Oxidation Of Alcohols

Question 1

How does structure affect the oxidation of alcohol

Answer 1

How much an alcohol can be oxidised depends on its structure

Question 2

What is the oxidising agent used oxidise alcohols

Answer 2

Acidified potassium dichromate, K2Cr2O7

Question 3

What is the colour change to show the oxidation of the dichromate ion

Answer 3

Cr2O72- is orange is reduced to green chromium(III) ion, Cr3+

Question 4

What functional group are primary alcohols oxidised into?

Answer 4

Aldehydes and carboxylic acids

Question 5

What functional group are secondary alcohols oxidised into?

Answer 5

Ketones only

Question 6

Are tertiary alcohols oxidised?

Answer 6

No

Question 7

What is the condition for oxidising tertiary alcohols

Answer 7

By burning them

Question 8

What is the functional group for aldehydes and ketones and give the formula

Answer 8

• C=O
• CnH2nO

Question 9

What is the functional groups for carboxylic acids and their general formula?

Answer 9

• COOH
• CnH2n+1COOH

Question 10

Give the structure of aldehydes and their suffix

Answer 10

• A hydrogen and one alkyl group attached to the carbonyl carbon atom

• al

Question 11

Give the structure and suffix of ketones

Answer 11

• two alkyl groups attached to the carbonyl atom
• one

Question 12

What is the carbonyl group of carboxylic acids and give their suffix

Answer 12

• COOH
• oic acid

Question 13

Give the mechanism for the oxidation of primary alcohols to form aldehydes and carboxylic acids

Answer 13

Check physical flashcards for answers

Question 14

Describe the process of how an aldehyde produced?

Answer 14

• Get it out of oxidising solution as soon as it forms
• Using distillation apparatus
• Aldehyde(which boils at a lower temperature than alcohol) is distilled off immediately.

Question 15

How is just carboxylic acids produced?

Answer 15

• Vigorously oxidised
• Mixed with excess oxidising agent under reflux
• Heating under reflux means you can increase the temperature of an organic reaction without loosing volatile solvents, reactants or products

Question 16

Name the reflux apparatus

Answer 16

• Round bottomed flask
• Heat
• Anti-bumping granules to provide a surface area to make boiling smoother
• Liebig condenser

Question 17

How are secondary alcohols oxidised to produce ketones

Answer 17

Reflux

Question 18

How can aldehydes and ketones be distinguished

Answer 18

• Fehlings solution and Benedict’s solution: Both deep blue Cu2+ complexes that are reduced to brick red Cu2O when warmed with an aldehyde but stay blue in a ketone

• Tollens reagent: Reduced to silver when warmed with an aldehyde but not with a ketone. The silver will coat the inside of the apparatus to form a silver mirror

Question 19

What process is the oxidation of an alcohol (separation)

Answer 19

FRACTIONAL DISTILLATION

Question 20

Suggest why anti-bumping granules prevent bumping

Answer 20

They form smaller bubbles

Question 21

Write an equation for the oxidation reaction of propane-1,2-diol under reflux, using [O] to represent the oxidising agent

Show the displayed formula for the reaction

Answer 21

Check physical flashcards for answers

Question 22

Give two ways of maximising the yield of propanal obtained by distillation of the
reaction mixture.

Answer 22

• Keep the temperature of the reaction mixture below the boiling point
  of propan-1-ol/below 97 °C
• Cool the distillate / collecting vesse