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Organic Chemistry > Carbonyl Compounds > Flashcards

Carbonyl Compounds Flashcards

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1
Q

What is

the carbonyl group?

A

C=O

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2
Q

What are

carbonyl compounds?

A

Organic compounds that have the carbonyl group

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3
Q

What two homologous series are considered

when talking about carbonyl compounds?

A

Aldehydes & Ketones

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4
Q

What is another name for

an Aldehyde?

A

an Alkanal

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5
Q

What is another name for

a Ketone?

A

an Alkanone

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6
Q

What is the general formula for an aldehyde?

A

RCOH

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7
Q

What is the general formula for a ketone?

A

RCOR’

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8
Q

What is more reactive: an aldehyde or a ketone?

A

An aldehyde

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9
Q

What reactions do carbonyl compounds typically undergo?

A

Nucleophilic addition reactions

the nucleophiles are attracted to the electron-rich C=O

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10
Q

Why do carbonyl compounds undergo nucleophilic addition reactions?

A

The carbon in the C=O bond has a partially positive charge due to the electronegativity difference between carbon and oxygen

Therefore the carbon there is an electrophile (e- deficient specie)

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11
Q

Can aldehydes be oxidised?

A

Yes. They oxidise to carboxylic acids

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12
Q

Can ketones be oxidised?

A

No

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13
Q

Why can’t ketones be oxidised?

A

Oxidation is also the removal of hydrogen, in the ketone structure, RCOR, there is no hydrogen directly bonded to the carbon atom to be removed

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14
Q

Can aldehydes be reduced?

A

Yes. They are reduced to PRIMARY alcohols

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15
Q

Can ketones be reduced?

A

Yes. They are reduced to SECONDARY alcohols

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16
Q

How are aldehydes produced?

A

The oxidation of primary alcohols

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17
Q

What are reaction conditions for the production of aldehydes by the oxidation of primary alcohols

A
  1. Distillation
  2. Heating of the reacting system
  3. Acidified K2Cr2O7 / Acidified KMnO4
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18
Q

In what other way

can aldehydes be produced?

A

The (incomplete) reduction of carboxylic acids

19
Q

How are ketones produced?

A

The oxidation of secondary alcohols

20
Q

What are reaction conditions for the production of ketones by the oxidation of secondary alcohols

A
  1. Heating of the reacting system
  2. Acidified K2Cr2O7 / Acidified KMnO4
21
Q

What are both aldehydes and ketones reduced to?

A

Alcohols

22
Q

Name the nucleophile

that can reduce aldehydes and ketones to alcohols

A

The hydronium ion (H-)

23
Q

Name the 2 nucleophiles

that can reduce aldehydes and ketones reduced to alcohols

A
  1. The water molecule
  2. The hydroxide group
24
Q

What type of isomerism

relates an aldehyde to its corresponding ketone

(by that I mean they have the same number of carbons)

A

Structural Isomerism

Specifically functional group isomerism

25
Q

What is

a symmetric ketone?

A

A ketone with the same number of carbons on either side of the carbonyl group

Eg: Propanone

26
Q

What is

an asymmetric ketone?

A

A ketone with an unequal number of carbons on either side of the carbonyl group

27
Q

Can aldehydes be symmetric or asymmetric?

A

No

28
Q

Why can’t aldehydes be symmetric or asymmetric?

A

Because they are formed from primary alcohols that have only one other alkyl group attached to them. The carbonyl group is always on the terminal carbon

29
Q

What result is expected

in the reaction of carbonyl compounds with 2,4-dinitrophenylhydrazine?

A

There will be a red-orange precipitate

30
Q

Do carboxylic acids

produce any precipitate with 2,4-dinitrophenylhydrazine?

A

No

31
Q

What is the limitation

of the reaction of carbonyl compounds with 2,4-dinitrophenylhydrazine?

A

It does not differentiate between aldehydes and ketones, it just shows the presence of the carbonyl group

32
Q

What type of reaction is the

reaction of carbonyl compounds with 2,4-dinitrophenylhydrazine?

A

A condensation reaction

A molecule of water is eliminated

33
Q

How can we differentiate between

aldehydes and ketones?

A

Using the Tollen’s test

34
Q

What is observed

when aldehydes react with Tollen’s reagent?

A

A silver precipitate is formed on the walls of the test tube

Tollen’s reagent contains silver ions which are reduced to metallic silver when they react with the aldehyde.

35
Q

What is observed

when ketones react with Tollen’s reagent?

A

Nothing

Ketons do not react with Tollen’s reagent.

36
Q

What difference between aldehydes and ketones

is typically exploited when using the Tollen’s test?

A

Aldehydes are readily oxidised and ketones are not, hence, they do not react with Tollen’s reagent

37
Q

What other solution

can you use to distinguish between aldehydes and ketones besides Tollen’s reagent?

A

Fehling’s solution

38
Q

What is observed

when ketones react with Fehling’s solution?

A

Nothing

Ketones do not reduce Fehling’s solution, so the blue coloured Cu2+ ions remain

39
Q

What is observed

when aldehydes react with Fehling’s solution?

A

The solution turns from blue to (brick) red

Fehling’s solution contains Cu2+ ions which are **reduced to Cu+ ions ** when they react with the aldehyde. Copper (I) is brown in colour

40
Q

What is observed

when ketones react with Acidified potassium dichromate?

A

No visible change

41
Q

What is observed

when aldehydes react with Acidified potassium dichromate?

A

The solution turns from orange to green

Acidified potassium dichromate is an oxidising agent; oxidising the aldehyde to an alkanoic acid and getting reduced from Cr6+ to Cr3+ in the process.

42
Q

What is the precipitates

when aldehydes react with Fehling’s solution?

A

Copper (I) oxide (Cu2O)

43
Q

What are the reaction conditions

for an aldehyde to react with Fehling’s solution?

A

The solution must be warmed

44
Q

What are the reaction conditions

for an aldehyde to react with Acidified potassium dichromate?

A

The reacting system must be warmed

Organic Chemistry (7 decks)

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