4.38C: Know that Esters Contain the Functional Group -COO-

ESTERS: Group of organic compounds that all contain the same functionalgGroup -COO-
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COMMON PROPERTIES OF ESTERS:

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• Volatile - liquids that can easily form into vapours
• Distinctive odor - 'fruity’ smell

Examples:

METHYL ETHANOATE	ETHYL ETHANOATE	PROPYL ETHANOATE

4.39C: Know that Ethyl Ethanoate is the Ester produced when Ethanol and Ethanoic Acid React in the Presence of an Acid Catalyst

ESTERS: Group of organic compounds that all contain the same functional group -COO-

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FORMATION OF ETHYL ETHANOATE:

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• In the presence of an acid catalyst, Ethanoic acid will react with Alcohol to form Esters

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Example: Ethanoic Acid will react with Ethanol in the presence of concentrated Sulfuric acid (catalyst) to form Ethyl Ethanoate:

The Formation of Ethyl Ethanoate:

Diagram showing the Formation of Ethyl Ethanoate

4.40C: Understand How to Write the Structural and Displayed Formulae of Ethyl Ethanoate

ESTERS: Group of organic compounds that all contain the same functional group -COO- (CH3COOCH2CH3)

STRUCTURAL AND DISPLAYED FORMULAE OF ETHYL ETHANOATE:

ETHYL ETHANOATE    (CH3CO2C2H5)
STRUCTURAL FORMULA	CH3COOCH2CH3
DISPLAYED FORMULA

4.41C: Understand How to Write the Structural and Displayed Formulae of an Ester, Given the Name or Formula of the Alcohol and Carboxylic Acid from Which it is Formed and Vice Versa

ESTERS: Group of organic compounds that all contain the same functional group -COO-

STRUCTURAL AND DISPLAYED FORMULAE OF ESTERS:

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• Ester is composed of Alcohol and Carboxylic acid

• First part of name of Ester compound comes from Alcohol, and ends with '-yl'

• Second part of name of Ester compound comes from Carboxylic acid, and ends with '-oate'

Examples:

NAME OF ALCOHOL	NAME OF CARBOXYLIC ACID	NAME OF ESTER
ETHANOL	Propanoic Acid
BUTANOL	Methanoic Acid
PENTANOL	Ethanoic Acid

4.42C: Know that Esters are Volatile Compounds with Distinctive Smells and are Used as Food Colourings and in Perfumes

ESTERS: Group of organic compounds that all contain the same functional group -COO-

  

Picture showing Different uses of Esters

PROPERTIES OF ESTERS:

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Properties of Esters that makes them useful for food colouring and perfume:

• VOLATILITY - Esters are volatile as they have weak intermolecular forces of attraction so can evaporate easily (readily change from liquid to gas)

• DISTINCTIVE SMELL - Esters have pleasant 'fruity' smells (e.g Pentyl Butanoate has the smell of Strawberries)

4.43C: Practical: Prepare a Sample of an Ester such as Ethyl Ethanoate

ESTERS: Group of organic compounds that all contain the same functional group -COO-

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PREPARING A SAMPLE OF AN ESTER:

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PREPARATION OF ETHYL ETHANOATE

Diagram showing the Preparation of Ethyl Ethanoate

METHOD: Conical flask containing mixture of Ethanoic acid, Ethanol and concentrated Sulfuric acid is gently heated in a water bath for several minutes Vapors of Esters will rise and evaporate Vapors pass through condenser where it cools and condenses, turning into a liquid that is collected in a beaker - this prevents the reverse reaction from occurring as Ester has the lowest boiling point of any substance present in mixture

RESULT: METHOD 1: If Ester is present, 'fruity' odour can be smelt METHOD 2: If Ester is present, insolubility of Ester will cause a thin layer to form on top when poured into Water