有机化学（加州大学伯克利分校）.pdf

I,too,startedsmall.Peter VollhardtUniversity of California at BerkeleyOrganic Chemistry:Organic Chemistry:The Chemistry of CarbonThe Chemistry of CarbonOrganic Organic Chemicals Chemicals in in ActionActionChemicalsChemicalsSaccharin(1879):300 Times Saccharin(1879):300 Times as Sweet as Sugaras Sweet as SugarMmmmmmmmmmmmmhhhhMmmmmmmmmmmmmhhhh!Chemical Warfare in Nature:Chemical Warfare in Nature:BenzoquinoneBenzoquinone,Hydrogen Hydrogen peroxide,peroxide,100C100CThe Bombardier BeetleThe Bombardier BeetleSeahareSeaharePinkFloydPinkFloydChemical Protection in NatureChemical Protection in NatureNature is not always green.Nature is not always green.PolyacetylenePolyacetylene:Organic ConductorsOrganic ConductorsThe Polyamide The Polyamide KevlarKevlarBulletproof!Bulletproof!Organics Harder Than MetalOrganics Harder Than MetalPolystyrene Polystyrene from styrenefrom styreneSuntan lotionSuntan lotionThe Sands Hotel,Las Vegas,11.26.1996Nature is the Biggest PolluterNature is the Biggest PolluterTop Four US Prescription DrugsTop Four US Prescription DrugsTotal U.S.sales of pharmaceuticals reached$224 billion in 2003,with lipitor leading at$6.3 billion.Male ChromosomesMale ChromosomesClonesClonesDNA:the Double HelixDNA:the Double HelixBan Ban DihydrogenDihydrogen MonoxideMonoxideMatthewJames Tvedten(Poison:Chlordane)Michigan(1/27/81)6,000+and continuing at a rate of 10 to 15 per month(Poison:methyl isocyanateand others)Bophal,India(Deaths since 12/2/84)Death/Injury ongoing(Poison:Dows Agent Orange)New Plymouth,NZ(1965-present)Jesse(Poisons:NIX and Lindane)U.S.(9/11/93)Dedicated to the Martyrs of Pesticide Poisoning Dedicated to the Martyrs of Pesticide Poisoning May they(and we)find justiceMay they(and we)find justiceBaby Evans(Poison:Termiticide)St.Petersburg,FL(5/2000)Colette Chuda(Poison:various pesticides)New Jersey(4/21/91)Cindy Duehring(Poison:various pesticides)Bismark,ND(6/30/99)24 Children(Poison:methyl parathion by Bayer)Tauccamarca,Peru(10/24/99)Julia Kendall(Poison:Malathion)California(7/12/97)Marianna Catesand Family(Poison:various agricultural)Ulster County,New York(6/1995)Memorial Memorial 547 Men,Women and Children will Die today 547 Men,Women and Children will Die today from Pesticide Poisoning from Pesticide Poisoning(Statistically known as acceptable risks for pesticide poison(Statistically known as acceptable risks for pesticide poison registration)registration)No Chemicals in KailuaNo Chemicals in KailuaWater:The Solvent of LifeWater:The Solvent of LifeThe The HydroniumHydronium IonIonOrbitalOrbitalHHHOChargeChargeCornflowers:Cornflowers:Blue Blue(UnprotonatedUnprotonated)Poppies:Poppies:RedRed(Protona(Protonatedted)What to Expect:an OutlineWhat to Expect:an OutlineC CC CHHHHHHHHHHHHStructure and BondingStructure and BondingAlkanesAlkanesHaloalkanesHaloalkanesCycloalkanesCycloalkanesStereoisomerismStereoisomerismC CHH3 3ClCl-+C CHH2 2C CHH2 2C CHH2 2HH2 2C CHH2 2C CC CHH2 2Basic ReactionsBasic ReactionsC CHH3 3HH+ClCl2 2C CHH3 3ClCl+HHClClhvhv,SubstitutionSubstitutionC CHH3 3ClCl+K K I I+-C CHH3 3I IK K ClCl+-+Radical Radical HalogenationHalogenationReaction versus MechanismReaction versus MechanismCHCH2 2CHCH2 2+HH2 2C CHC CH2 2HHI IbasebaseEliminationEliminationReaction:Reaction:The recipe and molecular alteration.The recipe and molecular alteration.Mechanism:Mechanism:What is the exact pathway by which What is the exact pathway by which alteration occurs?alteration occurs?Functional GroupsFunctional GroupsOHOHC CC CC CC CC CR RCOHCOHOOR RRROOC CNHNH2 2R RSpectroscopy:Spectroscopy:NMR,IRNMR,IRSynthesisSynthesis:WhlerWhler(1828):(1828):Made anMade an“organic”“organic”compound compound from an from an“inorganic”“inorganic”salt.salt.Pb(OCN)Pb(OCN)2 2+2 H+2 H2 2O+2 NHO+2 NH3 32 H2 H2 2NCNHNCNH2 2+Pb(OH)+Pb(OH)2 2OOUreaUreaHow do we make penicillin?How do we make penicillin?OOOONNNNS SC COOOOHHOr cubane?Or cubane?HHHHHHHHHHHHHHHHBefore we get into this,we need to review the basics.Before we get into this,we need to review the basics.HHBondingBondingAtom 1Atom 1+Atom 2Atom 2A:A:A A or or A A A A“favorable”favorable”“Rules”:Rules”:1.1.Opposite charges attract each other Opposite charges attract each other(Coulombs LawCoulombs Law).).2.Electrons spread out in space 2.Electrons spread out in space(delocalization).(delocalization).3.Noble gas configuration is desirable.3.Noble gas configuration is desirable.17361736-18061806Covalent Bonding:Sharing Covalent Bonding:Sharing ElectronsElectronsDimensions:Dimensions:Nuclear diameter 10Nuclear diameter 10-1515mmElectronic orbit 10Electronic orbit 10-1010mmfive five orders of orders of magnitudemagnitudeMass ratio proton:electron=1800Mass ratio proton:electron=1800InternuclearInternuclear PotentialPotentialIonic Bonding:Ionic Bonding:“No”Sharing of Electrons“No”Sharing of Electrons Who donates and who accepts?Who donates and who accepts?Valence electronsDuetOctetsPartial Periodic TablePartial Periodic TableWhy Do Elements React?Why Do Elements React?AimAim1.1.“Ionic”BondsIonic”BondsLiLi2,12,1NaNa2,8,12,8,1F F2,72,7LiLi2 2+NaNa2,82,8+FF2,82,8-+1e+1e-1e1e-1e1eTherefore:Therefore:+-Noble Gas ConfigurationNoble Gas Configuration2 Na F2 Na FF F2 22 Na2 Na+Transfer Transfer of of Valence Valence ElectronsElectronsCovalent Bonds-4e4eShows onlyShows onlyvalencevalence e e(He)(He)(NeNe)Compromise:electronCompromise:electron-sharingsharingC C.HHHHHHHH.HH OO HH.2.“Covalent”Bonds2.“Covalent”BondsC C4+4+4e+4e4 4 HHC CC C2 2 HH2 2OO2 2+C C4 4-Elements in the“middle”of the periodic table Elements in the“middle”of the periodic table have a problem withhave a problem with electron affinity(EA)electron affinity(EA)andand ionization potential(IP)ionization potential(IP):Lakehurst,NJ,Lakehurst,NJ,May 3,1937May 3,1937The Hindenburg:The Hindenburg:3.Most Bonds Are“Between”Covalent and 3.Most Bonds Are“Between”Covalent and Ionic:Ionic:Polar CovalentPolar CovalentPaulingPaulingelectronegativity scaleelectronegativity scaleHHI I ClClHH3 3C CF F:-+:-+-+F F:A A:B B-19011901-1994 Nobel prizes for chemistry and peace1994 Nobel prizes for chemistry and peacepushpull :0.3 0.3 0.30.3 2.0 2.0 h(momentum)hh=Plancks constant=1.34 x 10h=Plancks constant=1.34 x 10-3434cal seccal secOrbitalsOrbitals:SolutionsSolutions to wave equations to wave equations(wavefunctionswavefunctions)BornBorn:Square of a value of the:Square of a value of the wavefunctionwavefunction=probability of finding probability of finding the electron therethe electron there19271927 SchrSchr dingerdinger:Wave equationsWave equations for for an electron moving around the an electron moving around the nucleusnucleusSpherical(threeSpherical(three-dimensional)shape.dimensional)shape.Contrast to mechanical waves Contrast to mechanical waves(guitar string,rubber band)(guitar string,rubber band)TwoTwo-dimensional dimensional wavewave+/+/-=signs,not charges=signs,not chargesOrbitalsOrbitalsnodenodeamplitudeamplitude+-0 0“ballball”spherical spherical“eighteight”Actual solutions:1Actual solutions:1s s,2,2s s,2,2p px x,2,2p py y,2,2p pz z,3 3s s,3,3p px x,3,3p py y,3,3p pz z,etc.,etc.(increasing energyincreasing energy)+-nodenodeMost important orbitals(for us):Most important orbitals(for us):#s are related to#s are related toclassical shellsclassical shellss Orbitals Orbitalp Orbitalp OrbitalThe 1s OrbitalThe 1s Orbitals-OrbitalThe 2s OrbitalThe 2s OrbitalThe Three 3p OrbitalsThe Three 3p Orbitalsp p-OrbitalOrbitalEnergy diagram depicting solutions as energy Energy diagram depicting solutions as energy“levelslevels”:There are rules There are rules for for“filling upfilling up”levels withlevels with e e1.1.Lower energy orbitals filled first(Lower energy orbitals filled first(closed shellclosed shell)2.2.PauliPauli:Exclusion principleExclusion principle:2:2e e maxmax3.3.HundsHunds rulerule:Equal energy orbital(i.e.:Equal energy orbital(i.e.p px,y,zx,y,z)filled)filled with one with one e e each firsteach firstelectrons(He)electrons(He)1 1s s2 2s sp px xp py yp pz zAufbauAufbau PrinciplePrincipleor:where the electrons goor:where the electrons goEnergies of Orbitals Calculated for H AtomEnergies of Orbitals Calculated for H AtomTherefore,Therefore,electronic electronic configurations:configurations:H(1H(1s s)1 1;He(1He(1s s)2 2;Li(1Li(1s s)2 2(2(2s s)1 1;Be(1Be(1s s)2 2(2(2s s)2 2;B(1B(1s s)2 2(2(2s s)2 2(2(2p p)1 1;C(1C(1s s)2 2(2(2s s)2 2(2(2p p)2 2.BondingBonding occurs by occurs by overlapoverlap of atomic of atomic orbitals to give orbitals to give molecular orbitalsmolecular orbitalsIn phaseIn phase overlap overlap?bondingbonding molecular orbitalmolecular orbitalOut of phaseOut of phase overlap overlap?antibondingantibonding molecular orb.molecular orb.antibondingantibonding(node)(node)bondingbondingEnergy Energy diagramsdiagrams1 1s s1 1s s1 1s s2 2p pBondingBondingE E-Orbitals“split”energy levels when entering into overlap.-The better the overlap e.g.same type of orbital,same energy(shell),the larger the splitting.-For orbitals of unequal energy,the higher orbital“goes up”,the lower“down”.e go downe go downno eno egoodgoodbadbad1 1s s2 2p pThe Types of Orbital OverlapThe Types of Orbital OverlapThis is Real!This is Real!Direct Observation of dDirect Observation of d-Orbitals in CuOrbitals in Cu2 2OOZuoZuo et al.et al.Nature Nature 19991999,401401,4949.Li:H 2Li:H 2s s+1+1s sno shape no shape“issuesissues”H:Be:H is linear;but Be atom H:Be:H is linear;but Be atom has filled shells(1has filled shells(1s s)2 2(2(2s s)2 2!How does it bond?How does it bond?Use an empty Use an empty p porbital:orbital:Hybridization and ShapeHybridization and Shape-+This allows for bonds,but gives This allows for bonds,but gives wrong structure:wrong structure:IntraatomicIntraatomic overlapoverlap of 2s and one 2p of 2s and one 2p orbitals generates two new hybrid orbitals generates two new hybrid molecular orbitals:molecular orbitals:s+p s+p?two two spsp hybrids,hybrids,with with linearlinear arrangement:arrangement:Better:“Hybridization”of OrbitalsBetter:“Hybridization”of Orbitalsspsp-HybridHybridNote:Note:n n atomic orbitals atomic orbitals?n n new orbitalsnew orbitalsWe shall see next that other We shall see next that other combinations of combinations of intraatomicintraatomic overlap overlap(hybridization)are possible:(hybridization)are possible:s+p+p s+p+p?3 3 spsp2 2with with trigonaltrigonal shapeshapes+p+p+p s+p+p+p?4 4 spsp3 3with with tetrahedraltetrahedralshapeshapeExample:Bonding in BHExample:Bonding in BH3 3.Hybridization to Hybridization to TrigonalTrigonalspsp2 2-HybridHybridBonding in Methane:Bonding in Methane:Hybridization to TetrahedralHybridization to Tetrahedralspsp3 3-HybridHybridMethaneMethaneBonding in Ethane:Bonding in Ethane:Overlap of Two Overlap of Two spsp3 3Hybrid OrbitalsHybrid OrbitalsEthaneEthaneMore More spsp3 3Hybrids:NHHybrids:NH3 3and Hand H2 2OODouble and Triple Bonds:Double and Triple Bonds:A PreviewA PreviewEtheneEtheneEthyneEthyneDelocalized Electrons:Delocalized Electrons:Fe Atoms on a Cu SurfaceFe Atoms on a Cu SurfaceMolecular Models:Molecular Models:Use Them!Use Them!The DashedThe Dashed-Wedged Line Wedged Line NotationNotationRhondaRhondaWalbaWalbaChapter 10:Nuclear Magnetic Chapter 10:Nuclear Magnetic Resonance(NMR)SpectroscopyResonance(NMR)SpectroscopyWhat is spectroscopy?What is spectroscopy?Molecular response to Molecular response to radiativeradiative stimulus is stimulus is quantizedquantized(“geared”).(“geared”).(Molecule=nuclei+electronsMolecule=nuclei+electrons).).Excitation:Excitation:1.Electronic(UV1.Electronic(UV-visible spectra)visible spectra)2.Vibrational(IR)2.Vibrational(IR)3.Rotation(microwave)3.Rotation(microwave)4.Nuclear spin orientation in magnet(NMR)4.Nuclear spin orientation in magnet(NMR)SpectrometerSpectrometer scans scans to find to find E E:The sThe spectrumpectrumE E=h h =c/=c/Excitation causes Excitation causes an“an“absorptionabsorption”,a”,apeakpeak in a graphin a graphA General SpectrometerA General Spectrometerkcal molkcal mol-1 1What is What is E E in NMR?Nuclei in NMR?Nuclei behave as tiny behave as tiny magnets magnets(random(random orientation).orientation).In a In a magnetic field Hmagnetic field H0 0,they,they organize organize with(with(,lower energy),lower energy)or or againstagainst(,higher energy),higher energy)the field.the field.E E=h=h 0 0resonance frequency:resonance frequency:The frequency that The frequency that matchesmatchesexactly the exactly the energy differenceenergy difference.Protons as Tiny Magnets Line Up With Protons as Tiny Magnets Line Up With and Against an External Magnetic Filedand Against an External Magnetic FiledRatio Ratio :1:1 1:1Absorption of Light,Spin Flip,and Absorption of Light,Spin Flip,and Resonance Resonance Spectral LineSpectral Line 0 0is is proportionalproportional to to HH0 0.(0 0 is is specific specific forfor element/isotopeelement/isotope)For For 1 1H:at H:at HH0 0=21,150 gauss,=21,150 gauss,0 0=90 MHz.=90 MHz.E E(300 MHz)10(300 MHz)10-5 5kcal molkcal mol-1 1.NN/NN=1.000004=1.000004NMR“NMR“activeactive”nuclei:”nuclei:1 1HH and and 1313C C(not not 1212C C)At At HH0 0=70500 gauss,=70500 gauss,0 0=300 MHz.=300 MHz.HH0 0(earth):0.7 gauss!(earth):0.7 gauss!A Hypothetical NMR Spectrum:A Hypothetical NMR Spectrum:Active Elements Absorb at Differing Active Elements Absorb at Differing FrequenciesFrequenciesThe NMR SpectrometerThe NMR SpectrometerSolvents:CDClSolvents:CDCl3 3,CD,CD2 2ClCl2 2,THF,THF-d d8 8,etc.,etc.High Resolution NMR!High Resolution NMR!Why are there two peaks?Why are there two peaks?The Chemical ShiftThe Chemical ShiftCausesCauses shieldingshielding,i.e.,i.e.,Peak moves to the rightPeak moves to the rightElectrons in Vicinity of Nucleus Affect Electrons in Vicinity of Nucleus Affect Consider HConsider H+:No:No e e,no shieldingno shielding,peakpeak furthest to the furthest to the leftleft.But:But:When we add an When we add an e e-withdrawingwithdrawing group:group:e.g.,e.g.,CHCH3 3ClCl,causes causes deshieldingdeshielding(to(to leftleft).).Chemical shift provides a finely tuned picture Chemical shift provides a finely tuned picture of of electronic environmentelectronic environment around each H.around each H.C CHHHHHHHH+-ElectronsElectrons cause cause shieldingshielding:Peak moves Peak moves upfieldupfield(to(to rightright).).If we substitute with If we substitute with e e-negativenegative groups,shielding of groups,shielding of observed nucleus is observed nucleus is diminisheddiminished;or nucleus is;or nucleus is“deshieldeddeshielded”(relatively).”(relatively).One eOne e-poor poor neighborneighborTwo eTwo e-poor poor neighborsneighborsThe Chemical Shift The Chemical Shift The position of peak relative to an The position of peak relative to an internal standard.Most common isinternal standard.Most common isTetramethylsilaneTetramethylsilane:(CH:(CH3 3)4 4SiSi or or“TMS”“TMS”,the the“zero”“zero”point in the spectrum.point in the spectrum.=(from TMS)(from TMS)HzHzRF(e.g.,300 MHz)RF(e.g.,300 MHz)ppmppm,is is independent