Question

Which configuration has no stereo genic center?

a)		b)		c)
d)		e)		f)
g)		h)

Answer 1

Hint: Stereo genic center means a particular location in a molecule where a switching of any two groups should generate a new stereoisomer. Maximum stereo genic centers are chiral in nature. Generally chiral carbons generate stereo genic centers.

Complete Solution :
 - In the given question there are eight molecules present. We have to find the molecules which have a stereo genic center in it. Coming to the given molecules.
- Molecule (a)

- The molecule (a) has stereo genic center nothing but a chiral center and it is labeled with a star mark.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

 

- Molecule (b)

- The molecule (b) has stereo genic center nothing but a chiral center and it is labeled with a star mark.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

- Molecule (c)

- The molecule (c) has stereo genic center nothing but a chiral center and it is labeled with a star mark.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

- Molecule (d)

- The molecule (d) does not contain any chiral carbon. Then molecule (d) won’t generate any stereo isomers by changing the groups. So, molecule (d) does not contain stereo genic center.
- Molecule (e)
 

- The molecule (e) has stereo genic center nothing but a chiral center and it is labeled with a star mark.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

- Molecule (f)

- The molecule (f) has four stereo genic centers with nothing but four chiral centers and they are labeled with star marks.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

 - Molecule (g)

- The molecule (g) has stereo genic center nothing but a chiral center and it is labeled with a star mark.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

- Molecule (h)

- The molecule (h) has two stereo genic centers with nothing but two chiral centers and they are labeled with star marks.
- On interchanging the groups on chiral carbon the molecule formed a new stereo isomer and we can see it in the following picture clearly.

So, the correct answer is “Option D”.

Note: Don’t be confused with stereo genic center and chiral carbon. Both are the same. If a molecule contains chiral carbon means it has a stereo genic center in it. By interchanging the groups on chiral carbon generates a new stereoisomer.