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

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.

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

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

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

The Degree of

Unsaturation

saturated

Unsaturated(cis or trans

configuration)

monounsaturated

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

Omega-3

Omega-6

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

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

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

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

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 Fatty Acids

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

2 H2, Ni

CH3 CH2 C

O

OH16

CH2CH CH CH2 C

O

OHCH3 CH2 CH CH4 7

Hydrogenation

•An ester of glycerol with three fatty acids.

•Also known as triacylglycerols

•One type of lipid categorised as simple lipid.

Triglycerides

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

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.

CH2OC(CH2)14CH3

CH2OC(CH2)16CH3

CH3(CH2)7CH=CH(CH2)7COCH

O

O

O

oleate (18:1)

stearate (18:0)

palmitate (16:0)

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 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

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

Hydrolysis

Saponification

Hydrogenation

QUIZ

What’s What?

•Identify the glycerol molecule

•The fatty acids

THANK YOU