Week 3 Esters, Fats, Oils, Proteins, Oxidation and Chemistry of Cooking Higher Supported Study

Esters Naming esters. Structural formulae for esters. Characteristics and uses of esters. Making esters by condensation reactions. Hydrolysis of esters.

Esters – Naming from Names Made from alcohol and carboxylic acid – Alcohol = first part of Esters Name – Carboxylic Acid = second part of Esters Name Methanol + Butanoic Acid  Methyl Butanoate + water

Esters – Naming from Structural Formula Key – Identify where the ester link is.

Drawing Esters Start with ester link Add carbon chains Ensure each carbon making 4 bonds Ensure each oxygen making 2 bonds Ethyl Butanoate

Ester Formation Steal Oxygen from Acid (has another one wont notice)

Making Esters Condensation Reaction

Characteristics and Uses of Esters Characteristic smells Immiscible (doesn’t dissolve) in water Used as flavourings and fragrances. Also used as industrial solvents.

Hydrolysis of Esters The breakdown of a large molecule into smaller molecules by the addition of a small molecule (such as water)

1. The molecule shown below has a pear odour. a)Name the functional group found in the molecule. b)The compound can be produced in the lab by reacting a alcohol with a carboxylic acid in the presence of a catalyst. (i) Which alcohol and carboxylic acid would be used? (ii) Name the catalyst used in this reaction. Ester link Propan-1-ol & ethanoic acid concentrated sulphuric acid

Fats and Oils Fats and oils are esters formed glycerol and three carboxylic acid molecules. The melting points of fats and oils. Oils can be converted to fats by hydrogenation. The importance of fats and oils

Structure ESTERS (Very specific Esters) Glycerol propane-1,2,3-triol

Structure cont. One Glycerol Three Fatty Acid Molecules (one for each Hydroxyl group) Fatty acids are saturated or unsaturated straight- chain (long chain) carboxylic acids Making Fats and oils = Condensation Reaction (same as making esters)

Oils (l) Higher degree of unsaturation Double bonds cause kinks in structure Molecules DO NOT PACK tightly together WEAKER VDWF’s

Fats (s) Lower degree of unsaturation More regular structure Molecules DO PACK tightly together Stronger VDWF’s

Hydrogenation = an addition reaction with hydrogen Used to turn an oil into a fat (hardening of an oil) This reduces the degree of unsaturation Molecules able to pack more closely together VDWF’s increases so melting point increases.

Why are Fats and Oils important concentrated source of energy essential for the transport and storage of fat soluble vitamins in the body

Fatty Acid Saturated vs Unsaturated Each carbon has a hydrogen above and below One hydrogen at very end of chain

Proteins Proteins importance. The formation of proteins from amino acids. peptide link (CONH) Essential amino acids. Enzyme hydrolysis of proteins to produce amino acids. Enzymes are proteins which act as biological catalysts

Protein Importance Proteins are the major structural materials of animal tissue and are also involved in the maintenance and regulation of life processes.

Amino Acids building blocks used to make proteins small molecules contain an amino group (NH 2 ), and a carboxyl group (COOH)

Formation of Proteins Condensation reaction Amide/peptide links form between amino acids

Protein Chain Bonds open at end – as a polymer, chain will continue on.

Essential Amino Acids The body cannot make all the amino acids required for body proteins and relies on dietary protein for supply of certain amino acids known as essential amino acids.

H OHH H Proteins hydrolyse to give amino acids. When keratin is hydrolysed 3 different amino acids are formed. Draw the structures of these amino acids

Hydrolysis of Protein Happens during digestion.