5.2 Spectroscopy Flashcards
What is mass spectrometry used for?
determine the mass of compounds in a sample
What is the product of mass spectrometry?
mass readout with peaks corresponding to molecular mass
What types of molecules is UV/visible spectroscopy used for?
- complexes of transition metals
- highly conjugated organic systems
What is UV/visible spectroscopy?
focuses on energetic wavelengths of radiation in the UV and visible spectra that is strong enough to induce electronic excitation
What is IR spectroscopy?
electromagnetic radiation in the IR range has the proper energy to cause bonds in organic molecules to become vibrationally excited
What are wave numbers?
v = reciprocal of the wavelength; used in IR spectroscopy
Where are C=O stretches located?
1700
Where are C=C stretches located?
1650
Where are triple bond stretches located?
2260-2100
Where are OH stretches located?
3600-3200
Where are aliphatic CH bond stretches located?
3000-2850
Where are aromatic CH bond stretches located?
3300-3000
What are the four essential features of a molecule that can be deduce from proton NMR?
- number of chemically unequivalent sets of protons
- how many protons interact with protons in a specific set
- relative numbers of protons in each set
- environment of protons in each set
How do you determine the number of chemically unequivalent sets of protons?
sets of peaks
How do you determine how many protons are interacting with protons in a specific set?
splitting pattern per peak
