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32 Cards in this Set

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1) What is the hybridization of the central carbon of allene (1,2-propadiene)?
A) sp
B) sp2
C) sp3
D) p
E) none of the above
A) sp
2) What descriptive term is applied to the type of diene represented by 2,4-hexadiene?
A) conjugated diene
B) cumulated diene
C) isolated diene
D) alkynyl diene
E) none of the above
A) conjugated diene
3) What descriptive term is applied to the type of diene represented by 1,5-octadiene?
A) conjugated diene
B) cumulated diene
C) isolated diene
D) alkynyl diene
E) none of the above
C) isolated diene
4) Which of the following molecules is chiral?
A) 1,2-pentadiene
B) 2,3-pentadiene
C) 2-methyl-2,3-pentadiene
D) 2-chloro-4-methyl-2,3-pentadiene
E) none of the above molecules is chiral
B) 2,3-pentadiene
5) Which of the following compounds has the most negative heat of hydrogenation?
A) 1,4-hexadiene
B) 1,5-hexadiene
C) 1,2-hexadiene
D) 1,3-hexadiene
E) hex-1-ene
C) 1,2-hexadiene
6) Which comopund has the smallest heat of hydrogenation?
A) 5-methyl-1,2-hexadiene
B) (E)-5-methyl-1,3-hexadiene
C) 5-methyl-1,4-hexadiene
D) 2-methyl-1,5-hexadiene
E) (E)-2-methyl-2,4-hexadiene
E) (E)-2-methyl-2,4-hexadiene
7) Rank the following dienes in order of increasing stability: trans-1,3-pentadiene, cis-1,3-pentadiene, 1,4-pentadiene, and 1,2-pentadiene.
A) 1,4-pentadiene < 1,2-pentadiene < cis-1,3-pentadiene < trans-1,3-pentadiene
B) 1,2-pentadiene < 1,4-pentadiene < cis-1,3-pentadiene < trans-1,3-pentadiene
C) 1,4-pentadiene < cis-1,3-pentadiene < 1,2-pentadiene < trans-1,3-pentadiene
D) 1,2-pentadiene < cis-1,3-pentadiene < 1,4-pentadiene < trans-1,3-pentadiene
B) 1,2-pentadiene < 1,4-pentadiene < cis-1,3-pentadiene < trans-1,3-pentadiene
8) When the relative energies of the s-cis and s-trans conformers of 1,3-butadiene are compared, one finds:
A) that the s-cis conformer is lower in energy than the s-trans.
B) that the s-trans conformer is lower in energy than the s-cis.
C) that the two conformers are of equal energy.
B) that the s-trans conformer is lower in energy than the s-cis.
9) How many nodes, other than the node coincident with the molecular plane, are found in the highest energy π MO of 1,3-butadiene?
A) 0
B) 1
C) 2
D) 3
E) none of the above
D) 3
11) When (S)-3-bromopent-1-ene is heated in water, which of the following compounds is not produced?
A) (S)-pent-1-en-3-ol
B) (R)-pent-1-en-3-ol
C) pent-4-en-1-ol
D) (E)-pent-2-en-1-ol
E) (Z)-pent-2-en-1-ol
C) pent-4-en-1-ol
12) Which of the following alkyl halides yields the most stable carbocation intermediate during solvolysis in hot ethanol?
A) methyl iodide
B) (S)-2-bromopentane
C) (R)-2-bromopentane
D) (S)-3-bromopent-1-ene
E) 1-chlorobutane
D) (S)-3-bromopent-1-ene
14) What is the major organic product which results when cycloheptene is irradiated in the presence of N-bromosuccinimide?
A) 1-bromocycloheptene
B) 2-bromocycloheptene
C) 1,2-dibromocycloheptane
D) 3-bromocycloheptene
E) 4-bromocycloheptene
D) 3-bromocycloheptene
15) Including all possible stereoisomeric forms, how many distinct allylic bromides could be produced when 2-methylpent-1-ene is treated with NBS under irradiation by a sunlamp?
A) 2
B) 3
C) 4
D) 5
E) 6
D) 5
16) In the allyl radical, which π molecular orbital is singly occupied?
A) The bonding π molecular orbital.
B) The nonbonding π molecular orbital.
C) The antibonding π molecular orbital.
D) None of the above.
B) The nonbonding π molecular orbital.
17) How many electrons are present in the nonbonding π molecular orbital of the allyl cation?
A) 0
B) 1
C) 2
D) 3
E) 4
A) 0
18) How many electrons are present in the nonbonding π molecular orbital of the allyl cation?
A) 0
B) 1
C) 2
D) 3
E) 4
A) 0
19) How many electrons populate the π molecular orbitals of the allyl radical?
A) 0
B) 1
C) 2
D) 3
E) 4
D) 3
20) Which substrate would react most rapidly in an SN2 reaction?
A) CH3CH2CH=CHCH2Br
B) BrCH2CH2CH=CHCH3
C) CH3CHBrCH=CH2CH3
D) CH3CH2CH2CH=CHBr
A) CH3CH2CH=CHCH2Br
21) Which of the following terms best describes a Diels-Alder reaction?
A) a [4+2] cycloaddition
B) a [2+2] cycloaddition
C) a sigmatropic rearrangement
D) a 1,3-dipolar cycloaddition
E) a substitution reaction
A) a [4+2] cycloaddition
22) When 1,3-butadiene reacts with CH2=CHCN, which of the terms below best describes the product mixture?
A) a mixture of two diastereomers
B) a single compound
C) a racemic mixture
D) optically active
E) a mixture of bicyclic compounds
C) a racemic mixture
23) The Diels-Alder reaction is a concerted reaction; this means:
A) a mixture of endo and exo products are formed.
B) all bond making and bond breaking occurs simultaneously.
C) the products contain rings.
D) the reaction follows Markovnikov's rule.
E) the reaction is highly endothermic.
B) all bond making and bond breaking occurs simultaneously.
24) Which of the following compounds is the most reactive dienophile in a Diels-Alder reaction with 1,3-butadiene?
A) CH2=CHOCH3
B) CH2=CHCHO
C) CH3CH=CHCH3
D) (CH3)2C=CH2
E) CH2=CH2
B) CH2=CHCHO
26) Absorption of UV-visible energy by a molecule results in:
A) vibrational transitions
B) electronic transitions
C) rotational transitions
D) nuclear transitions
E) none of the above
B) electronic transitions
27) Which of the following compounds absorbs the longest wavelength of UV-visible light?
A) (E)-but-2-ene
B) (Z)-but-2-ene
C) hex-1-ene
D) (Z)-1,3-hexadiene
E) (E)-1,3,5-hexatriene
E) (E)-1,3,5-hexatriene
28) UV spectroscopy measures the energy required to promote an electron from the __________ molecular orbital to the __________ molecular orbital.
A) highest occupied, lowest unoccupied
B) lowest occupied, lowest unoccupied
C) lowest occupied, highest unoccupied
D) highest occupied, highest unoccupied
E) None of the above
A) highest occupied, lowest unoccupied
29) In the UV-visible spectrum of (E)-1,3,5-hexatriene, the lowest energy absorption corresponds to:
A) a σ to π transition.
B) a σ to π* transition.
C) a π to σ* transition.
D) a σ to σ* transition.
E) a π to π* transition.
E) a π to π* transition
30) How many nodes, other than the node coincident with the molecular plane, are present in the HOMO of 1,3,5-hexatriene?
A) 1
B) 2
C) 3
D) 4
E) 5
B) 2
31) How many nodes, other than the node coincident with the molecular plane, are present in the LUMO of 1,3,5-hexatriene?
A) 1
B) 2
C) 3
D) 4
E) 5
C) 3
10) How many molecular orbitals are needed to represent the conjugated pi system of β-carotene?
A) 1
B) 10
C) 11
D) 20
E) 22
E) 22
25) According to the 1,3-butadiene structure below, which positions would be best to place methoxy groups to yield the most reactive dimethoxy-1,3-butadiene isomer in the Diels-Alder reaction?
A) c and d
B) a and c
C) b and c
D) a and d
E) a and f
D) a and d
32) Which sequence correctly ranks the following conjugated systems in order of increasing UV 8max absorption values?
A) 1 - 2 - 3
B) 2 - 1 - 3
C) 2 - 3 - 1
D) 3 - 1 - 2
E) 3 - 2 - 1
C) 2 - 3 - 1
13) When 1 mole of anhydrous HCl is reacted with excess 1,3-pentadiene, both the 1,2 and the 1,4-addition products are formed. Which of the following structures shown below is the least likely to be one of these products? (Note: When a chiral carbon is formed in this reaction a racemic mixture results, only one of the two possible enantiomers is shown.)
D