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 long-chain 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

General formula of a triacylglycerol.

• 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:

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 even2) Can be saturated or unsaturated3) May contain three different fatty acids

oleic acid

18 carbon chain length1 double bond

linoleic acid

18 carbon chain length2 double bonds

Saturated Fatty Acids

O

OH

lauric acid

O

OH

palmitic acid

O

OH

stearic acid

• 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

• 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

WikipediaHeating 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• Emulsification• Heavy metals• Acidity• Unsaturations

Acidification of a soap molecule(test for unsaturations)

O

O-Na+

HCl

O

OH

+ NaCl

Bromination

• Addition of Bromine across double bonds.• Test for unsaturations• Yellow/Orange to Clear

O

O-Na+

Br2

O

O- Na+

+ NaCl

BrBr