2) Atoms with the same number of protons but different numbers of

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Organic Chemistry, 6e (Wade)
Chapter 1: Introduction and Review
4) Draw the shape of a 2p orbital.
Answer:
6) An oxygen atom has __________ valence electrons.
Answer: 6
Diff: 1
10) Draw a correct Lewis structure for acetonitrile, CH3CN.
Answer:
12) Covalent bonds may be polar or nonpolar. What property of the atoms forming a given bond determines this?
Answer: Electronegativity
13) The compound methylamine, CH3NH2, contains a C–N bond. In this bond, which of the following best
describes the charge on the carbon atom?
A) +1
B) slightly positive
C) uncharged
D) slightly negative
E) -1
Answer: B
16) Which of the following choices represent(s) a pair of resonance forms?
A)
B)
C)
D) both A and C
E) both B and C
Answer: E
27) Write a completed equation for the acid-base pair shown below.
HCN + NaOH →
Answer: HCN + NaOH → NaCN + H2O
30) Methanesulfonic acid, CH3SO3H, has a pKa of -7 while ethanol, CH3CH2OH, has a pKa of 15.9. Which is the
stronger acid and what accounts for this large difference in relative acidity?
Answer: Methanesulfonic acid is the stronger acid. The lower the pKa, the stronger the acid. A lower pKa is
associated with a larger Ka which signifies greater dissociation. The large relative difference in acidity in this case
can be most easily seen by gauging the relative basicities of the conjugate bases. The weaker the base, the stronger
the corresponding conjugate acid. Methanesulfonate, CH3SO3-, is considerably stabilized by resonance
delocalization which is not found in ethoxide, CH3CH2O-. This effect greatly reduces the basicity of
methanesulfonate relative to ethoxide.
31) Would you predict trifluoromethanesulfonic acid, CF3SO3H, to be a stronger or weaker acid than
methanesulfonic acid, CH3SO3H? Explain your reasoning.
Answer: Trifluoromethanesulfonic acid is a stronger acid. Compare the strengths of the conjugate bases and
remember that the weaker the base, the stronger the conjugate acid. Both bases are stabilized by resonance, but in
the case of the trifluoro derivative, the presence of the highly electronegative fluorine atoms serves to delocalize the
negative charge to an even greater extent. This additional delocalization makes trifluoromethanesulfonate a weaker
base.
42) Consider the species CH3O-, NH2-, and CH3COO-. Rank these ions in order of increasing basicity, and explain
your rationale.
Answer: CH3COO- < CH3O- < NH2The first factor to consider is the nature of the atom which bears the negative charge. The more electronegative the
atom that bears the negative charge, the more stable the anion. Stable anions are less reactive and are hence weaker
bases. Since O is more electronegative than N, the NH2- is the strongest base in the set. In the remaining two
species, the negative charge is on the O, but in the case of CH3COO-, the negative charge is also delocalized by
resonance.
49) Draw the important resonance forms for the structure shown below.
Answer:
3) When orbitals on different atoms interact, __________ are produced.
Answer: molecular orbitals
11) Which of the following statements about π molecular orbitals is/are correct?
A) π molecular orbitals are cylindrically symmetric.
B) Most of the electron density in a π molecular orbital is centered above and below the internuclear axis.
C) When two atoms are connected by a double bond, both of these bonds are π bonds.
D) Both statements B and C are correct.
2
E) Statements A, B, and C are all correct.
Answer: B
17) Structures which differ only in rotations about a single bond are called __________.
Answer: Conformations
Diff: 2
21) Choose the correct hybridization for the atom indicated in the molecule below.
A) sp
B) sp2
C) sp3
D) none of the above
Answer: B
26) The structure of vitamin C is shown below. Which one of the following statements concerning this structure is
not correct?
A) The molecule contains 2 pi bonds.
B) The molecule contains 1 sp2 hybridized oxygen atom.
C) The molecule contains 3 sp2 hybridized carbon atoms.
D) The molecule can be classified as an aldehyde.
E) The molecule contains more than one hydroxyl group.
Answer: D
32) Which of the molecules below has the higher boiling point? Briefly explain your choice.
(CH3)3N or CH3CH2CH2NH2
Answer: CH3CH2CH2NH2 has the higher boiling point since it is capable of intermolecular hydrogen bonding.
Diff: 3
34) Would you expect sodium chloride (NaCl) to be highly soluble in the organic solvent hexane
(CH3CH2CH2CH2CH2CH3)? Briefly explain your answer.
Answer: One would not expect NaCl to be highly soluble in hexane. NaCl is an ionic solid (i.e., a very polar
material) while hexane is nonpolar. Nopolar solvent molecules do not solvate ions well. The attractions of
oppositely charged ions to each other are vastly greater than the weak attractions of the ions for the solvent.
Diff: 2
8) Provide an acceptable name for the alkane shown below.
3
Answer: 2,5-dimethylheptane
10) Provide an acceptable name for the alkane shown below.
Answer: 4-isopropyldecane or 4-(1-methylethyl)decane
11) Provide an acceptable name for the alkane shown below.
Answer: 3-ethyl-7-methyl-5-propylnonane
22) Why are alkanes described as hydrophobic?
Answer: Alkanes are nonpolar and as such they do not dissolve to any appreciable extent in water.
25) Consider the three isomeric alkanes n-hexane, 2,3-dimethylbutane, and 2-methylpentane. Which of the
following correctly lists these compounds in order of increasing boiling point?
A) 2,3-dimethylbutane < 2-methylpentane < n-hexane
B) 2-methylpentane < n-hexane < 2,3-dimethylbutane
C) 2-methylpentane < 2,3-dimethylbutane < n-hexane
D) n-hexane < 2-methylpentane < 2,3-dimethylbutane
E) n-hexane < 2,3-dimethylbutane < 2-methylpentane
Answer: A
34) Draw a Newman projection of the most stable conformation of 2-methylpropane.
Answer:
35) The structures below are:
A) not isomers.
B) conformational isomers.
C) cis-trans isomers.
D) structural isomers.
E) both B and D
Answer: D
4
36) Define the term conformation.
Answer: Conformations are different arrangements of the same molecule formed by rotations about single bonds.
37) Use a sawhorse structure to depict the eclipsed conformer of ethane.
Answer:
38) View a butane molecule along the C2–C3 bond and provide a Newman projection of the lowest energy
conformer.
Answer:
45) Describe the sources of angle strain and torsional strain present in cyclopropane.
Answer: The angle strain arises from the compression of the ideal tetrahedral bond angle of 109.5° to 60°. The large
torsional strain occurs since all C–H bonds on adjacent carbons are eclipsed.
47) Draw the most stable conformation of trans-1,2-dimethylcyclohexane.
Answer:
48) Draw the most stable conformation of cis-1,2-dimethylcyclohexane.
Answer:
66) From the perspective of viewing down the C2-C3 bond, draw the Newman projection of the most stable
conformation of 2,3-dimethylbutane.
Answer:
78) In the lowest energy conformation of the compound below, how many alkyl substituents are equatorial?
5
A) 0
B) 1
C) 2
D) 3
E) 6
Answer: B
59) Does 1,1-dichloroethene (Cl2C=CH2) have a net molecular dipole moment? If it does, draw the molecule and
indicate the direction of this molecular dipole moment.
Answer: Net molecular dipole moment present.
66) Which of the molecules below can hydrogen bond to another of the same compound?
A) CH3CH2OCH2CH3
B) CH3CH2COOCH3
C) (CH3CH2)2CHOH
D) CH3CH2COCH2CH3
E) all of the above
1) What is meant by the mechanism of a chemical reaction?
Answer: The mechanism of a reaction is the complete, step-by-step description of exactly which bonds break, which
bonds form, and the order in which these events occur in the transformation of reactants into products.
2) __________ is the study of reaction rates.
Answer: Kinetics
6) Species with unpaired electrons are called __________.
Answer: radicals or free radicals
10) Write a detailed, stepwise mechanism for the following reaction.
Answer:
17) Which is a measure of the randomness of a system?
A) entropy
B) enthalpy
C) free energy
6
D) halogenation
E) stoichiometry
Answer: A
22) Energy is __________ when bonds are formed and is __________ when bonds are broken; therefore, bond
dissociation energies are always __________.
A) released / consumed / exothermic
B) released / consumed / endothermic
C) consumed / released / exothermic
D) consumed / released / endothermic
E) consumed / released / isothermic
Answer: B
30) __________ is the minimum kinetic energy reacting molecules must possess to overcome the repulsions
between their electron clouds when they collide.
Answer: The activation energy or Ea
Diff: 1
31) The rate of a reaction typically increases as the temperature increases because:
A) the A term in the Arrhenius equation increases.
B) the fraction of molecules with kinetic energy greater than Ea increases.
C) the activation energy decreases.
D) the activation energy increases.
E) the molecules make more collisions with the wall of the reaction vessel.
Answer: B
33) What term describes the highest-energy structure in a molecular collision which leads to reaction?
Answer: transition state
44) Rank the free radicals (I-III) shown below in order of decreasing stability (i.e., from most stable to least stable).
A) I > III > II
B) II > III > I
C) I > II > III
D) II > I > III
E) III > II > I
Answer: A
Diff: 2
50) Predict the major monobromination product in the following reaction.
Answer:
7
Diff: 2
54) List the following radicals in order of increasing stability (i.e., from least stable to most stable).
(CH3)3C·, CH2=CHCH2·, CH3CH2·, CH3·, (CH3)2CH·
Answer: CH3· < CH3CH2· < (CH3)2CH· < (CH3)3C· < CH2=CHCH2·
Diff: 2
58) How do alkyl substituents stabilize a carbocationic center to which they are attached?
A) Through an inductive donation of electron density to the cationic center.
B) Through an inductive removal of electron density from the cationic center.
C) Through hyperconjugation.
D) both A and C
E) both B and C
Answer: D
Diff: 2
3) Is the molecule shown below chiral or achiral?
Answer: achiral
4) Is the molecule shown below chiral or achiral?
Answer: chiral
8) Is the molecule shown below chiral or achiral?
Answer: achiral
Answer: chiral
11) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the
same compound?
8
Answer: the same compound
13) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the
same compound?
Answer: enantiomers
15) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the
same compound?
Answer: diastereomers
16) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the
same compound?
Answer: the same compound
17) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the
same compound?
Answer: the same compound
20) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the
same compound?
Answer: enantiomers
50) If (S)-glyceraldehyde has a specific rotation of -8.7°, what is the specific rotation of (R)-glyceraldehyde?
A) 0.0°
B) -8.7°
C) +8.7°
D) cannot be determined from the information given
Answer: C
9
52) Stereoisomers which are not mirror image isomers are __________.
Answer: diastereomers
54) A mixture of equal amounts of two enantiomers __________.
A) is called a racemic mixture
B) is optically inactive
C) implies that the enantiomers are meso forms
D) both A and B
E) none of the above
Answer: D
64) Which of the following statements is (are) true for the compound (R)-2-butanol?
A) This compound is chiral.
B) This compound is optically active.
C) This compound has an enantiomer.
D) all of the above
E) none of the above
Answer: D
6) Provide an acceptable name for the compound shown below.
Answer: cis-1, 2-dichlorocyclopentane
8) Provide the structure of 1-bromo-3-methylhexane.
Answer: CH3CH2CH2CH(CH3)CH2CH2Br
13) Which of the following is a secondary alkyl halide?
A) methyl bromide
B) isopropyl chloride
C) t-butyl iodide
D) propyl bromide
E) isobutyl chloride
Answer: B
21) Provide a detailed, stepwise mechanism for the reaction below.
(CH3)2CHCH2CH2CH2I + CN- → (CH3)2CHCH2CH2CH2CH2CN + IAnswer:
23) Rank the species below in order of increasing nucleophilicity in hydroxylic solvents:
CH3CO2-, CH3S-, HO-, H2O.
Answer: H2O < CH3CO2- < HO- < CH3S26) Consider the reaction of (CH3)3CO- with iodomethane. Will the reaction rate increase, decrease, or remain the
same if the concentration of iodomethane is increased? Explain.
Answer: This is an SN2 reaction with a rate = k[(CH3)3CO-] [CH3I]. The reaction rate will increase as [CH3I]
10
increases.
27) Which of the following compounds will undergo an SN2 reaction most readily?
A) (CH3)3CCH2I
B) (CH3)3CCl
C) (CH3)2CHI
D) (CH3)2CHCH2CH2CH2I
E) (CH3)2CHCH2CH2CH2Cl
Answer: D
31) Provide the major organic product of the reaction below and a detailed, stepwise mechanism which accounts for
its formation.
Answer:
Diff: 3
33) When ionization occurs at the single sterocenter of a chiral compound, the resulting carbocation is:
A) achiral
B) chiral
C) racemic
D) optically active
E) none of the above
Answer: A
34) SN1 reactions usually proceed with:
A) equal amounts of inversion and retention at the center undergoing substitution.
B) slightly more inversion than retention at the center undergoing substitution.
C) slightly more retention then inversion at the center undergoing substitution.
D) complete inversion at the center undergoing substitution.
E) complete retention at the center undergoing substitution.
Answer: B
11
37) Provide a series of synthetic steps by which (CH3)2C=CH2 could be prepared from 2-methylpropane.
Answer:
1. Br2, hν
2. NaOCH3, CH3OH
38) Why does CH2=CHCHBrCH3 undergo solvolysis much more rapidly than 2-bromobutane?
Answer: The intermediate carbocation is resonance stabilized.
39) When 1-bromo-2, 2-dimethylcyclopentane is heated in ethanol, one of the products which results is shown
below. Provide a detailed, stepwise mechanism for the production of this compound, and give the name of the
mechanism by which it is produced.
Answer:
40) Provide the structure of the major organic products which result in the reaction below.
Answer:
46) List the following compounds in order of increasing reactivity in an S N1 reaction.
CH3Br, CH3CH2CH2I, (CH3)3CI, CH3CHBrCH3, CH3CHICH3
Answer: CH3Br < CH3CH2CH2I < CH3CHBrCH3 < CH3CHICH3 < (CH3)3CI
50) What is Zaitsev's rule?
Answer: In elimination reactions, the most highly substituted alkene product is the major product.
53) Provide the structure of the major organic product in the following reaction.
12
Answer:
55) Show the best way to prepare CH3OCH(CH3)2 by an SN2 reaction.
Answer: CH3I + NaOCH(CH3)2
57) Predict the most likely mechanism for the reaction shown below.
A) SN1
B) SN2
C) E1
D) E2
E) E1cb
Answer: D
88) Which is more nucleophilic, t-butoxide or ethoxide? Explain.
Answer: Ethoxide is the better nucleophile. The steric bulk of t-butoxide decreases its effectiveness as a nulcoephile.
6) Provide the structure of the major organic product in the reaction below.
Answer:
8) Provide the structure of the major organic product in the reaction below.
Answer:
13
9) Provide the structure of the major organic product in the reaction below.
(CH3)2CHCH2CH2CHO
1. LiAlH4
2. H3O +
Answer: (CH3)2CHCH2CH2CH2OH
→
10) Provide the structure of the major organic product in the reaction below.
Answer:
11) Provide the reagents necessary to carry out the transformation shown below.
Answer: 1. BH3·THF
2. H2O2, NaOH
12) Provide the reagents necessary to carry out the transformation shown below.
Answer: 1. LiAlH4
2. H3O+
14) 1-Methylcyclopentan-1-ol is classified as __________.
A) a primary alcohol
B) a secondary alcohol
C) a tertiary alcohol
D) a phenol
E) an enol
Answer: C
16) Provide an acceptable name for the compound below.
Answer: cis-3-chlorocyclohexan-1-ol
26) Which is more soluble in water, butan-1-ol or decan-1-ol? Explain briefly.
Answer: Butan-1-ol is more soluble in water. Decan-1-ol's larger alkyl group makes this compound more
hydrophobic which leads to increased disruption of the dipole-dipole attractions (hydrogen bonding) among
14
neighboring water molecules.
27) __________ is the major intermolecular attraction responsible for the relatively high boiling points of alcohols.
Answer: Hydrogen bonding
34) Provide the reagents necessary to accomplish the following transformation.
2-methyl-2-octene to 2-methyloctan-3-ol
Answer: 1. BH3
2. H2O2, -OH
40) Which is the stronger acid, phenol or 4-nitrophenol?
Answer: 4-nitrophenol
41) Which is the stronger acid, cyclohexanol or 2-fluorocyclohexan-1-ol?
Answer: 2-fluorocyclohexan-1-ol
44) Provide the reagents necessary to convert (E)-but-2-ene to meso-butane-2,3-diol.
Answer: 1. HCO3H
2. H3O+
45) Provide the reagents necessary to carry out the conversion shown below.
Answer: 1. Hg(OAc)2, H2O
2. NaBH4
48) Provide the structure of the major organic product in the reaction shown below.
Answer:
51) Provide the structure of the major organic product in the reaction shown below.
Answer:
52) A novice chemist wished to prepare 1-methylcyclohexane-1,4-diol from the keto alcohol shown below by
treating it with the appropriate Grignard reagent. Was the chemist successful? Explain.
15
Answer: Unsuccessful. The Grignard would deprotonate the hydroxyl group instead of reacting at the carbonyl.
Diff: 2
54) Provide a detailed, stepwise mechanism for the reaction of acetyl chloride (CH 3COCl) and 2 equivalents of
PhMgCl.
Answer:
55) Why are ether solvents used in the preparation of Grignard and organolithium reagents?
Answer: Ethers provide a polar, aprotic environment in which these species can form. The polar nature of these
reagents demands a polar solvent be used to facilitate their formation. Additionally, ethers are unreactive toward
strong bases and have no functional groups that react with nucleophiles.
68) Which of the following terms best describes the reactive nature of a Grignard reagent?
A) carbocation
B) free radical
C) electrophile
D) nucleophile
E) carbene
Answer: D
81) What Grignard reagent and carbonyl compound could be used to prepare 1-ethylcyclohexanol?
Answer:
2) Classify the reaction below as an oxidation, a reduction, or neither.
PhCO2H → PhCH2OH
A) oxidation
B) reduction
C) neither
16
Answer: B
4) Provide the structure of the major organic product in the reaction below.
Answer:
5) Provide the structure of the major organic product in the reaction below.
Answer:
9) Provide the structure of the major organic product in the reaction below.
Answer:
15) The Williamson ether synthesis proceeds via an __________ mechanism.
A) SN1
B) SN2
C) E1
D) E2
E) none of the above
Answer: B
20) Draw the tosylate ion and explain why it is a particularly good leaving group.
Answer: Extensive resonance stabilization of this ion makes it a particularly good leaving group.
22) Why are alcohols unreactive toward nucleophilic substitution reactions?
Answer: The hydroxide ion, a relatively strong base, is a very poor leaving group.
24) Provide the structure of the major organic product in the reaction below.
17
1. TsC1, pyridine
→
2. NaCN, acetone
Answer: PhCH2CH2CN
PhCH2CH2OH
27) Predict the major product of the reaction below and provide a stepwise mechanism which accounts for its
formation.
(CH3)3CCH2OH + HBr →
Answer:
34) Provide the structure of the major organic product in the reaction below.
PBr3
(CH3)2CHCH2OH 
Answer: (CH3)2CHCH2Br
36) Which set of reagents will best convert 2,2-dimethylpropan-1-ol (neopentyl alcohol)
to 4,4-dimethylpentan-2-ol?
A) 1. HCl
2. Mg
3. CH3CHO
4. H3O+
B) 1. HCl, ZnCl2
2. Mg
3. CH2O
4. H3O+
C) 1. SOCl2
2. Mg
3. CH3CHO
4. H3O+
D) 1. HCl, ZnCl2
2. Mg
3. CH3CHO
4. H3O+
Answer: C
39) Provide the structure of the major organic product in the reaction below.
Answer:
18
40) What is Zaitsev's rule?
Answer: When the product distribution of a series of isomeric alkenes is governed by their thermodynamic
stabilities, the most substituted isomer will predominate.
47) Draw the products formed in the Fischer esterification reaction between acetic acid (CH 3CO2H) and
cyclohexanol.
Answer:
52) What series of synthetic steps could be used to prepare hexan-3-ol from propan-1-ol?
Answer: 1. PCC
2. CH3CH2CH2MgBr
3. H3O+
or
1. HBr or PBr3
2. Mg, Et2O
3. CH3CH2CHO
55) What series of synthetic steps could be used to carry out the transformation shown below?
Answer: 1. PBr3 or HBr
2. Mg, ether
3. CH3CH2CHO
4. H3O+
5. PCC or Na2Cr2O7 or KMnO4
63) Name the product which results when 1-methylcyclohexanol is treated with PCC.
1) What is the hybridization of the oxygen atom in dialkyl ethers?
A) sp3
B) sp2
C) sp
D) s
E) p
Answer: A
2) Draw structures which show the hydrogen bonding interaction that exists between water and dimethyl ether.
Answer:
19
3) Which has the higher boiling point, diethyl ether or butan-1-ol? Briefly explain.
Answer: Butan-1-ol has the higher boiling point since intermolecular hydrogen bonding can occur. Molecules of
diethyl ether are incapable of hydrogen bonding with each other.
4) Give two properties of ethers which allow them to be commonly used as solvents in organic reactions.
Answer: 1. Dissolve a wide variety of both polar and nonpolar compounds.
2. Tend to be unreactive under a large number of reaction conditions.
3. Have low boiling points; easily removed from product mixture.
6) Provide a structural representation of 2-ethoxypentane.
Answer:
7) Provide a structural representation of isopropyl tert-butyl ether.
Answer: (CH3)2CHOC(CH3)3
18) Show the best method for preparing methoxycyclopentane via the Williamson ether synthesis.
Answer:
26) Predict the products of the following reaction and give a reasonable mechanism for their formation.
Answer:
30) Provide the major organic product in the reaction below.
Answer:
33) When ethers are stored in the presence of oxygen, what explosive materials can result from autoxidation of the
ether?
Answer: hydroperoxides or dialkylperoxides
35) Provide the major organic product in the reaction below.
20
Answer:
40) Provide the major organic product in the reaction below.
Answer:
42) Provide the major organic product in the reaction below.
Answer:
43) Provide the major organic product in the reaction below.
Answer:
49) Provide the major organic product in the reaction below.
Answer:
52) Provide an acceptable name for the compound shown below.
21
CH3OCH2CH(CH3)2
Answer: isobutyl methyl ether or 1-methoxy-2-methylpropane
68) What term is given to the sulfur analogues of ethers?
Answer: sulfides or thioethers
69) Which of the following is produced by the reaction of (CH3CH2)2S with CH3CH2I?
A) CH3CH2CH2CH2I
B) (CH3CH2)3S+ IC) (CH3CH2)3S
D) CH3SCH2CH2CH3
E) CH3CH2SCH2CH2I
Answer: B
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