fatty acids and triglycerides
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Triglycerides and Chemistry of Fatty acids
CHM4201:SPECIAL TOPIC IN ORGANIC CHEMISTRY
Group Members:
Nur Fatihah binti Abas (154120)Faridah binti Sulaiman (154603)Wan Fatihah Nasuha binti Wan Nor (154115)
Lecturer’s Name:
Prof. Mawardi Rahmadi
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Learning outcomes:
1) To understand about fatty acid and triglycerides.
2) To know the physical and chemical properties of fatty acid and triglycerides.
3) To distinguish between fatty acid and triglycerides.
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Fatty Acids
• Long straight-chain carboxylic acids
▫no branching
• Most common chains range from 10–20 carbons in length
• Usually, an even number of carbons in the chain,
including the carboxyl carbon
• Can be saturated or unsaturated, but usually no other
functional groups present
▫Any fatty acid that cannot be synthesized by the body is
called an essential fatty acid
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Structure of fatty acids
• A fatty acid is nothing more than a long C-H chain with a carboxyl group (COOH) on the end.
• The COOH gives it an acid property.
• The 3….dots represent the chain is very long.
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Physical Properties of Fatty Acids
•Solubility>Longer chains
• more hydrophobic, less soluble.>Double bonds increase solubility.•Melting points
• Depend on chain length and saturation• Double bonds lead chain disorder and low melting
temperature.• Unsaturated FAs are solids at Room Temperature.
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Fatty Acids•The most common fatty acids.
Unsaturated Fatty Acids
Saturated Fatty Acids
20:418:318:218:116:1
20:018:016:014:012:0
Carbon Atoms:Double Bonds
Melting Point(°C)
Common Name
-49-11-5161
7770635844
Arachidonic acidLinolenic acidLinoleic acidOleic acidPalmitoleic acid
Arachidic acidStearic acidPalmitic acidMyristic acidLauric acid
Higher mp
Lower mp
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Types of fatty acids
• long-chain• medium-chain• short-chain
The Length of the Carbon
Chain
• saturated• unsaturated
The Degree of
Unsaturation
• omega-3 fatty acid• omega-6 fatty acid
The Location of Double
Bonds
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Medium-chain Fatty Acid(6-10 carbons)
Long-chain Fatty Acid(12 or more carbons)
Short-chain Fatty Acid(less than 6 carbons)
The Length of the Carbon Chain
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The Degree of
Unsaturation
saturated
Unsaturated(cis or trans
configuration)
monounsaturated
polyunsaturated
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Saturated and Unsaturated FAs
•Saturated FAs have no double bonds. (C-C) Double bonds lower the melting temperature
•Unsaturated FAs have at least one double bond (C=C) in one of the fatty acids
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Saturated Fatty Acid
All single bonds between carbons
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Monounsaturated Fatty Acid
One carbon-carbon double bond
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Polyunsaturated Fatty Acid
More than one carbon-carbon double bond
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Structure
•Stearic acid: a typical saturated fatty acid with 18 carbons in the chain
•Oleic acid: a typical unsaturated fatty acid with 18 carbons in the chain
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Cis-fatty acid: H’s on same side of the double bond; fold into U-like formation; naturally occurring.
Trans-fatty acid: H’s on opposite side of double bond; more linear; occur in partially hydrogenated foods
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Location of Double Bonds
•Polyunsaturated fatty acid (PUFA) are identified by position of the double bond nearest the methyl end (CH3) of the carbon chain; this is described as a omega number.
• If PUFA has first double bond 3 carbons away from the methyl end => omega 3 FA
•6 carbons from methyl end => omega 6 FA
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Omega-3
Omega-6
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Fatty Acid Nomenclature
•Nomenclature reflects location of double bonds
•Also used are common names (e.g: oleic, stearic, palmitic)
•Linoleic is also known as 18:2 n-6•This means the FA is 18 carbons in length, has
2 double bonds, the first of which is on the 6th carbon
•Arachidonic => 20:4 n-6
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Classification and Structure-Saturated Fatty Acids
Common Name Systematic Name Formula
Butyric acid n-butanoic
Caproic acid n-hexanoic
Caprylic acid n-octanoic
Capric acid n-decanoic
Lauric acid n-dodecanoic
CH3(CH2)2CO
OH
CH3(CH2)4CO
OH
CH3(CH2)6CO
OH
CH3(CH2)8CO
OH
CH3(CH2)10CO
OH
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Common Name Systematic Name Formula
Myristic acid n-tetradecanoic
Palmitic acid n-hexadecanoic
Stearic acid n-octadecanoic
Arachidic acid n-eicosanoic
Behenic acid n-docosanoic
Lignoceric acid n-tetracosanoic
CH3(CH2)12CO
OH
CH3(CH2)14CO
OH
CH3(CH2)16CO
OH
CH3(CH2)18CO
OH
CH3(CH2)20CO
OH
CH3(CH2)22CO
OH
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Naming for Unsaturated FAs
H C H 2 C H 2 C H 2 C H 2 C H 2 C H 2 C O H
O
C H 3 ( C H 2 ) 7 H C C 1 9
C 2 H
10 9 8 7 6 5 4 3 2 1
Δ 9, 10 - Octadecenoic acid
9 - Octadecenoic acid
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Common Name of Fatty Acids
Common Name Systematic Name
Myristoleic 9-tetradecenoic acid
Palmitoleic 9-hexadecenoic acid
Oleic 9-octadecenoic acid
Vaccenic 11-octadecenoic acid
Erucic 13-docosenoic acid
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Chemical Reactions of Fatty Acids
Esterification reacts fatty acids with alcohols to form esters and water
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Fatty Acid Hydrolysis
•Acid Hydrolysis reverses esterification▫Fatty acids are produced from esters
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Saponification•Saponification is the base-catalyzed hydrolysis of
an ester•Products of the reaction are
▫An alcohol ▫An ionized salt which is a soap
Soaps have a long uncharged hydrocarbon tail Also have a negatively charged carboxylate group at
end Form micelles that dissolve oil and dirt particles
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Reaction at the Double Bond
•Hydrogenation is an addition reaction•Unsaturated fatty acids can be converted to
saturated fatty acids•Hydrogenation is used in the food industry
2 H2, Ni
CH3 CH2 C
O
OH16
CH2CH CH CH2 C
O
OHCH3 CH2 CH CH4 7
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Hydrogenation
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•An ester of glycerol with three fatty acids.
•Also known as triacylglycerols
•One type of lipid categorised as simple lipid.
Triglycerides
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Structure of Triglycerides
•Glycerides are lipid esters•A triglyceride places fatty acid chains at each
alcohol group of the glycerol
CH2
CH
CH2
O
O
O CO
CO
CO
R1
R2
R3
Glycerolpart Fatty acid
chains
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Glycerol
•Glycerol Always looks the same
•3 C’s with 3 OH’s and everything else H’s.
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Formation of Triglycerides
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Example of triglycerides▫Triglyceride derived from one molecule each of
palmitic acid, oleic acid, and stearic acid, the three most abundant fatty acids in the biological world.
CH2OC(CH2)14CH3
CH2OC(CH2)16CH3
CH3(CH2)7CH=CH(CH2)7COCH
O
O
O
oleate (18:1)
stearate (18:0)
palmitate (16:0)
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Physical properties of triglycerides
•Physical properties depend on the fatty acid components.▫Melting point increases as the number of carbons in
its hydrocarbon chains increases and as the number of double bonds decreases.
▫Oils: Triglycerides rich in unsaturated fatty acids are generally liquid at room.
▫Fats: Triglycerides rich in saturated fatty acids are generally semisolids or solids at room temperature.
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Physical properties of triglycerides
▫Hydrocarbon chains of saturated fatty acids can lie parallel with strong dispersion forces between their chains; they pack into well-ordered, compact crystalline forms and melt above room temperature.
▫Because of the cis configuration of the double bonds in unsaturated fatty acids, their hydrocarbon chains have a less ordered structure and dispersion forces between them are weaker; these triglycerides have melting points below room temperature.
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Chemical Properties
Triglycerides have typical ester and alkene chemical properties as they are composed of these two groups:-
▫Saponification: replace H with salt from a strong base
▫Hydrolysis: produces the fatty acids and glycerol, a reverse of formation
▫Hydrogenation: saturates the double bonds
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Triglyceride Reactions
•Triglycerides undergo three basic reactions•These reactions are identical to those studied in
carboxylic acids
Triglyceride
GlycerolFatty Acids
GlycerolFatty Acid Salts
More saturatedtriglyceride
H2O, H+
NaOH
H2, Ni
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Hydrolysis
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Saponification
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Hydrogenation
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QUIZ
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What’s What?
•Identify the glycerol molecule
•The fatty acids
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THANK YOU