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Chemistry Dawes Y13 > Carbonyl And Carboxylic Acids > Flashcards

Carbonyl And Carboxylic Acids Flashcards

1
Q

Why does heating under reflux give a high yield

A

Mixture evaporated but can’t escape so goes back into the round bottomed flask

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2
Q

Apparatus needed for distillation

A

Still head
Receiver
Pear shaped flask
Condenser

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3
Q

Carbonyl group formula equation

A

HnH2nO

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4
Q

What are carbonyls used for

A

Preservation
Nail polish remover
Almond flavour

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5
Q

Why is the carbon atom of a carbonyl group open to nucleophilic attack

A

The carbon has a lower electronegativity compared to the oxygen and the bond is polar

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6
Q

Conditions for the reduction of the carbonyl group

A

Reducing agent- aqueous NaBH4

Reaction is warmed

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7
Q

Equation for the reduction of carbonyl group

A

Aldehyde/ketone +2[H] —> alcohol

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8
Q

What does the C=O bond undergo

A

Attacked by nucleophile
Polar
Undergoes addition
Difference in electronegativity

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9
Q

What does the C=C bond undergo

A

Electrophilic Addition

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10
Q

Physical properties of carboxylic acids

A

Miscible in water (hydrogen bonding)
Higher melting point relative to the similar alcohol
Weak acid

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11
Q

Reactions of carboxylic acids

A

Reacts with
Metals
Bases
Carbonates

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12
Q

Products of sodium and propanoic acid

A

Sodium propanoate
Hydrogen
C2H5COO-Na+
0.5 H2

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13
Q

Reaction to form Ester and conditions needed

A 
Condensation reaction between an alcohol and carboxylic acid 
Conc H2SO4 (catalyst)
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14
Q

Describe esters volatility

A

Have no free OH

No hydrogen bonds so only London forces present (weaker) so more volatile

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15
Q

Describe how to obtain a sample of an ester

A

Combine 2cm3 of alcohol with 2cm3 of carboxylic acid
Add drop of CONC H2SO4 (catalyst)
Heat in hot water bath at 80°C for 5 minutes
Add NaCO3 to the top of the test tube

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16
Q

Why are esters used in the manufacture of foods

A

Flavouring

17
Q

How is an acyl chloride formed and other products

A

Carboxylic acid + thionyl chloride (SOCl2) —> acyl chloride + SO2 +HCl

18
Q

Uses of acyl chlorides (equations)

A

Acyl chloride + alcohol —> Ester +
HCl
Acyl chloride + water —> carboxylic acid + HCl

19
Q

Why are acyl chlorides and acid anhydride useful in organic synthesis

A

Can be easily converted into carboxylic acid derivatives such as esters and amides, with good yields

20
Q

Why are acyl chlorides and acid anhydrides useful for esterifying phenols

A

Carboxylic acids are not reactive enough to form esters with phenols, acyl chlorides and acid anhydrides are much more reactive so don’t need an acid catalyst

21
Q

Define hydrolysis chemical breakdown of a compound in the presence of water

A

chemical breakdown of a compound in the presence of water

22
Q

How to hydrolyse Ester with hot acid

A

Carboxylic acid and alcohol

23
Q

How to hydrolyse Ester with hot alkali

A

Carboxylate ion and alcohol

24
Q

Similarity in the conditions needed for hot aq acid/alkali

A

Heated under reflux

25
Q

Difference in the conditions needed for hot aq acid/alkali

A

Acid is reversible

Alkaline is irreversible

26
Q

What is an acid anhydride

A

OCOCO

product of a dehydration reaction between 2 carboxylic acid molecules

27
Q

What is an acyl group

A

O=C-(not C/H) -R

28
Q

How to test for an aldehyde/ketone using 2,4-DNP

A

Add 5cm of 2,4-DNP
Add 3 drops of unknown compound
If no crystals form add few drops of sulfuric acid
A yellow/orange precipitate will form if present

29
Q

How to make tollen’s reagent

A

Add 3cm of aqueous silver nitrate
Add aqueous NaOH until a brown precipitate of silver oxide forms
Add dilute ammonia until brown precipitate dissolves to form a clear colourless solution

30
Q

How to test for an aldehyde using Tollen’s reagent

A

Pour 2cm of unknown into test tube
Add equal volume of tollens
Leave to stand in a beaker of warm water at about 50°C for 10-15 mins and a silver mirror will form if present

31
Q

How is a silver mirror formed with tollens

A

Silver ions are reduced to silver as the aldehyde is oxidised go a carboxylic acid

32
Q

conditions for the reduction of carbonyl groups

A

aqueous NaBH4

reaction mixture warmed

33
Q

what did Schlesinger find

A

found NaBH4 was a good reducing agent for carbonyl groups

34
Q

describe the reaction of a carbonyl group

A

undergoes nucleophilic addition due to the difference in electronegativity

35
Q

what reaction do aldehydes and ketones undergo

A

nucleophilic addition

36
Q

do C=C and C=O show chemical similarity

A

the C=C and C=O groups might be expected to show chemical similarity but in fact they show very little

37
Q

similarities and differences between C=C and C=O

A

similarities- unsaturated/undergoes addition reactions
differences- alkenes react with electrophiles
carbonyl group is attacked by nucleophiles

Chemistry Dawes Y13 (4 decks)

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