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Chemistry (OCR) A-Level > Chapter 26 - Carbonyls and carboxylic acids > Flashcards

Chapter 26 - Carbonyls and carboxylic acids Flashcards

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1
Q

What is the carbonyl functional group?

A

C=O

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2
Q

What is the aldehyde group? (-al)

A

CHO

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3
Q

What is the ketone group? (-one)

A

CO

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4
Q

What product is made when you oxidise an aldehyde?

A

Carboxylic acid

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5
Q

How do you oxidise an aldehyde?

A

Reflux with acidified dichromate ions and sulfuric acid

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6
Q

What is the reactivity of aldehydes and ketones influenced by?

A

The nature of the carbon - oxygen double bond

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7
Q

What reaction can carbonyl groups undergo?

A

Nucleophilic addition

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8
Q

How does a nucleophile react with a carbonyl?

A

The nucleophile is attracted to and attacks the slightly positive carbon atom, resulting in addition across the C=O bond

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9
Q

What happens when you reduce an aldehyde?

A

A primary alcohol is made

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10
Q

What happens when you reduce a ketone?

A

A secondary alcohol is made

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11
Q

What do you use in the reduction of a carbonyl?

A

NaBH4, water and heat

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12
Q

How are oxidation agents represented in an equation?

A

[O]

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13
Q

How are reduction agents represented in an equation?

A

[H]

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14
Q

What is produced when an aldehyde is reduced using HCN?

A

A hydroxynitrile (with a CN triple bond)

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15
Q

What is HCN?

A

Hydrogen cyanide is a poisonous liquid which can is used as a means of increasing the length of the carbon chain

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16
Q

What are the two catalysts in a HCN reduction reaction?

A

H2SO4 and NaCN

17
Q

What is used to detect the presence of the carbonyl functional group?

A

Brady’s reagent (clear to orange)

18
Q

What can be used to distinguish between an aldehyde and a ketone after identifying a carbonyl group?

A

Tollen’s reagent (solution of silver nitrate in aqueous ammonia) which forms a silver mirror precipitate with the presence of an aldehyde group

19
Q

What is a carboxyl functional group?

A

A carbonyl group and a hydroxyl group

20
Q

Which carbon atom is a carboxyl group designated to?

A

Carbon-1

21
Q

Describe the solubility of carboxylic acids

A
  • C=O and O-H bonds are polar and so they dissolve in water
  • As the number of carbon atoms increases, the solubility decreases (non-polar chain has a greater effect on the overall polarity of the molecule)
22
Q

What kind of acid is a carboxylic acid?

A

Weak acids

23
Q

What reactions do carboxylic acids take part in?

A

Neutralisation (with bases/ alkalis, metal oxides, carbonates) and redox (with metals)

24
Q

What happens to the suffix of a carboxylic acid when it reacts?

A

-ic acid becomes -ate (carboxylic to carboxylate)

25
Q

What happens when a carboxylic acid reacts with metals in a redox reaction?

A

A carboxylate salt and hydrogen gas is produced (metal disappears and effervescence produced)

26
Q

What happens when a carboxylic acid reacts with a metal oxide?

A

A salt and water is produced

27
Q

What happens when a carboxylic acid reacts with an alkali?

A

A salt and water is produced (H+ + OH- > H2O)

28
Q

What happens when a carboxylic acid reacts with a carbonate?

A

A salt, water and carbon dioxide is produced

29
Q

What is a derivative of a carboxylic acid?

A

A compound that can be hydrolysed to form the parent carboxylic acid

30
Q

What is present in carboxylic acid derivatives?

A

An acyl group (common sequence of atoms in their sequence)

31
Q

Give some examples of carboxylic acid derivatives

A

Esters, acyl chlorides, acid anhydrides and amides

32
Q

What happens when a carboxylic acid becomes an ester?

A

The hydrogen of OH is removed and replaced by another element (eg. Cl/ Br)

33
Q

What happens when two carboxylic acids react?

A

They form an acid anhydride aswell as H2O

34
Q

What is esterification?

A

The reaction between alcohol and a carboxylic acid to form an ester and water

35
Q

What is required for esterification to occur?

A

Warm temperatures and concentrated H2SO4 (catalyst)

36
Q

How can you change an ester into a carboxylic acid?

A

Acid hydrolysis by heating an ester under reflux with dilute aqueous acid

37
Q

What are the products of acid hydrolysis?

A

A carboxylic acid and an alcohol

Chemistry (OCR) A-Level (28 decks)

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