Predict the splitting patterns for the signals given by the compounds in Problem 4. c.

Verified step by step guidance

1. Identify the different types of hydrogen environments in the molecule. In this compound, there are two types of hydrogen environments: the methyl groups (CH₃) and the hydrogens on the double-bonded carbon atoms.
2. Determine the number of neighboring hydrogens for each type of hydrogen. For the methyl groups, there are no neighboring hydrogens on the adjacent carbon, so they will not be split by other hydrogens.
3. For the hydrogens on the double-bonded carbon atoms, consider the coupling with the hydrogens on the adjacent carbon atoms. Each hydrogen on the double bond is adjacent to two equivalent methyl groups, which contain three hydrogens each.
4. Apply the n+1 rule to predict the splitting pattern. For the methyl groups, since there are no neighboring hydrogens, the signal will appear as a singlet. For the hydrogens on the double bond, they are coupled to six equivalent hydrogens (3 from each methyl group), so the signal will appear as a septet (6+1=7).
5. Consider the chemical shift and coupling constants to understand the relative positions and intensities of the signals, but focus on the splitting pattern as the primary goal.

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 (1H) and carbon (13C), to provide information about the number of hydrogen atoms and their environment in a molecule. The resulting spectrum displays signals that correspond to different chemical environments, allowing chemists to deduce structural information.

Spin-Spin Coupling

Spin-spin coupling, or J-coupling, occurs when neighboring nuclei influence each other's magnetic environments, leading to splitting of NMR signals. The number of peaks in a signal is determined by the number of adjacent protons, following the n+1 rule, where n is the number of neighboring protons. This concept is crucial for interpreting the multiplicity of signals in an NMR spectrum, which provides insights into the connectivity of atoms in a molecule.

Chemical Shifts

Chemical shifts in NMR spectroscopy refer to the variation in resonance frequency of a nucleus due to its electronic environment. Different functional groups and substituents can cause shifts in the position of NMR signals, allowing for the identification of specific types of hydrogen atoms. Understanding chemical shifts is essential for analyzing the structure of compounds, as they provide clues about the presence of electronegative atoms or groups, such as bromine in the given compound.