高等有機(jī)化學(xué)PPT

1、nAdvanced Organic Chemistry: Advanced Organic Chemistry: Structure and MechanismsStructure and Mechanisms (Part B), 5th Edition， 2007，By Francis A. Carey。n高等有機(jī)化學(xué)基礎(chǔ)高等有機(jī)化學(xué)基礎(chǔ)(面向21世紀(jì)課程教材) ，榮國(guó)斌,華東理工大學(xué)出版社，化學(xué)工業(yè)出版社，第3版，出版日期：2009年05月。n高等有機(jī)化學(xué)反應(yīng)、機(jī)理與結(jié)構(gòu)高等有機(jī)化學(xué)反應(yīng)、機(jī)理與結(jié)構(gòu)（原著第五版 修訂），美史密斯（Smith M.B）馬奇（March J），化學(xué)工業(yè)出版社I

2、. Lewis StructuresII.ResonanceIII.Hybrid orbitalsIV.AromaticityV.Functional GroupsPart 1: THE COVALENT BONDLewis structure: the electron-pair bondThe Lewis structural formula can serve as a convenient starting point to understanding the valence-bond theory of molecular structure.nThe ionic bonding f

3、orce arises from the electrostatic attraction between ions of opposite charge.nThe covalent bonding force arises from sharing of electron pairs between atoms.I. Lewis Structures Ionic, covalent, and polar bondsionic bonds: transfer of electronsNaClNaCl+covalent bonds: sharing of electronsHCl+HClelec

4、tro negativity, : relative attraction for electrons in a bond- increases going up and to the right in the periodic tablenThe valence-shell occupancy must not exceed 2 for hydrogen and must not exceed 8 for atoms of the first row of the periodic table.nFor elements of the second and later rows, the v

5、alence-shell occupancy may exceed 8. SF6, H2SO4The heat of hydrogenation of benzene is less exothermic by about 21 kcal mol-1 (88kj mol-1) than one would have expected from Lewis structure 1 on the basis of known properties of single and double bonds.+ 3H21Resonance structuresThe superposition of tw

6、o or more Lewis structures with different electron distributions but identical nuclear positions into a composite picture is called resonance.HCO2-HCOOHCOO= HCOO - -1.5 bond orderneither of these accurately describes the formate ionactual species is an average of the two (resonance hybrid)delocalize

7、delectronsRules for Resonance Structures:Rules for Resonance Structures:2. 2. In writing resonance structures In writing resonance structures we are only allowed to move we are only allowed to move electrons.electrons.O O OOO3 3OOORules for Resonance Structures:Rules for Resonance Structures:3. 3. A

8、ll of the structures must be All of the structures must be proper Lewis per Lewis structures.O O O O O OOO3 3Rules for Resonance Structures:Rules for Resonance Structures:5. 5. Equivalent resonance structures Equivalent resonance structures make equal contributions to the make equal co

9、ntributions to the hybrid, and a system described by hybrid, and a system described by them has a large resonance them has a large resonance stabilization.stabilization.O O O O O O Rules for Resonance Structures:Rules for Resonance Structures:6. 6. The more stable a structure is The more stable a st

10、ructure is (when taken by itself), the (when taken by itself), the greater its contribution to the greater its contribution to the hybrid.hybrid.C OHHC OHH C OHHRules for evaluating the relative Rules for evaluating the relative energies of resonance structures:energies of resonance structures:a. Th

11、e more covalent bonds a a. The more covalent bonds a structure has the more stable it structure has the more stable it is.is. C OHHC OHHCOHCOHmoremorestablestablemoremorestablestableRules for evaluating the relative Rules for evaluating the relative energies of resonance structures:energies of reson

12、ance structures:b. Structures in which all of the b. Structures in which all of the atoms have a complete valence atoms have a complete valence shell of electrons are more stable.shell of electrons are more stable. C OHHC OHHCOHCOHmoremorestablestablemoremorestablestableRules for evaluating the rela

13、tive Rules for evaluating the relative energies of resonance structures:energies of resonance structures:d. Resonance contributors with d. Resonance contributors with negative charge on negative charge on electronegative atoms are more electronegative atoms are more stable.stable. C OHHC OHHC OHH Ex

14、ceptions to the octet rule.Exceptions to the octet rule.1. 1. Molecules with second period elements Molecules with second period elements ( (egeg. C, N and O) without octet electronic . C, N and O) without octet electronic configurations will be extremely reactive.configurations will be extremely re

15、active.HCHmethylenemethyleneExceptions to the octet rule.Exceptions to the octet rule.2. 2. Molecules with third period elements Molecules with third period elements ( (egeg. . SiSi, P and S) can exceed octet , P and S) can exceed octet electron configurations because they electron configurations be

16、cause they have dhave d- -orbitals available for bonding.orbitals available for bonding.FPFFFFeither of these structures either of these structures would be considered correctwould be considered correctH3CSCH3Od-orbitalsH3CSCH3Ono d-orbitalsI. Lewis Structures Resonance structures=CONH2CH3CNH2OCH3CH

17、3CONH2+-more stablemajor contributorless stableminor contributorDraw resonance structures for the following species. If the structures are not equivalent, indicate which would be the major contributor.CH3NO2CH2CHOResonance and tautomerismResonance and tautomerismResonance and tautomerismTautomerism

18、and H-bondcelluloseProtein and H-bondn氫鍵是指在氫原子與電負(fù)性很大的原子X(jué) 以共價(jià)鍵相結(jié)合時(shí)，同另外一個(gè)具有孤對(duì)電子對(duì)的原子Y 形成的一個(gè)弱的鍵，是一種由氫原子參加成鍵的特殊的化學(xué)鍵。，如下式中虛線所示：AHBn其中A，B 是氧、氮或氟等電負(fù)性大且原子半徑比較小的原子。Tautomerism and H-bond原子A 到B 的距離。比范德華半徑之和要小，但比共價(jià)半徑之和大很多。例如甲酸分子之間的氫鍵，兩個(gè)氧原子之間的距離為O.267nm，而范德華半徑之和約為0.35nm共價(jià)半徑之和為0162nm。單體甲酸分子中的OH 鍵長(zhǎng)為0.098nm，其二聚體的OH

19、 鍵長(zhǎng)為0.104nm，OHO 鍵長(zhǎng)為0.267nm，因此形成氫鍵以后OH 鍵長(zhǎng)發(fā)生了變化，HO 鍵的鍵長(zhǎng)為O.163nm，要長(zhǎng)于O 一H 鍵的鍵長(zhǎng)。氫鍵的鍵長(zhǎng)常見(jiàn)氫鍵類型：850kJmol-1Resonance and tautomerismResonance and tautomerismtautomerismTetrahedron Letters 41 (2000) 12971301Tautomerism and reactivityExample:NNNClClOOClOHClClClOClClOClOOClOHOHClOClOOBr2ClOClOOBrClOClOONNNNNN+(

20、)( )+( )+( )+( )+( )( )( )ClONNNClOO丙環(huán)唑、噁醚唑異構(gòu)體均在縮合反應(yīng)過(guò)程中產(chǎn)生，主要是由于1，2，4三唑在堿性條件下容易轉(zhuǎn)化為1，3，4三唑造成的。 question:?n 在 以三唑類殺菌劑為主要生產(chǎn)產(chǎn)品的化工企業(yè)，1、2、4-三氮唑的質(zhì)量關(guān)乎幾乎所有三唑類殺菌劑的質(zhì)量，關(guān)乎企業(yè)生產(chǎn)效益和市場(chǎng)競(jìng)爭(zhēng)力。1、2、4-三氮唑合成中異構(gòu)體的分離技術(shù)顯得尤為重要。n 有限公司預(yù)計(jì)投資70萬(wàn)用于1、2、4-三氮唑中異構(gòu)分離技術(shù)的改進(jìn)，提高1、2、4-三氮唑含量，主要是控制其中異構(gòu)體1、3、4-三氮唑的含量。在保證1、2、4-三氮唑生產(chǎn)成本不影響最終三唑類的殺菌劑成本的

21、前提下，對(duì)1、2、4-三氮唑合成技術(shù)進(jìn)行優(yōu)化，對(duì)分離提純技術(shù)進(jìn)行改進(jìn),設(shè)計(jì)一條可以工業(yè)化的合理的小試路線。Tautomer and resonance:more subtle casesCrystalline omeprazole exists as solid solutions of twotautomers in a continuous composition range, and this raisesquestions pertaining to the definition of the term polymorph.We obtained single crystals of

22、five different forms ofomeprazole, with the 1 : 2 ratio varying from 0 : 100 to 15 : 85Tautomeric polymorphism in omeprazole，Prashant M. Bhatt Gautam R. Desiraju，Chem. Commun., 2007, 20572059The crystal structure consists of alternatelayers of molecules, first with the NH moiety anti to the aromatic

23、ring (2a) and the next with the NH syn to the ring (2b).(1:1)Diiminoisoindoline: tautomerism, conformations, and polymorphism, C h e m . C o m m u n . , 2 0 0 4 , 8 8 6 8 8 7, Zhi-Qin Zhang, Jeffrey M. Njus, Daniel J. Sandman, Chengyun Guo, Bruce M. Foxman, PeterErk , Richard van Gelder.only with th

24、e NH syn to the ringDiiminoisoindoline: tautomerism, conformations, and polymorphism, C h e m . C o m m u n . , 2 0 0 4 , 8 8 6 8 8 7, Zhi-Qin Zhang, Jeffrey M. Njus, Daniel J. Sandman, Chengyun Guo, Bruce M. Foxman, Peter Erk , Richard van Gelder.Colors in “ROY”Differences in color can be accounted

25、 for from differences in conformation5-Methyl-2-(2-nitro-phenylamino)-thiophene-3-carbonitrile共軛分子n染料光敏劑是納米晶體太陽(yáng)能電池的關(guān)染料光敏劑是納米晶體太陽(yáng)能電池的關(guān)鍵部分。作為光敏劑，不但要求其對(duì)太鍵部分。作為光敏劑，不但要求其對(duì)太陽(yáng)光具有良好的陽(yáng)光具有良好的nThis compound exhibits an intense red-shifted absorption spectrum (max ) 1417 nm; ) 1.2 105 M-1 cm-1) and a small elec

26、trochemical HOMO-LUMO gap (0.61 eV). The crystal structure shows that it forms -stacked dimers with a short Ni Ni distance (3.32 ).A Porphyrin Fused to Four AnthracenesJ Am Chem Soc. 2011 ;133(1):30-1. Nicola K. S. Davis, Amber L. Thompson, and Harry L. Anderson III. Valence Bond ModelA. Atomic and

27、molecular orbitalsH + H HHTwo electrons in s1s are lower energy than in the separate atoms covalent bondShape and Orientation n The electron distribution must have thecharacteristics of both s (spherical) and p(node) orbitals.n The four new electron distributions(orbitals) will orient as far away fr

28、om eachother as possible. Toward the corners of atetrahedron.III. Valence Bond ModelB. Hybrid atomic orbitals1. sp3 hybridizationCH4 facts:tetrahedral,4 equivalent bondsCHHHHC2s2ppromoteelectron2p2shybridizesp3hybrida.o.ssp3 hybrid a.o.s:C(sp3)tetrahedrals(sp3C + 1sH)4HCHHHHIII. Valence Bond ModelHy

29、brid atomic orbitals1. sp3 hybridizationCNOCNHHHHHCCHHHHHHCOHHHHs(sp3C + sp3C)s(sp3C + sp3N)s(sp3C + sp3O)lone pairsin sp3 a.o.sIII. Valence Bond ModelB. Hybrid atomic orbitals2. sp2 hybridizationC2H4 facts:all six atoms liein same planeCCHHHHtrigonal planar = sp22psp2CCsp22pH1s1sHH1s1sHCCHHHH2ps(sp

30、2C + 1sH)s(sp2C + sp2C)overlapp orbitalsCCHHHH bondall atoms coplanarfor p orbital overlap=CCHHHHdouble bond =1 bond +1 s bondIII. Valence Bond ModelB. Hybrid atomic orbitals2. sp2 hybridizationCOs(sp2C + sp2C) + s(sp2C + sp2O) + lone pairsin sp2 a.o.sCCHHHHCOHHCCHHHHCHHOIII. Valence Bond ModelB. Hy

31、brid atomic orbitals3. sp hybridizationC2H2 facts:linear = spHCCH2pspCCsp2pH1s1sHCCHH2ps(spC + 1sH)s(spC + spC)CCHH2 bonds=CCHHtriple bond =2 bonds +1 s bondIII. Valence Bond ModelB. Hybrid atomic orbitals3. sp hybridizationNs(spC + spN) + 2lone pairin sp a.o.CNHHCNIII. Valence Bond ModelB. Hybrid a

32、tomic orbitalsWhat is the hybridization of each indicated atom in the following compound?HOCH3OHCCH17-ethynylestradiol(“The Pill”)IV. Functional GroupsAtoms or groups of atoms that behave similarly, regardless of the structure to which they are attached.CH3OHCH3CH2OHOHOHOHmethanolethanolb-phenethyl

33、alcohol (lilacs)geraniolretinol (vit A)IV. Functional GroupsHydrocarbons (C & H only)Heteroatomic compoundsaliphaticaromaticalkanesalkenesalkynescyclic compoundsalcoholsethersaldehydesketonescarboxylic acidsestersaminesamidesCCCCCCROHRORRCOHRCORRCOOHRCOORRCONH2RNH2nIn the allyl system each carbo

34、n is trigonal, and each uses sp2 hybrids to make bonds to its neighbors. HHHHH+, _, or .Delocalized bonding Resonance and Aromaticity1. Benzene is much less reactive toward electrophiles, such as halogens,than are simple alkenes, and when it reacts it gives substitution rather than addition.2. NMR o

35、f benzene and its derivatives shows the protons bonded to the ring to be experiencing a stronger effective magnetic field than do protons attached to simple alkenes.3. The heat of hydrogenation of benzene is less exothermic by about 21 kcal mol-1 (88kj mol-1) than one would have expected from Lewis

36、structure 1 on the basis of known properties of single and double bonds.+ 3H21AROMATICITYnAromatic compounds are cyclic unsaturated molecules characterized by certain magnetic effects and by substantially different chemical reactivity and greater thermodynamic stability than would be expected from a

37、 noncyclic model.nAntiaromatic compounds are cyclic unsaturated compounds that are thermodynamically less stable than would be expected from a noncyclic model.Capable of existence only when immobilized by freezing in an inert matrix at very low temperature.Though a stable compd. , does not have a pl

38、anar ringcyclobutadienecyclooctatetraenenThe simple resonance theory fails to explain the contrast between the properties of benzene on the one hand and of cyclobutadiene and cyclooctatetraene on the other,but we may turn to molecular orbitals for the solution.Huckel theory: any regular plane polygo

39、n conjugated ringnIf the number of pairs is even(4n),the last pair will be the only occupants of a doubly degenerate level and so one electron will go into each orbital with spins parallel.nIt is found that the 4n+2 rings are stabilized compared with the openchain analog, whereas the 4n systems are

40、destabilized.4n+2 electrons4n electronseven number of pairsodd number of pairsnTheory thus explains the classification of cyclic conjugated systems as aromatic or antiaromatic according to the energy criterion, which we may define as follows: a molecule is aromatic if it is thermodynamically more st

41、able than expected for the open-chain analog, and it is antiaromatic if it is thermodynamically less stable. A compound showing neither stabilization nor destabilization would be classed as nonaromatic.nTheory suggests that an applied magnetic field perpendicular to a conjugated ring that has 4n+2 e

42、lectrons will cause the electrons to behave as though they were circulating around the ring and generating their own small magnetic field.This circulation is called the ring current.HomoaromaticitynThey are systems in which the systems is interrupted at one or more points by a saturated center but in which geometry still permits significant overlap of the p orbitals across the insulatin