Draw the NMR spectrum expected from ethanol that has been shaken with a drop of D2O.

Verified step by step guidance

1. Identify the structure of ethanol: Ethanol is ${\text{CH}}_3{\text{CH}}_2\text{OH}$.
2. Consider the effect of D2O: The $\text{OH}$ proton in ethanol will exchange with deuterium from D2O, resulting in ${\text{CH}}_3{\text{CH}}_2\text{OD}$.
3. Determine the number of unique proton environments: After deuterium exchange, there are two types of protons: the ${\text{CH}}_3$ and ${\text{CH}}_2$ groups.
4. Predict the splitting pattern: The ${\text{CH}}_3$ protons will appear as a triplet due to coupling with the ${\text{CH}}_2$ protons, and the ${\text{CH}}_2$ protons will appear as a quartet due to coupling with the ${\text{CH}}_3$ protons.
5. Consider the chemical shifts: The ${\text{CH}}_3$ protons will have a chemical shift around 1 ppm, and the ${\text{CH}}_2$ protons will have a chemical shift around 3.5-4 ppm.

Key Concepts

Nuclear Magnetic Resonance (NMR) Spectroscopy

NMR spectroscopy is a powerful analytical technique used to determine the structure of organic compounds. It relies on the magnetic properties of certain nuclei, such as hydrogen (1H) and carbon (13C), to provide information about the environment surrounding these nuclei. The resulting spectrum displays peaks that correspond to different chemical environments, allowing chemists to infer structural details about the molecule.

Deuterium Exchange

Deuterium exchange occurs when a hydrogen atom in a molecule is replaced by a deuterium atom (D), which is a stable isotope of hydrogen. In the context of ethanol shaken with D2O, the hydroxyl (–OH) hydrogen can exchange with deuterium, leading to a change in the NMR spectrum. This exchange can simplify the spectrum by removing the signal from the hydroxyl proton, which is often broad and difficult to interpret.

Chemical Shift

Chemical shift refers to the position of a peak in an NMR spectrum, which is influenced by the electronic environment surrounding the nucleus. In ethanol, the chemical shifts of the protons in the methyl (–CH3) and methylene (–CH2) groups will appear at specific frequencies, allowing for differentiation between them. Understanding chemical shifts is crucial for interpreting the NMR spectrum and identifying the presence of functional groups and their interactions.