Manyanimals,especiallyinsects,communicatewithother

membersoftheir

speciesbasedontheodors

ofpheromones.1)

Pheromonesaresecreted(藏匿，分泌)byinsectsinextremelysmallamountsbut

theycancauseprofoundandvariedbiologicaleffects.2)

Pheromonesareusedassexattractants(性吸引劑)

incourtship(求偶),warning

substances,or

“aggregation(集合)

compounds”(tocausemembersoftheir

speciestocongregate(聚集)).Pheromones(信息素):CommunicationbyMeansofChemicals3)

Pheromonesareoftenrelativelysimplecompounds.CH3(CH2)9CH3

(cockroach(蟑螂)

aggregation

pheromone)(CH3)2CH(CH2)14CH3

(sexattractantoffemale

tigermoth燈蛾)5)Manyinsectsexattractantshavebeensynthesizedandareusedto

lureinsectsintotrapsasameansofinsectcontrol.4)

Muscalureisthesexattractantofthecommonhousefly(家蠅)

(Musca

domestica).chain~(鏈烴)Chapter2Alkaneshydrocarbons(碳氫化合物—烴)aliphatic~(脂肪烴)

saturatedaliphatic~(飽和脂肪烴)alkanes(烷烴)unsaturatedaliphatic~alkenes(烯烴)alkynes

(炔烴)cyclic~(環(huán)烴)alicyclic~(脂環(huán)烴)aromatic~(芳香烴)1.Homologousseriesandconstitutionalisomersofalkanes(烷烴的同系列與構(gòu)造異構(gòu))1.1Homologousseries

Hybridization?Bonding?1.2Structure1.3Constitutionalisomers（構(gòu)造異構(gòu)體）structureconstitution(構(gòu)造)configuration(構(gòu)型)conformation(構(gòu)象)Orderofatomicconnectionsthatdefinesamolecule

ArrangementofatomsthatcharacterizesaparticularstereoisomerDifferentarrangementsofatomsthatcanbeconvertedintooneanotherbyrotationaboutsinglebondsconstitutionalformulaconfigurationalformulaconstitutionalisomers(構(gòu)造異構(gòu)體)1.4Classesofcarbonatomsandhydrogenatoms(碳原子和氫原子的類型)primary(伯)secondary(仲)tertiary(叔)quarternary(季)2.Nomenclatureofalkanes(烷烴的命名)2.1Commonnames(普通命名法)methane甲烷ethane乙烷propane丙烷n-butane正丁烷n-pentane正戊烷n-hexane正己烷n-heptane正庚烷n-octane正辛烷n-nonane正壬烷n-decane正癸烷n-undecane正十一烷...straightchain(直鏈)Branchedchain(支鏈)?isobutane異丁烷isopentane異戊烷neopentane新戊烷5constitutionalisomers?IUPAC(internationalunionofpureandappliedchemistry)namesSystematicnames(系統(tǒng)命名法)2.2Systematicnames(系統(tǒng)命名法)2.2.1Fundamentalknowledge(基礎(chǔ)知識)methane甲烷ethane乙烷propane丙烷n-butane正丁烷n-pentane正戊烷n-hexane正己烷n-heptane正庚烷n-octane正辛烷n-nonane正壬烷n-decane正癸烷n-undecane正十一烷...straightchain2.2.2Alkylgroups(烷基)-ane

-yl(alkanealkyl)Methyl甲基

Ethyl乙基n-Butyl正丁基n-Propyl正丙基isopropyl異丙基1-methylethyl1-甲基乙基i-Pr

isobutyl異丁基2-methylpropyl2-甲基丙基i-Butert-butyl叔丁基1,1-dimethylethyl1,1-二甲基乙基t-Busec-butyl仲丁基1-methylpropyl1-甲基丙基s-Buneopentyl新戊基2,2-dimethylpropyl2,2-二甲基丙基仲某基異某基叔某基2.2.3Nomenclature(命名)1)Selectastheparentstructurethelongestcontinuouschain.2)Numberthecarbontowhichthealkylgroupisattached.3)Name5-butyl-3,5,8-trimethylundecane3,5,8-三甲基-5-丁基十一烷4-甲基-6-乙基癸烷6-ethyl-4-methyldecaneasystemofrulesbasedonatomicnumber.Sequencerule(次序規(guī)則)4-甲基-8-異丙基十一烷4-isopropyl-8-methylun-decane-H（氫）<-D（氘）<-CH3（甲基）<-CH2CH3（乙基）<-CH2CH2CH3（丙基）<-CH2C6H5（苯甲基、芐基）<-CH(CH3)2（異丙基）<-CH=CH2（乙烯基）<-C(CH3)3（叔丁基）<-C6H5（苯基）<-C≡CH（乙炔基）<-CH2NH2（氨甲基）

<-C≡N（氰基）<-CH2OH（羥甲基）<-CHO（醛基、甲?；?lt;-COCH3（乙?；?lt;-COOH（羧基）<-COOCH3（甲氧羰基、甲酯基）<-NH2（氨基）<-NHCHO（甲酰氨基）<-NHCOCH3（乙酰氨基）<-N(CH3)2（二甲氨基）<-N+≡N（重氮基）<-NO（亞硝基）<-NO2（硝基）<-OH（羥基）<-OCH3（甲氧基）<-OCOH（甲酰氧基）<-OCOCH3（乙酰氧基）<-F（氟）<-SH（巰基）<-SO3H（磺酸基）<-Cl（氯）<-Br（溴）<-I（碘）

2,7,9-三甲基-6-異丁基十一烷2,7,9-三甲基-6-(2-甲丙基)十一烷Englishname??3-甲基-5-乙基-4-丙基庚烷Englishname?2,5-二甲基-4-異丁基庚烷Whenyourmusclescontractitislargelybecausemany

C–Csigma

(single)bondsareundergoing

rotation(conformational

changes構(gòu)象轉(zhuǎn)變)ina

muscleproteincalled

myosin(肌球蛋白).Nanotubes,anewclassofcarbon-basedmaterialswith

strengthroughly

onehundredtimesthatofsteel,alsohave

anexceptionaltoughness.Thepropertiesofthesematerialsdependsonmanythings,but

centralto

themiswhetherornotrotationispossiblearound

C–Cbonds.3.Conformationsofalkanes(烷烴的構(gòu)象)3.1EthaneConformations:thetemporarymolecularshapes

thatresult

from

rotationsofgroupsaboutsinglebonds.Thestaggeredconformation(交叉式構(gòu)象)

ofethane

Staggeredconformation:allowsthemaximumseparationoftheelectronpairsofthesixC—H

bondshasthelowestenergy

moststableconformation.傘形式鋸架式紐曼式Theeclipsedconformation(重疊式構(gòu)象)ofethaneEclipsedconformation:

maximumrepulsiveinteraction

betweentheelectronpairsofthe

sixC—Hbondshasthehighestenergy

leaststableconformation.傘形式鋸架式紐曼式Potentialenergy(勢能)changesthataccompanyrotationofgroupsaboutthecarbon-carbonbondofethane.Conformationsinwhichthetorsionanglesbetweenadjacentbondsareotherthan60oaresaidtohavetorsionalstrain(扭轉(zhuǎn)張力).V.Pophristic,L.Goodman.Hyperconjugationnotstericrepulsionleadstothestaggeredstructureofethane.Nature2001,411,565-568.

1)Inethanethedifferenceinenergybetweenthe

staggeredandeclipsedconformationsis12KJ/mol2)Unlessthetemperatureisextremelylow(?250℃),many

ethanemolecules(atanygivenmoment)willhaveenoughenergyto

surmountthisbarrier.3)Anethanemoleculewillspendmostofitstimeinthelowest

energy,staggeredconformation,orina

conformationverycloseto

beingstaggered.Many

timeseverysecond,itwillacquireenoughenergy

throughcollisionswithothermoleculestosurmountthe

torsionalbarrierandwillrotatethroughan

eclipsedconformation.4)Intermsofalargenumberofethanemolecules,

mostofthe

molecules(atanygivenmoment)will

beinstaggeredornearly

staggeredconformations.3.2ButaneImportantconformationsofbutaneAnti(對位交叉式)eclipsed(部分重疊式)gauche(鄰位交叉式)eclipsed(全重疊式)EnergychangesthatarisefromrotationabouttheC2–C3bondofbutanetorsionalstrain/vanderWaalsrepulsion

force1)Theanticonformation(I):doesnothavetorsionalstrain

moststable.2)Thegaucheconformations(IIIandV):thetwomethylgroupsarecloseenoughtoeachother

thevanderWaalsforcesbetweenthemarerepulsive.

3)Theeclipsedconformation(II,IV,andVI):energymaxima

II,IVandVIhavetorsionalstrainandvanderWaalsrepulsionsarisingfromtheeclipsedmethylgroupandhydrogenatoms;IV

hasthegreatestenergyduetothelargevanderWaalsrepulsion

forcearisingfromtheeclipsedmethylgroups.4)Theenergybarriersarestilltoosmalltopermitisolationofthegaucheandanticonformationsatnormaltemperatures.EnergychangesthatarisefromrotationabouttheC2–C3bondofbutane1,2-二溴乙烷(對位交叉式構(gòu)象約占84％)乙二醇(主要為鄰位交叉式構(gòu)象)SirDerekH.R.Barton(1918-1998,formerlyDistinguished

Professorof

ChemistryatTexasA&MUniversity)andOdd

Hassell(1897-1981,formerlyChairofPhysical

Chemistryof

OsloUniversity)sharedtheNobelprizein1969“fordevelopingandapplyingtheprinciplesofconformationinchemistry.”4.Physicalproperties(物理性質(zhì))5.有機反應中的熱力學(thermodynamics)與動力學(kinetics)?G?=-RTInK=?H?-

T?S??H?—焓變，是在標準狀態(tài)下生成物與反應物焓之差，基本上是反應物與生成物之間的鍵能差，即所有形成新鍵的鍵能之和減去所有斷裂鍵的鍵能之和。?S?—熵變，是在標準狀態(tài)下生成物與反應物熵之差。熵可以看做是體系內(nèi)的混亂度，因此熵變也就是在反應過程中體系內(nèi)熵的變化，混亂度增加，?S?為正值，對反應有利；混亂度減少，?S?為負值，對反應不利。6.Reactions(反應)Alkanesaregenerallyinerttomanychemicalreagents.

C—CbondsarequitestrongC—Hbondsofalkanesareonlyslightlypolarized

Alkanesaregenerallyunaffectedbymostbases

Alkanemoleculeshavenounsharedelectronstooffer

sitesforattackbyacids

Reactivityofalkanes:1)Alkanesreactvigorouslywithoxygenwhenan

appropriatemixtureisignited(點燃)——

combustion(燃燒)(oxidation).2)Alkanesreactwithchlorineandbromine

under

heatorlight,andtheyreact

explosively

withfluorine——halogenation(鹵化)6.1Combustion(燃燒)6.2Pyrolysis(熱解)“cleavagebyheat”Hydrolysis(水解)(“cleavagebywater”)freeradical(自由基)Cracking(裂解)Themorevolatile,lower-molecular-weighthydrocarbonsareusefulasautomotivefuelsandasasourceofpetrochemicals.Freeradical(intermediate)Production(產(chǎn)生):Energymustbesuppliedbyheatingorby

irradiation(照射)withlighttocausehomolysis(均裂)ofcovalentbondsinthegasphase(氣相)orinanonpolarsolvent(非極性溶劑).Reactivity(活性):

Almostallsmallradicalsareshort-lived,highlyreactivespecies.Stability(穩(wěn)定性):ArCH2·，CH2=CHCH2·，3o>2o>1o>CH3·>Ar·，CH2=CH

·

Configuration(構(gòu)型):

theCH3radicalisplanar(sp2

hybridizedcarbon)6.3Autoxidation(自動氧化)R-HReactivity(活性):3o>2o>1o

TheO–Obondofanalkylhydroperoxideisquiteweak,anditcanbreakand

produceradicalsthatcaninitiateotherchains:RO–OH

RO?+?OHBenzoylPeroxide(過氧化苯甲酰)Benzoylperoxideisanorganiccompoundintheperoxidefamily.Itconsistsoftwobenzoylgroupsbridgedbyaperoxidelink.Theoxygen-oxygenbondinperoxidesisweak.Thusbenzoylperoxidereadilyundergoeshomolysis,formingfreeradicals:

(C6H5CO)2O2→2C6H5COO?Benzoylperoxideisusedasaradicalinitiatortoinducepolymerizations.Othermajorapplicationsincludetreatingacne(痤瘡,粉刺),dyeinghair,whiteningteeth,andbrighteningflour.TheFDA(theFoodandDrugAdministration)eventuallyclassifiedbenzoylperoxideas“safetyunknown”.especiallysusceptibletoabstractionbyO2radical(Lin?)autoxidationhydroperoxiderancidity(酸敗)Autoxidationoccursinthebodywhichmaycauseirreversible

damage.

linoleicacid(亞油酸)(asanester)Antioxidants(抗氧劑)Autoxidationisinhibitedbyantioxidants，whichcanrapidly“trap”peroxylradicalsbyreactingwiththemtogivestabilizedradicalsthatdonotcontinuethechain.VitaminE

VitaminC

BHT:addedtofoodstopreventautoxidation

Therearetworeasonswhysomeradicalsaremorepersistentthanothers:(1)sterichindrance;(2)electronicstabilization.Manyofthemoleculesthatmakeupthestructureofhumantissuearesusceptibletohomolysisinintenselight,andthebodymakesuseofsophisticatedchemistrytoprotectitselffromtheactionofthereactiveradicalproducts.VitaminEplaysanimportantroleinthe‘taming’oftheseradicals:abstractionofHfromthephenolichydroxylgroupproducesarelativelystableradicalthatdoesnofurtherdamage.Polydimethylsiloxane(PDMS,聚二甲基硅氧烷)PDMSisthemostwidelyusedorganicpolymer,andisparticularlyknownforitsunusualflowproperties.Itsapplicationsrangefromcontactlenses(隱形眼鏡)toelastomers(彈性體)。AccordingtotheHandbookofFoodAdditives,PDMSisasuspectedcarcinogen(致癌物)andanestablishedmutagen(誘變劑).BetyouneverthoughtthosewereinyourchickenMcNuggets!AccordingtoAConsumer'sDictionaryofFoodAdditives,TBHQcancomprisenomorethan0.02percentoftheoilinanugget.IngestingasinglegramofTBHQcancause“nausea,vomiting,ringingintheears,delirium(精神錯亂),asenseofsuffocation,andcollapse.”IngestingfivegramsofTBHQcankill.tert-Butylhydroquinone(TBHQ,特丁基對苯二酚)6.4Nitration(硝化)(Substitution)6.5Sulfonation(磺化)(Substitution)Reactivity:F2>Cl2>Br2>>I2Fluorineisanextremelyaggressiveoxidizingagent,anditsreactionwithalkanesisstrongly

exothermic(放熱的)anddifficulttocontrol.Chlorinationofalkanesislessexothermicthanfluorination,andbrominationlessexothermicthanchlorination.Iodineisuniqueamongthehalogensinthatitsreactionwithalkanesisendothermic(吸熱的).6.6Halogenation(鹵化)(Substitution)6.6.1Chlorinationofmethane(甲烷的氯化)Mechanism(機理)(鏈引發(fā))(鏈增長)（c）Chain-terminatingstep