Skip to main content
Ch. 15 - Structural Identification 2: Nuclear Magnetic Resonance Spectroscopy
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Non è quello che usi tu?Cambia libro di testo
Capitolo 14, Problema 43

Replace Hₐ, H₆, and H꜀ in methyl benzene with a deuterium. What is the relationship between the three products you obtain? Based on this, how many signals would you expect for these hydrogens in the ¹H NMR spectrum?
Diagram showing methyl benzene with Hₐ, H₆, H꜀ replaced by deuterium, illustrating ¹H NMR signal prediction.

Guida verificata passo dopo passo
1
Identify the structure of methyl benzene, also known as toluene. It consists of a benzene ring with a methyl group (CH₃) attached to it.
Recognize that Hₐ, H₆, and H꜀ refer to different hydrogen atoms on the benzene ring. In toluene, these hydrogens are located at different positions relative to the methyl group: ortho (Hₐ), meta (H₆), and para (H꜀).
Replace each of these hydrogens with deuterium (D), which is an isotope of hydrogen. This results in three different deuterated toluene molecules: ortho-deuterated, meta-deuterated, and para-deuterated toluene.
Determine the relationship between the three deuterated products. Since the benzene ring is symmetrical, the ortho, meta, and para positions are chemically distinct, leading to different chemical environments for each deuterium substitution.
Predict the number of signals in the ¹H NMR spectrum. Each unique chemical environment for the hydrogens in the original toluene will result in a separate signal. Consider the symmetry and the effect of the methyl group on the chemical shift of each hydrogen position.

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:
5m

Concetti chiave

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

Isotopic Substitution

Isotopic substitution involves replacing an atom in a molecule with its isotope, such as replacing hydrogen (H) with deuterium (D). This substitution can affect the physical and chemical properties of the molecule, including its behavior in spectroscopic analysis, due to the difference in mass between isotopes.
Video consigliato:
03:06
Understanding the hydrogen isotopes.

NMR Spectroscopy

Nuclear Magnetic Resonance (NMR) Spectroscopy is a technique used to observe the local environment of nuclei in a molecule. In ¹H NMR, hydrogen atoms in different chemical environments produce distinct signals. The number of signals corresponds to the number of unique hydrogen environments in the molecule.
Video consigliato:
10:06
General NMR Features

Chemical Equivalence

Chemical equivalence refers to atoms or groups in a molecule that are in identical environments and thus indistinguishable by NMR. In methyl benzene, the symmetry of the molecule can lead to some hydrogens being chemically equivalent, resulting in fewer NMR signals than the total number of hydrogens.
Video consigliato:
Percorso guidato
3:11
Chemical Reactions of Phosphate Anhydrides Concept 1