Unit 2 Esters

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.Which of the following compounds is an ester?

a. b.

c. d.

CH

CH

C

CH

CH

CH

CO CH3

C

CH

CH

CH

CH

CH

C

CH2

OH

C

CH

CH

CH

CH

CH

C

O

CH3 CH

CH

C

CH

CH

CH

CO O

CH3

1st hintWhat is the functional group in an ester?

a hint!!!!

2nd hintThe functional group of an ester is

C

O

O

R

R1

This functional group is -OH

a hint!!!!

Which of the following compounds is an ester?

Correct because…………..

CH

CH

C

CH

CH

CH

CO O

CH3

C

O

O

R

R1

The functional group in an ester is

d.

The structural formula of the ester formed betweenethanol and propanoic acid is.

a. b.

c. d.

CH3 CH2 C

O

O CH2 CH2 CH3

CH2 CH2 C

O

O CH2 CH3

CH3

CH2 CH C

O

O CH2 CH2 CH3

CH2 CH2 C

O

O CH2 CH2 CH3

CH3

1st hintPropanoic acid forms the functional group of the ester

a hint!!!!

2nd hintThe functional group of an ester –oate.

C

O

O R1

R

3rd hintThe ethyl group is R1

The structural formula of the ester formed betweenEthanol ( R ) and propanoic acid ( R ) is.

Correct because……

CH2 CH2 C

O

O CH2 CH3

CH3

R-OH + R-COOH => R-COOR + Water

Ethanol gives the ethyl and the propanoic acid gives the propanoate. C3H7COOC2H5 ethyl propanoate.

a.

What is the systematic name of the acid usedto make this ester?

a. 2-methylpropanoic acid

b. 3-methylpropanoic acid

c. Butanoic acid

d. 2-methylethanoic acid

C C C

O

O C C C

C

H

H

H H

H

H

H

H

H

H

H

H

H

C HH

H

1st hintLook at the functional group and the carbon chains attachedto it

a hint!!!!

2nd hintThe carbon chain the produces the –yl part of the name comes from the alcohol used to make the ester.

What is the systematic name of the acid used to make this ester?

Correct because…….

The name of this ester is butyl 2-methyl propanoate.

Butanoic acid The portion that doesnot carry the COO group would be the butyl part of the ester.

C C C

O

O C C C

C

H

H

H H

H

H

H

H

H

H

H

H

H

C HH

H

The ester that is an isomer of pentanoic acid is?

a. Ethyl methanoate

b. Ethyl propanoate

c. Propyl methanoate

d. Methyl propanoate

1st hintWhat is the link between isomers and molecular formula

a hint!!!!

2nd hintThe molecular formula for isomers is identical.

The ester that is an isomer of pentanoic acid is?

Correct because ………..The molecular formula for pentanoic acid isC5H10O2 (C5H9COOH)

a. Ethyl methanoate : Molecular formula C3H6O2

HCOOC2H5

b. Ethyl propanoate : Molecular formula C5H10O2

C2H5COOC2H5 c. Propyl methanoate: Molecular formula C3H6O2 HCOOC2H5 d. Methyl propanoate: Molecular formula C5H6O2

C2H5COOCH

Esters are most likely to be used as

a. Making plastics

b. Making industrial acids

c. As solvents

d. As preservatives

Polyesters are condensation polymers made from the reactionbetween two monomers, a diol and a diacid.

a hint!!!!

Esters are used for flavouring and salts of carboxylic acidsare used as preservatives e.g. sodium benzoate.

a hint!!!!

Industrial acids, e.g. HNO3, HCl, H2SO4, CH3COOH are notmade from esters.

a hint!!!!

Esters are most likely to be used as

Correct because………

SolventsEsters are more volatile than carboxylic acids. Their intermolecular forces are weaker. They cannot formhydrogen bonds. This volatility helps give them theircharacteristic pleasant, fruity smells.This property of their volatility is used in solvent forglues. E.g. Polystyrene cement consists of ploystyrenedissolved in ethyl ethanoate.

What type of reaction takes place when a olive oilis converted into glycerol and fatty acids?

a. Dehyrdation

b. Hydrogenation

c. Condensation

d. Hydrolysis

Olive oil is a triglyceride it has three ester links.

a hint!!!!

Water can react with these ester links

What type of reaction takes place when a olive oilis converted into glycerol and fatty acids?

Correct because……….

Hydrolysis Oils, like fats are naturally occurring esters. Like allEsters, they can be hydrolysed.

Alcohol + Carboxylic Acid => Ester + Water

Alcohol + Carboxylic Acid <= Ester + Water

Condensation

Hydrolysis

Oleic acid is a constituent of olive oil. It’s formulae isC17H33COOH. What structure of this molecule makes it different from a similar fat molecule?

a. Fat molecules have much longer carbon chains

b. Fat molecules do not have carbonyl groups.

c. Oleic acid is unsaturated.

d. Oleic acid forms straight hydrocarbon chains in olive oil.

Stearic acid is a fatty acid.

a hint!!!!

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CO

OH

CnH2n+1COOH is the general formula for a saturated fatty acid.

a hint!!!!

Oleic acid is a constituent of olive oil. It’s formulae isC17H33COOH. What structure of this molecule makes it different from a similar fat molecule?

Correct because………

Oleic acid is unsaturated.The general formula for an saturated fat is CnH2n+1COOHThis means that there are no C=C bonds in its structure.

CH3(CH2)7CH=CH(CH2)7COOH

Oleic Acid (olive oil) Unsaturated

C17H33COOH

When the ester glyceryl tristearate is reacted withsodium hydroxide, soap is made. The name of the soapmolecule is?

a. Sodium tristearate

b. Sodium glycerate

c. Sodium stearate

d. Sodium triglycerate

Glycerol’s structural formula is

a hint!!!!

C

C

C

O

O

O

H

H H

H H

H

H

H

The ester glyceryl tristearate structural formula is

a hint!!!!

C

C

C

O

O

O

H

H C

H C

C

H

H

O

C17

H35

O

C17

H35

O

C17

H35

When the ester glyceryl tristearate is reacted withsodium hydroxide, soap is made. The name of the soapmolecule is?

Correct because ………..

Sodium stearateGylceryl tristearate molecule consists of 3 stearate fatty acid chains

C

C

C

O

O

O

H

H C

H C

C

H

H

O

C17

H35

O

C17

H35

O

C17

H35

3 Na +H35

C17

O

O-

Sodium stearate

NaOH

1.