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Assignment of Spin Systems. For each compound: Describe all spin systems Determine the number of protons that are: Chemical shift equivalent Magnetic equivalent Enantiotopic Diastereotopic. Splitting of Signals – Structure determination. MW 114. MW 116. - PowerPoint PPT Presentation
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ASSIGNMENT OF SPIN SYSTEMSNMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 1
For each compound:
Describe all spin systems
Determine the number of protons that are: • Chemical shift equivalent• Magnetic equivalent • Enantiotopic• Diastereotopic
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 2
MW 114
MW 116
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 3
MW 169has -Br
MW 150
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 4
MW 100
MW 74
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 5
MW 73
MW 56
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 6
MW 89
MW 138
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 7
MW 122
MW 102
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 8
MW 113
MW 94
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 9
MW 152
MW 157has -Cl
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 10
MW 208
MW 98
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 11
MW 126
MW 116
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 12
MW 1622 -Cl
MW 122
SPLITTING OF SIGNALS – STRUCTURE DETERMINATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 13
MW 96
PRACTICE WITH POPLE NOTATIONNMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 14
On graph paper, draw a schematic (line) representation of the pure first-order spectrum AMX3 corresponding to the following parameters:
n (Hz from TMS): nA = 80; nM = 220; nX = 320J (Hz): JAM = 10; JAX = 12; JMX = 0
• Assume spectrum is a pure 1st order spectrum and ignore small
distortions in relative intensities that would occur in a ‘real’ spectrum.
• Sketch in “splitting diagrams” above the schematic spectrum to indicate which splittings correspond to which coupling constants.
• Give the shifts on the d scale corresponding to the above spectrum on a 60 MHz NMR (1H).
PRACTICE WITH POPLE NOTATIONNMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 15
AMX3
n (Hz from TMS): nA = 80; nM = 220; nX = 320J (Hz): JAM = 10; JAX = 12; JMX = 0
STRUCTURE DETERMINATION WITH POPLE NOTATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 16
The 400 MHz 1H NMR spectrum of one of the following isomeric hydroxycinnamic acids is given below. Which one is it? Justify your answer based on chemical shift and coupling constants.
STRUCTURE DETERMINATION WITH POPLE NOTATION
NMR - The Coupling Constant 4-1
CHEM 430 – NMR Spectroscopy 17