3.5 Alcohols Flashcards
Secondary alcohol to ketone
Oxidation
Reactants : K2Cr2O7
Conditions : Reflux or distillation
Primary alcohol to aldehyde
Oxidation
Reactants : K2Cr2O7 , H2SO4
Conditions :Distillation
Primary alcohol to carboxylic acid
Oxidation
Reagents : K2Cr2O7, H2SO4
Conditions : Reflux, excess oxidising agent
Aldehyde to carboxylic acid
Oxidation
Reagents : K2Cr2O7, H2SO4
Conditions : Reflux
Glucose to alcohol
Conditions: Yeast, no oxygen, 35C
OH group name
Hydroxy
Ethanol general formula
CnH2n+1OH
Aldehyde functional group
Ending
CHO
al
Ketone functional group
Ending
CO
one
Carboxylic acid functional group
Ending
COOH
oic acid
Ethanal
H
|
H-C-C=O
| |
H H
Observation for alcohol oxidation
Orange to green
CH3CH2OH oxidation equation (to aldehyde)
CH3CH2OH + [O] –> CH3CHO + H2O
CH3CHO oxidation equation
CH3CHO + [O] –> CH3COOH
CH3CH2OH oxidation equation (to carboxylic acid)
CH3CH2OH + 2[O] –> CH3COOH + H2O
CH3CH(O)CH3 oxidation equation
CH3CH(OH)CH3 + [O] –> CH3COCH3 + H2O
Oxidation of tertiary alcohols
Tertiary alcohols cannot be oxidised
Features of condensers
- Open at both ends
- Cold water flows around outside
Purpose of condenser
Cools hot vapour and condenses it to liquid
Purpose of anti-bumping granules
Prevents the formation of large bubbles
Why is reflux used to oxidise a primary alcohol to carboxylic acid
Reflux doesn’t allow any reactant vapour to escape so it can be further oxidised
Describe what happens when a reaction mixture is refluxed and why it is necessary to complete oxidation to a carboxylic acid
- Ethanol and acidified potassium dichromate are heated to bp for a prolonged time
- Ethanal vapour formed which escapes from liquid mixture and is condensed back to a liquid and returned back to reaction mixture
- Any ethanal and ethanol that initially evaporated can be oxidised
Why is there an open end in distillation
To prevent a build up of pressure and explosion
Why is there a bung under the thermometer in distillation
It is a closed system to prevent gases escaping
