Organic chemistry practical course OCP1WS 04/05 529-0229-00 Assistant: Fabio Di Lena Isolation of cholesterol, lecithin and fatty acids from egg yolks HO CH 3 CH 3 CH 3 CH 3 CH 3 Present
Trang 1Organic chemistry practical course (OCP1)
WS 04/05
529-0229-00
Assistant: Fabio Di Lena
Isolation of
cholesterol, lecithin and fatty acids
from egg yolks
HO
CH 3
CH 3
CH 3
CH 3
CH 3
Presented by Moreno Wichert Student of Interdisciplinary Natural Sciences (Biochem.-Phys.)
D-CHAB, ETH Zurich
Nuolen SZ January 29, 2005
H 2 C HC
H 2 C
O C R 2
O C R 1
O O
O P O
O
-O
CH 2 CH 2 N(CH 3 ) 3
Choline
Trang 21 Method
Isolation of cholesterol from egg yolks Many other compounds are also present in egg yolks, including lecithins and fats, which will also be isolated Cholesterol, lecithins and fats are all soluble in a combination of ether and alcohol Extraction of pulverized egg yolks with ether and alcohol therefore seperates these compounds and some others from all the insoluble compounds in egg yolks
H 2 C
O
O
O
3 KOH
H 2 C
OH
- O C R 2
- O C R 1
O
O
O
K +
K +
2 Outline of the procedure
Egg
yolks
extraction
with ether
and alcohol
Insoluble compounds (separate)
Solution of cholesterol, lecithins, fats and other compounds evaporation
of solvent Residue of cholesterol, lecithins, fats and other compounds ether
Solution of cholesterol,
lecithins, fats and other
compounds
acetone Precipitation
of lecithins
(seperate)
Solution of cholesterol, lecithins, fats and other compounds
evaporation
of solvent
Residue of cholesterol, lecithins, fats and other compounds
KOH, ethanol, reflux Solution of cholesterol, glycerol, soap and other compounds
1 add water
2 extract with water
Aqueous solution of soap and glycerol (seperate)
Ether solution
of cholesterol
and other
compounds
(seperate)
evaporation
of solvent
Residue of
cholesterol and
other compounds
recrystallization
Cholesterol
HCl
Glycerol and precipitation
of fatty acids
extract with ether Ether solutionof fatty acids
evaporation Fatty acids
Trang 34 Experimental accomplishment
Removal of insoluble material
Two eggs were heated in boiling water for 10 minutes The rest of the eggs was seperated from the yolks which then were pulverized and weight
The pulverized yolks were placed into a 250 ml beaker and 40 ml of methanol1 and 50 ml of diethyl ether2 were added After mixing well for 5 minutes, the substance was gravity fi ltered into another 250 ml beaker while keeping the insoluble material in the fi rst beaker Another
20 ml of ether were added to the insoluble material in the fi rst beaker and fi ltered once again The alcohol-ether solution was evaporated to dryness with a rotation evaporator A thin yellow residue appeared
Isolation of lecithins
25 ml of ether were added to the residue and it was slightly warmed to dissolve all the ma-terial Acetone3 was added slowly with constant stirring until the lecithins precipitated as a gummy bulk As much as 150 ml of acetone were needed
The solution was gravity fi ltered into a 250 ml round-bottom fl ask using a loose wad of cot-ton The lecithins were washed with 10 ml of acetone and fi ltered into a round-bottom fl ask using the same cotton wad The lecithins were thoroughly dried, weight and the percentage yield was determined
Isolation of cholesterol
The acetone-ether solution was distilled to obtain a liquid oil residue 25 ml of a 15 % potas-sium hydroxide4 solution in ethanol were added to the distillate The mixture was refl uxed for
25 minutes
The solution was cooled to room temperature and it was poured into a 250 ml seperatory funnel 35 ml of water were added to the round-bottom fl ask and after swirling the wash water was added to the seperatory funnel This procedure was repeated with another 35 ml
of water
The water-alcohol solution was extracted twice with 35 ml portions of ether The two extracts were combined, then the ether was washed with 10 ml of water This water was also added
to the alcohol-water solution and it was saved for the isolation of the fatty acids
The ether solution was shaken with 15 ml of saturated salt solution to lower the water content The solutions were seperated and further the ether solution was dried over a small amount of calcium chloride5 The solution was fi ltered into a tared 150 ml beaker and it was evaporated to dryness with the rotation evaporater
The cholesterol was recrystallized from methanol using decolorizing carbon6 The purifi ed product was dried thoroughly and the weight and the percentage yield was determined Isolation of the fatty acids
The aqueous solution containing the soap was acidifi ed by carefully adding concentrated hydrochloric acid7 with stirring until a drop of the solution turned blue litmus paper red and the fatty acids had precipitated Then the entire mixture was placed into a 250 ml seperatory funnel and extracted with 25 ml portions of ether The ether extracts were combined, shaken with 15 ml of saturated salt solution to reduce the water content, seperated, then further dried over a small amount of calcium chloride
The dried ether was fi ltered into a 125 ml Erlenmeyer fl ask and the solvent was evaporated with a rotation evaporater The yield and the percentage yield were then determined
Trang 4Physical and safety data of the substances
poison class 3 ; WGK 1 ; risk phrases: R11-23-24-25-39 ; safety phrases: S7-16-36-37-45 ;
WGK 1 ; risk phrases: R12-19-22 ; safety phrases: S9-16-29-33
poison class 2 ; WGK 1 ; risk phrases: R11-22-34-35 ; safety phrases: S7-16-26-36-37-39-45
poison class 5 ; WGK 1 ; risk phrases: R36 ; safety phrases: S22-23-24
5 Analytical results and characterization
Yield:
IR bands [cm-1]:
3352 (-NH or crystal water) 3607 (O-H stretch)
6 Literature
http://www.aist.go.jp/RIODB/SDBS/sdbs/owa/sdbs_sea.cre_frame_disp?sdbsno=887
sheets which our assistant handed out (no source)
Trang 5IR reference spectrum for cholesterol
http://www.aist.go.jp/RIODB/SDBS/sdbs/owa/sdbs_sea.cre_frame_disp?sdbsno=887 (January 29, 2005)