Esters Revision Matching names/structures of esters.

Give examples of: saturated and unsaturated hydrocarbons. cis–trans (E/Z) isomerism. esterification reaction.

HYDROLYSIS OF ESTERS Hydrolysis is the opposite of esterification ESTER + WATER CARBOXYLIC ACID + ALCOHOL The products of hydrolysis depend on the conditions used... Acidic CH 3 COOCH 3 + H 2 O CH 3 COOH + CH 3 OH Alkaline CH 3 COOCH 3 + NaOH → CH 3 COO¯ Na + + CH 3 OH If the hydrolysis takes place under alkaline conditions, the organic product is a water soluble ionic salt The carboxylic acid can be made by treating the salt with HCl CH 3 COO¯ Na + + HCl → CH 3 COOH + NaCl

USES OF ESTERS Despite being fairly chemically unreactive, esters are useful as... flavouringsapple2-methylbutanoate pear3-methylbutylethanoate banana1-methylbutylethanoate pineapplebutylbutanoate rum2-methylpropylpropanoate solventsnail varnish remover - ethyl ethanoate plasticisers

© Pearson Education Ltd 2009 This document may have been altered from the original Describe a triglyceride as a triester of glycerol (propane-1,2,3-triol) and fatty acids. Compare the structures of saturated fats, unsaturated fats and fatty acids. What you should be able to do

NATURALLY OCCURING ESTERS - TRIGLYCERIDES triglycerides are the most common component of edible fats and oils they are esters of the alcohol glycerol (propane-1,2,3-triol) Saponification alkaline hydrolysis of triglycerol esters produces soaps a simple soap is the salt of a fatty acid as most oils contain a mixture of triglycerols, soaps are not pure the quality of a soap depends on the oils from which it is made CH 2 OH CHOH CH 2 OH

Draw the displayed formula of hexadecanoic acid (palmitic acid) Draw the skeletal formula of hexadecanoic acid

Write down the reaction between hexadecanoic acid and propan-1-ol

hexadecanoic acid and propan-1-ol → propylhexadecanoate + water C 15 H 31 COOH + C 3 H 7 OH→ C 15 H 31 COOC 3 H 7 + H 2 O

© Pearson Education Ltd 2009 This document may have been altered from the original Formation of a triglyceride

Skeletal formula of octadec-9-enoic (oleic acid)

Structure of octadeca-9,12-dienoic acid

Compare the structures of cis and trans isomers of unsaturated fatty acids. Compare the link between trans fatty acids, the possible increase in ‘bad’ cholesterol and the resultant increased risk of coronary heart disease and strokes. Describe and explain the increased use of esters of fatty acids as biodiesel fuels. You should be able to:

Cis and trans configurations around a double bond

Skeletal formula of octadec-9-enoic (oleic acid) Draw the two skeletal formulae of the cis and trans forms of this structure

Structures of cis and trans-octadec-9-enoic acid.

Transesterification for the production of biodiesel 

Homework suggestions How many C=C bonds are there in a molecule of C 17 H 35 COOH? How many straight-chain structural isomers are there for this formula? Draw and name one pair of cis–trans isomers for this formula. Check your fridge. Do your margarines or other fat-containing foods give helpful data about the types of fat they contain?