CSUS, CH6B
[Lipids]
Instructor: J.T.,
P. 1
Glycerol, also well known as glycerine
OH
HO
OH
Example of saturated fatty acids:
Hexanoic acid
CH3 (CH2)4-COOH
Alcohol + Organic acid → Ester
(You know about it!)
glycerol + fatty acid
→ glyceride
glycerol + 3 fatty acids → tri glyceride
Note:
First, the -OH bond on the acid is broken and the -H bond on the alcohol is also
broken. Both join to make HOH, a water molecule.
glycerol + 3 Lauric acids → tri laurorylglycerol
C3H5 (OH)3 + 3 CH3 (CH2)10COOH →
O
O
C
O
CH2 10 CH3
O
C
CH2 10 CH3
O
C
CH2 10 CH3
O
CSUS, CH6B
[Lipids]
Instructor: J.T.,
P. 2
Basic hydrolysis of an ester:
CH2-OOC-R - CH-OOC-R - CH2-OOC-R (fat) + 3 NaOH (Both heated) →
CH2-OH -CH-OH - CH2-OH (glycerol) + 3 R-COO- Na+ (soap)
Where R= (CH2)14CH3 in this example.
Fatty acids are classified as saturated or unsaturated, according to whether they have carbon-carbon
double bond or not:
a)
Saturated fatty acid:
H3C(CH2)16COOH + Br2
b)
No Reaction
Unsaturated fatty acid:
H3C(CH2)7
H3C(CH2)7
C
C
H
H
Br
Br
C
C
H
H
(CH2)7
COOH
(CH2)7
COOH
+ Br2
→
CSUS, CH6B
[Lipids]
Instructor: J.T.,
P. 3
A steroid is a type of organic compound that contains a specific arrangement of four cycloalkane rings.
D
C
A
B
Liebermann - Burchard Test:
Pronunciation: lē-bər-mən-bu r-kärt
Application: A test for unsaturated steroids (as cholesterol).
Regents: Acetic anhydride in the presence of concentrated sulfuric acid.
Results: The change in color may be gradual pink - blue purple – Deep Green.
Chemical Reactions:
Hydroxyl group at C3 of cholesterol + (CH3CO)2O + H2SO4 → Cholestery acetate
Cholestery acetate → aromatic sulfonic acids
The chemical origin of the LB color remains unknown *.
21
22
20
24
18
11
12
16
9
1
8
14
15
10
3
4
5
HO
*
25
13
19
2
Reference: Lipids (2007) 42:87–96
6
27
23
17
7
Cholesterol
26