Without referring to Table 14.1, label the proton or set of protons in each compound that gives the signal at the lowest frequency a, at the next lowest b, and so on.
h.

Verified step by step guidance

1. Step 1: Analyze the structure of the molecule provided. The molecule contains a bromine atom attached to a CH2 group, which is connected to another CH2 group bonded to an oxygen atom. The oxygen atom is further bonded to a methyl group (CH3).
2. Step 2: Understand the concept of chemical shift in NMR spectroscopy. Protons in different chemical environments resonate at different frequencies due to the electronic environment around them. Electronegative atoms like bromine and oxygen deshield nearby protons, causing them to resonate at higher frequencies.
3. Step 3: Identify the protons in the molecule. There are three sets of protons: (1) the CH2 group attached to bromine, (2) the CH2 group attached to oxygen, and (3) the CH3 group attached to oxygen.
4. Step 4: Determine the relative chemical shifts. The CH2 group attached to bromine will resonate at the highest frequency due to the strong deshielding effect of bromine. The CH2 group attached to oxygen will resonate at the next highest frequency due to the deshielding effect of oxygen. The CH3 group attached to oxygen will resonate at the lowest frequency because it is less deshielded compared to the other groups.
5. Step 5: Assign labels based on frequency. Label the CH3 protons as 'a' (lowest frequency), the CH2 protons attached to oxygen as 'b' (next lowest frequency), and the CH2 protons attached to bromine as 'c' (highest frequency).

Key Concepts

Chemical Shift in NMR Spectroscopy

In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift refers to the resonance frequency of a nucleus relative to a standard in a magnetic field. It is influenced by the electronic environment surrounding the nucleus, with protons in electron-rich environments appearing at higher frequencies (lower ppm values) and those in electron-poor environments at lower frequencies (higher ppm values). Understanding chemical shifts is crucial for identifying the types of protons present in a compound.

Electronegativity and Inductive Effect

Electronegativity is the tendency of an atom to attract electrons towards itself. In organic compounds, electronegative atoms (like Br or O) can withdraw electron density from nearby protons, affecting their chemical shift in NMR. This inductive effect can lead to downfield shifts (lower frequency) for protons adjacent to electronegative atoms, making it essential to consider when analyzing NMR spectra.

Integration and Multiplicity in NMR

Integration in NMR spectroscopy refers to the area under the peaks in the spectrum, which correlates to the number of protons contributing to that signal. Multiplicity indicates the splitting of NMR signals due to neighboring protons, following the n+1 rule, where n is the number of adjacent protons. Understanding these concepts helps in determining the number of protons and their environments, which is vital for interpreting the NMR data accurately.