topic 17C

Question 1

carboxylic acid functional group

Answer 1

-COOH

Question 2

melting and boiling points of carboxylic acid

Answer 2

• high melting and boiling points
• strong intermolecular forces - hydrogen bonds

Question 3

solubility of carboxylic acids

Answer 3

• form hydrogen bonds with water
• completely soluble

Question 4

how can carboxylic acids be prepared

Answer 4

• by the oxidation of alcohols or aldehydes
• hydrolysis of nitriles

Question 5

how are carboxylic acids stabilised

Answer 5

• by delocalisation
• this makes dissociation more likely

Question 6

preparing carboxylic acids - oxidation of primary alcohols
- reaction
- reagent
- condition

Answer 6

• reaction: primary alcohol to carboxylic acid
• reagent: potassium dichromate solution and dilute sulfuric acid
• conditions: excess dichromate, heat under reflux
• observation: orange dichromate ion reduces to green Cr3+ ion

Question 7

preparing carboxylic acids - oxidation of aldehydes
- reaction
- reagent
- condition

Answer 7

• reaction: aldehyde to carboxylic acids
• reagent: potassium dichromate and dilute sulfuric acid
• conditions: heat under reflux

Question 8

preparing carboxylic acids - hydrolysis of nitriles
- reaction
- reagent
- condition

Answer 8

• reaction: nitrile to carboxylic acid
• reagent: dilute HCl/ sulfuric acid
• conditions: heat under reflux

Question 9

reduction of carboxylic acids
- reaction
- reagents
- conditions
- type of reaction
- role of reagent

Answer 9

• reaction: carboxylic acid to alcohol
• reagent: LiAlH4 in dry ether
• conditions: room temp & pressure
• type: reduction
• role: reducing agent

Question 10

carboxylic reactions with bases

Answer 10

• acid + metal -> salt + hydrogen
• acid + alkali -> salt + water
• acid + carbonate -> salt + water + CO2

Question 11

reduction of carboxylic acids
- reaction
- reagents
- conditions
- type of reaction
- role of reagent

Answer 11

• reaction: carboxylic acid to acyl chloride
• reagent: PCl5
• conditions: room temp
• observation: misty fumes

Question 12

esterification of carboxylic acids
- reaction
- reagents
- conditions
- type of reaction

Answer 12

• reaction: carboxylic acid to ester
• conditions: acid catalyst
• type of reaction: esterification

Question 13

acyl chloride functional group

Answer 13

-COCl

Question 14

ester functional group

Answer 14

-COO-

Question 15

reaction of acyl chloride with water
- change in functional group
- reagent
- conditions

Answer 15

• acyl chloride to carboxylic acid
• water
• room temp

Question 16

reaction of acyl chloride with alcohol
- change in functional group
- reagent
- conditions

Answer 16

• acyl chloride to ester
• alcohol
• room temp

Question 17

reaction of acyl chloride with concentrated ammonia
- change in functional group
- reagent
- conditions

Answer 17

• acyl chloride to primary amide
• ammonia
• room temp

Question 18

reaction of acyl chloride with primary amines
- change in functional group
- reagent
- conditions

Answer 18

• acyl chloride to secondary amide
• primary amine
• room temp

Question 19

hydrolysis of esters in acidic solution
- reagent
- conditions

Answer 19

• dilute HCl
• heat under reflux
• reversible reaction
• low yield of products

Question 20

hydrolysis of esters in alkaline solution
- reagent
- conditions

Answer 20

• dilte NaOH
• heat under reflux
• not reversible

Question 21

condensation polymerisation

Answer 21

• two different monomers are added together
• small molecule such as H2O or HCl is given off