Oxidation

Question 1

What does a secondary alcohol oxidise to?

Answer 1

Ketone

Question 2

What is the colour change when a secondary alcohol is oxidised?

Answer 2

Orange to green

Question 3

What oxidising agent is used for alcohols?

Answer 3

a chromium (6+ ) reagent 
Na2Cr2O7

Question 4

Why is the oxidation of secondary alcohols a bad process?

Answer 4

Lots of Cr waste is generated

Question 5

What alternative name does the oxidation of a secondary alcohol have?

Answer 5

Jones oxidation

Question 6

How many chromate molecules are used in the Cr(VI) oxidation ?

Answer 6

2

Question 7

What is the order of the oxidation states for the Cr(VI) oxidation mechanism?

Answer 7

Cr (VI)
Cr (IV)
Cr (III)

Question 8

In the mechanism for the Cr (VI) oxidation, what is the key oxidising agent?

Answer 8

CrO3

Question 9

What does a primary alcohol oxidise to initially?

Answer 9

Aldehyde

Question 10

How does a primary alcohol oxidise to a carboxylic acid (final oxidation state)?

Answer 10

First it is oxidised to an aldehyde, then a water molecule is added which forms a hydrate (two OH), then the hydrate is oxidised to form the carboxylic acid

Question 11

What is a jones reagent?

Answer 11

Reagent involved in the oxidation of primary and secondary alcohols

Question 12

What type of reagent oxidises hydrates?

Answer 12

Jones reagents

Question 13

Alcohols can be oxidised to aldehydes under basic conditions, what reagent would be used in this instance?

Answer 13

Pyridinium chlorochromate

PCC

Question 14

Apart from basic, what other conditions would you need to use when using PCC?

Answer 14

Anhydrous

Question 15

How are alkenes oxidised?

Answer 15

Through epoxidation
uses peracid RCO3H
C-O bonds form through syn addition

Question 16

What type of reaction is synaddition, what does this mean?

Answer 16

Sn2

there will be an inversion of stereochemistry

Question 17

What are the issues with using Osmium Tetroxide?

Answer 17

Rare
Expensive
Sublimes straight to gas

Question 18

What are the issues with using Osmium Tetroxide for oxidation of alkene?

Answer 18

Rare
Expensive
Sublimes straight to gas

Question 19

What happens when osmium tetroxide is used for oxidation of alkene?

Answer 19

C-O bonds are formed in syn addition

Forms cyclic osmate ester through hydrolysis of the ester

Question 20

What is the product when you use osmium tetroxide to oxidise an alkene?

Answer 20

syn-1,2-diol

Question 21

What issues can Os (VI) cause?

Answer 21

Reduced to a metal so it forms a metal sheen across the eyeball if it comes close

Question 22

What type of osmium is needed for the catalytic version of oxidation of the alkene?

Answer 22

Only catalytic OsO4 is needed

Question 23

In the catalytic version using osmium tetroxide, what is the oxidising agent?

Answer 23

NMO

Question 24

In the catalytic version, what oxidation happens inside of the reaction?

Answer 24

Oxidation of Os (VI) back to Os (VIII)

Question 25

When using ozone to oxidise alkenes, what do you need to avoid using?

Answer 25

Oxidising agent as O3 is susceptible to oxidation

Question 26

When ozone is used to oxidise alkenes, which bond is formed?

Answer 26

C=O formed from C=C

Question 27

When ozone is used to oxidise alkenes, which bonds of the alkene are cleaved?

Answer 27

Pi and sigma bonds

Question 28

When ozone is used to oxidise alkenes, what reducing agent is used?

Answer 28

Dimelthylsulfide

Question 29

What is the product of oxidisation with ozone?

Answer 29

Aldehydes

Question 30

When ozone reacts with the alkene, what type of reaction is it?

Answer 30

concerted | as pi bond broken at the same time as its added

Question 31

When ozone reacts with the alkene, what type of addition is it?

Answer 31

Syn

Question 32

What cyclic product can be formed from ozone reacting with the alkene?

Answer 32

Ozonide

Question 33

What is formed when Me2S reacts with the cyclic ozonide?

Answer 33

It generates Me2SO and also 2 aldehydes

Question 34

Because Me2S is a mild reducing agent, what does it prevent?

Answer 34

Prevent the reduction of RCHO to alcohol and prevents the oxidation of RCHO to acid

Question 35

When oxidising alkenes with ozone, how do you make an alcohol your product instead of an aldehyde?

Answer 35

Use a stronger reducing agent | NaBH4

Question 36

When oxidising alkenes with ozone, how do you make an acid your product instead of an aldehyde?

Answer 36

Use an oxidising agent | H2O2