che 31 organic chemistry：车31有机化学

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1、CHE31:OrganicChemistryNameTest1March12,19991.Multiplechoice(2pointseach)Whichofthefollowingisnottrueaboutaromaticcompounds?(a)Theyhave4n+2pelectrons.(b)Theymusthaveacyclicarrangementoftheatomsinthearomaticgroup.(c)Theycannotbecharged.(d)Allatomsintheri

2、ngmustbesp2hybridized.(e)Thearomaticringisalwaysplanar.Whichisthebestmethodtoaccomplishthetransformationshown?(a)(1)Mg,ether;(2)CH3CH2CHO;(3)H3O+;(4)NaBH4(b)(1)HOCH2CH2OH,H+;(2)Mg,ether;(3)CH3CH2CHO;(4)H3O+;(5)NaBH4(c)(1)TMSCl;(2)Mg,ether;(3)CH3CH2CHO;

3、(4)H3O+;(5)NaBH4(d)(1)LiAlH4;(2)H3O+;(3)HOCH2CH2OH,H+;(4)Mg,ether;(5)CH3CH2CHOWhichisthebestmethodtopreparetheethershown?Whichofthefollowingspeciesisnotaromatic?Whichisthebestmethodtoaccomplishthetransformationshown?(a)(1)Mg,ether;(2)CH3CH2CHO;(3)H3O+;

4、(4)PCC(b)(1)TMSCl;(2)Mg,ether;(3)CH3CH2CHO;(4)H3O+;(5)Jonesreagent(c)(1)TMSCl;(2)Mg,ether;(3)CH3CH2CHO;(4)H3O+;(5)PCC(d)(1)Mg,ether;(2)CH3CH2CHO;(3)H3O+;(4)Jonesreagent2.Proposeamechanismtoaccountfortheacidcatalyzedhydrolysisoftheimineshownbelow.Usearr

5、owstoshowtheflowofelectronsandshoweverystep!(20points)3.Providethemajorproductsforthefollowingreactions,indicatingstereochemistrywhererelevant.(4pointseach)4.Dotwooutofthefollowingthreesynthesisproblems.(10pointseach)(a)(b)(c)5.ElectrophilicadditionofB

6、r2toisopreneyieldsthefollowingproductmixture.Ofthe1,2-additionproducts,explainwhy3,4-dibromo-3-methyl-1-butene(21%)predominatesover3,4-dibromo-2-methyl-1-butene(3%).Whyisthemajorproducttheoneshown?Explain,usingenergyleveldiagrams.(10points)6.Astudentwa

7、sdirectedtopurifymaleicanhydride(shownbelow)byrecrystallizingitfromcyclopentaneandsheusedcyclopentadienebymistake.Showthereactionthatislikelytohappeninherheatedmixture.(10points)7.Anisole(C6H5OCH3)wasreactedunderconditionsthatwouldcreatemethylcationsas

8、anelectrophile.Analyzethe1HNMRandIRspectraonthenextpage,anddeterminethestructureofthemajorproductfromthisreaction.Youmayfindthetablesonthefollowingpageshelpfulinyourassignmentofthepeaks.(10points)