IntroductoryOrganicChemistryChem 222&Chem 234
Summer2015
Dr.LauraPavelkaDepartmentofChemistry
Pulp&[email protected]
CHAPTER9:TOOLSFORSTRUCTUREDETERMINATION
CHEM222/234 LectureChapter9 2
NOWTHATWEHAVEAHANDLEON13C&1HNMRSPECTROSCOPY
TIMETOMOVEONTOMASSSPEC!
LectureChapter9
LETS SEEWHATELSEWECANDO...
Section2 NMRSpectroscopyandMassSpectrometryChapter9 ToolsforStructureDetermination(Part2)
IntrotoMassSpectrometry(MS)IonizationandFragmentationIsotopesinMSIntegratedStructureDetermination
CHEM222/234 3
MassSpectrometry
CHEM222/234 LectureChapter9 4
MassSpectrometry electromagneticradiationNOTinvolved
Spectroscopy studying/plottingtheinteractionofmoleculeswithelectromagneticradiation
MassSpectrometry
CHEM222/234 LectureChapter9 5
UsesofMassSpectrometry:1. MolecularWeightand/orFormulaDetermination2. StructuralAnalysis fragmentationpatterns3. IsotopeAnalysis
MassSpectrometry electromagneticradiationNOTinvolved
Spectroscopy studying/plottingtheinteractionofmoleculeswithelectromagneticradiation
TypicalMassSpectrum
CHEM222/234 LectureChapter9 6
KeyFeaturesofaMassSpectrumA. Mass/ChargeRatio formulaweightofeachionfragmentproducedB. IonAbundance amountofeachionfragmentproduced(%)C. BasePeak mostabundantionfragment(tallestpeak)D. MolecularIon unfragmented ion(originalformulaweight)E. IsotopePeaks molecularionscontainingheavierisolopes (ex.13C)
LectureChapter9
LETS SEEWHATELSEWECANDO...
Section2 NMRSpectroscopyandMassSpectrometryChapter9 ToolsforStructureDetermination(Part2)
IntrotoMassSpectrometry(MS)IonizationandFragmentationIsotopesinMSIntegratedStructureDetermination
CHEM222/234 7
MassSpectrometry
CHEM222/234 LectureChapter9 8
sampleinlet
sampleinlet
ionizationchamberionizationchamber
massanalyzermass
analyzer
CollectinganMassSpectrum: ionizecompound(electronbeamcommon ElectronImpactMS) sendthroughmassanalyzer(magnetortimeofflightToF)
detectordetector
EIMS:Ionization
CHEM222/234 LectureChapter9 9
ex.IonizationofPropane
*electronremovedfromnonbondingandelectronseasiest*
Fragmentation:BondCleavage
CHEM222/234 LectureChapter9 10
RadicalCation
Cation +Radical
Radical+Cation
TwoPossibleCleavageOptions:
*stabilityofcation determinesrelativeabundanceoffragments*(highlysubstituted/resonancestabilizedR+ formedmore!)
Practice:Ionization/Fragmentation
CHEM222/234 LectureChapter9 11
CHEM222/234 LectureChapter9 12
Fragmentation:BondCleavage
ex.Hexane
CHEM222/234 LectureChapter9 13
Fragmentation:BondCleavage
ex.CH3F
Practice:Fragmentation
CHEM222/234 LectureChapter9 14
IdentifytheM+peakandbasepeakintheMSofethylbenzene.Whatfragmentgivesrisetothebasepeak?
Fragmentation:BondCleavage
CHEM222/234 LectureChapter9 15
Ethers
Fragmentation:BondCleavage
CHEM222/234 LectureChapter9 16
Aldehydes
Fragmentation:BondCleavage
CHEM222/234 LectureChapter9 17
CarboxylicAcids
Fragmentation:BondCleavage
CHEM222/234 LectureChapter9 18
OftenNOMolecularion
Alcohols
Fragmentation:BondCleavage
CHEM222/234 LectureChapter9 19
Halides
Practice:AlcoholFragmentation
CHEM222/234 LectureChapter9 20
MW:88.15g/mol
Practice:AlkeneFragmentation
CHEM222/234 LectureChapter9 21
MW:84.16g/mol
LectureChapter9
LETS SEEWHATELSEWECANDO...
Section2 NMRSpectroscopyandMassSpectrometryChapter9 ToolsforStructureDetermination(Part2)
IntrotoMassSpectrometry(MS)IonizationandFragmentationIsotopesinMSIntegratedStructureDetermination
CHEM222/234 22
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 23
m+1
m+2
CHEM222/234 LectureChapter9 24
12CH4 13CH4
IsotopePeaksandMolecularIon
m+1:13C(and15N)IsotopePeaks
OneCarbon:Methane(CH4)
RatioMW
98.916
1.117
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 25
m+1:13C(and15N)IsotopePeaks
OneCarbon:Methane(CH4)
13C~1.1%naturalabundance
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 26
LargerMolecules(>1carbon)
1.1%x3(possible13Clocations)+0.37%x2(possible15Nlocations)
m+1:13C(and15N)IsotopePeaks
1.1%x5(possible13Clocations)
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 27
DeterminingMolecularFormulas(#ofCarbons)
m+1:13C(and15N)IsotopePeaks
Intensity[M+ +1]peak x100=max#carbonsIntensity[M+]peak
13C~1.1%naturalabundance
Practice:Determining#Carbons
CHEM222/234 LectureChapter9 28
EstimatethenumberofcarbonspresentinthecompoundthatproducedthefollowingMS.
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 29
m+2:34S,37Cl,or81BrIsotopePeaks
OneSulfur:Methanethiol (CH3SH)
CH332SH CH334SH
RatioMW
9548
450
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 30
m+2:34S,37Cl,or81BrIsotopePeaks
OneChlorine:Chloromethane(CH3Cl)
CH335Cl CH337Cl
RatioMW
7550
2552
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 31
m+2:34S,37Cl,or81BrIsotopePeaks
OneBromine:Bromomethane (CH3Br)
CH379Br CH381Br
RatioMW
5094
5096
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 32
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 33
m+4:Twoof34S,37Cl,or81BrIsotopePeaks
TwoBromines:Dibromomethane (CH2Br2)
CH279Br2 CH281Br2
Ratio
MW
25
172
25
176
CH279Br81Br
50
174
IsotopePeaksandMolecularIon
CHEM222/234 LectureChapter9 34
Nitrogen (Even Electron)Rule
CHEM222/234 LectureChapter9 35
Nitrogen Rule even mass(M+)=even number ofnitrogens (including zero)odd mass(M+)=odd number ofnitrogens
*mostly odd massfragmentsforeven massM+ **mostly even massfragmentsforodd massM+ *
M+M F1+ F2+
odd odd eveneven even odd
Nitrogen (Even Electron)Rule
CHEM222/234 LectureChapter9 36
Nitrogen Rule even mass(M+)=even number ofnitrogens (including zero)odd mass(M+)=odd number ofnitrogens
*mostly odd massfragmentsforeven massM+ **mostly even massfragmentsforodd massM+ *
Practice:DeterminingMolecularFormula
CHEM222/234 LectureChapter9 37
Whatisapossibleformulaforthiscompound?
CHEM222/234 LectureChapter9 38
NOWTHATWEKNOWABOUTIR,13C&1HNMRSPECTROSCOPYANDMASSSPECTROMETRY
YOURCANTRYSOMEINTEGRATEDEXAMPLESANDSOLVEUNKNOWNS!
LectureChapter9
LETS SEEWHATELSEWECANDO...
Section2 NMRSpectroscopyandMassSpectrometryChapter9 ToolsforStructureDetermination(Part2)
IntrotoMassSpectrometry(MS)IonizationandFragmentationIsotopesinMSIntegratedStructureDetermination
CHEM222/234 39
StructureDetermination
CHEM222/234 LectureChapter9 40
ORGANICSYNTHESISORGANICSYNTHESIS
ISOLATIONOFNATURALPRODUCTS
ISOLATIONOFNATURALPRODUCTS
STRUCTUREDETERMINATION&
ANALYSIS(MS,IR,NMR)
STRUCTUREDETERMINATION&
ANALYSIS(MS,IR,NMR)
StructureDetermination
CHEM222/234 LectureChapter9 41
1. MS molecular weight/formulaandunits ofunsaturation2. IR identificationofpolarfunctional groups(OH,NH,C=O,etc)3. 13CNMR #typesofcarbons,possiblechemical environments4. 1HNMR #typesofhydrogens,possiblechemical environments,number
ofeach typeofhydrogen,number ofneighbouring hydrogens
MSMS IRIR13CNMR13CNMR
1HNMR1H
NMRSTRUCTURE!STRUCTURE!
EXTRAPRACTICEhttp://www.chem.ucla.edu/~webspectra/
Practice:IntegratedExample
CHEM222/234 LectureChapter9 42
SupposetheIRspectrumofthecompoundthatgaverisetotheMSbelowcontainsastrongabsorptionat1670cm1 andnoabsorptionsabove3000cm1.Drawthreepossiblestructures.
Practice:IntegratedExample
CHEM222/234 LectureChapter9 43
AnunknownhastheMSbelow.Thiscompoundalsohasa13CNMRspectrumthatcontainsfoursignalsandanIRspectrumwithanintensepeakat1720cm1.Proposeastructure.
Practice:IntegratedExample
CHEM222/234 LectureChapter9 44
1HNMRZOOM(6.0 7.3ppm)
AcompoundhastheformulaC8H9NO2.Labelallpeaksandproposeastructure.
Practice:IntegratedExample
CHEM222/234 LectureChapter9 45
AcompoundhastheformulaC8H9NO2.Labelallpeaksandproposeastructure.
Practice:IntegratedExample
CHEM222/234 LectureChapter9 46
AcompoundhastheformulaC8H9NO2.Labelallpeaksandproposeastructure.
Practice:IntegratedExample
CHEM222/234 LectureChapter9 47
AcompoundhastheformulaC8H9NO2.Labelallpeaksandproposeastructure.
1HNMRZOOM(6.0 7.3ppm)
Practice:IntegratedExample
CHEM222/234 LectureChapter9 48
AcompoundhastheformulaC9H10O3.Labelallpeaksandproposeastructure.
Chapter9(MS):MainObjectives
CHEM222/234 LectureChapter9 49
1. UnderstandbasicsofMStheory(ionizationandfragmentationofcommonfunctionalgroups).
2. Useamassspectratohelpelucidatethestructureofanunknown(findmolecularweight/formula).
3. Recognizebasepeakandmolecularion.4. RecognizeisotopepatternsforC,S,Cl,Br.5. UseNitrogen/EvenElectronRuletodifferentiate
fragmentsfromM+ anddetermineeven/odd#Ns.
Chapter9:MSSummary
Section2 NMRSpectroscopyandMassSpectrometryChapter9 ToolsforStructureDetermination(Part2)
IntrotoMassSpectrometry(9.13)IonizationandFragmentation(9.149.16)IsotopesinMS(9.17)IntegratedStructureDetermination
CHEM222/234 50LectureChapter9
Chapter9:MSPractice
CHEM222/234 LectureChapter9 51
Section2 NMRSpectroscopyandMassSpectrometryChapter9 ToolsforStructureDetermination(Part2)
AssignedProblems(Solomons,10th Edition):9.16 9.19,9.21,9.22,9.32,9.33,9.37 (MS)9.39 9.47 (Integrated)14.14,14.30 14.39 (Integrated Aromatic)
AssignedProblems(Solomons,11th Edition):9.17 9.21,9.31,9.32,9.36 (MS)9.38 9.46 (Integrated)14.14,14.30 14.39 (Integrated Aromatic)
Sapling(ExtraPractice):Ch 9Assignment