波譜分析讀書筆記

本文格式為Word版，下載可任意編輯——波譜分析讀書筆記第五章色譜和光譜

——化合物的純化和結(jié)構(gòu)研究方法

重點(diǎn)講授內(nèi)容一、純化方法、色譜技術(shù)簡介

二、質(zhì)譜三、紅外光譜四、紫外光譜五、核磁共振

推薦參考書：1、寧永成編著，《有機(jī)化合物結(jié)構(gòu)鑒定與有機(jī)波譜學(xué)》，科學(xué)出版社，20232、謝晶曦編著，《紅外光譜在有機(jī)化學(xué)和藥物化學(xué)中的應(yīng)用》，科學(xué)出版社，3、陳耀祖編著，《有機(jī)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)

有機(jī)波譜法（質(zhì)譜、紅外光譜、紫外光譜、核磁共振譜）

?波譜法特點(diǎn)

(1)樣品用量少，一般來說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、質(zhì)譜——確定分子量、分子式，了解分子內(nèi)原子連接的詳細(xì)狀況1、基本原理

Inatechniquecalledmassspectroscopy,amoleculeisvaporizedandthenionizedby

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

eMmoleculeM+eelectronmolecularionaradicalcationFragments

（插入儀器工作原理圖及質(zhì)譜圖樣式）

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、分子式的確定

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、分子離子峰的斷裂規(guī)律與分子內(nèi)原子連接狀況（只要求把握最基本的一些規(guī)律，參閱教材）1）產(chǎn)生氮正離子、氧正離子、鹵正離子的裂解：α-裂解、β-裂解2）產(chǎn)生碳正離子的裂解：3）脫去中性分子的裂解

烴類和鹵代烴：

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

對于第四個裂解方程式，請表示出兩種碎片離子的形成過程，并寫出各自丟失的片段。

二、紅外光譜——反映分子中鍵的振動能級的變化狀況，提供官能團(tuán)的信息

1、紅外光譜基本原理——紅外吸收光譜與化合物結(jié)構(gòu)特征關(guān)系A(chǔ)、常見的鍵的振動方式：伸縮振動StretchingVibrations，

HCHHHCsymmetricstretchasymmetricstretch

彎曲振動BendingVibrations（面內(nèi)、面外）

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

一個官能團(tuán)由于有多種振動方式，在紅外光譜中將有一組相應(yīng)的吸收峰

B、伸縮振動頻率與成鍵原子質(zhì)量、鍵的強(qiáng)度（鍵能、鍵長）的關(guān)系

Hooke定律：

~v=12ck(m1+m2)m1m2

其中

m1m2m1+m2

為折合質(zhì)量

振動頻率與成鍵原子折合質(zhì)量倒數(shù)的平方根成正比，即原子質(zhì)量愈輕，振動頻率愈高；

與鍵的力常數(shù)的平方根成反比，即鍵能愈大，鍵長愈短，鍵的力常數(shù)愈大，振動頻率愈高。C=CC=CC-C-C-H=C-H=C-Hυ（cm-1）2100~22601600~1670800~12002850-29603010~3100~3300C=OC-OO-H（游離）1660~17801000~13003580~3670C=NC=NC-NN-H（游離）

2210~22601630~16901250~13603310~3400（單峰或雙峰）

StrongerbondsandlighteratomsgiverisetohigherwavenumbersC、影響紅外吸收頻率的因素——共振結(jié)構(gòu)、電子效應(yīng)、氫鍵、空間效應(yīng)影響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