Carbonyl Compounds - 6 Flashcards

1
Q

What are aldehydes and ketones classified as?

A

Carbonyl compounds

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2
Q

Where is the carbonyl group located in aldehydes?

A

At the end of the compound (-CHO)

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3
Q

Where is the carbonyl group located in ketones?

A

In the middle of the chain (R-C=O-R)

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4
Q

How are aldehydes named?

A

By adding the ending –al

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5
Q

How are ketones named?

A

By adding the ending –one

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6
Q

What is the method to prepare aldehydes from primary alcohols?

A

Oxidising primary alcohols using acidified potassium dichromate

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7
Q

What preparation method is used for aldehydes?

A

Distillation

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8
Q

What happens to aldehydes if subjected to repeated reflux cycles?

A

They are further oxidised into carboxylic acids

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9
Q

What is the method to prepare ketones from secondary alcohols?

A

Refluxing secondary alcohols with acidified potassium dichromate

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10
Q

What reducing agent can be used to reduce aldehydes and ketones?

A

Sodium borohydride (NaBH4)

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11
Q

Aldehydes are reduced to _______

A

Primary alcohols

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12
Q

Ketones are reduced to _______

A

Secondary alcohols

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13
Q

What role does the hydride ion play in the reduction of carbonyl compounds?

A

It acts as a nucleophile

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14
Q

What is a nucleophile?

A

A species with a lone pair of electrons attracted to positive charges

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15
Q

What happens during the nucleophilic addition reaction of aldehydes?

A

The hydride nucleophile attacks the slightly positive carbon atom on the carbonyl functional group

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16
Q

What is formed as a negatively charged intermediate in the nucleophilic addition reaction?

A

A negatively charged intermediate

17
Q

What product is formed when hydrogen cyanide reacts with aldehydes and ketones?

A

A hydroxynitrile

18
Q

What is used instead of hydrogen cyanide in laboratory preparations?

A

Sodium cyanide

19
Q

What test is used to identify the presence of carbonyl functional groups?

A

2,4-dinitrophenylhydrazine (2,4-DNP) test

20
Q

What indicates the presence of a ketone or aldehyde in the 2,4-DNP test?

A

Formation of an orange precipitate

21
Q

What is the purpose of crystallising the compound after the 2,4-DNP test?

A

To record its melting point for identification

22
Q

What is the purpose of Tollens’ reagent in distinguishing between aldehydes and ketones?

A

It forms a silver mirror if an aldehyde is present

23
Q

What happens when Tollens’ reagent is added to a ketone?

A

Nothing will be seen; ketones do not react

24
Q

What does Tollens’ reagent contain?

A

Silver nitrate dissolved in ammonia solution

25
Q

Why do ketones not give a result in the Tollens’ test?

A

Ketones cannot be further oxidised