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ORG CHEM 2 Flashcards

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1
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

What is the IUPAC name for CH3CHClCH(CH3)CH2CH2CH2CH2Br?

1-bromo-6-chloro-5-methylheptane
7-bromo-2-chloro-3-methylheptane
1-bromo-6-chloro-5,6-dimethylhexane
6-bromo-1-chloro-1,2-dimethylhexane

A

1-bromo-6-chloro-5-methylheptane

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2
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

What is the IUPAC name for
(CH3)3CCH(OH)CH2CH(OH)CH2CH(CH3)2?

1,1,1,6-tetramethyl-2,4-heptanediol
2,2,7-trimethyl-3,5-octanediol
2,2,6,6-tetramethyl-3,5-heptanediol
2,7,7-trimethyl-4,6-octanediol

A

2,2,7-trimethyl-3,5-octanediol

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3
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following is a chiral C5H12O 1º-alcohol?

3-methyl-2-butanol
2-methyl-2-butanol
3-methyl-1-butanol
2-methyl-1-butanol

A

2-methyl-1-butanol

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4
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following reagents would you expect to react with bromocyclopentane by an SN2 mechanism?

C2H5OH
C2H5O(-) K(+)
NaCN
(CH3)3N

A

NaCN

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5
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Chloroethane, C2H5Cl, does not react with methanol under mild conditions. What reagent could be added to the reaction mixture to increase the rate of substitution?

HCl (conc.)
NaOH
NH4OH
AgNO3

A

AgNO3

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6
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following compounds is unlikely to react with sodium metal?

C2H5OC2H5
C2H5OH
C2H5Br
C2H5NH2

A

C2H5OC2H5

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7
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

The reaction of sodium ethoxide with iodoethane to form diethyl ether is classified as …

an electrophilic substitution
a nucleophilic substitution
a radical substitution
an electrophilic addition

A

a nucleophilic substitution

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8
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Compound X reacts with HI. The product of this reaction, when treated with KOH in ethanol, gives Y (an isomer of X ). Ozonolysis of Y (H2O2 workup) produces two compounds: a two carbon carboxylic acid, and a four carbon ketone.
What is X?

2-methyl-2-pentene
4-methyl-1-pentene
2,3-dimethyl-2-butene
3-methyl-1-pentene

A

3-methyl-1-pentene

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9
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

The SN2 reaction of 1-chloro-3-methylbutane with sodium methoxide is relatively slow, but can be accelerated by the addition of a small amount of NaI. How is this catalysis best explained?

The sodium cation helps pull off the chloride anion

The iodide anion activates the methoxide nucleophile

SN2 reaction of iodide ion converts the alkyl chloride to the more reactive alkyl iodide

The NaI changes the mechanism to SN1

A

SN2 reaction of iodide ion converts the alkyl chloride to the more reactive alkyl iodide

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10
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which one of the following alcohols will be oxidized by Jones’ reagent (CrO3 in 50% sulphuric acid) to a ketone having the same number of carbon atoms ?

1-methylcyclohexanol
3,3-dimethylcyclopentanol
3-methyl-1-hexanol
3-ethyl-3-hexanol

A

3,3-dimethylcyclopentanol

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11
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

What reagent would be suitable for distinguishing 1-methoxy3-methyl-2-butene from its isomer 4-methyl-3-penten-1-ol?

bromine in methylene chloride
KMnO4 in aqueous base
AgNO3 in dilute NH4OH
sodium metal suspended in hexane

A

sodium metal suspended in hexane

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12
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Synthesis of hexane-3,4-diol from trans-3-hexene may be accomplished in two ways:

(i) OsO4 hydroxylation & (ii) C6H5CO3H epoxidation followed by NaOH opening of the epoxide ring.
Which of the following statements about the products from these reactions is correct?

the two methods give the same product
(i) gives a chiral isomer, (ii) gives an achiral isomer
(i) gives an achiral isomer, (ii) gives a chiral isomer
two different isomers are formed, but both are chiral

A

(i) gives an achiral isomer, (ii) gives a chiral isomer

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13
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Reaction of 1,4-dibromobutane with Mg turnings in ether gives the bis-Grignard reagent,

BrMgCH2CHCH2CH2MgBr. What is the product from the reaction of meso-2,3dibromobutane with Mg under the same conditions?

trans-2-butene
cis-2-butene
meso-CH3CH(MgBr)CH(MgBr)CH3
racemic-CH3CH(MgBr)CH(MgBr)CH3

A

trans-2-butene

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14
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

I. OH(-) II. CH3CO2(-) III. HO2(-) IV. H2O
The above molecules and ions are all nucleophiles. What is the relative order of their reactivity in an SN2 reaction with ethyl bromide?

I > II > III > IV
IV> III > II > I
III > I > II > IV
II > III > IV > I

A

III > I > II > IV

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15
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following does not convert a 1º-hydroxyl group into a good leaving group for a SN2 reaction?

SOCl2
CH3SO2Cl
PBr3
NaI

A

NaI

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16
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

How is the following reaction best classified? (CH3)3CBr + (CH3CH2)3N —–> (CH3)2C=CH2 + (CH3CH2)3NH(+)
Br(-)

SN2 substitution
E2 elimination
electrophilic addition
cationic rearrangement

A

E2 elimination

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17
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following isomeric chlorides will undergo SN2 substitution most resdily?

4-chloro-1-butene
1-chloro-1-butene (cis or trans)
1-chloro-2-butene (cis or trans)
2-chloro-1-butene

A

1-chloro-2-butene (cis or trans)

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18
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which reagent would be best for achieving an E2 elimination of 3-chloropentane?

C2H5ONa
CH3CO2Na
NaHCO3
NaI

A

C2H5ONa

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19
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which reaction conditions would be best for the synthesis of isobutyl sec-butyl ether
CH3CH2CH(CH3)-O-CH2CH(CH3)2 ?

(CH3)2CHCH2OH + H2SO4 + heat
CH3CH2CH(CH3)OH + H2SO4 + heat
CH3CH2CH(CH3)ONa + (CH3)2CHCH2Br
(CH3)2CHCH2ONa + CH3CH2CH(CH3)Br

A

CH3CH2CH(CH3)ONa + (CH3)2CHCH2Br

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20
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

A C7H13Br compound reacts with KOH in ethanol to form 3methylcyclohexene as the major product. What is a likely structure for the starting alkyl bromide?

cis-4-methylcyclohexyl bromide
trans-3-methylcyclohexyl bromide
cis-2-methylcyclohexyl bromide
trans-2-methylcyclohexyl bromide

A

trans-2-methylcyclohexyl bromide

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21
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

A synthesis of 2,5-dimethyl-2-hexanol from 2-methylpropene requires the formation of two four-carbon intermediates, X and Y.
These intermediates combine to give the desired product after the usual hydrolysis work-up.
Select appropriate methods of preparing X and Y from 2methylpropene

X add HBr, then react with Mg in ether Y add water, acid-catalysis

X add HBr (peroxides), then react with Mg in ether
Y react with C6H5CO3H in CH2Cl2

X add HOBr Y add B2H6in ether, then NaOH

X add HOBr Y add HBr (peroxides) ,then react with Mg in ether

A

X add HBr (peroxides), then react with Mg in ether

Y react with C6H5CO3H in CH2Cl2

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22
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

All of the following alkyl bromides react by SN2 substitution when treated with sodium cyanide in methanol. Which one does not undergo an inversion of configuration?

(R)-1-bromo-2-methylbutane
(S)-2-bromo-3-methylbutane
(R)-1-bromo-3,3-dimethylcyclohexane
cis-4-ethyl-1-bromocyclohexane

A

(R)-1-bromo-2-methylbutane

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23
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Reaction of (R)-2-chloro-4-methylpentane with excess NaI in acetone gives racemic 2-iodo-4-methylpentane. How can this be explained?

the reaction mechanism changes to SN1

the reaction proceeds via a rapidly inverting radical
intermediate

the substitution is SN2, but repeated attack by iodide anion (with inversion) leads to racemization

iodide anion preferentially attacks chlorine, giving a rapidly inverting carbanion intermediate

A

the substitution is SN2, but repeated attack by iodide anion (with inversion) leads to racemization

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24
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Consider the SN1 solvolysis of the following 1º-alkyl chlorides in aqueous ethanol.

I. CH3CH2CH2Cl
II. CH2=CHCH2Cl
III. CH3OCH2Cl
IV. CF3CF2CH2Cl

What is the order of decreasing reactivity?

III > II > I > IV
II > I > III > IV
IV > III > II > I
I > II > III > IV

A

III > II > I > IV

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25
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

In the SN2 reaction of iodide ion with (CH3)2CHCH2CH2X what is the order of decreasing reactivity for the following X substituents?

I. X = -OH II. X = CH3CO2- III X = CF3SO3- IV X = CCl3CO2-

I > II > III > IV
IV > III > II > I
III > II > IV > I
III > IV > II > I

A

III > IV > II > I

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26
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

A C6H14O chiral alcohol is converted to a bromide by treatment with PBr3. Reaction of this bromide, first with Mg in ether, followed by quenching in 0.1 N HCl produces an achiral C6H14 hydrocarbon.
Which of the following is the original alcohol.?

2-ethyl-1-butanol.
4-methyl-1-pentanol.
3-methyl-3-pentanol.
3-methyl-1-pentanol.

A

3-methyl-1-pentanol.

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27
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following reaction sequences would best serve to convert 2-methyl-1-bromopropane to 4-methyl-1iodopentane?

(i) Mg in ether; .(ii) ethylene oxide (C2H4O); (iii) HI & heat
(i) NaC≡CH in ether; .(ii) H2 + Lindlar catalyst; (iii) HI
(i) KOH in alcohol; . (ii) C6H5CO3H in CH2Cl2; (iii) NaC≡CH in ether ; (iv) 2 H2 + Pt catalyst
(i) NaC≡CH in ether; .(ii) H3O+ + HgSO4; (iii) HI & heat

A

(i) Mg in ether; .(ii) ethylene oxide (C2H4O); (iii) HI & heat

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28
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following organic halides will undergo an E2 elimination on heating with KOH in alcohol?

2,2-dimethyl-1-bromopropane
2,2-dimethyl-1-bromocyclohexane
benzyl chloride (C6H5CH2Cl)
2,5-dimethyl-1-bromobenzene

A

2,2-dimethyl-1-bromocyclohexane

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29
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following reagents and conditions would best serve to convert 1-butyne to 1-bromo-1-butene?

1 equivalent of HBr, no peroxides.
1 equivalent of HBr, with peroxides.
1 equivalent of Br2, followed by 1 equivalent of KOH.
2 equivalents of HBr, followed by 1 equivalent of KOH.

A

1 equivalent of HBr, with peroxides.

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30
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

Which of the following reagents would be best for oxidizing a 1º-alcohol to an aldehyde?

H3PO4
PCC in CH2Cl2
Jones’ reagent (H2CrO4)
OsO4

A

PCC in CH2Cl2

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31
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

If the rate of reaction of [0.1 M] sodium cyanide with [0.1M] 1-bromoethane is 1.4 x 10-4, what effect will an increase in NaCN concentration to [0.3] and alkyl bromide concentration to [0.2] have on the overall reaction rate?

increase by 2 times
increase by 3 times
iincrease by 6 times
increase by 1.5 times

A

iincrease by 6 times

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32
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

A chiral C5H10O alcohol is reduced by catalytic hydrogenation to an achiral C5H12O alcohol. The original alcohol is oxidized by activated MnO2 to an achiral carbonyl compound (C5H8O).
Which of the following might be the chiral alcohol?

1-penten-3-ol
4-penten-2-ol
3-methyl-2-buten-1-ol
2-methyl-2-buten-1-ol

A

1-penten-3-ol

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33
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

A water soluble C6H14O2 compound is oxidized by lead tetraacetate (or periodic acid) to a single C3H6O carbonyl compound. Which of the following would satisfy this fact?

meso-2,3-dimethoxybutane
1,2-diethoxyethane
meso-2,5-hexanediol
meso-3,4-hexanediol

A

meso-3,4-hexanediol

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34
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

What reagents and conditions are used for the SimmonsSmith reaction?

CH3I + Mg in ether
CH2I2 + Zn (Cu) in ether
BrCH2CH2Br + Zn in ether
CBr4 + Zn (Cu) in ether

A

CH2I2 + Zn (Cu) in ether

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35
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

The Lucas test is used to distinguish small (7 or fewer carbons) 1º, 2º and 3º -alcohols. The alcohol to be tested is added to a solution of anhydrous ZnCl2 in conc. HCl at room temperature. Which of the following statements is not correct?

1º-alcohols dissolve, but do not react

3º-alcohols react quickly to give an insoluble alkyl chloride

3º-alcohols rapidly dehydrate, and the gaseous alkene bubbles out of the test solution

2º-alcohols dissolve and react slowly to give an insoluble alkyl chloride

A

3º-alcohols rapidly dehydrate, and the gaseous alkene bubbles out of the test solution

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36
Q

Alkyl Halides, Alcohols, Ethers and Epoxides

A C6H12O compound does not react with Br2 in CCl4, produces a flammable gas on treatment with LiAlH4, and reacts with H2CrO4 changing the color from orange to green. Which of the following compounds best agrees with these facts?

1-methylcyclopentanol
methoxycyclopentane
2-cyclopropyl-2-propanol
2-cyclobutylethanol

A

2-cyclobutylethanol

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37
Q

Stereochemistry

The spatial orientation of the atoms of a molecule is called its what?

constitution
configuration
handedness
composition

A

configuration

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38
Q

Stereochemistry

An object that has no element of symmetry is called what?

tetrahedral
achiral
symmetric
asymmetric

A

asymmetric

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39
Q

Stereochemistry

Stereoisomers differ from each other in what respect?

composition.
configuration
constitution
steric hindrance

A

constitution

40
Q

Stereochemistry

Which of the following must be true for an optically active compound?

the molecular configuration is achiral

the molecular configuration is chiral

the compound is a racemic mixture of enantiomers

the molecular configuration must have two or more stereogenic centers

A

the molecular configuration is chiral

41
Q

Stereochemistry

Enantiomers are?

stereoisomers having non-identical mirror image configurations

stereoisomers that do not have non-identical mirror image configurations

stereoisomers having a mirror plane of symmetry

achiral stereoisomers

A

stereoisomers having non-identical mirror image configurations

42
Q

Stereochemistry

Which conformation of cyclohexane has a C3 axis of symmetry?

boat
twist boat
chair
envelope

A

chair

43
Q

Stereochemistry

Hydration, by oxymercuation, of 3-methyl-1-butene gives 3methyl-2-butanol. What is the observed rotation of this product, using a 20% solution in ethanol in a 1dm polarimeter cell? Assume the specific rotation of the pure (S)-enantiomer
to be +16º

+3.2º
-3.2º
180º (+ or -)
0º

A

0º

44
Q

Stereochemistry

Consider the Fischer projection formula for (S)-2chlorobutane. Which of the following changes does not convert this structure to the (R)-enantiomer?

rotation 180º in the plane of the paper (or screen)

flipping the structure over (a 180º rotation out of the plane)

exchanging the two vertical substituents (i.e. top and bottom)

exchanging the two horizontal substituents (i.e. right and left)

A

rotation 180º in the plane of the paper (or screen)

45
Q

Stereochemistry

Designate the CIP priority order of the following C5H11- groups. (Lowest < Highest priority order)
I. CH3(CH2)4– II. (CH3)3CCH2–
III. C3H7CH(CH3)– IV. (CH3)2CHCH2CH2–

I < II < III < IV
IV < III < II < I
I < IV < II < III
III < II < IV < I

A

III < II < IV < I

46
Q

Stereochemistry

Which of the following isomeric dienes is chiral?

2,3-pentadiene
3-methyl-1,2-butadiene
2-methyl-1,3-butadiene
none, all are achiral

A

2,3-pentadiene

47
Q

Stereochemistry

Two equivalents of bromine add to one equivalent of 1,7octadiene. How many stereoisomeric tetrabromides will be formed?

1
2
3
4

A

3

48
Q

Stereochemistry

Two equivalents of OsO4 hydroxylate one equivalent of 1,5cyclooctadiene. How many stereoisomeric cyclooctane1,2,5,6-tetraols will be formed?

1
2
3
4

A

2

49
Q

Stereochemistry

The optically active bromohydrin (1R, 2R)-2bromocyclohexanol reacts with base to produce cyclohexene oxide (C6H10O). Which of the following statements is true?

a racemic product is formed
the observed optical rotation changes sign
the observed optical rotation does not change sign
the product is achiral

A

the product is achiral

50
Q

Stereochemistry

Pure (S)-2-butanol has a specific rotation of +13.52 degrees. You have made and purified a sample that has a calculated specific rotation of +6.76 degrees. What can you conclude about this sample?

the sample has completely racemized
50% the sample has rearranged into a meso isomer
50% of the sample has racemized
75% of the sample has racemized

A

50% of the sample has racemized

51
Q

Stereochemistry

How many stereoisomers of (CH3)2CHCH=CHCH2CH(OH)CH2Br are possible?

2
3
4
5

A

4

52
Q

Stereochemistry

If two isomers have been classified correctly as epimers, they may also be called…?

diastereomers
enantiomers
tautomers
conformers

A

diastereomers

53
Q

Stereochemistry

Which of the following statements must be true for two pure chiral isomers ?

they must be enantiomers
they must be diastereomers
they must be stereoisomers
they must be optically active

A

they must be optically active

54
Q

Stereochemistry

Which of the following statements is true for a pair of diastereomers?

they will have identical physiological properties.

they will have specific rotations of opposite sign.

they will have identical chemical properties (e.g. reactivity)

they will have different physical properties.

A

they will have different physical properties.

55
Q

Stereochemistry

Which of the following descriptive terms would never be applied to a pair of stereoisomers ?

enantiomers
tautomers
diastereomers
epimers

A

tautomers

56
Q

Stereochemistry

What kind of reagent would be needed to resolve a racemic amine, such as 2-aminobutane ?

the pure optically active amine to serve as a template for crystallization.

an achiral carboxylic acid to give a racemic mixture of amine salts
.
an enantiomerically pure chiral carboxylic acid to
give a diastereomeric mixture of amine salts .

a racemic chiral carboxylic acid to give a complete mixture of isomeric amine salts.

A

an enantiomerically pure chiral carboxylic acid to

give a diastereomeric mixture of amine salts .

57
Q

Stereochemistry

What common symmetry elements if any are found in the stable chair conformer of trans-1,4-Stereochemistry
dichlorocyclohexane?

a single mirror plane and a C2 rotational axis.

a C3 rotational axis but no mirror plane.

two orthogonal mirror planes and a C2 rotational axis.

a single C2 rotational axis but no mirror plane.

A

a single mirror plane and a C2 rotational axis.

58
Q

Stereochemistry

What common symmetry elements if any are found in the stable chair conformer of trans-1,2-dichlorocyclohexane?

a single mirror plane and a C2 rotational axis.

a single mirror plane and a C3 rotational axis

two orthogonal mirror planes and a C2 rotational axis.

a single C2 rotational axis but no mirror plane.

A

a single C2 rotational axis but no mirror plane.

59
Q

Stereochemistry

Reaction of 3-methyl-1,4-cycloheptadiene with excess perbenzoic acid (C6H5CO3H) forms a diepoxide product. How many stereoisomers, counting enantiomers, are expected from this reaction ?

4 (two pairs of enantiomers)
4 (two meso compounds and a pair of enantiomers)
5 (two pairs of enantiomers and a meso compound)
6 (two pairs of enantiomers and two meso compounds)

A

4 (two meso compounds and a pair of enantiomers)

60
Q

Stereochemistry

The antimalarial alkaloid quinine, C20H24N2O2, is optically active. An ethanol solution of 8g quinine in 100mL displays a rotation of -13.6º in a 1dm polarimeter tube. What is the specific rotation of quinine?

  • 85º
  • 170º
  • 43º
  • 26º
A

-170º

61
Q

Stereochemistry

Which of the following compounds has a prochiral methylene group (i.e. the hydrogen atoms are diastereotopic)?

propane , CH3CH2CH3
cyclopropane , (CH2)3
2-methylpropene , CH2=C(CH3)2
ethanol , CH3CH2OH

A

ethanol , CH3CH2OH

62
Q

Stereochemistry

The thermal electrocyclic closure of (2E,4Z,6E)-2,4,6octatriene gives which of the following?

cis-5,6-dimethyl-1,3-cyclohexadiene
trans-5,6-dimethyl-1,3-cyclohexadiene
cis-3,6-dimethyl-1,4-cyclohexadiene
cis-3,6-dimethyl-1,4-cyclohexadiene

A

cis-5,6-dimethyl-1,3-cyclohexadiene

63
Q

Stereochemistry

The Cope rearrangement, [3,3]-sigmatropic shift, of meso3,4-dimethyl-1,5-hexadiene gives which of the following?

1,7-octadiene
(2Z,6Z)-2,6-octadiene
(2E,6Z)-2,6-octadiene
(2E,6E)-2,6-octadiene

A

(2E,6Z)-2,6-octadiene

64
Q

Stereochemistry

Which of the following statements is not an essential feature of an optically active compound?

the molecules of an optically active compound will be dissymetric or asymmetric.

the molecules of an optically active molecule must have at least one stereogenic site.

an optically active compound’s molecular configuration will not be identical with its mirror image.

an optically active compound will have at least one stereoisomer.

A

the molecules of an optically active molecule must have at least one stereogenic site.

65
Q

Stereochemistry

Which of the following statements is not correct?

a pair of enantiomeric compounds will have the same melting point.

a pair of enantiomeric compounds will have the same solubility in ethanol.

a pair of enantiomeric compounds will have exactly the same functional groups.

a pair of enantiomeric compounds will have identical optical rotations.

A

a pair of enantiomeric compounds will have identical optical rotations.

66
Q

Structure and Reactivity of Aromatic Compounds

How many isomeric tribromobenzenes exist?

none! (such a compound cannot exist)
1
2
3

A

3

67
Q

Structure and Reactivity of Aromatic Compounds

A C8H10 hydrocarbon is nitrated by HNO3 and sulfuric acid. Two, and only two, C8H9NO2 isomers are obtained. Which of the following fits this evidence?

ethylbenzene
ortho-xylene
meta-xylene
para-xylene

A

ortho-xylene

68
Q

Structure and Reactivity of Aromatic Compounds

Which of the following is an important reactive electrophile in aromatic ring nitration?

NO2(+)
NO(+)
N2(+)
N2O(+)

A

NO2(+)

69
Q

Structure and Reactivity of Aromatic Compounds

Bromination of meta-chloronitrobenzene may produce how many C6H3ClBrNO2 isomers?

1
2
3
4

A

4

70
Q

Structure and Reactivity of Aromatic Compounds

How many isomeric dinitrobenzoic acids can exist?
C6H3(NO2)2CO2H

3
4
5
6

A

6

71
Q

Structure and Reactivity of Aromatic Compounds

Which of the following is phenol?

C6H5OH
C6H5CH2OH
C6H5COCH3
C6H5OCH3

A

C6H5OH

72
Q

Structure and Reactivity of Aromatic Compounds

What is the order of reactivity of the following compounds in electrophilic substitution?

(more reactive > less reactive)
I toluene II nitrobenzene III benzene IV phenol

I > II > III > IV
IV > III > II > I
I > III > IV > II
IV > I > III > II

A

IV > I > III > II

73
Q

Structure and Reactivity of Aromatic Compounds

What is the order of reactivity of the following compounds in electrophilic substitution? (more reactive > less reactive) I chlorobenzene II aniline III ethylbenzene IV benzoic acid

I > II > III > IV
II > III > I > IV
I > III > IV > II
II > I > IV > III

A

II > III > I > IV

74
Q

Structure and Reactivity of Aromatic Compounds

What is the order of increased meta electrophilic substitution for the following compounds?

( more meta product > less meta product)

I. C6H5N(CH3)3(+) II. C6H5CH2Cl
III. C6H5CHCl2 IV. C6H5CCl3

I > II > III > IV
III > II > IV > I
I > II > IV > III
I > IV > III > II

A

I > IV > III > II

75
Q

Structure and Reactivity of Aromatic Compounds

Which of the following benzene ring substituents is deactivating but ortho-para directing?

  • N=O
  • OCH3
  • COCH3
  • NO2
A

-N=O

76
Q

Structure and Reactivity of Aromatic Compounds

Which of the following organic chlorides will not give a Friedel-Craft alkylation product when heated with benzene and AlCl3.

(CH3)3CCl
CH2=CHCH2Cl
CH3CH2Cl
CH2=CHCl

A

CH2=CHCl

77
Q

Structure and Reactivity of Aromatic Compounds

Which of the following substituents on a benzene ring is ortho-para directing?

  • OCOCH3
  • COCH3
  • CO2H
  • CN
A

-OCOCH3

78
Q

Structure and Reactivity of Aromatic Compounds

Which of the following compounds reacts rapidly with Br2 in the dark?

benzene
anisole C6H5OCH3
acetophenone C6H5COCH3
none of the above

A

anisole C6H5OCH3

79
Q

Structure and Reactivity of Aromatic Compounds

Which of the following reaction sequences would be best for converting para-bromoanisole to ortho-ethylanisole?

(i) H2 & Pt catalyst (ii) C2H5Cl & AlCl3

(i) Mg in ether (ii) aqueous alcohol (iii) C2H5Cl &
AlCl3

(i) Mg in ether (ii) C2H5Cl & AlCl3
(i) C2H5Cl & AlCl3 (ii) Mg in ether (iii) aqueous alcohol

A

(i) C2H5Cl & AlCl3 (ii) Mg in ether (iii) aqueous alcohol

80
Q

Structure and Reactivity of Aromatic Compounds

When Friedel-Craft alkylation of benzene is carried out with 1 equiv. of tert-butyl chloride, a large amount of para-di-tertbutylbenzene is formed, along with the mono-substitution product. Why doesn’t all the benzene react to give tertbutylbenzene (the mono-substitution product)?

the tert-butyl substituent activates the benzene ring to further substitution.

the reaction is bimolecular, so two tert-butyl chloride molecules combine with one benzene molecule.

the tert-butyl substituent is large and favors reaction at the para-position.

the disubstituted product is favored in equilibrium with the mono-substituted ring..

A

the tert-butyl substituent activates the benzene ring to further substitution.

81
Q

Structure and Reactivity of Aromatic Compounds

When para-bromotoluene is treated with NaNH2 in ether, the bromine is lost and a mixture of para & meta-CH3C6H4NH2 products is obtained. What kind of intermediate would account for this?

a charge delocalized anion formed by nucleophilic addition of NH2(-) to the benzene ring..

a charge delocalized anion formed by abstraction of a methyl proton by the base NH2(-).

an aryl cation formed by loss of bromide anion.

a benzyne species formed by elimination of HBr.

A

a benzyne species formed by elimination of HBr.

82
Q

Structure and Reactivity of Aromatic Compounds

Sulfonation of naphthalene by conc. sulfuric acid produces the 1-sulfonic acid at 120 ºC and the 2-sulfonic acid at 160 ºC. Which of the following statements is not true?

the 2- sulfonic acid is kinetically favored

sulfonation is a reversible reaction

the 2- sulfonic acid is thermodynamically favored
(more stable)

electrophilic attack at C-1 is favored over attack at C-2

A

the 2- sulfonic acid is kinetically favored

83
Q

Structure and Reactivity of Aromatic Compounds

C6H5OCH2CH2Br is heated with Mg in ether and then quenched in cold 10% HCl. What organic product will be obtained by ether extraction of the aqueous acid?

C6H5OCH2CH3
C6H5OCH2CH2OH
C6H5OH
C6H6

A

C6H5OH

84
Q

Structure and Reactivity of Aromatic Compounds

A C9H12O compound is reacted with a solution of lithium in liquid ammonia. After evaporation of the ammonia, the residue is warmed with 10% HCl and extracted with ether. The product is identified as 2-cyclohexenone. Which of the following might be the starting compound?

C6H5OC3H7
C6H5CH2CH2CH2OH
C6H5CH2CH2OCH3
C6H5CH2CH(OH)CH3

A

C6H5OC3H7

85
Q

Structure and Reactivity of Aromatic Compounds

Which of the following procedures would be best for the preparation of phenyl benzyl ether? C6H5OCH2C6H5

C6H5Cl + C6H5CH2O(-) Na(+)
C6H5O(-) Na(+) + C6H5CH2Cl
2 C6H5Cl + Na2O
2 C6H5MgBr + CH2O

A

C6H5O(-) Na(+) + C6H5CH2Cl

86
Q

Structure and Reactivity of Aromatic Compounds

Which reaction sequence would be best for preparing 3,5dibromoaniline from nitrobenzene?

(i) 3 H2 & Pt or Ni catalyst (ii) 2 Br2 in ether
(i) excess Br2 + FeBr3 & heat (ii) 3 H2 & Pt or Ni catalyst
(i) 3 H2 & Pt or Ni catalyst (ii) H2SO4 & heat (iii) excess HBr

(i ) H2SO4 & heat (ii) excess Br2 + FeBr3 & heat (iii) 3 H2 & Pt or Ni catalyst

A

(i) excess Br2 + FeBr3 & heat (ii) 3 H2 & Pt or Ni catalyst

87
Q

Structure and Reactivity of Aromatic Compounds

How could one prepare 3,4,5-tribromoaniline from paranitroaniline?

note: HNO2 = NaNO2 + 10% H2SO4

(i) 3 H2 & Pt or Ni catalyst (ii) 2 Br2 in ether (iii)
HNO2 0 ºC (iv) H3PO2

(i) 3 H2 & Pt or Ni catalyst (ii) HNO2 0 ºC (iii) excess Cu2Br2 + HBr

(i) 2 Br2 in ether (ii) 3 H2 & Pt or Ni catalyst (iii)
HNO2 0 ºC (iv) H3PO2

(i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) Cu2Br2 (iv) 3 H2 & Pt or Ni catalyst

A

(i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) Cu2Br2 (iv) 3 H2
& Pt or Ni catalyst

88
Q

Structure and Reactivity of Aromatic Compounds

How could one prepare 3,5-dibromophenol from paranitroaniline?

note: HNO2 = NaNO2 + 10% H2SO4
(i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) H3PO2 (iv) 3 H2 & Pt or Ni catalyst (v) HNO2 0 ºC, then heat
(i) 3 H2 & Pt or Ni catalyst (ii) HNO2 0 ºC (iii) excess Cu2Br2 + HBr (iv) KOH & heat
(i) HNO2 0 ºC, then heat (ii) 2 Br2 in ether (iii) 3 H2 & Pt or Ni catalyst (iv) HNO2 0 ºC (v) Cu2Br2 + HBr

(i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) Cu2Br2 (iv) 3
H2 & Pt or Ni catalyst (v) HNO2 0 ºC, then heat

A

(i) 2 Br2 in ether (ii) HNO2 0 ºC (iii) H3PO2 (iv) 3 H2 & Pt or Ni catalyst (v) HNO2 0 ºC, then heat

89
Q

Structure and Reactivity of Aromatic Compounds

Iodination of benzene is not easily caried out. How can one prepare para-iodobenzoic acid from para-nitrotoluene?

note: HNO2 = NaNO2 + 10% H2SO4

(i) Br2 + FeBr2 (ii) Mg in ether, then CO2 (iii) 3 H2
& Pt or Ni catalyst (iv) HNO2 0 ºC (v) KI solution

(i) NBS in CCl4 & heat (ii) NaI in acetone (iii) 3 H2 & Pt or Ni catalyst (iv) HNO2 0 ºC (v) H3PO2

(i) 3 H2 & Pt or Ni catalyst (ii) HNO2 0 ºC (iii)
Cu2Br2 + HBr (iv) KMnO4 & heat (v) KI solution

(i) KMnO4 & heat (ii) 3 H2 & Pt or Ni catalyst (iii)
HNO2 0 ºC (iv) KI solution

A

(i) KMnO4 & heat (ii) 3 H2 & Pt or Ni catalyst (iii)
HNO2 0 ºC (iv) KI solution

90
Q

Structure and Reactivity of Aromatic Compounds

An important group of comercial dyes, known as azo dyes, are prepared by a diazo coupling reaction. What functional group characterizes an azo dye?

–N=O
–N3
–N=N–
–NO2

A

–N=N–

91
Q

Structure and Reactivity of Aromatic Compounds

Which sequence of reactions would be best for preparing meta-propylaniline from benzene?

(i) HNO3 & H2SO4 & heat (ii) C3H7COCl + AlCl3 (iii) 5 H2 & Pt or Ni catalyst
(i) C3H7COCl + AlCl3 (ii) HNO3 & H2SO4 & heat (iii) 5 H2 & Pt or Ni catalyst
(i) C3H7COCl + AlCl3 (ii) 2 H2 & Pt or Ni catalyst (iii) HNO3 & H2SO4 & heat (iv) 3 H2 & Pt or Ni catalyst
(i) HNO3 & H2SO4 & heat (ii) 3 H2 & Pt or Ni catalyst (iii) C3H7COCl (iv) 2 H2 & Pt or Ni catalyst

A

(i) C3H7COCl + AlCl3 (ii) HNO3 & H2SO4 & heat (iii) 5 H2 & Pt or Ni catalyst

92
Q

Structure and Reactivity of Aromatic Compounds

The aromatic heterocyclic base pyridine is sulfonated by heating with conc. sulfuric acid Which of the following statements about this reaction is correct? (note that in numbering the ring nitogen is #1)

pyridine reacts more rapidly than benzene and is sulfonated at C-3

pyridine reacts more rapidly than benzene and is sulfonated at C-2 & C-4

pyridine reacts more slowly than benzene and is sulfonated at C-3

pyridine reacts more slowly than benzene and is sulfonated at C-2 & C-4

A

pyridine reacts more slowly than benzene and is sulfonated at C-3

93
Q

Structure and Reactivity of Aromatic Compounds

Heating benzene in a large excess of 80% D2SO4 in D2O results in what product?

C6H5SO3D
C6H5OD
C6H5D
C6D6

A

C6D6

94
Q

Structure and Reactivity of Aromatic Compounds

A solution of cyclohexene in benzene is stirred at 0 ºC while concentrated sulfuric acid is added. After washing away the acid and removing the excess benzene, what product is isolated?

cyclohexylbenzene
1-cyclohexylcyclohexene
trans-1,2-diphenylcyclohexane
1,1-diphenylcyclohexane

A

cyclohexylbenzene

95
Q

END

A

END

ORG CHEM (4 decks)

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