大二上学期有机化学题库ch06

Chapter6Chapter6PagePagePAGE26ConsidertheS2reactionofbutylbromidewithOH-ion.NCHCHCHCHBr + OH- CHCHCHCHOH + Br-3 2 2 2 3 2 2 2Assumingnootherchanges,whateffectontheratewouldresultfromsimultaneouslydoublingtheconcentrationsofbothbutylbromideandOH-ion?Noeffect.Itwoulddoubletherate.Itwouldtripletherate.Itwouldincreasetheratefourtimes.ItwouldincreasetheratesixAns:Selecttheratelawforasecondorderreaction,RX+OH- ROH+X-.Rate=k[RX]Rate=k[RX][OH-]Rate=k[RX]2[OH-]Rate=k[RX][OH-]2Rate=k[RX]2Ans:Increasingthetemperatureofachemicalreactionusuallyincreasesgreatlytherateofthereaction. Theimportantreasonforthisisthatincreasingthetemperatureincreases:thecollisionfrequency.theprobabilityfactor.thefractionofcollisionswithenergygreaterthantheenergyofactivation.theamountofheatreleasedinthereaction.Ans:

.actTherateequationforanRate=k[RBr]Rate=k[I-]Rate=k[RBr][I-]Rate=k[RBr]2[I-]Rate=k[RBr][I-]2Ans:

1reactionofanalkylbromide(R-Br)withI-ionwouldbe:NConsidertheS1reactionoftert-butylchloridewithiodideion.N(CH)C–Cl + I- (CH)C–I + Cl-33 33Assumingnootherchanges,howwoulditaffecttherateifonesimultaneouslydoubledtheconcentrationoftert-butylchlorideandiodideion?NoeffectItwoulddoubletherate.Itwouldtripletherate.Itwouldquadrupletherate.ItwouldincreasetheratefiveAns:Whatwouldyouexpecttobethechieforganicproduct(s)whentert-butylbromidereactswithsodiumacetylide,i.e.,IIIIIIIVNoneofAns:Whatproduct(s)wouldyouexpecttoobtainfromthefollowingreaction?IIIAnequimolarmixtureofIandII.IIINoneofAns:Treating(CH)C-ClwithamixtureofHOandCHOHatroomtemperaturewouldyield:33 2 3CH=C(CH)2 32(CH)COH33(CH)COCH33 3AlloftheseNoneofAns:Themajorproductofthefollowingreactionwouldbe:IIIIIIIVAnequimolarmixtureofIandAns:Whichwouldbeformedinthefollowingreaction?IIIIIIIVAlloftheAns:Whichwouldbethemajorproductofthefollowingreaction?IIIIIIIVNoneoftheAns:12.Whenproductformedis:A)

(0.10mol)istreatedwith0.10molofNaCNindimethylsulfoxideat30C,theB)C)bothA)andD)E)Ans:Themajorproduct(s)ofthefollowingreactionis(are):IIIIIIIVEqualamountsofIandAns:Whatwouldbethemajorproductofthefollowingreaction?IIIIIIIVAnequimolarmixtureofIandAns:Whatwouldbethemajorproductofthefollowingreaction?IIIIIIIVAnequimolarmixtureofIandAns:Whatwouldbethemajorproductofthefollowingreaction?A)B)C)D)E)17.A)B)C)

IIIIIIIVEqualamountsofIandIIIAns:Youwanttosynthesize2-methyl-1-butenefrom2-chloro-2-methylbutane. WhichreagentwouldyouNaOH/HO2KOH/HO2CHONa/CHOH3 3CHCHONa/CHCHOH3 2 3 2(CH)COK/(CH)COH33 33Ans:18.A)B)C)

Yourtaskistoconvert2-chloropentaneinto1-pentene. WhichreagentswouldyouNaOH/HO2KOH/CHOH3CHONa/CHOH3 3CHCHONa/CHCHOH3 2 3 2(CH)COK/(CH)COH33 33Ans:Whentert-pentylchlorideundergoessolvolysisinaqueousethanolatroomtemperature,thereis/areformed:19.Whentert-pentylchlorideundergoessolvolysisinaqueousethanolatroomtemperature,thereis/areformed:A)B)332C)CHCH=C(CH332E)AlloftheseAns:20.A)

Reactionofsodiumethoxidewith1-bromopentaneat50Cyieldsprimarily:CHCHCHCH=CH3 2 2 2CHCHCH=CHCH3 2 3CHCHCHCHCH3 2 2 2 3CHCHCHCHCHOH3 2 2 2 2CHCHCHCHCHOCHCH3 2 2 2 2 2 3Ans:If0.10molofHSCHCHOHreactsat25C,sequentially,with0.20molofNaH,0.10molofCHCHBrandHO,2 2 3 2 2whichisthemajorproduct?HSCHCHOCHCH2 2 2 3CHCHSCHCHOH3 2 2 2CHCHSCHCHOCHCH3 2 2 2 2 3CH=CH2 2CHCH3 3Ans:When0.10molofICHCHCHCHClreactswith0.10molofNaOCHinCHOHat40C,themajorproductis:2 2 2 2 3 3CHOCHCHCHCHCl3 2 2 2 2CHOCHCHCHCHI3 2 2 2 2CHOCHCHCHCHOCH3 2 2 2 2 3CH=CHCHCHCl2 2 2CH=CHCHCHI2 2 2Ans:Ina60:40mixtureofethanolandwateratroomtemperaturearedissolved0.10molofCHCHCHOSOCHand3 2 2 2 30.10moleachofNaCl,NaI,NaFandNaBr. Whatistheprincipalproductofthesubsequentreaction?CHCHCHCl3 2 2CHCHCHI3 2 2CHCHCHF3 2 2CHCHCHBr3 2 2CHCHCHOCHCH3 2 2 2 3Ans:24.A)B)C)D)E)

S2reactionsofthetype,Nu- + RL Nu-R + L-,arefavored:Nwhentertiarysubstratesareused.byusingahighconcentrationofthenucleophile.byusingasolventofhighpolarity.bytheuseofweaknucleophiles.bynoneoftheabove.Ans:25.

Whichofthefollowingstatementsis(are)trueofS

1reactionsofalkylhalidesingeneral?NTherateofanS1reactiondependsontheconcentrationofthealkylhalide.NTherateofanS1reactiondependsontheconcentrationofthenucleophile.

Nreactionsofalkylhalidesarefavoredbypolarsolvents.NAnswersA)andC)onlyaretrue.AnswersA),B)andC)areAns:26.A)B)C)D)E)

S1reactionsofthetype,Nu- + RL NR + -,arefavored:Nwhentertiarysubstratesareused.byusingahighconcentrationofthenucleophile.whenL-isastrongbase.byuseofanon-polarsolvent.bynoneoftheabove.Ans:Whichofthefollowingstatementsis(are)trueofan

reactionof(R)-2-bromobutanewithhydroxideion?NDoublingthehydroxideionconcentrationwoulddoubletherateofthereaction. (Assumethatallotherconditionsareunchanged.)Thereactionwouldoccurwithinversionofconfiguration.Doublingtheconcentrationof(R)-2-bromobutanewoulddoubletherateofthereaction. (Assumethatallexperimentalconditionsareunchanged.)AlloftheaboveNoneoftheAns:S1reactionsofthefollowingtype,NNu:- + R-X R-Nu + :X-arefavored:bytheuseoftertiarysubstrates(asopposedtoprimaryorsecondarysubstrates).byincreasingtheconcentrationofthenucleophile.byincreasingthepolarityofthesolvent.byuseofaweaknucleophile.bymorethanoneoftheAns:29.A)

Atruestatementaboutthetransitionstate(s)ofanSthetwotransitionstatesareofunequalenergy.

2reactionis:Nthetransitionstatesprecedeandfollowanunstablereactionintermediate.thesingletransitionstaterepresentsthepointofmaximumfreeenergyofthereaction.existenceofthistransitionstateimpliesanexothermicreaction.thetransitionstatewillalwayshaveanetchargeofAns:30.A)B)C)D)E)

Eliminationreactionsarefavoredovernucleophilicsubstitutionreactions:athightemperatures.whentert-butoxideionisused.when3alkylhalidesareusedassubstrates.whennucleophilesareusedwhicharestrongbasesandthesubstrateisa2alkylhalide.inallofthesecases.Ans:ForthenucleophilicsubstitutionreactionBr- + CHCHCHCHCHOH 3 2 2 2 2tobesuccessful,itisnecessarythat:thereactionbecarriedoutathightemperature.alargeexcessofBr-beused.thereactionbecarriedoutatlowpH.apolaraproticsolventbeused.UndernoneoftheseconditionscanthissynthesisbeAns:32.A)B)C)D)E)33.

Thehybridizationstateofthechargedcarboninacarbocationissp4sp3sp2spsAns:Theporbitalofamethylcation,CH+,containshowmanyelectrons?312340Ans:ConsideringtherelativesolvationofreactantsandthetransitionstatesofSN

reactionsofthesereactants,predictwhichgeneraltypeofreactionwouldbemostfavoredbytheuseofapolarsolvent.A)Y: + RX RY+ + X:-B)Y:- + RX RY + X:-C)Y: + RX+ RY+ + X:D)Y:- + RX+ RY + X:E)RX+ R+ + Ans:Whichisnotapolaraproticsolvent?35.Whichisnotapolaraproticsolvent?A)3B)CHC)3D)E)CHOH3Ans:36.A)B)C)D)E)

37.A)B)C)D)E)

Identifythenucleophileinthefollowingreaction.2H2O + RX ¾¾¾¾® ROH + H3O+ + X-H3O+ROHH2ORXAns:Anincreaseinthekineticenergyofreactingmoleculesresultsin:adecreaseinreactionrate.anincreaseintheprobabilityfactor.adecreaseintheprobabilityfactor.anincreaseinthereactionrate.nochanges.Ans:Identifytheleavinggroupinthefollowingreaction.CHS-Na+ + CHCHI CHSCHCH + Na+ + I-65 3 2 65 2 3CHS-65Na+CHCHI3 2CHSCHCH65 2 3I-Ans:39.A)B)C)D)

Whichistheweakestnucleophileinpolaraproticsolvents?I-Br-Cl-F-Ans:40.A)B)C)D)

Whichofthefollowingisthepoorestleavinggroup?H-2Cl-HO2E)Ans:41.A)B)C)D)E)Ans:

Whichofthefollowingisnotanucleophile?HO2CHO-3NH3NH+4Allarenucleophiles.42.A)B)C)D)E)43.A)B)C)D)

Whichionisthestrongestnucleophileinaqueoussolution?F-Cl-Br-I-AlloftheseareequallyAns:WhichofthefollowingisnotagoodleavingOH-Cl-Br-E)Ans:Identifytheleavinggroupinthefollowingreaction:CHOH3CHOH+3 2CHOCH3 3HO2NoneofAns:45.A)B)C)

SelectthestrongestnucleophileforanSHO2ROHRCO-2

2reaction.NOH-RO-Ans:Whichisthestrongestnucleophile?OH-3 2CHCHC)3 2CHCHOH3 2HO2Ans:47.A)B)C)D)E)

WhichofthefollowingisnotagoodleavingCl-Br-I-3CHO-3Ans:48.WhichisthemostreactivenucleophileinDMF,i.e.,in ?F-Cl-Br-I-Theyareallequallyreactive.Ans:Whichofthesespecies,actinginaproticsolvent,exhibitsgreaternucleophilicactivitythanexpectedonthebasisitsbasicity?OH-CHO-3SH-Cl-HO2Ans:50.A)B)C)D)E)

Therelativenucleophilicitiesofspeciesdonotnecessarilyparalleltherelativebasicitiesofthesamespeciesbecause:notallnucleophilesarebases,andviceversa.experimentalmeasurementsofsufficientaccuracyarenotavailabletomakethecomparisons.nucleophilicityisathermodynamicmatter;basicityisamatterofkinetics.basicityisathermodynamicmatter;nucleophilicityisamatterofkinetics.Actually,therelativevaluesdoparalleloneanother.Ans:Ambidentnucleophilesareoneswhichcanreactwithasubstrateateitheroftwonucleophilicsites. Whichoffollowingisnotanambidentnucleophile?A)B)C)D)E)52.A)B)C)D)E)53.A)

IIIIIIIVVAns:Whichionisthestrongestnucleophileinanaproticsolventsuchasdimethylsulfoxide?I-Br-Cl-F-Theseareallequal.Ans:Whichofthefollowingisasubstitutionreaction?CHCHCl + I- CHCHI + Cl-3 2 3 2CHCH + Cl CHCHCl + HCl3 3 2 3 2CHCHCl + OH- CH=CH + HO + Cl-3 2 2 2 2MorethanoneoftheaboveNoneoftheAns:Whichofthefollowingisasubstitutionreaction?CHCH + Br CHCHBr + HBr3 3 2 3 2CHCHBr + OH- CH=CH + HO + Br-3 2 2 2 2CHCHBr + OH- CHCHOH + Br-3 2 3 2D)E)55.

MorethanoneoftheaboveNoneoftheaboveAns:Heatingtert-butylchloridewith1.0MNaOHinamixtureofwaterandmethanolwouldyieldmainly:(CH)COHthroughan33

reaction.N(CH)COCHthroughanS1reaction.33 3 N(CH)COHthroughan33

reaction.N(CH)

throughanS

2reaction.33CH=C(CH

NthroughanE2reaction.2 32Ans:56.A)B)C)D)E)

S2reactionsofthetype,Nu- + R–L Nu–R + L-arefavored:Nwhentertiarysubstratesareused.whenprimarysubstratesareused.whentheleavinggroup,L-,isastrongbase.bymorethanoneoftheabove.bynoneoftheabove.Ans:Selectthepotentialenergydiagramthatrepresentsanexothermic(exergonic)reaction.IIIIIIIVVAns:58.A)

TheHammond-Lefflerpostulatewhenappliedtonucleophilicsubstitutionsandeliminationreactionsstatesthat:anegatively-chargednucleophileisstrongerthanitsconjugateacid.polaraproticsolventsstronglyacceleratetherateof

2processes.Nbimolecularnucleophilicsubstitutionsare2nd.orderkinetically.thetransitionstateforanendergonicreactionstep(oneaccompaniedbyanincreaseinfreeenergy)resemblesproductofthatstep.eliminationreactionswillalwayscompetewithnucleophilicsubstitutionreactions.Ans:59.A)B)C)D)E)

Whichwillbetrueforanyactualorpotentialnucleophilicsubstitutionreaction?Hispositive.Hisnegative.G‡ispositive.Gispositive.Gisnegative.Ans:ForthetypicalS2reactionNY- + RX RY + X-itcanbepredictedthatS‡willbe:positive.zero.negative.eitherpositiveornegative.unpredictableastoalgebraicAns:Thereaction,hasthefollowingthermodynamicvaluesat27ºC:H=-75.3kJmol-1;S=54.4JK-1mol-1. WhatisthevalueofGforthisreaction?-73.8kJmol-1-76.8kJmol-1-59.0kJmol-1+91.6kJmol-1-91.6kJAns:Increasingtheconcentrationofeitherofthereactantsofanreasonforthisisthatincreasingtheconcentrationincreases:thecollisionfrequency.theorientationfactor.thefractionofcollisionswithenergygreaterthanE

2reactionincreasestherateofthereaction. TheNtheenergyofactivation.theamountofheatreleasedinthereaction.Ans:

act.63.A)B)

Anincreaseinthekineticenergyofreactingmoleculesincreases:thecollisionfrequency.thefractionofmoleculeswithproperorientation.thefractionofmoleculeswithenergygreaterthanMorethanoneoftheaboveNoneoftheAns:

.act64.A)B)C)D)E)

Thedifferenceinthebondenergiesofreactantsandthetransitionstateofareactionisdesignatedbythenotation:HH‡GG‡S‡Ans:65.A)B)C)D)E)

Whichisatruestatementconcerningthetransitionstateoftherate-determiningstepofanSStructurally,itcloselyresemblesthecarbocationintermediate.Bothcovalentbond-breakingandbond-makingareoccurring.Formationofthetransitionstateisanexothermicreaction.Necessarily,thetransitionstatehaszerochargeoverall.MorethanoneoftheaboveAns:

1reaction?NWhichofthefollowingreactionsproceedswithinversionofconfigurationatthecarbonbearingtheleavinggroup?S2NS1NE2E1AllofAns:Considerthesubstitutionreactionthattakesplacewhen(R)-3-bromo-3-methylhexaneistreatedwithmethanol.Whichofthefollowingwouldbetrue?Thereactionwouldtakeplaceonlywithinversionofconfigurationatthestereogeniccenter.Thereactionwouldtakeplaceonlywithretentionofconfigurationatthestereogeniccenter.Thereactionwouldtakeplacewithracemization.Noreactionwouldtakeplace.ThealkylhalidedoesnotpossessastereogenicAns:68.A)B)C)D)E)

WhichalkylhalidewouldyouexpecttoundergoS(CH)CI33(CH)CBr33(CH)CCl33(CH)CF33Theywouldallreactatthesamerate.Ans:

hydrolysismostrapidly?NWhichofthefollowingpentylhalideswouldyouexpecttogivethehighestyieldofsubstitutionproductconditionsforabimolecularreactionwithethoxideion?3 2 2 2 2A)CHCHCHCHCHB)3 2 2 2 2C)D)E)Ans:Whichalkylhalidewouldgivethehighestyieldoftheeliminationproductwhentreatedwithsodiumethoxideethanol?CHCHBr3 2CHCHCHBr3 2 23 2 2 2CHCHCHCHD)3 2 2 2E)Ans:Whichofthefollowingalkylhalideswouldyouexpecttobemostreactiveinaunimolecularreaction?611 2 2 2A)C611 2 2 2C)D)E)Ans:

CHCHCHBr72.

WhichS

reactionwilloccurmostrapidlyinamixtureofwaterandethanol?NI- + CHCH–Br CHCH–I + Br-3 2 3 2I- + CHCH–Cl CHCH–I + Cl-3 2 3 2I- + CHCH–F CHCH–I + F-3 2 3 2Br- + CHCH–Cl CHCH–Br + Cl-3 2 3 2Br- + CHCH–F CHCH–Br +F-3 2 3 2Ans:Which

2reactionwilloccurmostrapidlyinaqueousacetonesolution? AssumeconcentrationsandtemperatureNarethesameineachinstance.HO- + CH-Cl CHOH + Cl-3 3HO- + CHCH-Cl CHCHOH + Cl-3 2 3 2HO- + (CH)CH-Cl (CH)CHOH + Cl-32 32HO- + (CH)C-Cl (CH)COH + Cl-33 33HO- + (CH)CCH-Cl (CH)CCHOH + Cl-Ans:

33 2

33 274.

WhichS

2reactionwilloccurmostrapidlyinaqueousacetonesolution?NHO- + CH-F CHOH + F-3 3HO- + CH-Cl CHOH + Cl-3 3HO- + CH-Br CHOH +Br-3 3HO- + CH-I CHOH + I-3 3Theywillalloccuratthesamerate.Ans:Whichalkylhalidewouldyouexpecttoundergoan3 2 2 2 2A)CHCHCHCHCHB)3 2 2 2 2C)D)E)Ans:

2reactionmostslowly?NWhichalkylhalidewouldyouexpecttoreactmostrapidlyinan3 2 2 2 2A)CHCHCHCHCHB)3 2 2 2 2C)D)E)Ans:

reaction?NNWhichA)NB)C)D)E)Ans:Which

reactionwouldtakeplacemostrapidly?2reactionwouldbeexpectedtooccurmostrapidly?NCHCHF + CN-3 2CHCHCl + CN-3 2CHCHBr + CN-3 2CHCHI + CN-3 2CHCHOH + CN-3 2Ans:Whichreactionwouldbeexpectedtooccurmostslowly?CHCHF + CN-3 2CHCHCl + CN-3 2CHCHBr + CN-3 2CHCHI + CN-3 2CHCHOH + CN-3 2Ans:Whichnucleophilicsubstitutionreactionwouldbeunlikelytooccur?Br- + CH–OH+ CH–Br + HO3 2 3 2NH + CH–OH+ CH–NH+ + HO3 3 2 3 3 2I- + CH–Cl CH–I + Cl-3 3MorethanoneoftheaboveNoneoftheAns:Whichnucleophilicsubstitutionreactionwouldbeunlikelytooccur?HO- + CHCH–I CHCH–OH + I-3 2 3 2I- + CHCH–H CHCH–I + H-3 2 3 2CHS-+ CH–Br CH

+ Br-3 3 3 3AlloftheaboveNoneoftheAns:Whichalkylhalidewouldbethemostreactiveinan3 2 2 2A)CHCHCHCHB)3 2 2 2C)D)E)Ans:

2reaction?N83.A)B)C)D)E)

Whichalkylhalidewouldyouexpecttoreactmostslowlywhenheatedinaqueoussolution?(CH)C-F33(CH)C-Cl33(CH)C-Br33(CH)C-I33Theywouldallreactatthesamerate.Ans:Which

2reactionwouldyouexpecttotakeplacemostrapidly? AssumetheconcentrationsofthereactantsandNthetemperaturearethesameineachinstance:3333CHS- + CH–I 33333333C)CHO- + CH–I 3333E)CHS- + CH–Cl CH

+ I-+ I-+ Cl-3 3 3 3Ans:85.A)

WhichnucleophilicsubstitutionreactionisnotlikelytoI- + CHCH–Cl CHCH–I + Cl-3 2 3 2I- + CHCH–Br CHCH–I + Br-3 2 3 2I- + CHCH–OH CHCH–I + OH-3 2 3 2CHO- + CHCH–Br CHCH

+ Br-3 3 2 3 2 3OH- + CHCH–Cl