6.1.3: Carboxylic acids and esters

Question 1

Describe the solubility of carboxylic acids and how it changes

Answer 1

Soluble in polar solvents due to O-H bond forming hydroxy group to hydrogen bond with water. Changes as hydrocarbon part increases as this is non-polar

Question 2

What type of acid are carboxylic acids ?

Answer 2

Weak acids as they partially dissociate to form H+ ion and carboxylate ion

Question 3

Describe the test for carboxylic acids

Answer 3

Sodium carbonate
Effervescense

Question 4

Give an equation to support the test for carboxylic acids

Answer 4

2RCOOH + NaCO3 = 2RCOONa + CO2 +H2O

Question 5

Carboxylic acid + metal carbonate =

Answer 5

Salt + water + carbon dioxide

Question 6

Carboxylic acid + metal =

Answer 6

salt + hydrogen

Question 7

Carboxylic acid + alkali/metal hydroxide =

Answer 7

Salt + water

Question 8

Carboxylic acid + metal oxide =

Answer 8

Salt + water

Question 9

What is a use of esters ?

Answer 9

Fragrances

Question 10

What type of intermolecular force do esters contain ?

Answer 10

Permanent-dipole-dipole interactions

Question 11

Carboxylic acid + alcohol
What is catalst

Answer 11

Ester and water
Acid catalyst: conc. H2S04

Question 12

Why is conc H2S04 catalyst used in esterification reactions?

Answer 12

Means less water so equilibrium shifts to the right and produces higher ester yield aswell

Question 13

Acid anhydride + alcohol =

Answer 13

Ester + carboxylic acid

Question 14

Give an equation for acid hydrolysis of esters and what conditions used ?

Answer 14

Ester + water = carboxylic acid + alcohol
Hot aq acid HCl to increase conc of water and shift equilibrium to the right to give high product yield

Question 15

What practical conditions are used for ester hydrolysis ?

Answer 15

Reflux conditions

Question 16

Give an equation to represent the base hydrolysis of esters and what conditions are used ?

Answer 16

Ester + alkali = carboxylate salt + alcohol
Hot aq alkali metal hydroxide used

Question 17

What further reaction can turn a carboxylate salt into a carboxylic acid ?

Answer 17

Carboxylate salt + HCl –> Carboxylic acid + Chloride salt (e.g. NaCl)

Question 18

Why are acyl chlorides more reactive with nucleophiles than aldehydes and ketones ?

Answer 18

There are 2 electronegative elements bonded to the central carbon atom in acyl chlorides

Question 19

Acyl chloride + water =
Give features of reaction

Answer 19

Carboxylic acid + HCl

Question 20

Acyl chloride + ammonia =

Answer 20

Amide + HCl

Question 21

Acyl chloride + alcohol

Answer 21

Ester + HCl

Question 22

Acyl chloride + primary amide

Answer 22

Secondary amide + HCl

Question 23

Give features of the acyl chloride reactions

Answer 23

Nucleophilic addition elimination reaction
Vigorous reaction
White misty HCl toxic fumes produced so require fume cupboards

Question 24

Give an equation for the synthesis of acyl chlorides

Answer 24

Carboxylic acid + thionyl chloride (SOCl2) = acyl chloride + SO2 +HCl

Question 25

Give the formula and bond angle/shape of thionyl chloride

Answer 25

SOCl2
107 pyrimidal

Question 26

Give an equation for the esterification of phenol

Answer 26

Acyl chloride + phenol = ester + HCl

Question 27

What is the product from carboxylic acid + steam + H3PO4 ?

Answer 27

Alcohol