Carbonyls Compounds

Question 1

What functional group do aldehydes and ketones contain?

Answer 1

Carbonyl functional group, C=O

Question 2

Where is the carbonyl functional group located in aldehydes?

Answer 2

At the end of a carbon chain

Question 3

How is the aldehyde group represented in its structural formula?

Answer 3

CHO

Question 4

What is the common name for the simplest aldehyde, methanal?

Answer 4

Formaldehyde

Question 5

What is the primary use of formaldehyde?

Answer 5

To preserve biological specimens

Question 6

Where is the carbonyl functional group located in ketones?

Answer 6

Joined to two carbon atoms in the carbon chain

Question 7

How is the ketone group represented in its structural formula?

Answer 7

C=O

Question 8

What is the common name for the simplest ketone, propanone?

Answer 8

Acetone

Question 9

What is acetone commonly used for?

Answer 9

As an industrial solvent and in nail-varnish removers

Question 10

What suffix is used to name aldehydes?

Answer 10

-al

Question 11

What suffix is used to name ketones?

Answer 11

-one

Question 12

In an aldehyde, which carbon atom is designated as carbon-1?

Answer 12

The carbon atom of the carbonyl group

Question 13

In a ketone, what needs to be done when numbering the carbon atoms?

Answer 13

The carbonyl carbon atom needs to be numbered

Question 14

What are carbonyl compounds?

Answer 14

Compounds that contain a carbon-oxygen double bond (C=O)

Carbonyl compounds include aldehydes and ketones.

Question 15

What happens to aldehydes when they are oxidised with acidified potassium dichromate (VI)?

Answer 15

They are oxidised to carboxylic acids

The oxidation process can be represented by the equation involving butanal converting to butanoic acid.

Question 16

What is the role of acidified potassium dichromate (VI) in the oxidation of aldehydes?

Answer 16

It acts as an oxidising agent

The solution changes color from orange to green during the reaction.

Question 17

What is the result of the oxidation of butanal?

Answer 17

Formation of butanoic acid

The reaction involves refluxing with acidified potassium dichromate.

Question 18

Do ketones undergo oxidation reactions?

Answer 18

No, ketones do not undergo oxidation reactions

This property helps distinguish ketones from aldehydes.

Question 19

What is the nature of the carbon-oxygen double bond in carbonyl compounds?

Answer 19

It is polar

Oxygen is more electronegative than carbon, resulting in an unequal sharing of electron density.

Question 20

What type of reaction occurs between nucleophiles and carbonyl compounds?

Answer 20

Nucleophilic addition

The nucleophile attacks the slightly positive carbon atom.

Question 21

What is a nucleophile?

Answer 21

A species that is attracted to a positive charge

Nucleophiles attack the slightly positive carbon atom in carbonyl compounds.

Question 22

What distinguishes the C=C double bond in alkenes from the C=O double bond in carbonyl compounds?

Answer 22

The C=C double bond is non-polar, while the C=O double bond is polar

This difference influences their reactivity.

Question 23

Fill in the blank: Aldehydes can be oxidised to _______ when refluxed with acidified dichromate(VI) ions.

Answer 23

carboxylic acids

Question 24

True or False: Ketones can be oxidised similarly to aldehydes.

Answer 24

False

Question 25

What is the composition of the carbon-oxygen double bond in carbonyl compounds?

Answer 25

It consists of a sigma bond and a pi bond ## Footnote The pi bond is formed by sideways overlap of p-orbitals.

Question 26

What is the reaction of carbonyl compounds with NaBH4?

Answer 26

NaBH4 is used as a reducing agent to reduce aldehydes and ketones to alcohols.

Question 27

How are aldehydes reduced by NaBH4?

Answer 27

Aldehydes are reduced to primary alcohols by NaBH4.

Question 28

What is the product of reducing butanal with NaBH4?

Answer 28

Butan-1-ol.

Question 29

What is the definition of a nucleophile?

Answer 29

An atom or group of atoms that is attracted to an electron-deficient carbon atom, where it donates a pair of electrons to form a new covalent bond.

Question 30

How are ketones reduced by NaBH4?

Answer 30

Ketones are reduced to secondary alcohols by NaBH4.

Question 31

What is the product of reducing propanone with NaBH4?

Answer 31

Propan-2-ol.

Question 32

What does hydrogen cyanide (HCN) do in reactions with carbonyl compounds?

Answer 32

HCN adds across the CO bond of aldehydes and ketones.

Question 33

Why is hydrogen cyanide considered hazardous?

Answer 33

It is a colourless, extremely poisonous liquid that boils slightly above room temperature.

Question 34

What is a common method for generating hydrogen cyanide in laboratory reactions?

Answer 34

Using sodium cyanide and sulfuric acid.

Question 35

What is the significance of the reaction between propanal and hydrogen cyanide?

Answer 35

It provides a means of increasing the length of the carbon chain.

Question 36

Fill in the blank: Aldehydes are reduced to _______ by NaBH4.

Answer 36

primary alcohols.

Question 37

Fill in the blank: Ketones are reduced to _______ by NaBH4.

Answer 37

secondary alcohols.

Question 38

What are the organic products formed from the reaction of an aldehyde with hydrogen cyanide?

Answer 38

Hydroxynitriles (or cyanohydrins) ## Footnote These compounds contain a hydroxyl group (-OH) and a nitrile group (C≡N).

Question 39

What functional groups do hydroxynitriles contain?

Answer 39

Hydroxyl group (-OH) and nitrile group (C≡N) ## Footnote Hydroxynitriles are products of aldehydes reacting with hydrogen cyanide.

Question 40

What is the mechanism for nucleophilic addition to carbonyl compounds?

Answer 40

The carbon atom in the C=O double bond is electron deficient and attracts nucleophiles ## Footnote Aldehydes and ketones react through this mechanism to form alcohols.

Question 41

What role does NaBH4 play in nucleophilic addition reactions?

Answer 41

NaBH4 provides the hydride ion (H-) as the nucleophile ## Footnote It facilitates the reduction of carbonyl compounds.

Question 42

What happens in the first step of the nucleophilic addition reaction with NaBH4?

Answer 42

The lone pair of electrons from the hydride ion is attracted to the carbon atom in the C=O double bond ## Footnote This forms a dative covalent bond.

Question 43

What occurs after the formation of the dative covalent bond in the reaction with NaBH4?

Answer 43

The π-bond in the C=O double bond breaks by heterolytic fission, forming a negatively charged intermediate ## Footnote This intermediate is then protonated to form an alcohol.

Question 44

What is the first stage of the reaction of an aldehyde or ketone with NaCN/H?

Answer 44

The cyanide ion (CN-) attacks the electron-deficient carbon atom in the C=O double bond ## Footnote This leads to the formation of a dative covalent bond.

Question 45

What happens after the cyanide ion donates its lone pair to the carbon atom in the C=O double bond?

Answer 45

The π-bond in the C=O double bond breaks by heterolytic fission, forming a negatively charged intermediate ## Footnote This is similar to the mechanism with NaBH4.

Question 46

What are the two steps involved in addition to carbonyl groups?

Answer 46

* Nucleophilic attack on the carbonyl group to form a negatively charged intermediate * Protonation of the intermediate to form an alcohol ## Footnote This process is crucial in organic synthesis.

Question 47

True or False: The reaction of carbonyl compounds with nucleophiles can lead to an increase in carbon chain length.

Answer 47

True ## Footnote This reaction is useful in organic synthesis for extending carbon chain length.

Question 48

What is the result of the reaction between propanal and sodium cyanide in the presence of acid?

Answer 48

The product is a hydroxynitrile ## Footnote This reaction involves the formation of a covalent bond between the cyanide ion and the carbon atom of propanal.

Question 49

What occurs during the intermediate stage of the reaction with propanal and sodium cyanide?

Answer 49

The intermediate is protonated by donating a lone pair of electrons to a hydrogen ion ## Footnote This step is crucial for the formation of the final product.

Question 50

Which ion attacks the carbon atom in the reaction of propanal?

Answer 50

Cyanide ion ## Footnote The cyanide ion forms a covalent bond with the carbon atom.

Question 51

Fill in the blank: The mechanism for the reaction of propanal with sodium cyanide includes the formation of an _______.

Answer 51

intermediate

Question 52

True or False: The second stage of the reaction mechanism can involve protonation by water.

Answer 52

True ## Footnote This is similar to the mechanism involving NaBH.