1、Advanced Organic Chemistry(1)高等有机化学（I）Instructor:JingKui YANGCollege of Chemistry and Chemical EngineeringGraduate University of CAS(GUCAS)1Advanced Organic Chemistry(1)Chapt1:Organic Reaction Mechanism (3-4)Chapt2:Solvents Effects (5)National Holiday Day (6)Solvents Effects (7)Chapt3:Stereochemistr
2、y (9,10,11)Chapt4:Organic reaction active intermediates and determination.(12,13)Chapt5:Concerted Reaction (14)Chapt6:Organic Photochemistry and Electrochemistry (15,16A)Chapt7:Catalytic Reaction and Mechanism (16A,17)2Chapt4:Organic reactive intermediates 有机活性中间体Free radicals(自由基)Ion radicals(Catio
3、n radical,anion Radicals)离子自由基Carbene(卡宾),Nitrenes(乃春)Benzyne(arynes)(苯炔)Carbocations(Carbon Cation)(碳正离子)Carbanions (Carbon Anion)(碳负离子)Antiaromatic compounds(反芳香化合物)Strained rings(张力环)Introduction,Properties,Preparations,Reactions,Determination3Nobel Prize for Chemistry in 1994 George Olah,1927-,H
4、ungary(匈牙利）USAUniversity of Southern CaliforniaLos Angeles,CA,USA Biography for his contribution to carbocation chemistry6Others Nobel Prize for Chemistry in 1999 in femtosecond spectroscopyAhmed H.Zewail,1946-,Egypt and USACalifornia Institute of TechnologyPasadena,CA,USA Nobel Prize for Chemistry
5、in 1992 in The Theory of electron transfer reactions Marcus,1923-Montreal,Canada and USA California Institute of Technology Pasadena,CA,USAAlso in 1967,19837Reactive Intermediates:The Methods The Field of Reactive Intermediates is a highly interdisciplinary field that requires the combination of a m
6、ultitude of methods traditional spectroscopic methods ultrafast spectroscopic methods electrochemistry computational chemistry synthetic chemistry photochemistry kinetics biochemistry Intelligence/Imagination8Reactive Intermediates:The Compounds What unifies these disciplines and defines the field i
7、s the simple question of:How short lives species determine the outcome of chemical reactions(生命力多短的片段决定反应的结果).The reactions in question can in themselves come from totally different fields.Studies of the visual process in the eyes retina(视网膜),explosions or growth of material through CVD processes.Me
8、chanistic research nearly synonymous(同意,等同于)with research into reactive intermediates because the majority of chemical reactions involve short lived intermediates.CVD:Chemical Vapor Deposition(化学气相沉积法）9http:/chiuserv.ac.nctu.edu.tw/htchiu/cvd/home.html /CVDChemical Vapor Deposition is chemical react
9、ions which transform gaseous molecules(precursor),into a solid material in the form of thin film or powder,on the surface of a substrate GasSolid materialssubstrate10 Radicals Carbenium cation Carbenium anions Sextet species(六电子体系)(carbenes,nitrenes etc)16 VE transition metal complexes Antiaromatic
10、compounds Strained rings Biochemical reactions frequently involve species from the list above and,in addition,unusually reactive intermediates that owe their high reactivity to the violation of more subtle stability criteria.Examples:11carbenes,nitrenes,silylenes,free radicals,radical ions,diradical
11、s,carbocations,carbanions,C+C-C.C-.C+.C+B-CC:CCN,S,O,P,Si等及其他两性元素有相似可能性12中间体稳定性不一样 some very stable can be isolated,but others(highly reactivity)do not Two types of Organic Reactions:1),Step wise Reactions(分步反应):可以分出中间体2),Concerted Reaction(协同反应)理想状态:没有中间体(?)My Hypothesis:too fast and very high reac
12、tivityand can not be checked by current instrument?13(活性中间体)14ABA B(均裂成为自由基)A B (均裂成为离子)(中性分子)15CB(键没有完全短裂得到一部分电荷,成为阴离子自由基)(中性分子)CBe-DonorAcceptor(键没有完全形成 失去一部分电荷,成为阳离子自由基)DAcceptorCBDA电荷转移复合物(Charge Transfer Complex,CTC)Electron Transfer,ET16多重性2I+1I000117Halonium ionEnolate/enol/Ynol(烯醇或炔醇)diradic
13、alsOxireneBenzyne(苯炔)18keteneisocyanateYlide(叶立德)Ketyl Radical 羰游离基16 VE19ONBrBrBrSbCl6SSSSSSSSOOCNNCCNNCCation/Anion Radical(阳/阴离子自由基)20只作参考21222324http:/www.pacifichem.org/c_symposia/c_symp_9.htm25 Angewandte Chemie International Edition Volume 37,Issue 24,1999,3340-3350 Dynamic Behavior of Organi
14、c Reactive Intermediates(p 3340-3350)Barry K.Carpenter Abstract|Full Text:PDF(Size:301K)只做参考!“Organic Reactive Intermediates,Chem.Rev.1992,92,1611-1647.26Keywords Computer chemistry;Diradicals;Kinetics;Molecular dynamics;Supercritical fluids;Computer chemistry;Diradicals;Kinetics;Molecular dynamics;
15、Supercritical fluids AbstractAn unexpected yes is the answer the author gives to the following questions:If a reactive intermediate was faced with two equally high energy barriers to product formation,could the kinetic product ratio ever be anything other than 1:1?If the two barriers were of unequal
16、 height,could there ever be a preference to form the product that corresponds to the higher barrier pathway?The basis for this yes are the results from molecular dynamics simulations and experiments that suggest that the interpretation of reaction mechanisms by statistical models is not always corre
17、ct.只做参考!27Chapt 4.2 Free Radicals(自由基)有未成对（unpaired)电子的中性原子、基团或分子。Neutral Chemical species that have a single unpaired electron反应特点：与溶剂极性无关 易在气相生成 不被酸或碱催化 取代基效应与离子型反应不同 (既可被吸电子，也可被供电子基团稳定？）一般没有很好的线性自由能关系（或特别小0）对杂质非常敏感：O2，NHR1R2，SH，PhOH(可形成不 活泼的自由基，可用于反应机理判断）有特定的电子自旋（ESR/EPR）或核磁（CIDNP）共振谱28First used
18、 by:Lavoisier in 18 th century to designate some polyatomic fragment of a molecule which remains unchanged during 1 or more chemical transformations.1849,Frankland,believed but really produce mixture gases.1900 Moses Gomberg Ph3CCl+Hg/PhH =Ph3C.-Dimer yellow colour1927:Paneth/Hofeditz;1937,Kharasch(
19、Radical Chain mechanism),Hey/Waters:Proposing a radical mechanism 30 years later,theory suggested,and more and more free radicals reactions found as the important intermediates in many reactionsCH3CH2IZnZnICH3CH2.PhPhHPh3CHistory of Radical29OButButBu-tBu-tO.NO2NO2NO2Ph2N_N.Deep violet(紫)crystalsBlu
20、e CrystalsNO.Bu-tBu-tRed-Brown liquid30Structure of Organic Free Radicals Most of the Organic Free Radicals have the following stereo structure:SP3CR1R2R3CR1R2R3 SP2(planar conformation)(unpaired electron in P orbit)G=2.5KJ/mol31G=2.5KJ/mol is too small,turn over of it is very easy,so many free radi
21、cal reaction of achiral compounds will give the raceme(外消旋体)Stability of radicals:More substitutes,more stable R3C.R2CH.RCH2.Reason:Hyper conjugation32CClClClClClClClClClClClClClClClIn solution:several days As solid:Stable up to 300oC 33The Production of Free Radicals Thermolysis(热解)Photolysis(光解)Ox
22、idation_Reduction (氧化还原)OOOOOOCMeMeN=N CMeMehvN2CMeMeOOOOOOCu+-Cu2+OOOOO-O34ESR:Electron Spin Resonance 电子自旋共振谱EPR:Electron Paramagnetic Resonance 电子顺磁共振谱CIDNP:Chemically Induced Dynamic nuclear Polarization 化学诱导动态核极化（核磁）ENDOR:Electron_Nuclear Double Resonance Spectroscopy 电子和核双重共振谱自由基的检测手段和仪器35自由基波
23、谱特征有未成对电子的顺磁性未成对电子在磁场中有两种可能的能态：其能量差E随外磁场的增加而增加E=h =gH光谱分裂因子玻尔磁子外磁场强度 当外场符合上述关系时即发生能量吸收产生磁能级间跃迁(Lande g factor)36电子自旋矢量磁矩矢量（负电荷电子）电子自旋量子数 +1/2 或-1/2未成对电子无外场时自旋是随机无顺序，宏观无磁性未成对电子有外场时自旋要分裂，态（低能量）：-1/2对应磁矩与外场（H0）方向相同 态（高能量）：+1/2对应磁矩与外场（H0）方向相反37E=hv=gHEeH0eh/2mcms=-1/2ms=+1/2H0H00H0:外场强度g:磁旋比 =磁矩/电子角动量 自
24、由电子：2.002319e:波尔磁子9.2732x10-24J/T38Similar to Chemical Shift,Coupling Constant,area amount,and spilt info.of HNMR,used to predict/determine the structure of compounds,ESR info.can be used to check the structure info.Of free radicals too.Position,strength,hyperfine split constant(位置，强度，超精细分裂常数得到自由基结构
25、信息）39For most organic compounds:g=2.0022.006(in HNMR as Chemical shifts,对等于核磁中的化学位移)depending on the electronic environment of the unpaired electron(less useful than HNMR because of little difference)40Two important hyperfine spiltting H at-Carbon and Unpaired Electron H at-Carbon and Unpaired Elect
26、ron long distance effect is very smaller (S Orbit of H on-C may have hyperconjugation with Unpaired electron43The Interaction between the Unpaired electron coupling with the neighbored nuclear spin(核自旋）1H,13C,14N,19F,31P,35Cl will give the hyperfine structure(精细结构）spiltting,fit to the（n+1)(2nI+1)rul
27、e used in HNMR.44CH3.:1:3:3:123.0GC spinSlight excess of spinHSlight excess of spin45CH3CH2.Proton spit the signal to 4,then Proton spilt to it to 3,total 3x4=1226.9G22.4Ga=-2.24mT(2H)a=+2.69mT(3H)偶合常数46CCH3H3CH()()()The split constant a in the hyperstructure will give special info.of the free radic
28、al structureaH=22 gaussaH=25 gauss47ESR:very sensitive:10-9 M can be checkedhighly reactive How to increase the concentration of radical1),heating or photo to produce the radial without stop2),adjust the reaction condition,slow down or stop the reaction of radical(Matrix tech:mixed the resource of r
29、adical with solvent or inert gas,cooling it to the surface of coolant,heating with light to produce radical3),capture the spin compounds by addition of other reactants to react with the radicals48-Free Radical:unpaired electron coupling with all the conjugated H in the system simple ESR because all H are equals.n+1 peaks(n:amount of same H)环戊二烯自由基苯负离子自由基0.375mT49Triplet(三线态）2 unpaired electrons X Y ZS:singlet50Zero Field Splitting(零场裂分）无外场时三态能量有差别51
