2.4 Esters, fats and oils Flashcards

1
Q

Ester

A

An ester is a molecule containing an ester link: ─COO─.

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2
Q

How are esters named?

A
  • names of their parent alcohol and carboxylic acid
  • structural formulae of esters formed from primary, straight-chain alcohols containing no more than eight carbons and straight-chain carboxylic acids containing no more than eight carbons
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3
Q

Use of esters

A

Esters are used as flavourings and fragrances as many have pleasant, fruity smells. Esters
are also used as solvents for non-polar compounds that do not dissolve in water.

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4
Q

How are esters formed?

A

by a condensation reaction between an alcohol and carboxylic acid

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5
Q

What is a condensation reaction?

A

two molecules joined together with the elimination of a small molecule

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6
Q

What small molecule is eliminated when an ester is formed?

A

Water

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7
Q

Hydrolysis of an ester

A

produces an alcohol and carboxylic acid

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8
Q

What is a hydrolysis reaction ?

A

a molecule reacts with water to break down into smaller molecules

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9
Q

How are edible fats and oils formed?

A

Edible fats and oils are esters formed from the condensation reaction of glycerol (propane-1,2,3-triol) and 3 carboxylic acid molecules.
The carboxylic acids are known as ‘fatty acids’ and can be saturated or unsaturated straight-chain carboxylic acids

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10
Q

Edible oils and fats melting points

A

Edible oils have lower melting points than edible fats.
Double bonds in fatty acid chains prevent oil molecules from packing closely together, so the greater the number of double bonds present, the weaker the van der Waals forces.
Greater degree of unsaturation, the lower the mpt

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11
Q

How does bromine solution indicate presence of double bonds?

A

Unsaturated compounds quickly decolourise bromine solution.
The bromine molecules add across the carbon-carbon double bonds in an addition reaction. The greater the number of double bonds present in a substance, the more bromine solution can be decolourised

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12
Q

Fats and oils are:

A
  • a concentrated source of energy
  • essential for the transport and storage of fat-soluble vitamins in the body
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