Lipids
• Oil, greasy organic substances found in living
organisms
• Insoluble in water (because water is very
polar)
• Soluble in organic solvents (benzene,
chloroform (trichloromethane), diethylether
(ethoxy ethane)).
• No common chemical structure
Classes of Lipids
• Fats and oils – obtained from natural sources;
important source of energy
• Phospholipids – water insoluble components
which biological membranes are constructed.
• Glycolipids – lipids attached to a sugar; energy
storage and cell recognition
• Steriods – chemical messengers
Fats and Oils
• Esters of glycerol and predominantly longchain fatty acids (carboxylic acids)
• Fats and oils are esters of glycerol and
predominantly long chain fatty acids.
• Fats and oils are esters of glycerol and
predominantly long chain fatty acids.
Ester Functional Group
Long Chain Fatty Acids
• Fats and oils are called triacylglycerols or
triglycerides since each molecule is derived
from one molecule of glycerol and three
molecules of fatty acid. Typical triacylglycerol:
General formula of a
triacylglycerol.
contains 3 fatty acids.
Triglycerides
• Vary in 3 ways…
1) length of fatty acid chain can contain
between 4 and 20 carbons, but carbon
number is almost always even
2) Can be saturated or unsaturated
3) May contain three different fatty acids
18 carbon chain length
1 double bond
oleic acid
18 carbon chain length
2 double bonds
linoleic acid
Saturated Fatty Acids
• The human body can produce all but two fatty
acids: Linoleic, alpha-Linolenic (Omega 3 and
Omega 6)
• These must be supplied in the diet.
• Impaired growth and reproduction
• Eczema and dermatitis.
• Fats are solid at room temperature.
• Fats contain a higher proportion of saturated fatty
acids.
• Oils are liquid at room temperature.
• Oils contain higher amounts of unsaturated fatty
acids.
• Polyunsaturated means that the molecules of a
particular product each contain several double
bonds.
• Monounsaturated and polyunsaturated fats are
better for humans than saturated.
Soap is made by hydrolyzing fats or oils
with aqueous NaOH or KOH. This is
called saponification.
Saponification
• When a triglyceride is reacted with KOH (potassium
hydroxide) or NaOH (sodium hydroxide or lye) a
soap is formed and glycerol.
• Triglycerides are esters.
• The base hydrolyzes the ester into soap and
glycerol.
• This is known as saponification.
• If the soap is a sodium salt, it is a “hard soap”.
• If the soap is a potassium salt, it is a “soft soap”.
Example of a “hard soap” :
Soaps
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•
•
•
Very long chain
One end is polar and the other is nonpolar
Polar end orients itself toward polar water
Nonpolar ends orient them selves toward one
another and trap grease and oil
Micelles
Wikipedia
Lipid formations
• Liposome is spherical
and contains a lipid
bilayer (2 layers)
• Micelle is also spherical,
but contains a lipid
monolayer (1 layer)
• Can also have a bilayer
sheet.
Heavy Metal Ions
• Emulsify means combining two liquids together
which normally don't mix easily.
• Iron (III), calcium and magnesium create an
insoluble salt which does not have the same
emulsification properties as soap made with
potassium and sodium.
• Addition of phosphate solves this problem but
causes another pollution problem, eutrophication.
• Eutrophication – fish and other organisms are killed
due to insufficient oxygen
LAS, ABS, SDS
• LAS - Linear alkyl sulfonates – sodium salt of an
alkylbenzenesulfonate.
– Biodegradable
– Non-branched side chain
– Soft detergent, less foam
• ABS - Alkylbenzene sulfonates
– Not biodegradable
– Branched side chain
– Hard detergent, no longer used in US
• SDS – a sodium alkyl sulfates
– Sodium dodecyl sulfate
– Very common detergent (major ingredient in carpet
shampoos)
Reflux
• Continual boiling of a solution in a vial or flask
• Solvent is continually returned to the reaction vessel
from a condenser atop the vial or flask
• Ethanol has a low boiling point and would easily
evaporate from the reaction flask without a condensor
• A common technique for carrying out organic reactions
• Reaction mixture can be heated to boiling without
solvent loss.
Reflux Equipment
Wikipedia
Heating
Mantel
What you’re doing…
• Day 1: Synthesize soap via reflux and then
cooling!
• Day 2: Testing various properties of your soap
– Tube #1 = DI water (negative control),
Tube #2 = your Soap,
Tube #3 = Detergent (positive control)
– Tests
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Emulsification
Heavy metals
Acidity
Unsaturations
Acidification of a soap molecule
Bromination
• Addition of Bromine across double bonds.
• Test for unsaturations
• Yellow/Orange to Clear