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WorksheetsStereochemistry
Total questions: 23
Worksheet time: 18mins
Structures which differ only in rotations about a single bond are called
Conformers
Isomers
Enantiomers
Conformations
From a molecular orbital perspective why isn't there relatively free rotation about the carbon-carbon double bond in ethene (CH2=CH2)?
Because C=C bond is cylindrical
Because of double bond
Because of steric strain
Because of torsional strain
Which of the following best explains the relative stabilities of the eclipsed and staggered forms of ethane? The ________ form has the most ________ strain
staggered; torsional
eclipsed; steric
staggered; steric
eclipsed; torsional
Identify the most stable conformation of butane
gauche
eclipsed
anti
totally eclipsed
Among the butane conformers, which occur at energy minima on a graph of potential energy versus dihedral angle?
gauche only
anti only
eclipsed and totally eclipsed
gauche and anti
Which of the following correctly ranks the cycloalkanes in order of increasing ring strain per methylene?
cyclohexane < cyclopentane < cyclobutane < cyclopropane
cyclopropane < cyclobutane < cyclohexane < cycloheptane
cyclopentane < cyclobutane < cyclopentane < cyclopropane
cyclopentane < cyclopropane < cyclobutane < cyclohexane
In the boat conformation of cyclohexane, the "flagpole" hydrogens are located:
on the same carbon
on adjacent carbons
on C-1 and C-3
on C-1 and C-4
Which conformer is at a local energy minimum on the potential energy diagram in the chair-chair interconversion of cyclohexane?
half- chair
twist boat
fully eclipsed
boat
Which of the following correctly lists the conformations of cyclohexane in order of increasing energy?
chair < twist-boat < boat < half-chair
chair < boat < twist-boat < half-chair
chair < twist-boat < half-chair < boat
half-chair < twist-boat < boat < chair
Which of the following is the most stable conformation of bromocyclohexane?
I
II
III
IV
V
Which Newman projection shows the most stable conformation of the following compound?
A
B
C
D
None of the above
Which of the following structures (a-d) is another resonance structure of the following organic molecule?
A
B
C
D
Which of the following pairs are resonance structures?
I
II
III
IV
V
Which of the following pairs are resonance structures?
I
II
III
IV
V
Which one of the following will exhibit conformational isomerism?
Ethylene
methane
chloromethane
propane
Which of the following compound has gauche as it stable conformer?
n-butane
n-propane
1,2-dicloroethane
1,2-dihydroxyethane
The most unstable conformer in cyclohexane?
Boat
Chair
Twist boat
half chair
Which of the following conformers is not a transition state?
Boat
half chair
fully eclipsed
twist boat
Identify the conformation
Boat
Chair
twist boat
half chair
