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1、7512J.Org.Chem.1997,62,7512-7515NMRChemicalShiftsofCommonLaboratorySolventsasTraceImpuritiesHugoE.Gottlieb,*VadimKotlyar,andAbrahamNudelman*DepartmentofChemistry,Bar-IlanUniversity,Ramat-Gan52900,IsraelReceivedJune27,1997InthecourseoftheroutineuseofNMRasanaidfororganicchemistry,ad
2、ay-to-dayproblemistheidentifica-tionofsignalsderivingfromcommoncontaminants(water,solvents,stabilizers,oils)inless-than-analyti-cally-puresamples.Thisdatamaybeavailableintheliterature,butthetimeinvolvedinsearchingforitmaybeconsiderable.Anotherissueistheconcentrationdependenceofche
3、micalshifts(especially1H);resultsobtainedtwoorthreedecadesagousuallyrefertomuchFigure1.ChemicalshiftofHDOasafunctionoftempera-moreconcentratedsamples,andrunatlowermagneticture.fields,thantoday'spractice.Wethereforedecidedtocollect1Hand13Cchemicaldependent(videinfra).Also,anypotent
4、ialhydrogen-shiftsofwhatare,inourexperience,themostpopularbondacceptorwilltendtoshiftthewatersignaldown-ªextrapeaksºinavarietyofcommonlyusedNMRfield;thisisparticularlytruefornonpolarsolvents.Insolvents,inthehopethatthiswillbeofassistancetocontrast,ine.g.DMSOthewaterisalreadystrong
5、lythepracticingchemist.hydrogen-bondedtothesolvent,andsoluteshaveonlyanegligibleeffectonitschemicalshift.ThisisalsotrueExperimentalSectionforD2O;thechemicalshiftoftheresidualHDOisveryNMRspectraweretakeninaBrukerDPX-300instrumenttemperature-dependent(videinfra)but,maybecounter-(300
6、.1and75.5MHzfor1Hand13C,respectively).Unlessintuitively,remarkablysolute(andpH)independent.otherwiseindicated,allwererunatroomtemperature(24(1Wethenadded3íLofoneofourstocksolutionsto°C).Fortheexperimentsinthelastsectionofthispaper,probetheNMRtube.Thechemicalshiftswerereadandaretem
7、peraturesweremeasuredwithacalibratedEurotherm840/TpresentedinTable1.Exceptwhereindicated,thedigitalthermometer,connectedtoathermocouplewhichwascouplingconstants,andthereforethepeakshapes,areintroducedintoanNMRtubefilledwithmineraloiltoap-proximatelythesamelevelasatypicalsample.Ate
8、achessentiallysolvent-independent
