What information does NMR spectroscopy provide about a molecule?

What information does NMR spectroscopy provide about a molecule?

• A. Chemical environments of nuclei, including chemical shifts, splitting patterns, and integration.
• B. Molar mass of the molecule.
• C. Infrared absorption frequencies for functional groups.
• D. The color of the compound.

Answer: (A)

NMR spectroscopy tells you about the chemical environments of nuclei in a molecule. By measuring the chemical shift, you learn how electron-rich or electron-poor each nucleus is, which identifies different environments like various types of carbon or hydrogen neighbors. The splitting pattern reveals how many nearby magnetic nuclei (usually adjacent hydrogens) are influencing the nucleus, following the n+1 rule, so you can infer how many neighboring spins exist. The integration of each signal corresponds to the relative number of nuclei contributing to that environment, letting you gauge how many hydrogens (or carbons, in carbon-13 NMR) are present in each type of environment. Put together, these features let you map out the molecule’s structure and how its functional groups are arranged. NMR does not give molar mass (that’s mass spectrometry), nor does it provide infrared vibrational frequencies for functional groups or a compound’s color.

NMR spectroscopy tells you about the chemical environments of nuclei in a molecule. By measuring the chemical shift, you learn how electron-rich or electron-poor each nucleus is, which identifies different environments like various types of carbon or hydrogen neighbors. The splitting pattern reveals how many nearby magnetic nuclei (usually adjacent hydrogens) are influencing the nucleus, following the n+1 rule, so you can infer how many neighboring spins exist. The integration of each signal corresponds to the relative number of nuclei contributing to that environment, letting you gauge how many hydrogens (or carbons, in carbon-13 NMR) are present in each type of environment. Put together, these features let you map out the molecule’s structure and how its functional groups are arranged. NMR does not give molar mass (that’s mass spectrometry), nor does it provide infrared vibrational frequencies for functional groups or a compound’s color.