Chapter 2: Carbon Compounds

H. FATS

What is fats & oils?

FATS:

An ester that is formed from 1 molecule

of glycerol and 3 molecules of fatty acids.

Can exist in both solid and liquid state –

in liquid state is known as OIL.

Fats & oils are chemically very similar but

difference in their physical states.

Differences between fats & oils

Fats Oils

Fats are solid at room

temperature

Oils are liquid at room

temperature

Found in animal (cow &

goat)

Found in plant

e.g: soybean, sunflower,

peanuts, olive & palm oil

fruit

Melting point: more than

20 °C

Melting point: less than

20 °C

Saturated compounds Unsaturated compounds

Importance of fats & oils

1. Source of energy

Important source energy for living things

2. Source of nutrients

The absorption of fat-soluble vitamin A,

D, E and K

3. Structural role

Needed to build membranes of all cells

4. Thermal insulation

Layer of fat – protect our body from

cold & internal organs from freezing

5. Protection

Fat protect vital internal organs in our

body

Uses of fats & oils

Cooking

Food manufacture

Cosmetic

Candle (fats from animal)

Soap making (vegetable oil are often used)

Structural formulae

Mixture of different esters derived from

variety of long-chain carboxylic acid

(fatty acids) with the alcohol,

propane-1,2,3-triol (glycerol).

Fatty acids: Long straight-chain carboxylic

acids containing between 10-20 carbon

atoms per molecule.

Fatty

acidFormula

Myristic

acidCH3 – (CH2)12 − COOH

Palmitic

acidCH3 – (CH2)14 − COOH

Stearic

acidCH3 – (CH2)16 − COOH

Lauric

acidCH3 – (CH2)10 − COOH

Oleic

acidCH3 – (CH2)7 – CH = CH – (CH2)7 − COOH

Linoleic

acidCH3 – (CH2)4 – CH = CH – CH2 – CH = CH − (CH2)7 − COOH

Linolenic

acidCH3 – (CH2 – CH = CH – CH2 – CH = CH – CH2 – CH = CH − (CH2)7 − COOH

Formation of fats

By condensation of fatty acids and

glycerol

1 molecule glycerol combines with 3

molecules of fatty acids

Name of reaction: Esterification

R1COOH

R2COOH

R3COOH

CH2 OH

CH2 OH

CH2 OH

+

3H2O

Fatty acid Glycerol

Fat/Oil

+

C O C R1

O

C O C R2

O

C O C R3

O

H

H

H

H

H

Try this:

Draw the structural formula for reaction

between palmitic acid with glycerol to form

a certain fat.

Saturated & unsaturated fats

Compare and contrast between saturated

and unsaturated fats

Converting unsaturated fats to

saturated fats Name of process:

Hydrogenation

Unsaturated fats (alkenes) from

vegetable oils such as palm oil can be

converted to saturated fats (margerine)

Example:

Name of reaction: Manufacture of

margerine

Condition:

(i) Catalyst: nikel/platinum

(ii) Temperature: 180 °C

(iii) Pressure: 4 atmospheres

Procedures:

Hydrogen gas is passed through the

unsaturated fats at 180 °C with small

amount of nikel/platinum

Effects of eating food high in fats on

health Cholesterol from fats can deposit on awll

of arteries. The wall of arteries will

harden. This cause arteriosclerosis.

Cholestrol can block the flow of blood in

the arteries

Also causing obesity, high blood pressure,

heart attacks

Industrial extraction of palm

Process

Sterilisation Stripper Digestor

Pressing

ClarificationPurificationVacuum drying

Use of palm oil

To make cooking oil and margerine

Better than the other oil such as coconut

oil (palm oil is unexpensive)

Cholestrol free thus reducing the risk of

heart disease