carboxylic acids Flashcards

1
Q

Why are carboxylic acids stronger acids than phenols?

A

both are resonance stabilised

  • carboxylic acids are more acidic because they have 2 oxygen atoms
  • carboxylate resonance structures are stronger than phenoxide anion
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2
Q

What is the the effect of electron-withdrawing groups on acidity?

A

electron withdrawing groups = electronegative groups

  • increase acidity
  • electronegative atoms pull electron density with the sigma bonds
  • weakens the O-H bond inductively

lower the pka the more acidic

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3
Q

What are the properties of carboxylic acids?

A

highly polar
low molecular weight carboxylic acids are soluble in water
- can be tested by adding drops of water and using blue litmus paper which would turn red
high boiling point
- form extensive hydrogen bonds to themselves and water

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4
Q

What is esterification?

A

formation of esters from carboxylic acids and alcohols
- is a condensation reaction = removal of water (formed as a product)

carboxylic acid + alcohol = ester + water
- replaces the H atom on the OH group of the carboxylic acid with the R group of the alcohol

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5
Q

What are the requirements of esterification? How can you tell which carboxylic acid and alcohol an ester has been formed from?

A

acid catalyst

ethyl acetate

  • ethyl = tells you which alcohol
  • acetate = tells you which carboxylic acid
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6
Q

What is the difference in physical properties between carboxylic acids and esters?

A

carboxylic acids have higher boiling points than esters
- carboxylic acids can form hydrogen bonds but esters cannot
carboxylic acids are more soluble in water than esters
- esters of low molecular weight are soluble in water = solubility decreases with chain length

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7
Q

What is the medicinal use of salicylic acid?

A

salicylic acid is used in anti-acne cream

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8
Q

What are fats and oils?

A

fats and oils are triesters of glycerol

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9
Q

What is saponification? What is soap?

A

saponification
- hydrolysis of lipids and fats under basic conditions to form alcohol and soap

soap
- esters of glycerol = salts of fatty acids

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10
Q

What are the requirements of saponification?

A

aqueous alkali - basic conditions

water - creates aqueous conditions

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11
Q

How do detergents work?

A

have a hydrocarbon chain = non-polar
sulfonate = polar

form micelles

  • hydrophobic tail face inward and hydrophilic head face outwards
  • grease/dirt is suspended inside = is solubilised
  • removes dirt/grease by drawing it away
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