Chapter 4, Problem 4.26P

Interpretation Introduction

(a)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is:

The dash-wedge structure shows one hydrogen atom, two carbon atoms on the indicated bond, and the methyl group in one plane. One hydrogen atom on each carbon atom is oriented away from the viewer with bromine, and one hydrogen atom is oriented towards the viewer. For the purpose of determining the positions of the groups in the Newman projection, the carbon bearing the bromine atom is numbered 1, with the other carbon on the bond numbered 2. Looking along the bond in $\text{C1}\to \text{C2}$ the top hydrogen and methyl groups will be above the carbon atoms in the Newman projection, in eclipsed positions. The bromine on the front carbon will appear on the right. Therefore, the Newman projection of the molecule can be drawn as shown below:

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(b)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure shows two groups $-\text{OH and}-{\text{CH}}_{\text{3}}$ along with C1 and C2, and the carbon atoms on the indicated bond are in the same plane. This means $-\text{OH and}-{\text{CH}}_{\text{3}}$ groups will appear in eclipsed position in the Newman projection. When looking down the indicated bond in $\text{C1}\to \text{C2}$ direction, the bromine on the front carbon (C1) will appear going toward the right and down as it is shown with a wedge bond in the dash-wedge representation. The $-{\text{C(CH}}_{\text{3}}{\text{)}}_{\text{3}}$ on the back carbon (C2) will appear going toward left and down in the Newman projection. Therefore, the Newman projection can be drawn as shown below.

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(c)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is:

It shows that the carbon on the indicated bond along with $-\text{OH}$ on one carbon and one of the methyl groups on the other carbon are in the plane of the paper. Moreover, $-\text{OH}$ and the methyl groups are shown on the opposite sides of the bond. Therefore, these two groups will appear in staggered positions in the Newman projection.

Looking along the indicated bond in $\text{C1}\to \text{C2}$ direction, the second methyl group on the back carbon (C2) will appear going to the right and up. Therefore, the Newman projection of the given molecule can be drawn as

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(d)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is:

The molecule is substituted cyclopentane. The two groups on each of the carbons C2 and C3 are in axial-equatorial positions. On C3, both are hydrogen atoms. On C2, one is a methyl group in the axial position, and the other is hydrogen in equatorial position.

Looking along the indicated bond in $\text{C2}\to \text{C3}$ direction, the methyl group on the back carbon (C2) will appear going straight up, with the hydrogen to its right, angled at ${120}^{\text{o}}$. One of the hydrogen atoms in C3 will be oriented straight down with the other one going to its right, angled at ${120}^{\text{o}}$. The remaining part of the ring appears on the left with C4 angled left and up on the back carbon and C6 angled left and down on the front carbon.

Therefore, the Newman projection of the given molecule can be drawn as:

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(e)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is:

The molecule is substituted cyclopentane. The two groups attached to the ring carbon C2 are methyl in an equatorial up position and hydrogen in an axially down position. The two groups attached to C3 are both hydrogens, one in axial up position and the other in equatorial down position. Looking down the indicated bond in the $\text{C2}\to \text{C3}$ direction, the methyl group on the front carbon (C2) in the Newman projection will appear going toward right and up. The hydrogen will appear going to the right and down. The two hydrogens on the back carbon (C3) appear going straight down and to the right and down. The remaining part of the ring will appear on the left with C6 carbon on front slanted up and C4 carbon on back slanted down.

The Newman projection of the molecule can therefore be drawn as

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(f)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is:

The molecule is substituted cyclohexane in a chair conformation. The methyl groups on the two carbons (C2 and C3) on the indicated bond are both in equatorial positions. The other two groups, both hydrogens, are in axial positions. Looking along the indicated bond in the $\text{C2}\to \text{C3}$ direction, the methyl group on the front carbon (C2) in the Newman projection will appear going to the left and up with the hydrogen straight down. The methyl group on the back carbon (C3) will appear going to the left and down with the hydrogen going straight up. The remaining part of the ring will appear on the right with C7 carbon, on the front, going right and up. C4 carbon, on the back, will go toward right and down.

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(g)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is

The molecule is substituted cyclohexane in a chair conformation. The two groups attached to C1 are bromine in axial down position and hydrogen in equatorial up position. The two groups attached to C2 are methyl in axial up position and hydrogen in equatorial down position. Looking down the indicated bond, the bromine on the front carbon (C1) and the methyl group on the back carbon (C2), in the Newman projection, will appear straight up and straight down respectively, in staggered positions. The hydrogen on front carbon C1 will appear going to the left, slanted up. The hydrogen on back carbon C2 will appear going left, slanted down. The rest of the ring will appear on right with C6 carbon, on the front. slanted up. C3 carbon, on the back, will appear going to right, slanted down.

The Newman projection of the molecule can then be drawn as

Conclusion

Newman projection represents a molecular structure looking along a particular bond.

Interpretation Introduction

(h)

Interpretation:

The Newman projection for the species shown is to be drawn looking down the bond indicated in red.

Concept introduction:

A Newman projection is used to visualize the conformation of a molecule by representing it as viewed down the bond of interest. The dot represents front atom, and the circle represents the back atom. The bonds to the front carbon converge on the central point while the bonds to the back carbon end on the circle.

Answer to Problem 4.26P

Newman projection of the given structure is:

Explanation of Solution

The dash-wedge structure of the molecule is

The molecule is substituted cyclohexane in boat conformation. The two groups on C1 are $-\text{OH}$ in an equatorial up position and hydrogen in an axial down position. The two groups on C2 are bromine in axial down position and hydrogen in equatorial up position. The two groups on the indicated carbon atoms are in eclipsed positions.

Looking down the indicated bond, the $-\text{OH}$ on the front carbon (C1) of the Newman projection will appear going to the left, slanted up, with hydrogen going straight down. The bromine on the back carbon (C2) will appear going straight down, with the hydrogen to the left, slanted up. The remaining part of the ring will appear on the right with C6 carbon, on front, slanted up, and C3 carbon, on back, slanted down. The Newman projection of the molecule can therefore be drawn as

Conclusion

Newman projection represents a molecular structure looking along a particular bond.