Post on 13-Mar-2022
Chemistry 130, Midterm Exam 2 Instructor: Bergdahl
Spring 2019
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PartA.1‐25Questions.Eachcorrectansweris3points.(Part1max75points)1)ConstitutionalisomersareA)Moleculeswiththesamemolecularformulaandthesameconnectivitybutadifferentspatialarrangementofatomsinthree‐dimensionalspaceB)MoleculeswiththesameconnectivitybutadifferentmolecularformulaC)MoleculeswiththesamemolecularformulabutdifferentconnectivityoftheatomsD)Moleculesthathaveidenticalchemicalproperties2)WhichalkanemolecularformulahastheleastnumberofconstitutionalisomersA)C2H6B)C4H10
C)C10H22
D)C6H14
3)Whichofthefollowingcompoundsis3‐methylheptane
4)pleaseprovidetheIUPACnameofthemoleculeshownbelow
A)5‐MethylheptaneB)3‐MethyloctaneC)2‐ethylheptaneD)2‐methylhexane5)ProvidetheIUPACnameofthemoleculeshownbelow
A)2,2‐dimethyl‐5‐ethyloctaneB)3,3‐dimethyl‐6‐ethylnonaneC)6‐ethyl‐3,3‐dimethylnonaneD)2,2‐dimethyl‐5‐propylnonane
A)
B)
C)
D)
6)PleaseprovidetheIUPACnameofthemoleculeshownbelow
A)methylcyclohexaneB)methylhexaneC)methylcycloheptaneD)cyclohexylmethyl7)InthehighestenergyconformationofbutanetheC‐Cbondsareinthe_______conformation.Butane: A)StaggeredB)eclipsedC)Gauche8)Inthebelowrepresentationofbutanethe2,3C‐Cbondisinthe________conformation.
A)StaggeredB)eclipsedC)Gauche9)Themoststablecyclohexaneconformationiscalledthe________conformationA)BoatB)TwistBoatC)HalfChairDChair10)Whichofthefollowingisthelowestenergyconformationofmethylcyclohexane
H3C CH3
H HH H
CH3CH3A)
B)
C)
D)CH3
CH3
CH3
11)Whichofthefollowingstructuresistrans‐1,4dimethylcyclohexane
12)Whichofthefollowing6carbonconstitutionalisomerswillhavethelowestboilingpoint
13)AccordingtoIUPACrulesthebelowalkeneis
A)CisB)TransC)ED)ZE)Neither14)Thenameofthealkenefrom13(above)isA)E‐1‐bromo‐1‐chloro‐1‐propeneB)Z‐1‐bromo‐1‐chloro‐1‐propeneA)E‐1‐chloro‐1‐bromo‐1‐propeneD)E‐2‐chloro‐3‐butene
Me
Me
Me
Me
Me
Me
A)
B)
C)
Me
D)
Me
E) A, B&C
A) C)
B)D)
15)WhichofthefollowingmoleculesisE‐5‐ethyl‐4‐methyl‐3‐octene
16)Whichofthefollowinghydrocarbonsisleastacidic?
17)Why?A)TheconjugatebaseislessstabilizedbecausetheorbitalthathousesthelonepairhasmorePcharacter.B)TheconjugatebaseisstabilizedbecausetheorbitalthathousesthelonepairofelectronshasmoreScharacter.C)Becausetheatomwiththenegativechargeislesselectronegative18)Predicttheproductofthebelowreaction
19)Thekeyintermediateofthereactionaboveis
20)Yougetthe‘markovnikov’regiochemistry(connectivity)ofyourproductbecauseA)ThereactionproceedsviatheleaststablecarbocationB)AlkenesarebasicC)Thereactiongoesthroughviathemorestablecarbocation
21)Theleaststablecarbocationbelowis
22)ThehybridizationofcarbocationsisA)sp3A)sp2A)sp
23)Predicttheproductofthebelowreaction
24)The2ndstepofthemechanismoftheabovereactionis
25)Predicttheproductofthebelowreaction
PartB.Shortanswerquestions,26‐32,eachproblemisworth5‐12points(total61points)Problem26.(9p)
Write IUPAC names for the following hydrocarbons: (a)
(b)
(c)
Problem27.(12p) A) Following is the structure of Germacrene A, a hydrocarbon synthesized in plants
and studied for its insecticidal properties. Classify each of the sp3 hybridized carbons on Germacrene A as 1°, 2°, 3°, or 4° (9p)
B) Classify each alkene as E or Z respectively (3p)
Problem 28.Use valence-shell electron-pair repulsion (VSEPR) to predict all bond angles about each of the following highlighted carbon atoms. (8p)
(a)
(b)
(c)
(d)
Problem 29. Which alkenes can exist as pairs of E/Z isomers?
For each alkene that does, draw both isomers. (6p)
(a) CH2═CHBr (b) CH3CH═CHBr (c) (CH3)2C═CHCH3 (d) (CH3)2CHCH═CHCH3
Problem 30. In many parts of South America, extracts of the leaves and twigs of Montanoa tomentosa are used as a contraceptive, to stimulate menstruation, to facilitate labor, and as an abortifacient. The compound responsible for these effects is zoapatanol:
(a) Specify the configuration about the carbon-carbon double bond to the seven-membered ring, according to the E,Z system. (3p) (b) How many cis-trans isomers are possible for zoapatanol? Consider the possibilities for cis-trans isomerism in cyclic compounds and about carbon-carbon double bonds. (2p)
Problem31.Draw a structural formula for an alkene with the indicated molecular formula that gives the
compound shown as the major(!) product. Note that more than one alkene may give the same compound as the major product. (9p)
(a)
(b)
(c)
Problem32.Complete these equations by predicting the major product formed in each reaction. (12p)
(a)
(b)
(c)
(d)
(e)
(f)