高中化学同分异构体High school chemistry isomers.docx
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高中化学同分异构体Highschoolchemistryisomers
高中化学同分异构体(Highschoolchemistryisomers)
Ofisomers
1.Conceptualanalysis(samekindofmaterialhomologue)
Isomericcompoundshavethesamemolecularformula,butthedifferentstructuresarecalledisomericphenomena.Compoundswithisomericphenomenaarecalledisomers.Inmiddleschool,therearethreemaincausesofisomerization:
carbonframeisomerism,positionisomerismandfunctionalgroupisomerism.Toidentifywhetherthetwoareisomers,thefirstistolookatthenumberofcarbonatoms,toseeifthemolecularformulaisthesame,andthenlookattheformula.Inthesamecase,ifthestructureisdifferent,thetwowillbeisomers.
Thesamesubstanceisnotonlythesamemolecularformulabutalsotheexactsamestructure,thesamesubstance.Thesamesubstanceshouldhavethesamephysicalparameters,suchasthesameboilingpoint.Therearetwomethodsfordeterminingwhethertwostructuresareidentical:
(1)to"overlap"themoleculesasawholeortorotatethemalongthesymmetricalelements(surfaces,lines);
(2)namedaftersystemnomenclature,withthesamename.
Homologuestructuresimilartothatonthemoleculesdifferoneorafew-materialCH2groupsclaimedhomologue.Structurereferstothesimilarmoleculescontainingfunctionalgroupsshouldhavethesamekindandnumber,suchasethanolandpropyleneglycolasthehomologue,butnothomologueinethyleneglycolandglycerol.
Iftwostructuresareknowntodeterminewhethertheyhavethesamemolecularformula,thenumberofnonsaturationsismuchfasterthanthenumberofhydrogenatoms.InthecaseofC.O.N.Clandotheratomicnumbercorrespondingtothesamecondition,thesamemolecularformulamustbethesamewithoutsaturation.Suchas
Bothofthemhavethesamenumberofatoms,andthey'reallfour,sothetwostructureshavethesamemolecularformula.Thestructureisobviouslydifferent,sotheyshouldbeisomers.
Itisconvenienttousethenumberofcommonedgestodeterminetherelationshipbetweentwoknownstructuraltypes.Ifthenumberofcommonedgesisthesame,andthesamesequenceofthebenzeneringsisthesame,thetwoarethesamesubstances;Ifthenumberofcommonedgesisthesame,andthesequenceofthebenzeneringsisdifferent,thetworepresentisomers.Ifthenumberofcommonedgesisdifferent,thenthetwoarenotisomers,noraretheythesamesubstance.See[practice1-3].
(1-1)thefollowingfourexpressionsarethesimplestructureofthefourtypesofpheromonesofthecottonseedweevil,whicharetheisomersofeachother.
Thereare10carbonatomsinit,andallofthemhave11carbonatoms,includingone-CH2OH,whichistwomorehydrogensthanone-CHO,sotheyarenotisomers.Theformulaisasix-memberedring,whichisaquaternaryring.Thetwostructuresaredifferent,sotheyareisomersofeachother.
(1-2)thefollowinggroupsofsubstancesbelongtothesameisomers,whichbelongtothesamefamily,whichbelongtothesamefamily,whichareneitherhomologousnordifferent.
1.5.
Aceticacidandstearicacid,ethaneandaminoaceticacid,benzoicacidandterephthalicacid
Itistheisomer,themolecularformulaisC7H8O,
Buttheformerisaromaticalcohol,thelatterisphenolic;Thegroupisahomologue,whichbelongstoaseriesofunarylipids,andthemolecularcompositionis16-CH2.Inthesameisomer,thenitroalkaneandaminoacidsofthecarboncountareeachother.ThegroupcontainsdifferentcarbonNumbers,notisomers,bothofwhichcontaincarboxyl-COOH,buthavedifferentcarboxylgroupsandarenothomologous.Itisimportanttonotethatthec-csinglekeycanrotatearoundthekeyaxis,sothetwostructuresarethesame,indicatingthesamesubstance.
Thestructureofthenaphthalenemoleculecanbeexpressedasor,thetwoareequivalent.Benzopyreneisastrongcarcinogen(foundinchimneyash,coaltar,burningsmokeandexhaustfrominternalcombustionengines).Itsmoleculescomposedoffivemergerofbenzenering,theformulacanbeexpressedas(Ⅰ)or(Ⅱ):
(Ⅰ)(Ⅱ)
It'sthesamething.TheexistingstructuralformulaA,B,C,D
A,B,C,D
Amongthem:
and(Ⅰ),(Ⅱ)equivalentformulais();And(Ⅰ),(Ⅱ)isomersis().
[resolution](Ⅰ)asthebenchmark,thegraphicsfromthepaperstickpaperbackagainafterturn180degreestotherightforAquickDtype,theDtypeonpaper45degreescounterclockwiserotationforAquicktypeA.Therefore,A,Dand(Ⅰ),(Ⅱ)type.Canalsobe(Ⅱ)asAbenchmark,will(Ⅱ)graphicsonpapercounterclockwiserotate180degreesforAquickAtype,(Ⅱ)onpapercounterclockwiserotate135degreesforAquickDtype.
Fromthepointofmolecules,isC20H12(Ⅰ)type,BtypeisC20H12,andCtypeisC19H12,soBisⅠ,Ⅱisomers,andCtypeisnot.Theansweris
(1)AD;
(2)B.
Therearesixpairsofcommonedgesofthethickcyclicaromatichydrocarbons,andthetwocommonedgesofAandDaresix,andtheorderoffivebenzeneringsisthesame,sothetworepresentthesamesubstance.AandB(orDandB)havesixedges,buttheorderofthebenzeneringsisdifferent,sothey'reisomersofeachother.Thec-typefivebenzeneringisthesamesevenedges,soCandtheotherthreearenotisomers,notthesamesubstance.
2hydrocarbonisomerism
2.1heterogeneityofalkanes(isomerismofcarbonframes)
C1-c6carbonchainheterogeneity:
CH4,C2H6,C3H8isomer;C4h102,c5h123,c6h145.
2.2isomerism(theheterogeneityofthecarbonframeandthepositionofthedoublebondorthethreekeyfunctionalgroup)
Therearethreeisomersofa2-carbonchainofbutyleneC4H8:
Theisomerizationofbenzenehomologues(heterogeneityofsidechaincarbonframeisomerizationandlateralchainposition),suchastheC9H12,thereare7isomers:
Theheterogeneityofthemonogenicsubstituentsof3hydrocarbon(insteadoftheequivalenthydrogenmethod)
Halogenatedhydrocarbons,alcohols,aldehydes,carboxylicacids,andaminescanalllookatasinglesubstitutionofhydrocarbons.Determinethattheirisomerscanreplacetheequivalenthydrogenmethod.
Equivalenthydrogenconcept
Theequivalenthydrogenintheorganicmoleculesiscalledtheequivalenthydrogen,andtheequivalentofthehydrogenatominthemoleculeisthefollowing:
It'sequivalenttothehydrogenthat'sattachedtothesamecarbonatom.
Theequivalentofthehydrogenatomonthesamecarbonatom.Suchasnewpentane(canbeviewedasthefourmethylreplacedthemethanemoleculesmadeupofthefourhydrogenatoms),equivalent,itsfourmethylhydrogenatomsonthemethylcompletelyequivalent,thatistosaynewmoleculesofthepentane12Hatomsareequivalent.
Theatomsinthemoleculeareequivalenttothehydrogenatomsinthemirrorimage.The18Hatomsinthemoleculeareequivalent.
Thesubstitutionofequivalenthydrogenmethodfortherelationshipoftheequivalenthydrogenatomcaneasilydeterminethenumberofisomersoforganiccompounds.Themethodistowriteouttheisomersofthehydrocarbon,andobservehowmanydifferenthydrogenatomsareinthemolecule.
TheC3H7Xisacarbonchain,therearetwodifferenttypesofisomersC4H9X,andtherearefourisomers
C5H11X3carbonchain,thereare8isomers
Here,theunitarysubstituentsX,whichcanbeatoms,suchashalogenatoms,orradicals,suchas-oh,-nh2,-cho,-cooh,HCOO,etc.Therefore,therearefourtypesofbutyl-C4H9,anditcanbeconcludedthattherearefourisomersofbutanol,butylamine,glutaric,penicacidandbutylformate.
Theisomerismof3cyclichydrocarbons
Forexample,feiandanthraceneareisomersofisomers,andthestructureofthefifeissimpleanalysisofthestructureofphi,andachlorinesubstituteofthePhilippinesiscommon(B).
A.fourkindsofb.fivec.10kindsd.14kinds
Hint:
findtheaxisofsymmetryofthefifestructure,andtheanswerisobvious.
ThereareeightdifferentisomersofbenzeneinthemolecularformulaofC11H16
[parsing]analkylsubstitutedbenzene[c6h5-c5h11]canbethoughtofasahydrogeninaphenylinsteadofpentane,andthereare8isomers,sothereare8differentisomersofC11H16.
[3-2]therearefourpossibleisomersofanilinewith-c4h9,andtheirstructureissimplified
Tip:
turntheproblemintoahydrogeninbutane
Themolecularstructureoftheblue-alkanesisatotalof4typesofchloroplastinthesampleofthebluealkanes
Tip:
themolecularstructureissymmetricalwithblue"handle".
Thenumberofsubstituentsforsomehydrocarbonisoftengiven,andthestructureoftheanti-pushhydrocarbonmoleculeisdescribed.Forexample:
(1)therearefourtypesofalkanescontaininglessthan10carbons,andtherearefourdifferentones.Theyare:
2.
ThereisonlyonechloroplastintheknownolefinsC6H12,andthestructureoftheolefinsis
Theheterogeneityofthebinary(ortriples)ofthehydrocarbon
4.1orderedmethod(1move1)
Inordertosolveproblems,anorderlymethodshouldfollowcertaincluesandstepstoexploreawayofthinking.Orderlymethodwasappliedtosolvetheproblemofmultiplealternativesofhydrocarbonisomersstepsequenceis:
writeaheterogeneouscarbon,invariouscarbonframeinturnagaintomakeafirstfunctionalgroups,andthenmoveonthebasisofthesecondfunctionalgroup,andsoon,isamove.
Therearefourisomersofdichloropropane,andtheirstructureissimple
Thereisonlyonecarbonchain(notincludingthering).SoI'mgoingtohaveachlorineatomoncarbon1,andthenI'mgoingtomovethesecondonetotheone,two,three,threeisomers.Andthenwe'regoingtoputachlorineonthenumbertwocarbon,andthenthesecondchlorineisonlygoingtobeabletoconnecttocarbonnumbertwo,sowehavefourisomers.Inthecaseofthesolution,youshouldbec