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5 Cards in this Set
- Front
- Back
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What are some uses of C NMR?
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-C NMR can verify that E2 elimination of an alkyl halide gives the more substituted alkene (Zaitsev's rule)
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What are the 4 possibilities for determining equivalence or nonequivalence of Protons?
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1. Protons are chemically unrelated and thus nonequivalent
2. Protons are chemically identical and thus electronically equivalent and homotopic 3. Protons are electronically equivalent but not identical (enantiotropic) ex. prochiral hydrogens (if pro-R and pro-S hydrogens replaced) 4. Replacement of hydrogen gives a unique diastereomer with a second chirality center (diastereotopic) |
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What are the ranges for the Hydrogen chemical shifts?
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COOH = 11-12
aldehyde = 9-10 attached to aromatic ring = 7-8 vinylic = 4.5 - 6.5 alkyl (primary) = 0.7 - 1.3 alkyl (secondary) = 1.2 - 1.6 alkyl (tertiary) = 1.4 - 1.8 allylic = 1.6 - 2.2 methyl ketone = 2.0 - 2.4 alcohol, ether = 3.3 - 4.5 alcohol = 2.5 - 5 |
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What are the ranges for the Carbon chemical shifts?
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C=O = 165 - 210
Aromatic C and C=C = 100 - 150 C triple bond C = 75 - 95 C - O = 55 - 90 C-Cl and C-Br = 30 - 60 Alkanes = 0 - 40 |
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What is the Coupling constant?
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distance between peaks in a multiplet
denoted J and measured in Hz falls between 0 - 18 Hz same coupling constant is shared by both groups of hydrogens whose spins are coupled coupling constants are independant of spectrometer field strength |
