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Advanced Organic ChemistryYan Zhang gnjuzy@Tel:83593072Overview•Objective:deeper understanding on structure and mechanism & their relationshipgeneral data •Contents:principles&specific and examples to illustrate them•Application:structureÆreactivityÆsynthesis and transformationsBooksReference 1Modern Physical Organic Chemistry (2004E V Anslyn D A Doupherty)1.(2004, E.V. Anslyn, D. A.Doupherty)‐‐‐translated version (【译者】计国桢;佟振合[同译者作品]【出版社】高等教育出版社【书号】9787040263596)2.Advanced Organic Chemistry (F. A. Carey, R. J. Sundburg)3.The Art of Writing Reasonable Organic Reaction Mechanisms (2nd Ed. Robert B, Grossman)4.Advanced Organic Chemistry (M.B. Smith, J. March) ‐‐‐translated version (March 高等有机化学‐‐‐反应,机理与结构李艳梅译化学工业出版社)Contents •Molecular Structure and Thermodynamics 1.Structure and models of bonding2and Stability2.Strain3.Non‐covalent binding forces4.Acid‐Base Chemistry5.Stereochemistry y•Reactivity & Kinetics6.Kinetic Analyses6Ki ti A l7.Experiments related to thermodynamics and kinetics8.Catalysis•Reactions & SynthesisChapter 1 Structure and models of bondingp1.1 Classical valence bond concepts:,g•atomic orbitals, electron configurations•hybridization, σand πbonds•inductive effects, electronegativity, bond dipoles, molecular dipole moments •resonance•polarizabilityElectronegativity of atoms and groups Table 1.1Bond dipoles •Bond dipoleDipole moment: μ=q×rin units of Debye (D), 1D=10‐18esu.cmTable 1.2T bl12Molecular dipole moments A sum of bond dipolesTable 1.3ResonanceHow to generate a resonance structure of a given Lewis structure?• for an electron‐deficient atom next lone‐pair‐Look to abearing atom.Look for an electron‐deficient atom adjacent to πbond.•a bond •Look for a radical adjacent to a πbond.•Look for a lone pair adjacent to a πbond.bond•πBonds move around in aromatic compounds.•The two electrons of a πbond can be divided evenly or unevenly between the two atoms making up the bond.Examples pResonanceAppropriate Resonance Structure•Having a noble gas configuration for the atoms•A maximum number of covalent bondsi i b f lik h•A minimum number of like chargesClose charges•proximity of unlike•Placement of negative charges on electronegative atomsImportant rules to remember:p p y g •A lone pair or empty orbital cannot interact with a πbond to which it is orthogonal •Two resonance structures must have the same number of electrons and atomsResonance related to charge densityScheme 1.2gAlerts in writing resonance structures •Tetravalent or N atoms do not participate in resonance T l C d i i i •Electronegative atoms like and O must have octetN their• one or two electrons to If you donate an atom that alreadyhas an octet, regardless of whether it has a formal positivecharge, another bond to that must break•In bridged bicyclic compounds with less than 7 atoms in a ring,b d b t b id h d t d it i hb ia bond between a bridgehead atom and its neighbor isforbidden due to ring strainSoftness Polarizability ‐‐‐Hardness and Numerical measures of hardness:η= (I ‐A)/2Table 1.4I: ionization potentiall ffA: electron affinity J. Am. Chem. Soc . 1983, 7512Fig 1.1Concepts you get to know now •Hybridization(consistent sets of hybrid atomic orbitals contributed bonding)g)•σand πbonds (both in VBT and in MOT)•Resonance (can be used to suggest subtle features of the(ggelectronic structure of functional groups)•Electronegativity and bond polarization (introduce polarityi t b d d lt i b d di l d l l di l)into bonds and result in bond dipoles and molecular dipoles)•Induction•Polarizability (important in understanding solvent properties and P l i bilit(i t t i d t di l t ti d many reactivity patterns)•StericChapter 1 Structure and models of bonding p g 1.2 Molecular OrbitalTheory(MOT)• reactivity organic Good at predicting the reacti it patterns ofmolecules•Development of advanced quantum mechanical analysis madeMOT powerfulcalculation provide accurate •Modern methodsrepresentations of the molecular orbitalsfor organic molecules MOT G d l l d h •Ground ‐state molecular geometry and charge distribution•Calculation of relative molecular energies (for l l i h h i l d l l )molecules in the gas phase ‐‐‐isolated molecules)•Estimate of energy change associated with chemical reactionsHückel (HMO)molecular orbital theory •For treatment of conjugated systemsF f j d• on assumption that πsystem can be treated Based theindependently of σframework in conjugated planarmolecules.•πsystem is of paramount importance in determining the chemical and spectroscopic properties of conjugated polyenesh l d f d land aromatic systems.•In HMO approximation, the electron wave function is p p zexpressed as a linear combination of the atomic orbitals.OrbitalQualitative Molecular Theory (QMOT) Some important rulesCreate molecular orbitalsFig. 1.2MO for 2MO for HHe+HMOs of COFig. 1.3 Energy levels in CO moleculeFig 1.4 shape of the CO molecule orbitalsExamples of MOT application ‐‐‐1application‐‐‐Examples of MOT 2Coordination Chemistry Reviews, 2000, 205, 3–40Examples of MOT application ‐‐‐3Chapter 1 Structure and models of bonding1.3 Application of VBT MOT to reactivity13A li ti f&t ti itrelated to reactivity terms•In VBT,structure is in of substitution effects, through assessment of the impact ofpolar and resonance effect on the electron distribution and reactants transition and intermediates stability of reactants, states intermediates…•In MOT, reactivity is related to the relative energies and shapes of orbitals that is involved in the transformation from reactant to products. The symmetry of the molecular orbits isa particularly important feature of many analyses ofreactivity…Discussion & Exercises1.1. Which of the two resonance structures is a better description of the ground state the following compound? Why?of1.2. Draw as many reasonable resonance structures for each of the following compounds as you can:。
