MEDCHEM.1 Introduction to chirality

Question 1

What are structural isomers

Answer 1

Structural isomers have the same molecular formula but differ in the arrangement of atoms within the molecule.

Question 2

What are stereoisomers

Answer 2

Stereoisomers have the same molecular formula and the same connectivity of atoms, but differ in their spatial arrangement.

Question 3

Define chirality

Answer 3

The property of an object or molecule that is not superimposable on its mirror image.

Question 4

Define chiral

Answer 4

A molecule is chiral if it cannot be superimposed onto its mirror image.

Question 5

Define achiral

Answer 5

A molecule is achiral if it can be superimposed onto its mirror image.

Question 6

Define stereogenic center

Answer 6

A stereogenic center, also known as a chiral center, is a carbon atom that is bonded to four different groups. It is responsible for generating stereoisomers.

Question 7

Define enantiomers

Answer 7

A pair of molecules that are non-superimposable mirror images of each other. They have the same connectivity of atoms but differ in their three-dimensional arrangement. Enantiomers are chiral molecules.

Question 8

Physical properties of enantiomers

Answer 8

Enantiomers have identical physical properties such as melting point, boiling point, and density.

Question 9

Discuss the optical activity of enantiomers

Answer 9

Enantiomers exhibit optical activity, which means they rotate the plane of polarized light in opposite directions. One clockwise while the other anticlockwise.

Question 10

What do you call an enantiomer that causes a clockwise (+) rotation of plane of polarized light?

Answer 10

dextrorotatory

Question 11

What do you call an enantiomer that causes an anticlockwise (-) rotation of plane of polarized light?

Answer 11

levorotatory

Question 12

Name the instrument that allows the differentiation between a pair of enantiomers

Answer 12

Polarimeter

Question 13

How can you differentiate between a pair of enantiomers.

Answer 13

By comparing the direction and angle of rotation of polarized light.

Question 14

What is specific rotation?

Answer 14

A measure of the extent and direction of optical rotation caused by a substance.

Question 15

What is the equation to calculate specific rotation?

Answer 15

[α] = α / (c × l)

Question 16

Define racemic mixture

Answer 16

A 50:50 mixture of two enantiomers.

Question 17

Does a racemic mixture exhibit optical activity? Why or why not

Answer 17

In a racemic mixture, the enantiomers are present in equal amounts, and their optical rotations cancel each other out. As a result, a racemic mixture exhibits no net optical rotation and is optically inactive.