波谱分析读书笔记

本文格式为Word版，下载可任意编辑——波谱分析读书笔记第五章色谱和光谱

——化合物的纯化和结构研究方法

重点讲授内容一、纯化方法、色谱技术简介

二、质谱三、红外光谱四、紫外光谱五、核磁共振

推荐参考书：1、宁永成编著，《有机化合物结构鉴定与有机波谱学》，科学出版社，20232、谢晶曦编著，《红外光谱在有机化学和药物化学中的应用》，科学出版社，3、陈耀祖编著，《有机分析》

Purification

1987KBrOHH2SO4BrReactionMixture:HBr,H2SO4,KBr,K2SO4,H2O1-butanol,1-bromobutane,1-butene,2-butene,dibutyletherdistillation1-butanol,1-bromobutanedibutylether,H2O,HBrWashingbyH2SO41-butanoldibutyletherH2SO4,HBr1-bromobutaneH2SO4,HBr1)Washingbywater2)Washingby10%NaCO33)Washingbywaterupperlayerlowerlayer1-bromobutaneH2O1)Drying2)DistillationPure1-bromobutane

H2SO4,KBr,K2SO4,H2O1-Butene2-ButeneCOOHOH+(CH3CO)2OH+COOHOOCCH3(solid)PurificationbyRrecrystallisationPureProduct

ChromatographTLC,CC,GC,HPLCisaseparationprocesswhichdependsonthedifferentialdistributionsofthecomponentsofamixturebetweenamobilebulkphaseandanessentiallythinfilmstationaryphase.

StructureDetermination

PhysicalpropertiesSpectroscopicMethodsMeltingPointIR(InfraredSpectroscopy)BoilingPointNMR(NuclearMagneticresonance)SpecificRotationMS(MassSpectrum)RefractiveIndexUV(UltravioletSpectrum)

有机波谱法（质谱、红外光谱、紫外光谱、核磁共振谱）

?波谱法特点

(1)样品用量少，一般来说2~3mg即可（最低可少到3002.3,7.1乙苯136.21.4959苯甲酸122.131.3,2.7,7.2265(23),271(2.2)269(2.3),274(2.3)267(2.7),275(2.7)206(4.5),259(2.2)

一、质谱——确定分子量、分子式，了解分子内原子连接的详细状况1、基本原理

Inatechniquecalledmassspectroscopy,amoleculeisvaporizedandthenionizedby

removinganelectron.Thisproducedamolecularion,whichisaradicalcation,aspecieswithanunpairedelectronandapositivecharge.Becauseofpossessinghighenergy,themolecularionmaybreakapartintocations,radicals,neutralmolecules,andotherradicalcations.

eMmoleculeM+eelectronmolecularionaradicalcationFragments

（插入仪器工作原理图及质谱图样式）

Theanalyzertubeissurroundedbyamagnet.Itsmagneticfielddeflectsthepositivelychargedfragmentsinacurvedpath.Atagivenmagneticfieldstrength,theradiusofthepathtraveledbyafragment,dependsonitsmass-to-chargeratio(m/z).Thesmallerthem/zofthefragment,themorethemagnetdeflectsit.Ifafragment’spathmatchesthecurvatureoftheanalyzertube,thefragmentwillpassthroughthetubeandouttheionexitslit.Acollectorrecordstherelativenumberoffragmentswithaparticularm/zpassingthroughtheslit.Themorestablethefragment,themorelikelyitwillmakeittothecollector.Byslowlyincreasingthestrengthofthemagneticfield,fragmentswithprogressivelylargervaluesofm/zcanbeguidedthroughthetubeandouttheexitslit.

2、分子量、分子式的确定

Molecularionthem/zvalueofthemoleculariongivesthemolecularweightofthecompoundBasepeakistheonewiththegreatestintensity.(itisassignedarelativeintensityof100%)M+1peakorM+2peakoftenoccursbecausetherearenaturallyisotopesofcarbon,orotheratomse.g.1.Themassspectrumofanunknowncompoundhasamolecularionwitharelativeintensityof43.27%,andanM+1peakwitharelativeintensityof3.81%.Howmanycarbonatomsareinthecompound?Solution:Therearetwonaturallyisotopesofcarbon:98.89%12Cand1.11%13CRelativeintensityofM+1peak3.81

Numberofcarbonatoms===80.011x(relativeintensityofMpeak)0.011x43.27

Table5.1TheNaturalAbundanceofIsotopesCommonlyFoundinOrganicCompounds

carbon12oxygen161718nitrogen14hydrogen1fluorine19chlorine35bromine79iodine127C98.89%C1.11%O99.76%O0.036%O0.204%N99.63%N0.37%H99.99%H0.01%F100%Cl75.77%Cl24.23%Br50.69%Br49.31%I100%131523781High-ResolutionMassSpectrometrycandeterminetheexactmolecularmassofafragmentwithaprecisionof0.0001amu.

e.g.Somecompoundswithanominalmolecularmassof122amuandtheirexactmolecularmassesMolecularFormulaC9H14C7H10N2C8H10OC7H6O2C4H10O4C4H10S2

ExactMolecularMass(amu)122.1096122.0845122.0732122.0368122.0579122.0225e.g.Whichmolecularformulahasanexactmassof86.1096amu:C6H14C4H10N2C4H6O2

Table5.2TheexactMassesofSomeCommonIsotopes

1H12C14N16O32S35Cl79Br1.007825

12.0000014.003115.994931.972134.968978.91833、分子离子峰的断裂规律与分子内原子连接状况（只要求把握最基本的一些规律，参阅教材）1）产生氮正离子、氧正离子、卤正离子的裂解：α-裂解、β-裂解2）产生碳正离子的裂解：3）脱去中性分子的裂解

烃类和卤代烃：

CH3CH2CH2m/z=43CH3CH2CH2CH2CH3molecularionm/z=72CH2CH3+m/z=69CH3CH2CH2CH2m/z=57CH3CH2CH2CH2CH3CH2CH2+CH3CH2+CH3CH2m/z=29+CH3+CH3m/z=15CH2CH3

CH3CH3H3CCHClH3CH3CCHCH3CH3535CH3ClH3CCHCH3ClH3CCH3737CH3ClH3CCH+Clm/z=43ClCH3CH2=35ClCH3CH2=Clm/z=63,65

37+CH3m/z=78m/z=80

醇醚的β-裂解：

OOm/z=87OOm/z=101OOHOm/z=101CH3CH2CH2CH2CH=OH+CH3CH=OHm/z=87m/z=45

对于第四个裂解方程式，请表示出两种碎片离子的形成过程，并写出各自丢失的片段。

二、红外光谱——反映分子中键的振动能级的变化状况，提供官能团的信息

1、红外光谱基本原理——红外吸收光谱与化合物结构特征关系A、常见的键的振动方式：伸缩振动StretchingVibrations，

HCHHHCsymmetricstretchasymmetricstretch

弯曲振动BendingVibrations（面内、面外）

HCHHHHHCHHCCemmetricout-of-asymmetricin-plasnyemmetricin-plansypslaynmemetricout-of-planebend(rock)bend(scissor)bend(twist)bend(wag)

一个官能团由于有多种振动方式，在红外光谱中将有一组相应的吸收峰

B、伸缩振动频率与成键原子质量、键的强度（键能、键长）的关系

Hooke定律：

~v=12ck(m1+m2)m1m2

其中

m1m2m1+m2

为折合质量

振动频率与成键原子折合质量倒数的平方根成正比，即原子质量愈轻，振动频率愈高；

与键的力常数的平方根成反比，即键能愈大，键长愈短，键的力常数愈大，振动频率愈高。C=CC=CC-C-C-H=C-H=C-Hυ（cm-1）2100~22601600~1670800~12002850-29603010~3100~3300C=OC-OO-H（游离）1660~17801000~13003580~3670C=NC=NC-NN-H（游离）

2210~22601630~16901250~13603310~3400（单峰或双峰）

StrongerbondsandlighteratomsgiverisetohigherwavenumbersC、影响红外吸收频率的因素——共振结构、电子效应、氢键、空间效应影响e.g.1.C=Oin2-pentanoneabsorbsat1720cm-1

OOC=Oin2-cyclohexenoneabsorbsat1680cm-1

2-Cyclohexenoneabsorsatalowerfrequencybecausethecarbonylgrouphasgreatersinglebondchaacterduetoelectrondelocalizion.Becauseadoublebondisstrongerthanasinglebond,acaronylgroupwithsignificantsinglebondcharacterwillstretchatalowerfrequencythanonewithlittleornosinglebondcharacter.

e.g.2.C-Oinethanolordiethylether~1050cm-1C-Oinaceticacidorethylacetate~1250cm-1

BecausetheC-Obondinanalcoholoretherisapuresinglebond,whereastheC-Obondinacarboxylicacidoranesterhaspartialdoublebondcharacter.

e.g.3.C=Oinanaldehyde~1720cm-1inanacidh