19.2.3 Using Combined Techniques

• What does Infrared (IR) Spectroscopy identify in a molecule?

  Functional groups
• Nuclear Magnetic Resonance (NMR) Spectroscopy provides information on molecular structure and environment
• Mass Spectrometry (MS) helps determine the mass-to-charge ratio of ions.
• Match each spectroscopic technique with its primary use:

  Infrared (IR) Spectroscopy ↔️ Identifying molecular structure

  Nuclear Magnetic Resonance (NMR) Spectroscopy ↔️ Elucidating molecular structure

  Mass Spectrometry (MS) ↔️ Identifying molecular weight
• What type of information does IR Spectroscopy provide?

  Functional groups
• NMR Spectroscopy provides information on molecular structure and environment
• Mass Spectrometry can determine both molecular weight and fragmentation patterns.
• What is the typical use of IR Spectroscopy?

  Identifying molecular structure
• Spectroscopic techniques are often used in combination to provide a more complete understanding of a molecule's structure.
• Mass Spectrometry determines the mass-to-charge ratio of ions
• What type of information does IR Spectroscopy provide?

  Functional groups
• NMR Spectroscopy provides information on molecular structure and environment
• What does Mass Spectrometry determine about a molecule?

  Molecular weight
• Spectroscopic techniques are often used in combination for a more complete understanding of molecular structure.
• Match each spectroscopic technique with its primary application:

  IR Spectroscopy ↔️ Functional groups

  NMR Spectroscopy ↔️ Molecular structure

  Mass Spectrometry ↔️ Molecular weight
• Spectroscopic techniques are complementary because they provide different aspects of molecular structure.
• What does Mass Spectrometry determine about molecular fragmentation?

  Patterns
• Combining IR, NMR, and MS spectra enhances structural elucidation by leveraging their complementary information.
• Steps to combine spectroscopic techniques for structural elucidation

  1️⃣ Analyze the IR spectrum to identify functional groups

  2️⃣ Use the NMR spectrum to elucidate molecular structure

  3️⃣ Determine the molecular weight from the MS spectrum

  4️⃣ Confirm fragmentation patterns
• The combined spectra of propanol suggest its molecular formula is $C_{3}H_{8}O$.