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Chem Module 6 - Organic chemistry and analysis > Chapter 26 - Carbonyls and carboxylic acids > Flashcards

Chapter 26 - Carbonyls and carboxylic acids Flashcards

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1
Q

describe the oxidation of aldehydes

A

they can be oxidised to carboxylic acids when reflux with acidified dichromate ions

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2
Q

do ketones undergo oxidation reactions?

A

no

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3
Q

what type of reaction is common in carbonyls?

A

nucleophilic addition

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4
Q

aldehydes can be reduced to form what?

A

Primary alcohols

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5
Q

what is used to detect carbonyls and what will be the positive result?

A

Brady’s Regent and a yellow/orange precipitable forms

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6
Q

what is used to distinguish between aldehydes and ketones?

A

tollen’s reagent

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7
Q

how do you make tollen’s reagent?

A

add aqueous sodium hydroxide to 3 cm of aqueous silver nitrate until a brown precipitate of silver oxide is formed, then add dilute ammonia until the brown precipitate dissolves

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8
Q

what is the positive test for aldehydes?

A

A silver mirror will form

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9
Q

what two groups does the carboxyl group contain?

A

A carbonyl group and a hydroxyl group

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10
Q

why are carboxylic acids soluble?

A

The C-O and O-H bonds are polar allowing them to form hydrogen bonds with the water

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11
Q

What is the maximum number of carbons a carboxylic acid can have before it becomes insoluble?

A

four

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12
Q

are carboxylic acids strong or weak

A

Weak

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13
Q

what are the two main reactions that carboxylic acids undergo?

A

redox and neutralisation

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14
Q

what are the products when an aqueous solution of carboxylic acid reacts with a metal?

A

Hydrogen gas and the carboxylate salt

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15
Q

what are the products when a carboxylic acid reacts with a metal oxide?

A

a Salt and water

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16
Q

what are the products when a carboxylic acid reacts with an alkali?

A

a Salt and water

17
Q

What are the products when a carbonate reacts with a carboxylic acid?

A

a salt, water and carbon dioxide

18
Q

What is a derivative of a carboxylic acid?

A

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

19
Q

give four examples of derivatives of carboxylic acids

A

Estes, acyl chlorides, acid anhydrides and amides

20
Q

how is an ester named?

A

Remove the oic acid suffix from the parent carboxylic acid and replace with oate. The chain attached the oxygen atom of the COO group is an added at the start.

21
Q

how is an acyl chloride named?

A

remove oic and replace it with oyl chloride

22
Q

how is an acid anhydride formed?

A

By the removal of water from two carboxylic acid molecules

23
Q

what is esterification?

A

The reaction of an alcohol with a carboxylic acid to form an ester

24
Q

what conditions are needed for esterification?

A

warm with a small amount of concentrated sulphuric acid which acts as a catalyst

25
Q

what two chemicals can esters be hydrolysed by?

A

Aqueous acid or alkali

26
Q

What is acid hydrolysis of an ester the reverse of?

A

Esterification

27
Q

describe the acid hydrolysis of an ester

A

The Ester is heated under reflux with dilute aqueous acid. Ester is then broken down by water with the acid acting as a catalyst.

28
Q

which one out of acid hydrolysis and hydrolysis is reversible?

A

Acid hydrolysis

29
Q

how can acyl chlorides be prepared and what are the other products of this reaction?

A

they can be prepared directly from their parent carboxylic acid by reaction with thionyl chloride, the other products of this reaction SO2 and HCL are evolved as gases.

30
Q

why are acyl chlorides useful?

A

they are very reactive and in organic synthesis can be easily converted into carboxylic acid derivatives with good yields

31
Q

what kind of compound do acyl chlorides react with?

A

nucleophiles

32
Q

acyl chlorides react with alcohols to form what?

A

esters

33
Q

why can’t carboxylic acids react with phenols to form esters?

A

They are not reactive enough

34
Q

acyl chlorides and acid anhydrides can react with phenols to form what?

A

phenyl esters

35
Q

What happens when water reacts with acyl chlorides?

A

A violent reaction takes place with the evolution of dense steamy hydrochloric acid fumes. A carboxylic acid is also formed.

36
Q

Acyl chlorine react with ammonia form what?

A

A primary amide

37
Q

A primary amine reacts with an acyl chloride to form what?

A

a secondary amide

38
Q

Why are acid anhydrides useful?

A

they react in a similar way to acyl chlorides but are less reactive

Chem Module 6 - Organic chemistry and analysis (3 decks)

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