Question 1

Which of the following is the most stable isomer?

Accepted Answer

The answer of Which of the following is the most...

Question 2

Which of the following is the least stable chair conformer of the most stable isomer of 1-ethyl-2,4-dimethylcyclohexane?

Accepted Answer

The answer of Which of the following is the least...

Question 3

Draw the most stable conformation of trans-1,4-diethylcyclohexane.

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The answer of Draw the most stable conformation of trans-1,4-diethylcyclohexane....

Question 4

Are the two substituents cis or trans?

Accepted Answer

The two substituents are on opposite sides of the double bond, indicating a trans configuration.

Question 5

Draw the most stable chair conformer of cis-1,4-diethylcyclohexane.

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Question 6

Which is more stable?

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The answer of Which is more stable?

...

Question 7

How many distinct signals would appear in the (proton-decoupled) ¹³C NMR spectrum of 2,4-dimethylpentane?

Accepted Answer

2,4-Dimethylpentane has three types of chemically non-equivalent hydrogen environments: the methyl groups at the ends of the molecule (which are equivalent to each other), the methyl groups on carbon 2 and 4 (which are also equivalent to each other), and the methylene group in the middle of the chain. This results in three distinct signals in the NMR spectrum.

Question 8

Which is more stable?

Accepted Answer

The answer of Which is more stable?

...

Question 9

Are the two substituents cis or trans?

Accepted Answer

The two substituents are on the same side of the double bond, so they are cis.

Question 10

Rank the following conformers of the isomers of 1-ethyl-2,4-dimethylcyclohexane from most to least stable. 
A) 
B) 
C) 
D)

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Question 11

Draw the lowest energy chair conformer of the most stable isomer of 4-isopropyl-1,2-dimethylcyclohexane.

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Question 12

Are the two substituents cis or trans?

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The answer of Are the two substituents cis or trans?...

Question 13

Are the two substituents cis or trans?

Accepted Answer

The answer of Are the two substituents cis or trans?...

Question 14

How many distinct resonances would appear in the (proton-decoupled) ¹³C NMR spectrum of 1,1-diethyl-3-methylcyclobutane?

Accepted Answer

1,1-diethyl-3-methylcyclobutane has 6 unique carbon atoms, thus it could have a maximum of 6 distinct resonances in its NMR spectrum. However, some of these carbons may be overlapping due to their similar chemical environments. 
Looking at the molecule, we can see that the two methyl (CH3) groups are chemically equivalent and will produce a single resonance at the same chemical shift. Thus, we can treat them as a single carbon. Similarly, the two ethyl (CH2CH3) groups are also chemically equivalent and will produce a single resonance at the same chemical shift, so we can treat them as a single carbon too. 
Therefore, the molecule can be simplified into a system of four distinct carbon atoms, which would give rise to a maximum of 4 distinct resonances in the NMR spectrum. Thus, the answer is C) 6 distinct resonances.

Quiz 4: Alkanes and Cycloalkanes

Which of the following is the most stable isomer?

Which of the following is the least stable chair conformer of the most stable isomer of 1-ethyl-2,4-dimethylcyclohexane?

Draw the most stable conformation of trans-1,4-diethylcyclohexane.

Are the two substituents cis or trans?

Draw the most stable chair conformer of cis-1,4-diethylcyclohexane.

Which is more stable?

How many distinct signals would appear in the (proton-decoupled) 13C NMR spectrum of 2,4-dimethylpentane?

Which is more stable?

Are the two substituents cis or trans?

Rank the following conformers of the isomers of 1-ethyl-2,4-dimethylcyclohexane from most to least stable. A) B) C) D)

Draw the lowest energy chair conformer of the most stable isomer of 4-isopropyl-1,2-dimethylcyclohexane.

Are the two substituents cis or trans?

Are the two substituents cis or trans?

How many distinct resonances would appear in the (proton-decoupled) 13C NMR spectrum of 1,1-diethyl-3-methylcyclobutane?

How many distinct signals would appear in the (proton-decoupled) ¹³C NMR spectrum of 2,4-dimethylpentane?

How many distinct resonances would appear in the (proton-decoupled) ¹³C NMR spectrum of 1,1-diethyl-3-methylcyclobutane?