Ch17 Spectroscopy
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What are the different types of covalent bond vibrations in IR spec and what does the frequency of vibration depend on?
What is the fingerprint region on IR graph? Where can functional groups be identified?
What is the fingerprint region on IR graph? Where can functional groups be identified?
• Fingerprint region = below 1500cm-1 wavenumber ; unique peaks that can be used to identify molecule by comparison w/ spectra of known compounds. Can help distinguish if compound contains impurities if compared to known spectra of pure compound. • Above 1500cm-1 peaks are useful to identify functional groups present in molecule.
LOOK AT IR SHEET on IPAD
What is a molecular ion on Mass Spec:
The molecular ion peak is the peak at highest m/z value on RHS of mass spec Might be a very small peak one unit after M+ peak, known as M+1 due to small % of carbon present at carbon-13 isotope rather than carbon-12.
What is fragmentation on a mass spec:
• Inside mass spec, some of molecular ions undergo fragmentation, where they break down into smaller fragments (covalent bonds break). • The fragment ions produce other peaks seen in mass spec • When M+ breaks down it produces both positively charged fragment ions and radicals, but only positive ions can be detected (not uncharged radicals)
LOOK THROUGH MASS SPEC SHEET ON IPAD