Describe the 1H NMR spectrum you would expect for each of the following compounds, indicating the relative positions of the signals: i.

Verified step by step guidance

1. Identify the different types of hydrogen environments in the molecule. In this compound, there are three distinct types of hydrogen environments: the methyl group (CH3) attached to the carbon with bromine, the methylene group (CH2) in the middle, and the methylene group (CH2) attached to the other bromine.
2. Determine the number of signals. Each unique hydrogen environment will give rise to a separate signal in the 1H NMR spectrum. Therefore, expect three signals corresponding to the three different hydrogen environments.
3. Consider the chemical shift. The CH3 group attached to the bromine will appear downfield due to the electron-withdrawing effect of bromine. The CH2 group next to the bromine will also be downfield, but less so than the CH3 group. The CH2 group in the middle will be the most upfield.
4. Analyze the splitting pattern. The CH3 group will appear as a doublet due to coupling with the adjacent CH2 group. The CH2 group next to the CH3 will appear as a quartet due to coupling with the CH3 group. The CH2 group next to the bromine will appear as a triplet due to coupling with the adjacent CH2 group.
5. Consider the integration of the signals. The integration of the signals will reflect the number of hydrogens in each environment: the CH3 group will integrate to 3, and each CH2 group will integrate to 2.

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, primarily hydrogen-1 (1H), to provide information about the number of hydrogen atoms in different environments within a molecule. The resulting spectrum displays peaks corresponding to these environments, allowing chemists to infer structural details.

Chemical Shifts

Chemical shifts in an NMR spectrum indicate the position of the signals and are measured in parts per million (ppm). They arise from the electronic environment surrounding the hydrogen atoms; for example, protons attached to electronegative atoms or in different hybridization states will resonate at different frequencies. Understanding chemical shifts helps in identifying functional groups and the overall structure of the compound.

Integration and Splitting Patterns

Integration in NMR refers to the area under the peaks, which correlates to the number of hydrogen atoms contributing to that signal. Splitting patterns, or multiplicity, arise from the interaction of neighboring hydrogen atoms and provide insight into the number of adjacent protons. Together, these features help deduce the connectivity and arrangement of atoms in the molecule, crucial for interpreting the spectrum accurately.