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1、7512J.Org.Chem.1997,62,7512-7515NMRChemicalShiftsofCommonLaboratorySolventsasTraceImpuritiesHugoE.Gottlieb,*VadimKotlyar,andAbrahamNudelman*DepartmentofChemistry,Bar-IlanUniversity,Ramat-Gan52900,IsraelReceivedJune27,1997InthecourseoftheroutineuseofNMRasanaidfororganicchemistry,
2、aday-to-dayproblemistheidentifica-tionofsignalsderivingfromcommoncontaminants(water,solvents,stabilizers,oils)inless-than-analyti-cally-puresamples.Thisdatamaybeavailableintheliterature,butthetimeinvolvedinsearchingforitmaybeconsiderable.Anotherissueistheconcentrationdependenceo
3、fchemicalshifts(especially1H);resultsobtainedtwoorthreedecadesagousuallyrefertomuchmoreconcentratedsamples,andrunatlowermagneticfields,thantoday’spractice.Wethereforedecidedtocollect1Hand13Cchemicalshiftsofwhatare,inourexperience,themostpopular“extrapeaks”inavarietyofcommonlyuse
4、dNMRsolvents,inthehopethatthiswillbeofassistancetothepracticingchemist.ExperimentalSectionNMRspectraweretakeninaBrukerDPX-300instrument(300.1and75.5MHzfor1Hand13C,respectively).Unlessotherwiseindicated,allwererunatroomtemperature(24(1°C).Fortheexperimentsinthelastsectionofthispa
5、per,probetemperaturesweremeasuredwithacalibratedEurotherm840/Tdigitalthermometer,connectedtoathermocouplewhichwasintroducedintoanNMRtubefilledwithmineraloiltoap-proximatelythesamelevelasatypicalsample.Ateachtemperature,theD2Osampleswerelefttoequilibrateforatleast10minbeforetheda
6、tawerecollected.Inordertoavoidhavingtoobtainhundredsofspectra,wepreparedsevenstocksolutionscontainingapproximatelyequalamountsofseveralofourentries,choseninsuchawayastopreventintermolecularinteractionsandpossibleambiguitiesinassignment.Solution1:acetone,tert-butylmethylether,di-
7、methylformamide,ethanol,toluene.Solution2:benzene,di-methylsulfoxide,ethylacetate,methanol.Solution3:aceticacid,chloroform,diethylether,2-propanol,tetrahydrofuran.Solution4:acetonitrile,dichloromethane,dioxane,n-hexane,HMPA.Solution5:1,2-dichloroethane,ethylmethylketone,n-pentan
8、e,pyridine.Solution6:tert-butylalcohol,BHT,cycl
