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8/2/2019 Organic Spectroscopy Mass Spec
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2.12 Mass Spectroscopy
Elemental isotopic and molecular
analyses.(March 2010)
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Spectroscopy
Mass Spectroscopy combined with IR andNMR are very powerful techniques in structure
determination UV/Visible (older more limited information)
spectroscopy is not used as much these days the other techniques superseded it.
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1) Mass spectroscopy.
Lister and Renshaw (New Understanding Chemistry)
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mass spec contd.elemental analysis
Lister and Renshaw (New Understanding Chemistry)
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mass spec contd.elemental analysis
Lister and Renshaw (New Understanding Chemistry)
e.g. forNeon
Note take care with s.f. Answer should b given in the same No of S.F. as was givenin in the data.If data = 20.00 and 22.00 as well as 100.0 and 10.00 for the %s
then the answer would be 20.18.
If No of s.f. in data vary e.g 20.00 and 22.0 then the answer is reported to the sames.f. as the least accurate data e.g. 22.0 i.e. answer is reported to 3 s.f.
Note 3 s.f. is very common for A-level.
2018.201010010*22100*20
rA
heightpeakTotal
intensity)(orabundanceits*peakisotopeEachr
A
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mass spec contd.elemental analysis
Mass specrevealed: No. ofisotopes and can beused to calculate
relative atomicmass
Lister and Renshaw (New Understanding Chemistry)
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mass spec contd .MOLECULARanalysis
Lister and Renshaw (New Understanding Chemistry)
Molecule can rearrange to produce exotic fragmentsonce it ionizes/turns into a radical
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mass spec contd .MOLECULARanalysis
In the M.S. shown,what name is given
to the peak at m/z=72?
43?
Try and assignpeaks at m/z= 29,
43, 57 and 72
What does theheight of the peaktell us about thestability of thespecies?
After, go back to slide 7
www.chemguide.co.uk Jim Clarke
http://www.chemguide.co.uk/http://www.chemguide.co.uk/8/2/2019 Organic Spectroscopy Mass Spec
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mass spec contd .MOLECULARanalysis
m.s. of 2-Chloropropane
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mass spec contd .MOLECULARanalysis
www.chemguide.co.uk Jim Clarke
http://www.chemguide.co.uk/http://www.chemguide.co.uk/8/2/2019 Organic Spectroscopy Mass Spec
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
(single nucleus) Aromatic m.s. of Benzaldehyde
CHO
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mass spec contd .MOLECULARanalysis
(again) m.s. of Napthalene
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
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mass spec contd .MOLECULARanalysis
Deduce the moleculeand assign labeledpeaks A,B,C and D
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mass spec contd .MOLECULARanalysis
Clue?... This organic compound contains at leastone halogen.
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mass spec contd .MOLECULARanalysis
Clue: Molecule not featured earlier. Theempirical formula is C2H3O1
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mass spec contd .MOLECULARanalysis
Thats all folks !!!