碳核磁共振谱..ppt

第四讲：核磁共振碳谱

Carbon-13NuclearMagneticResonanceSpectroscopy

庞文民

2013年12月
13CNMR概述核磁共振碳谱特点核磁共振碳谱特点13CNMR13CNMR化学位移13CNMR化学位移13CNMR化学位移化学位移影响化学位移的因素诱导效应诱导效应空间效应共轭效应和超共轭效应缺电子效应电场效应取代程度邻近基团的各向异性效应构型介质效应易离解的化合物在溶液稀释时会使化学位移有少许的变化。当化合物中含有—COOH、—OH、—NH2、SH等基团时，pH的改变会使化学位移发生明显变化。如，羧基碳原子在pH增大时受到屏蔽作用而使化学位移移向高场。温度效应顺磁离子效应烯烃及取代烯烃的化学位移炔碳的化学位移苯环碳的化学位移羰基化合物的碳化学位移氢键对碳化学位移的影响耦合裂分及耦合常数sepet,2J=5.7Hz耦合常数的典型值13C-X的偶合及偶合常数13C-X的偶合及偶合常数耦合常数的应用某化合物C18H18N3O3F3含下列结构片段，13C质子噪声去耦谱如上图所示，请标识C（1）和C（2）所对应的谱线。质子噪声去耦谱（protonnoisedecoupling）反转门控去耦谱（inversegateddecoupling）偏共振去偶谱偏共振去偶谱质子非去偶谱无NOE去偶谱选择性质子去偶谱选择性质子去偶谱DEPT（DistortionlessEnhancementbyPolarizationTransfer）谱DEPT谱P(CH)=B纵向弛豫时间T1测定及其意义纵向弛豫时间T1测定及其意义碳谱的解析步骤碳谱的解析步骤碳谱的解析步骤Twoisomerichydrocarbons,AandB,ofC5H10wereseparatedbyGCandgavethefollowing13Cdata:
A:13(q),17(q),26(q),118(d),and132(s)ppm
B:13(q),22(q),31(t),108(t),and147(s)ppmAcompoundgivesamolecularioninitsEIspectrumatm/z80.ThisvalueisunchangedwhenthecompoundisintroducedintothemassspectrometerinthepresenceofD2O.AhighresolutionmeasurementestablishesthemolecularformulaasC5H6N2.Thecompoundgivesthefollowing13CNMRspectrum:16(t),22(t),119(s)ppm.Deduceitsstructure.ThreecompoundsofmolecularformulaC4H8Ohavethefollowing13Cspectra,andthedescribedfeaturesintheirIRspectra.
Compound1:IR:1730cm-1,13CNMR:13.3,15.7,45.7,201.6ppm.
Compound2:IR:3200(broad)cm-1,13CNMR:36.9,61.3,117.2,134.7ppm.
Compound3:IR:nopeaksexceptCHandfingerprint,13CNMR:25.8and67.9ppm.
Suggestastructureforeachcompound,andthenseewhetheryoursuggestionsarecompatiblewiththefollowinginformation.Compound1reactwithNaBH4togivecompound4,C4H10O,IR3200(broad)cm-1and13CNMR15.2,20.3,36.0,and62.9ppm.Compound2reactswithhydrogenoverapalladiumcatalysttogivethesameproduct4,whilecompound3reactswithneitherreagent.参考答案Thankyou!