Solubility of Organic
Compounds
Solubility of organic compound
Solute:
• Any substance that is dissolved in a liquid
or gas substance (solvent) to create a
solution
Solvent:
• A solvent is a liquid or gas that dissolves a
solid, liquid, or gaseous solute, resulting in
a solution.
Solubility:A maximum amount of a solute (solid, liquid
and gas) could be dissolved in a specific amount
of a solvent.
weight of solute (gm or ml)
Solubility =
volume of solvent (gm or ml)
Solubility of organic compound
Solubility rules:
That simple rule is “like dissolves like” and it is
based on the polarity of the systems i.e. polar
molecules dissolve in polar solvents (e.g. water,
alcohols)
non-polar molecules dissolves in non-polar
solvents (e.g. n-hexane).
The polarity of organic molecules is determined
by polar bonds due to the presence of
electronegative atoms (e.g. N, O) in polar
functional groups such as amines (-NH2) and
alcohols (-OH )
Organic Functional Groups
alcohol
carboxylic
acid
nitro
ketone
nitrile
ester
ether
NO2
O
O
OH
O
N
O
HO
O
N
imine
amine
H
N
NH2
O
aldehyde
H
amide
alkene
alkyne
O
Organic Molecules with Several Functional Groups
7
Soap Structure
Soap molecules have two distinct parts:•
- Hydrophilic polar head.
- Hydrophobic nonpolar tail.
8
Solubility process
Solute
Solvent
Solution
When a solute (solid or liquid) dissolved in a
suitable solvent, the structural units of the solute becomes
separated from each other, and the spaces between them
occupied by the solvent molecules.
H
NaCl + H2O
OH OH
OH
Na
OH
OH
OH
H Cl H
H HH
Solvation of sodium chloride (NaCl) by water (H2O)
Depending upon the chemical common sense (Like
dissolves like), means the polar solute dissolved in polar
solvent, inversely non-polar solute dissolved in nonpolar solvent.
1-Polar protic solvent:Types polar solvent in which
containing an acidic hydrogen (proton) attached
directly to oxygen, halogen and sometimes sulfur atom.
R-O-H
R-X-H
R-S-H
2- Polar aprotic solvent:
Polar solvent doesn't contain acidic proton.
Example:Acetone, DMF & DMSO
Polar solvent:
A solvent in which behave an electrostatic
force between the different charges (positive & negative )
charges and have the ability to solvate the polar solutes.
Factors Affecting Solubility
Intermolecular Forces
Pressure
Temperature
Surface area.
Solution types
Ways of Expressing Concentration
• Mole Fraction, Molarity, and Molality
moles of component in solution
Mole fraction of component 
total moles of solution
moles solute
Molarity 
liters of solution
moles solute
Molality, m 
kg of solvent