chapter13_part2

chapter13_part2 - 13-13-1Signal AreasSignal...

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Unformatted text preview: 13-13-1Signal AreasSignal Areas◆Relative areas of signals are proportional to the number of H giving rise to each signal◆Modern NMR spectrometers electronically integrate and record the relative area of each signal13-13-2ChemicalChemicalShiftsShiftsH-NMRH-NMRRCH2OR(CH3)4SiArCH3RCH3RC CHRCCH3ROHRCH2OHArCH2ROORCH2RR3CHR2NHRCCH2RR2C=CRCHR2R2C=CHRRCHORCOHORCH2ClRCH2BrRCH2IRCH2FArHOOR2C=CH2RCOCH3RCOCH2RArOH9.5-10.13.7-3.93.4-3.6Type of Hydrogen0 (by definition)Type of HydrogenChemical Shift (δ)1.6-2.62.0-3.00.8-1.01.2-1.41.4-1.72.1-2.30.5-6.02.2-2.63.4-4.0Chemical Shift (δ)3.3-4.02.2-2.52.3-2.80.5-5.04.6-5.05.0-5.710-134.1-4.73.1-3.33.6-3.84.4-4.56.5-8.54.5-4.713-13-3Chemical Shift - Chemical Shift - 1H-NMRH-NMR13-13-4Chemical ShiftChemical Shift◆Depends on (1) electronegativity of nearby atoms, (2) the hybridization of adjacent atoms, and (3) diamagnetic effects from adjacent pi bonds◆ElectronegativityCH3OHCH3FCH3ClCH3BrCH3I(CH3)4C(CH3)4SiCH3-XElectroneg-ativity of XChemical Shift (δ)4.03.53.12.82.52.11.84.263.473.052.682.160.860.0013-13-5Chemical ShiftChemical Shift◆Hybridization of adjacent atomsRCH3, R2CH2, R3CHR2C=CHR, R2C=CH2RCHOR2C=C(R)CHR2RCCHAllylicType of Hydrogen(R = alkyl)Name ofHydrogenChemical Shift (δ)AlkylAcetylenicVinylicAldehydic0.8 - 1.71.6 - 2.64.6 - 5.79.5-10.12.0 - 3.013-13-6Chemical ShiftChemical Shift◆Diamagnetic effects of pi bonds•a carbon-carbon triple bond shields an acetylenic hydrogen and shifts its signal upfield (to the right) to a smaller δvalue•a carbon-carbon double bond deshields vinylic hydrogens and shifts their signal downfield (to the left) to a larger δvalueRCH3R2C=CH2RCCHType of HNameAlkylVinylicAcetylenic0.8- 1.04.6 - 5.72.0 - 3.0Chemical Shift (δ)13-13-7Chemical ShiftChemical Shift•magnetic induction in the pi bond of a carbon-carbon double bond13-13-8Chemical ShiftChemical Shift•magnetic induction of the pi electrons in an aromatic ring 13-13-9Signal Splitting; the (Signal Splitting; the (nn+ 1) Rule+ 1) Rule...
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This note was uploaded on 09/19/2011 for the course CHM 262 taught by Professor Staff during the Spring '08 term at Purdue.

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chapter13_part2 - 13-13-1Signal AreasSignal...

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