Concept explainers
(a)
Interpretation: The relation between the compounds A and B is to be determined.
Concept introduction: Newman projections are drawn to visualize the different conformations of a compound around
The stereochemistry of the compound is determined by prioritizing the groups attached to its stereogenic center. The groups are prioritized on the basis of
Answer to Problem 5.61P
Compounds A and B are identical.
Explanation of Solution
The given Newman projection A is,
Figure 1
In Newman projection, the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 2
In the given compound,
The given Newman projection B is,
Figure 3
In Newman projection the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 4
In the given compound,
Both A and B have same configuration around the stereogenic centers. Hence, compounds A and B are identical.
Compounds A and B are identical.
(b)
Interpretation: The relation between the compounds A and C is to be determined.
Concept introduction: Newman projections are drawn to visualize the different conformations of a compound around
The stereochemistry of the compound is determined by prioritizing the groups attached to its stereogenic center. The groups are prioritized on the basis of atomic number of their atoms. The group that contain atom with higher atomic number is given higher priority. Complete the circle in decreasing order of priority from
Answer to Problem 5.61P
Compounds A and C are enantiomers.
Explanation of Solution
The given Newman projection A is,
Figure 1
In Newman projection the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 2
In the given compound,
The given Newman projection C is,
Figure 5
In Newman projection the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 6
In the given compound,
Both A and C have opposite configuration around the stereogenic centers. Hence, compounds A and C are enantiomers.
Compounds A and C are enantiomers.
(c)
Interpretation: The relation between the compounds A and D is to be determined.
Concept introduction: Newman projections are drawn to visualize the different conformations of a compound around
Enantiomer of a compound has opposite configuration at stereogenic centers. Diastereomers of a compound have at least one stereogenic centre with same configuration and at least one with opposite configuration.
Answer to Problem 5.61P
Compounds A and D are diastereomers.
Explanation of Solution
The given Newman projection A is,
Figure 1
In Newman projection, the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 2
In the given compound,
The given Newman projection D is,
Figure 7
In Newman projection the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 8
In the given compound,
Both A and D have one stereogenic centre with same configuration and one with opposite configuration. Hence, A and D are diastereomers.
Compounds A and D are diastereomers.
(d)
Interpretation: The relation between the compounds C and D is to be determined.
Concept introduction: Newman projections are drawn to visualize the different conformations of a compound around
Enantiomer of a compound has opposite configuration at stereogenic centers. Diastereomers of a compound have at least one stereogenic centre with same configuration and at least one with opposite configuration.
Answer to Problem 5.61P
Compounds C and D are diastereomers.
Explanation of Solution
The given Newman projection C is,
Figure 5
In Newman projection the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 6
In the given compound,
The given Newman projection D is,
Figure 7
In Newman projection the circle represents the back carbon and the dot represents the front carbon. The back carbon is substituted by one hydroxyl, one hydrogen atom and one hydroxymethyl group and the front carbon is substituted by one hydrogen atom, one hydroxyl group and one formyl group. The skeletal structure for the given projection is,
Figure 8
In the given compound,
Both C and D have one stereogenic centre with same configuration and one with opposite configuration. Hence, compounds C and D are diastereomers.
Compounds C and D are diastereomers.
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Chapter 5 Solutions
PKG ORGANIC CHEMISTRY
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