Practical Organic Chemistry 1
-
Upload
allen-joie-navarro -
Category
Documents
-
view
243 -
download
0
Transcript of Practical Organic Chemistry 1
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 1/19
Solubility behavior of organic
compounds
Dotsha J. Raheem
Muslih S. Hamasharif
College of Science
Department of Chemistry
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 2/19
1. Solubility (definition)2. Information obtained from solubility
3. Types of solubility
4. Factors affecting solubility5. Water soluble compounds
2
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 3/19
The amount of solute needed to form a
solution in a given quantity of solvent.
Soluble if it dissolves to the extent of
(3.3g/ 100 ml ) of solvent
Solubility ( definition)
3
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 4/19
Information obtained from solubility
i. Presence of a functional group.
Because hydrocarbons are insoluble in water, observing thatan unknown is partially soluble in water indicates that a polar
functional group is present.
4
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 5/19
ii. Solubility in certain solvents often leads to
more specific information about functional
group.
5
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 6/19
iii. Certain conclusions about molecular size and
composition may sometimes be made from
solubility tests.
CH3(CH2)nCH2OH If ( n) higher than 5 is water insoluble
If ( n) fewer than 5 is water solublemonofunctional
compounds
6
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 7/19
types of solubilityThe solubility of organic compounds can be divided into two
categories:
e.g. benzoic aciddissolves in 5% NaOH but
not in H2O
e.g. CHCl3 in C2H5-O-C2H5
Utilized for identi-
fication of functional
groups
To determine
solvents for chemical
reactions and
purification (as in
recrystallization)7
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 8/19
Factors affecting solubility1-Temperature:
A-if the solution process absorbs energy then
the solubility will be increase with increasing
temperature.B-if the solution process releases energy then
the solubility will decrease with increasing
temperature.
8
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 9/19
Factors affecting solubility2-Polarity:
“Like dissolves like”
9
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 10/19
• Polar compounds dissolve in polar solvents
• Ionic compounds dissolve in polar solvents.
H
H
N
OH
H
CH3
H
H
N
OH
H
CH3
Hydrogen
bonding
CH3NH2 + H2O
methyl
amine
water
10
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 11/19
• non polar compounds dissolve in non polar
solvents
e.g. Iodine(I2)is a (non polar) and soluble in nonpolar solvents like carbon tetrachloride(CCl4).
11
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 12/19
Factors affecting solubility3-Molecular Size:
In general, an increases in molecular weight leads an increase inintermolecular forces and decreased solubility.
12
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 13/19
Q//What are the intermolecularforces?
Q//What is the relation
between melting point andsolubility
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 14/19
Factors affecting solubility4-Effect of chain branching on solubility.
1-Compounds having a branched chain are more
soluble than the corresponding straight-chain
compound (branching lowers intermolecular
forces and decreases intermolecular
attraction).
14
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 15/19
2-The position of the functional group in the
carbon chain also affects solubility.
15
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 16/19
Water soluble compounds
16
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 17/19
Solubility in H2OWhen a compound dissolves in water, it’s
expected to be:
- Low M. wt. compound- Polar
- ionic
17
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 18/19
A compound soluble in H2O and in
etherSA: Acids (carboxylic)
SB: Bases (amines)S1: Neutral compounds (alcohols, aldehydes,
ketones, esters)
General characteristics:
- Polar (non ionic)
- Contain 5 or less C atoms- Has a functional group that is polar and capable
of forming H-bonds
18
8/6/2019 Practical Organic Chemistry 1
http://slidepdf.com/reader/full/practical-organic-chemistry-1 19/19
A compound soluble in H2O but not in
etherS2: Salts of organic acids (RCO2Na, RSO3Na), amine
hydrochlorides (RNH3Cl), amino acids,carbohydrates, polyhydroxy compounds andpolybasic acids.
General characteristics:
- Ionic ( a salt)
- Contain two or more polar groups but not morethan 4C atoms per functional group
19