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Direct Chiral Analysis of Complex Mixtures by Fourier...
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Direct Chiral Analysis of Complex Mixtures by Fourier Transform Molecular Rota;onal Resonance (FT-MRR) Spectroscopy
LucaEvangelis.,NathanSeifert,LorenzoSpada,andBrooksH.Pate,DepartmentofChemistry,UniversityofVirginia
Ma@Muckle,Jus.nNeill,andRogerReynolds,BrightSpec,Inc.,Charlo<esville,VA
Acknowledgements:
ThisworksupportedbyBrightSpec,NSFMRICHE-0960074,UniversityofBologna(LS),andERS/EUMarieCuriePostdoctoralResearchFellowshipProgram(LE)
Introduc)onMolecular rota.onal spectroscopy provides a spectral signaturewith extreme sensi.vity to themassdistribu.on(3Dstructure)ofthemolecule. Instrumentsformeasuringrota.onalspectrausingpulsedjetsourcesofferhighsensi.vityandhighspectralresolu.on.Asaresult,itispossibletoperformdirectquan.ta.ve analysis of complex mixtures without chromatographic separa.on. For samples thatincludechiralmolecules,rota.onalspectroscopycaniden.fydiastereomersofmoleculeswithmul.plechiralcentersand,withfundamentaladvancesinthepasttwoyears*,canperformenan.omericexcessmeasurementsonthediastereomers.
BuchuOil(betulina)
BuchuOil(crenulata)
Molecule %
Obs AssignedinMixture
PreviousMWAnalysis
ReferenceSpectrum
Diosphenol 22 • •
Isomethone 20 • •
4-diosphenol 19 • •
Limonene 12 • •
Menthone 10 • •
1,8-cineole 4 • •
Z-8-mercaptomenthone 2 • •
Pulegone 1 •
E-isopulegone 0.5 • •
E-8-mercaptomenthone 0.5 • •
Linalool 0.5 •
α-pinene 0.4 • •
Z-isopulegone 0.4 • •
β-pinene 0.3 • •
Piperitone 0.06 • •
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Ini)alAnalysisofBuchuOilComposi)on
*DavidPa@erson,MelanieSchnell,JohnM.Doyle,“Enan.omer-specificdetec.onofchiralmoleculesviamicrowavespectroscopy”,Nature497,475(2013).
BroadbandRota)onalSpectrumoftheVola)leHeadSpace(65oC)
Enan)omericExcessMeasurementofMenthoneDirectlyintheMixtureusingThreeWaveMixingFT-MRRSpectroscopy
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Iden)fica)onoftheDiastereomersof8-mercaptomenthone
ThreeConforma)onsofMenthoneB3LYP/6-311++(d,p)
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Z-8-mercaptomenthone E-8-mercaptomenthone