounds.
Step 5: Rank the compounds in order of increasing basicity based on the above analysis. The amide group (-CONH2) is the least basic, followed by the amino group (-NH2) directly attached to the benzene ring, and the methylamino group (-CH2NH2) is the most basic.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
7m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Basicity of Amines

Basicity in amines refers to their ability to accept protons (H+) in a chemical reaction. This property is influenced by the availability of the lone pair of electrons on the nitrogen atom, which can bond with protons. Generally, the more electron-donating groups attached to the nitrogen, the higher the basicity, as they increase the electron density on the nitrogen.
Video consigliato:
07:12
Reductive Amination

Inductive Effect

The inductive effect describes how the presence of electronegative atoms or groups near a functional group can influence its properties, including basicity. Electron-withdrawing groups decrease electron density on the nitrogen, making it less basic, while electron-donating groups enhance basicity by increasing electron density. Understanding this effect is crucial for ranking the basicity of different amines.
Video consigliato:
01:47
Understanding the Inductive Effect.

Steric Hindrance

Steric hindrance refers to the repulsion between bulky groups in a molecule that can affect its reactivity and basicity. In amines, larger substituents around the nitrogen can hinder the approach of protons, reducing the amine's basicity. Thus, when ranking amines, considering the size and steric effects of substituents is essential for accurate comparisons.
Video consigliato:
02:53
Understanding steric effects.