Chapter 26

Question 1

What is an aldehyde

Answer 1

An aldehyde is a compound with the carbonyl functional group at the end of their chain

Question 2

How do you name an Aldehyde

Answer 2

Count the carbons to identify the stem

Identify the carbonyl functional group at the end of the chain to the suffix is Al

Question 3

What is a ketone

Answer 3

Ketones are compounds with the carbonyl functional group in the middle of the carbon chain

Question 4

How do you name a ketone

Answer 4

Count the carbons to identify the stem
Identify the carbonyl group in the middle of the chain so suffix is -one
Identify which carbon the carbonyl group is on

Question 5

Do aldehydes and ketones undergo oxidation reactions?

Answer 5

Aldehydes can be oxidised to carboxylic acids when reflux with potassium dichromate and sulfuric acid
Ketones do not undergo oxidation reactions

Question 6

Are aldehydes and ketones able to undergo nucleophilic addition

Answer 6

Aldehydes and ketones are able to undergo nucleophilic addition due to the polarity of the carbonyl bond due to the electronegativity difference between the carbon and oxygen which induces a dipole

Question 7

Draw the equation and mechanism for the nucleophilic addition of aldehydes with NaBH4

Answer 7

Aldehydes are reduced to primary alcohols by nabh4

Mechanism in notes

Question 8

Draw the equation and mechanism of nucleophilic addition of ketones with nabh4

Answer 8

Ketones are reduced to secondary alcohols by nabh4

Mechanism in notes

Question 9

Draw the nucleophilic addition of aldehydes with hydrogen cyanide

Answer 9

I’ll hides undergo nucleophilic addition with hydrogen cyanide and sulfuric acid to form a hydroxynitrile

Question 10

Show the nucleophilic addition of ketones with hydrogen cyanide

Answer 10

He tonnes undergo nucleophilic addition with hydrogen cyanide and sulfuric acid to form a hydroxynitrile
Mechanism in notes

Question 11

How do you test for a carbonyl group

Answer 11

Use a solution of 2 4 dinitrophenylhydrazine

1) add 5 cm of the 2 4 dnp to a test tube
2) add 3 drops of the unknown compound
3) if no crystals form had a few drops of sulfuric acid
4) a yellow / orange precipitate will form which indicates the presence of an aldehyde or ketone

Question 12

How can you tell whether a compound is either an aldehyde or ketone

Answer 12

4) pour the unknown solution into the prepared tollens reagent
5) leave in a beaker of 50 degrees water for 10-minutes a silver mirror forming indicates an aldehyde

Question 13

How does tollens reagent work

Answer 13

The aldehydes is further oxidised to carboxylic acid

The silver ions are reduced

Question 14

How can you identify exactly what aldehyde or ketone is present

Answer 14

1) filter the precipitate formed by 2 4 dnp
2) recrystallized the precipitate
3) measure the melting point of the purified sample and compared to a database

Question 15

What is a carboxylic acid

Answer 15

A carboxylic acid as a compound that contains a carboxyl group

Question 16

Are carboxylic acids soluble

Answer 16

Carbusonic acids are soluble due to the polarity of the c o & o h bonds with up to four carbons
As chain length increases solubility decreases due to the non-polar change affecting the overall polarity of the molecule

Dicarboxylic acid dissolve readily due to their two functional groups

Question 17

Carboxylic acid + metal oxide

Answer 17

–→ salt + water

Question 18

Carboxylic acid + alkali

Answer 18

→salt + water

Question 19

Carboxylic acid + carbonate

Answer 19

→ salt + water + carbon dioxide

Question 20

What is an ester and how can you make them

Draw example

Answer 20

An ester is made by reacting a carboxylic acid and an alcohol creating an ester and water under heat with a concentrated sulfuric acid catalyst

Question 21

How do you hydrolyse an ester

Draw examples

Answer 21

Acid hydrolysis:
Ester + water→ carboxylic acid + alcohol
Conditions: reflux, dilute aqueous acid

Alkaline hydrolysis:
Ester + sodium hydroxide→carboxylate salt + alcohol

Question 22

How do you make an ester using an acid anhydride draw example

Answer 22

Acid anhydride + alcohol→ester + carboxylic acid

Question 23

How do you make an ester from an acyl chloride

Drawer example

Answer 23

Acyl chloride + alcohol/phenol→ ester + HCL

Question 24

What is an acyl chloride

Answer 24

Acyl chlorides have the functional group CO-Cl

Question 25

How do you form an acyl chloride

Draw example

Answer 25

Carboxylic acidic acid + socl2→ acyl chloride + SO2 + HCL

Question 26

What are the three reactions of acyl chlorides

Answer 26

Acyl chloride + water→ carboxylic acid+ HCl

Acyl chloride + ammonia→ primary amide + nh4cl

Acyl chloride + primary amine→ secondary amide + salt