Question

Relative polarities of the components analgesic drugs: Ibuprofen, acetaminophen, caffeine, salicylamide, acetylsalicyclic acid, on their functional groups. What is the Behavior of components on the TLC plates based on structure polarity.

Answer 1

The relative polarity of a compound depends on their functional groups.Polarity of a compound is affected by the following factors.

1. hydrogen bond,
2. number of electronegative atoms
3. polarizability of the bonds or atoms
4. net dipole moment of the molecule
5. presence of hetro atoms like oxygen, nitrogen, sulphur

double salts are more polar and methyl is least polar.

• Behaviour of a compound on a TLC plate is governed by its structure.
• least polar compound moves the farthest on the TLC plate

ORDER OF POLARITY IS AS FOLLOWS:

Caffine

​It is a very polar molecule because it has 2 carbonyl groups and 4 nitrogens having lone pair on them.

Acetaminophen (paracetamol)

It has 3 polar groups which makes it highly polar.

Acetylsalicyclic acid(aspirin)

It conatins 2 highly polar groups ie acetyl group and carboxylic acid group.

Salicylamide

It has 2 polar groups but its polarity is lower than acetylsalicylic acid.

Iboprofen

It has only one polar functional group i.e. carboxylic acid group and hence has lower polarity.