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1、1Infrared SpectroscopyDeterminingthestructureofanorganicmoleculewasadifficultandtime-consumingprocessinthenineteenthandearlytwentiethcenturies,butextraordinaryadvanceshavebeenmadeinthepastfewdecades.Powerfultechniquesandspecializedinstrumentsthatgreatlysimplifystructuredeterminationarenowavailable.I
2、nfrared(IR)spectroscopyisamethodofstructuredeterminationthatdependsontheinteractionofmoleculeswithinfraredradiantenergy.Beforebeginningastudyofinfraredspectroscopy,however,weneedtolookintothenatureofradiantenergyandtheelectromagneticspectrum.Electromagnetic SpectrumVisiblelight,X-rays,microwaves,rad
3、iowaves,andsoforth,arealldifferentkindsofelectromagneticradiation.Collectively,theymakeuptheelectromagneticspectrum.Theelectromagneticspectrumislooselydividedintoregions,withthefamiliarvisibleregionaccountingforonlyasmallportionoftheoverallspectrum,from3.8x107to7.8xl07minwavelength.Thevisibleregioni
4、sflankedbytheinfraredandultravioletregions.Thatpartoftheelectromagneticspectrumoflongerwavelengththanthevisibleregionandshorterwavelengththanthemicrowaveregionisknownastheinfraredregion.比可见光区域更长的那部分电磁波谱和比微波区域更短的那部分波长区域，被称为红外区域。4However,thedecidedlylimitedportionoftheinfraredregionwhichliesbetweenwav
5、elengthsof2.5and15orbetweenfrequenciesof4000cm-1and660cm-1isofgreatestpracticalusetotheorganicchemist.然而，位于波长的2.5至15或频率在4000cm-1和660cm-1之间的红外区域的绝对有限的部分是有机化学家最大的实际使用区域之一。5Radiationenergyisthisregionmaybeabsorbedbyanorganicmoleculeandconvertedintomolecularvibrationalenergy.在这一区域的辐射能量可以由一个有机分子吸收并转换成分子振
6、动能量。6Organicmoleculesundergocontinualstretching,bending,androtationalmotions,and,whenthefrequencyoftheinfraredlightpassingthroughanorganiccompoundcorrespondstothefrequencyofonethemolecularmotionscitedabove,thelightisabsorbed.有机分子在做不断的拉伸、弯曲、和旋转运动，当有机化合物的红外光通过的频率对应于上述的分子运动频率时，光线被吸收。红外光谱是由于分子的振动能级的跃迁（同
7、时伴随着转动能级的跃迁）而产生的。当用一定频率的红外光照射物质时，若物质的分子中某基团的振动频率与之相同时，则物质就能吸收此种红外光。红外光谱原理8Onerestrictionoftheabovediscussionisworthyofmention,namely,thestretchingorbendingmotionofatomswithinamoleculemustcauseachangeintheinstantaneousdipolemomentinordertoproduceanabsorptionpeakintheinfraredspectrum.上述讨论的一个限制是值得一提的，即
8、一个分子内的原子拉伸或弯曲的运动必须引起瞬时偶极矩的变化，以产生红外光谱吸收峰。Symmetricalstretching对称伸缩对称伸缩Antisymmetricalstretching非对称伸缩非对称伸缩Scissoring剪刀式摆剪刀式摆动动RockingWaggingTwisting左右摇摆左右摇摆上下摇摆上下摇摆扭摆扭摆10Ofevengreaterusefulnesstotheorganicchemististhefactthatcertaingroupsofatoms(certainfunctionalgroups)giverisetostretchingorbendingvib
9、rationalabsorptionbandsatornearthesamewavelength,regardlessofthestructureoftheremainderofthemolecule.不管其分子的其余部分结构如何，一些原子组（官能团）在相同或接近相同波长产生的伸缩和变形振动吸收带，对有机化学有较大用处。11Thus,itisfrequentlypossibleforanexperiencedchemisttoexaminetheinfraredspectrumofanunknowncompoundanddecidewhatfunctionalgroupsarepresenti
10、nthemolecule,eventhoughhemightnothaveanyotherinformationaboutthecompoundwhatsoever.因此，一个经验丰富的化学家往往可以测定一个未知化合物的红外光谱，并决定分子中可能存在的官能团组别。即使他可能不会有这个化合物的任何其他信息。12Theliteratureonthesubjectofthecorrelationofstructurewithinfraredabsorptionspectraisvast,andnoattemptwillbemadeheretogivecompletedetails.涉及结构与红外吸收
11、谱关系的文献很多，这里不试图给出全部细节。Introduction to various types of organic compounds characteristic absorption AlkaneThe infrared spectrum of methyl cyclohexaneC-H伸缩振动伸缩振动3000cm-1 C-H弯曲振动弯曲振动有机物的命名烷烃（alkanes）直链烷烃类化合物的命名是有机命名的基础。英文名称除了含1到4个碳原子以外，其余均用希腊文和拉丁文的数词加上相应的词尾（-ane）来命名，10个碳原子以上的则在数词前加前缀un、do、tri、tetra、pent
12、a等。如：甲烷methane乙烷ethane丙烷propane丁烷butane戊烷pentane己烷hexane庚烷heptane辛烷octane壬烷nonane癸烷decane十一烷undecane十二烷dodecane Alkane=Numberprefix-aneforexample:CH4MethaneCH3CH2CH3PropaneCH3CH3Ethane CH3(CH2)2CH3ButaneCH3(CH2)3CH3PentaneCH3(CH2)4CH3HexaneCH3(CH2)5CH3HeptaneCH3(CH2)6CH3OctaneCH3(CH2)7CH3 Nonane CH3
13、(CH2)8CH3 Decane1119Alkane=Numberprefix-decanefor example:11-alkaneUndecane12-alkaneDodecane13-alkaneTridecane14-alkaneTetradecane15-alkanePentadecane16-alkaneHexadecane17-alkaneHeptadecane18-alkaneOctadecane19-alkaneNonadecane 20-alkaneIcosane2129Alkane=Numberprefix-cosaneforexample:21-alkaneHenico
14、sane22-alkaneDocosane23-alkaneTricosane24-alkaneTetracosane25-alkanePentacosane30-AlkaneTriacontane3139Alkane=Numberprefix-triacontane forexample:31-AlkaneHentriacontane32-AlkaneDotriacontane33-AlkaneTritriacontane 34-AlkaneTetratriacontane 35-Alkanepentatriacontane 36-AlkaneHexatriacontane4090Alkan
15、e=Numberprefix-contaneforexample:40AlkaneTetracontane50AlkanePentacontane60AlkaneHexacontane70AlkaneHeptacontane80AlkaneOctacontane90AlkaneNonacontane100AlkaneHectane环烃(cyclichydrocarbons)脂肪环烃(alicyclichydrocarbons)未取代的饱和单环烃命名时刻在相应的开链烃名前加“环”（cyclo）字。例如：CyclopropaneCyclohexaneSaturated monocyclic hyd
16、rocarbonsCyclicalkane=Cyclo-alkaneforexample:Unsaturated monocyclic hydrocarbonsCyclicalkene=Cyclo-alkeneforexample:24Ultraviolet spectrometryUltraviolet spectrometry：Molecular valence electron energy transition.分子价电子能级跃迁分子价电子能级跃迁Wavelength region：160-780 nm.(1)远紫外光区远紫外光区(far UV region):10-200nm (2)近紫外光区近紫外光区(near UV region):200-400nm(3)可见光区可见光区(Vis region):400-780nmElectromagnetic SpectrumEMR encompasses an enormous range of wavelengths and frequencies:Wave properties of electromagnetic radiati
