Quiz | Cycloalkanes

1

What is the general formula of regular cycloalkanes?

CnH2n

C2nHn

CnHn

CnH2n+2

Alkanes: CnH2n+2​​​​​​​;   Cycloalkanes: CnH2n

2

What is incorrect regarding cycloalkanes?

These have sp3 hybridized carbons

Stability of the cycloalkanes varies directly with their size

These have tetrahedral bond angles

These have different melting and boiling points as their corresponding alkanes

Due to ring strain and more particularly angle strain, small cycloalkanes do not have tetrahedral bond angles. For example, free sp3 orbitals: 120° vs. cyclopropane: 60°

3

What is the most stable cycloalkane?

Cyclobutane

Cyclopentane

Cyclohexane

Cycloheptane

By adopting a chair conformation, cyclohexane is free of bond-angle and eclipsing strain, which is not the case for cyclobutane, cyclopentane or cycloheptane

4

Which of the following is an acceptable IUPAC name?

1-methyl-2-ethylcyclopentane

1-ethyl-2-methylcyclopentane

2-methyl-1-ethylcyclopentane

2-ethyl-1-methylcyclopentane

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When 2 numbering sequences are possible for a polysubstituted system, the substituents are listed in alphabetical order

5

What is the most stable conformer of 1-bromo-2-methylcyclohexane?

cis stereoisomer

1 substituent in equatorial and 1 substituent in axial

2 substituents in the axial position

2 substituents in the equatorial position

Disubstituted cyclohexane: the more stable conformer is the conformer with its 2 substituents in equatorial position in order to avoid 1,3-diaxial interactions

6

What is the most stable stereoisomer of 1,4-dimethylcyclohexane?

cis stereoisomer

trans stereoisomer

both cis and trans stereoisomer

it depends on the temperature

The more stable conformer is the conformer with the maximum substituents in equatorial position
 

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