Fatty acids and triglyceridesPresentation Transcript
CHM4201:SPECIAL TOPIC IN ORGANIC CHEMISTRY Triglycerides and Chemistry of Fatty acidsGroup Members:Nur Fatihah binti Abas (154120)Faridah binti Sulaiman (154603)Wan Fatihah Nasuha binti Wan Nor (154115)Lecturer’s Name:Prof. Mawardi Rahmadi
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.
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
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.
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.
Fatty Acids • The most common fatty acids. Carbon Atoms: Common Melting Point Double Bonds Name (°C) Satur ated Fatty Acids 12:0 Lauric acid 44Higher mp 14:0 Myristic acid 58 16:0 Palmitic acid 63 18:0 Ste aric acid 70 20:0 Arachidic acid 77 Uns aturated Fatty AcidsLower mp 16:1 Palmitoleic acid 1 18:1 Oleic acid 16 18:2 Linole ic acid -5 18:3 Linole nic acid -11 20:4 Arachidonic acid -49
Types of fatty acidsThe Length of • long-chain the Carbon • medium-chain Chain • short-chainThe Degree of • saturatedUnsaturation • unsaturatedThe Location of • omega-3 fatty acid Double Bonds • omega-6 fatty acid
The Length of the Carbon Chain Short-chain Fatty Acid (less than 6 carbons) Medium-chain Fatty Acid (6-10 carbons) Long-chain Fatty Acid (12 or more carbons)
SaturatedThe Degree ofUnsaturation Monounsaturated Unsaturated (cis or trans configuration) Polyunsaturated
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
Saturated Fatty Acid All single bonds between carbons
Monounsaturated Fatty Acid One carbon-carbon double bond
Polyunsaturated Fatty Acid More than one carbon-carbon double bond
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
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
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
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
Classification and Structure-Saturated Fatty Acids Common Name Systematic Name Formula O Butyric acid n-butanoic CH3(CH2)2C OH O Caproic acid n-hexanoic CH3(CH2)4C OH O Caprylic acid n-octanoic CH3(CH2)6C OH O Capric acid n-decanoic CH3(CH2)8C OH O Lauric acid n-dodecanoic CH3(CH2)10C OH
Common Name Systematic Name Formula OMyristic acid n-tetradecanoic CH3(CH2)12C OH OPalmitic acid n-hexadecanoic CH3(CH2)14C OH OStearic acid n-octadecanoic CH3(CH2)16C OH OArachidic acid n-eicosanoic CH3(CH2)18C OH OBehenic acid n-docosanoic CH3(CH2)20C OH OLignoceric acid n-tetracosanoic CH3(CH2)22C OH
Naming for Unsaturated FAs 10 9 8 7 6 5 4 3 2 1 O 1 9 C H3(C H2)7 HC CH C H2 CH2 CH2 CH2 C H2 CH2 C H2 C OH Δ 9, 10 - Octadecenoic acid 9 - Octadecenoic acid
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
Chemical Reactions of FattyAcids Esterification reacts fatty acids with alcohols to form esters and water
Fatty Acid Hydrolysis• Acid Hydrolysis reverses esterification ▫ Fatty acids are produced from esters
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
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 O CH3 CH2 4CH CH CH2CH CH CH2 7 C OH 2 H2, Ni O CH3 CH2 16 C OH
Triglycerides• An ester of glycerol with three fatty acids.• Also known as triacylglycerols• One type of lipid categorised as simple lipid.
Structure of Triglycerides• Glycerides are lipid esters• A triglyceride places fatty acid chains at each alcohol group of the glycerol O CH2O C R1 Glycerol O part CH O C R2 Fatty acid O chains CH2O C R3
Glycerol• Glycerol Always looks the same• 3 C’s with 3 OH’s and everything else H’s.
Formation of Triglycerides
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. O p almitate (16:0) oleate (18:1) O CH2 OC(CH2 ) 1 4 CH3 stearate (18:0)CH3 ( CH2 ) 7 CH=CH(CH2 ) 7 COCH O CH2 OC(CH2 ) 1 6 CH3
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.
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.
Chemical PropertiesTriglycerides have typical ester and alkene chemicalproperties 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
Triglyceride Reactions • Triglycerides undergo three basic reactions • These reactions are identical to those studied in carboxylic acids Triglyceride H2O, H+ H2, Ni NaOHGlycerolFatty Acids More saturated Glycerol triglyceride Fatty Acid Salts
What’s What? • Identify the glycerol molecule • The fatty acids