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WS34chem205editedfinal12.pdf
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WS34chem205editedfinal12.pdf

CHEM 205 Worksheet (WS3) (58 points total)

– will result in zero on assignment and “F” for the course).

Key Topics: Nomenclature, Conformational Stability, Newman Projections, Chair Structures

1. Using IUPAC rules (see Chapter 2.14-2.18 and Table 2.4 and 2.5 in text) provide a name to each

structure below. Use common names for branched substituents were applicable. (6pts)

2. (a) Convert the semi-synthetic animal steroid shown below in bond-line form to its proper chair

form by drawing in the missing non-hydrogen groups in their proper orientation and circle the groups that

are axial. The skeleton is made up of the tetracyclic ring core. These 4 rings have been labeled A thru D

for clarity. (7pts)

(b) Identify the two fused rings that represent a trans-decalin system (1pt) __________________

3-isopropyl-2,4-dimethylhexane

2-Butylcyclopentane

1,4-diethyl-2-methylcyclohexane

A, B cis-fused

3. (a) Sighting down the C1  C2 bond, consider the bond-line structure shown below. Using the Newman

projection templates provided, draw all three staggered conformations in Newman projection form in

order of increasing stability about the C1  C2 bond. (6pts) You may assume that iPr > Et > Cl in terms of

size.

(b) Sighting down the C3  C4 bond, consider the bond-line structure shown below. Using the Newman

projection templates provided, draw all three eclipsed conformations in Newman projection form in

order of increasing stability about the C3  C4 bond. (6pts)

You need to fill in the empty boxes with the correct substituents (hydrogen and non-hydrogen groups). Use

the numbering scheme provided. (4pts)

(ii) Circle the bond-line structure below that best represents the same structure provided above in part c(i)

(2pts).

ipr

Me H

B, C trans-fused

(iii) (1pt) Is the iPr group at C-1 in the chair axial or equatorial? _____ ______________

(iv) (1pt) Is the CH3 group at C-2 in the chair axial or equatorial? ___________________

4. For (a) circle the most relative stable structure. Show work by drawing relevant chair structures

and/or Newman projections (as needed) to clearly illustrate why. Explain your choice with a few words

(no more than one sentence). It is best practice here that only the most stable conformations for each

compound are being compared. For (b), provide a brief explanation for why chair 1 is more stable than

chair 2. (10pts)

5. (a) (3pts) Provide a systematic (IUPAC) name for the structure below. You may ignore

stereochemistry.

7-methylbicyclo(4.2.1)nonane _________________________________________________________________________

(b) Draw the structure of each compound below. Be sure to clearly show the relative stereochemistry.

Then, circle the compound that will have the highest heat of combustion. (4pts)

Axial

Equatorial

B is more stable since

molecules are further

apart.

Chair 1 is more stable than chair 2

because the molecules are further apart

and unlikely to interact with each other.

6. Draw and compare the Newman projections of when the OH groups are anti to each other versus when

they are gauche to each other. Then, explain in a few words why the compound is more stable in the

conformation where the OH groups are gauche to each other. (6pts)

The compound is more stable where the OH groups are gauche as the two OH groups are too close

together leading to a repulsive interaction and more energy.

WS34chem205editedfinal12.pdf

CHEM 205 Worksheet (WS3) (58 points total)

– will result in zero on assignment and “F” for the course).

Key Topics: Nomenclature, Conformational Stability, Newman Projections, Chair Structures

1. Using IUPAC rules (see Chapter 2.14-2.18 and Table 2.4 and 2.5 in text) provide a name to each

structure below. Use common names for branched substituents were applicable. (6pts)

2. (a) Convert the semi-synthetic animal steroid shown below in bond-line form to its proper chair

form by drawing in the missing non-hydrogen groups in their proper orientation and circle the groups that

are axial. The skeleton is made up of the tetracyclic ring core. These 4 rings have been labeled A thru D

for clarity. (7pts)

(b) Identify the two fused rings that represent a trans-decalin system (1pt) __________________

3-isopropyl-2,4-dimethylhexane

2-Butylcyclopentane

1,4-diethyl-2-methylcyclohexane

A, B cis-fused

3. (a) Sighting down the C1  C2 bond, consider the bond-line structure shown below. Using the Newman

projection templates provided, draw all three staggered conformations in Newman projection form in

order of increasing stability about the C1  C2 bond. (6pts) You may assume that iPr > Et > Cl in terms of

size.

(b) Sighting down the C3  C4 bond, consider the bond-line structure shown below. Using the Newman

projection templates provided, draw all three eclipsed conformations in Newman projection form in

order of increasing stability about the C3  C4 bond. (6pts)

You need to fill in the empty boxes with the correct substituents (hydrogen and non-hydrogen groups). Use

the numbering scheme provided. (4pts)

(ii) Circle the bond-line structure below that best represents the same structure provided above in part c(i)

(2pts).

ipr

Me H

B, C trans-fused

(iii) (1pt) Is the iPr group at C-1 in the chair axial or equatorial? _____ ______________

(iv) (1pt) Is the CH3 group at C-2 in the chair axial or equatorial? ___________________

4. For (a) circle the most relative stable structure. Show work by drawing relevant chair structures

and/or Newman projections (as needed) to clearly illustrate why. Explain your choice with a few words

(no more than one sentence). It is best practice here that only the most stable conformations for each

compound are being compared. For (b), provide a brief explanation for why chair 1 is more stable than

chair 2. (10pts)

5. (a) (3pts) Provide a systematic (IUPAC) name for the structure below. You may ignore

stereochemistry.

7-methylbicyclo(4.2.1)nonane _________________________________________________________________________

(b) Draw the structure of each compound below. Be sure to clearly show the relative stereochemistry.

Then, circle the compound that will have the highest heat of combustion. (4pts)

Axial

Equatorial

B is more stable since

molecules are further

apart.

Chair 1 is more stable than chair 2

because the molecules are further apart

and unlikely to interact with each other.

6. Draw and compare the Newman projections of when the OH groups are anti to each other versus when

they are gauche to each other. Then, explain in a few words why the compound is more stable in the

conformation where the OH groups are gauche to each other. (6pts)

The compound is more stable where the OH groups are gauche as the two OH groups are too close

together leading to a repulsive interaction and more energy.

WS34chem205editedfinal12.pdf

CHEM 205 Worksheet (WS3) (58 points total)

– will result in zero on assignment and “F” for the course).

Key Topics: Nomenclature, Conformational Stability, Newman Projections, Chair Structures

1. Using IUPAC rules (see Chapter 2.14-2.18 and Table 2.4 and 2.5 in text) provide a name to each

structure below. Use common names for branched substituents were applicable. (6pts)

2. (a) Convert the semi-synthetic animal steroid shown below in bond-line form to its proper chair

form by drawing in the missing non-hydrogen groups in their proper orientation and circle the groups that

are axial. The skeleton is made up of the tetracyclic ring core. These 4 rings have been labeled A thru D

for clarity. (7pts)

(b) Identify the two fused rings that represent a trans-decalin system (1pt) __________________

3-isopropyl-2,4-dimethylhexane

2-Butylcyclopentane

1,4-diethyl-2-methylcyclohexane

A, B cis-fused

3. (a) Sighting down the C1  C2 bond, consider the bond-line structure shown below. Using the Newman

projection templates provided, draw all three staggered conformations in Newman projection form in

order of increasing stability about the C1  C2 bond. (6pts) You may assume that iPr > Et > Cl in terms of

size.

(b) Sighting down the C3  C4 bond, consider the bond-line structure shown below. Using the Newman

projection templates provided, draw all three eclipsed conformations in Newman projection form in

order of increasing stability about the C3  C4 bond. (6pts)

You need to fill in the empty boxes with the correct substituents (hydrogen and non-hydrogen groups). Use

the numbering scheme provided. (4pts)

(ii) Circle the bond-line structure below that best represents the same structure provided above in part c(i)

(2pts).

ipr

Me H

B, C trans-fused

(iii) (1pt) Is the iPr group at C-1 in the chair axial or equatorial? _____ ______________

(iv) (1pt) Is the CH3 group at C-2 in the chair axial or equatorial? ___________________

4. For (a) circle the most relative stable structure. Show work by drawing relevant chair structures

and/or Newman projections (as needed) to clearly illustrate why. Explain your choice with a few words

(no more than one sentence). It is best practice here that only the most stable conformations for each

compound are being compared. For (b), provide a brief explanation for why chair 1 is more stable than

chair 2. (10pts)

5. (a) (3pts) Provide a systematic (IUPAC) name for the structure below. You may ignore

stereochemistry.

7-methylbicyclo(4.2.1)nonane _________________________________________________________________________

(b) Draw the structure of each compound below. Be sure to clearly show the relative stereochemistry.

Then, circle the compound that will have the highest heat of combustion. (4pts)

Axial

Equatorial

B is more stable since

molecules are further

apart.

Chair 1 is more stable than chair 2

because the molecules are further apart

and unlikely to interact with each other.

6. Draw and compare the Newman projections of when the OH groups are anti to each other versus when

they are gauche to each other. Then, explain in a few words why the compound is more stable in the

conformation where the OH groups are gauche to each other. (6pts)

The compound is more stable where the OH groups are gauche as the two OH groups are too close

together leading to a repulsive interaction and more energy.

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