Lecture 21 - Redox 1 - Oxidation

Question 1

Define oxidation and reduction based on electrons.

Answer 1

Oxidation
Is
Loss
Reduction
Is
Gain

Question 2

Define redox/ oxidation and reduction in terms of oxidation

Answer 2

oxidation = gain in oxygen
reduction = loss of oxygen

Question 3

Define redox/ oxidation and reduction in terms of hydrogen

Answer 3

oxidation = loss of hydrogen
reduction = gain of hydrogen

Question 4

What do oxidation levels depend upon?

Answer 4

Oxidation levels depend upon how many bonds there are to an electronegative atom.

Question 5

What is the oxidation level of ethane?

Answer 5

0

Question 6

What is the oxidation level of ethanol?

Answer 6

1 - there is one bond to an electronegative oxygen atom

Question 7

What is the oxidation level of a ethanone?

Answer 7

2 - there is a double bond to electronegative oxygen

Question 8

What is the oxidation level of ethanal?

Answer 8

3 - there is a double bond to electronegative oxygen and also a single bond to oxygen

Question 9

What is the oxidation level of CO2?

Answer 9

4 - there are two double bonds to electronegative oxygen

Question 10

If the oxidation levels increase in a reaction, what is happening?

Answer 10

oxidation

Question 11

If the oxidation levels decrease in a reaction, what is happening?

Answer 11

reduction

Question 12

What is the oxidation level of methanenitrile?

Answer 12

3 - has triple bond to electronegative nitrogen

Question 13

Is the reaction from an acyl chloride to carboxylic acid oxidation? Explain why.

Answer 13

No.
The oxidation level of acyl chloride is 3. The oxidation level of carboxylic acid is also 3. There is no change in the oxidation level therefore it is neither oxidation or reduction

Question 14

Is this reaction oxidation, reduction or neither?

Answer 14

oxidation - loss of hydrogen atoms

Question 15

How does the body convert primary alcohols (oxidation level 1) to aldehydes (oxidation level 2) to carboxylic acids (oxidation level 3)?

Answer 15

Primary alcohol to aldehyde = enzyme alcohol dehydrogenase/ oxidase

Aldehyde to carboxylic acid = enzyme aldehyde dehydrogenase / oxidase

Question 16

In the lab, what can we oxidise primary alcohols into?

Answer 16

aldehydes and carboxylic acids

Question 17

How can we oxidise primary alcohols into aldehydes? Name and draw the structure of the oxidant.

Answer 17

• PPC a mild oxidant
• pyridinium chlorochromate.

Question 18

How can we oxidise primary alcohols into carboxylic acids?

Answer 18

strong oxidant - acidified potassium manganate - KMnO4 OR acidified potassium dichromate K2Cr2O7

Question 20

How can we oxidise aldehydes into carboxylic acids?

Answer 20

strong oxidant - acidified potassium manganate - KMnO4 OR acidified potassium dichromate K2Cr2O7

Question 21

Secondary alcohols can be converted into….

Answer 21

ketones

Question 22

What oxidant do we use to convert secondary alcohols to ketones?

Answer 22

mild or strong - it doesn’t matter because ketones cannot be further oxidised.

Question 23

Can tertiary alcohols be oxidised?

Answer 23

NO

Question 24

Alkenes can be oxidised into alcohols. Write/draw the dihydrolation reaction.

Answer 24

Question 25

Draw/write the oxidation reaction from alkene to epoxide

Answer 25

Question 26

Write/ draw the oxidation reactions from alkene to ketone/aldehyde. What is this reaction called?

Answer 26

ozonolysis

Question 27

What are free radicals?

Answer 27

species with an unpaired electron

Question 28

Name a stable type of radical and explain why it is more stable.

Answer 28

Allylic radical. Like allylic carbocations, the free radical is more stable because of the double bond - there is an overlap of electron density between the p orbital and pi bond.

Question 29

Draw the resonance forms for an allylic radical, making sure to use the correct arrows.

Answer 29

Question 30

Draw oxygen as a diradical

Answer 30

O.- O.

Question 31

Over time, why do creams/makeup become toxic?

Answer 31

oxidation - oxygen diradical will convert them into electrophiles which are toxic to the human body.