Oxidation Of Alcohols
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How does structure affect the oxidation of alcohol
How much an alcohol can be oxidised depends on its structure
What is the oxidising agent used oxidise alcohols
Acidified potassium dichromate, K2Cr2O7
What is the colour change to show the oxidation of the dichromate ion
Cr2O72- is orange is reduced to green chromium(III) ion, Cr3+
What functional group are primary alcohols oxidised into?
Aldehydes and carboxylic acids
What functional group are secondary alcohols oxidised into?
Ketones only
Are tertiary alcohols oxidised?
No
What is the condition for oxidising tertiary alcohols
By burning them
What is the functional group for aldehydes and ketones and give the formula
• C=O • CnH2nO
What is the functional groups for carboxylic acids and their general formula?
• COOH • CnH2n+1COOH
Give the structure of aldehydes and their suffix
• A hydrogen and one alkyl group attached to the carbonyl carbon atom • al
Give the structure and suffix of ketones
• two alkyl groups attached to the carbonyl atom • one
What is the carbonyl group of carboxylic acids and give their suffix
• COOH • oic acid
Give the mechanism for the oxidation of primary alcohols to form aldehydes and carboxylic acids
Check physical flashcards for answers
Describe the process of how an aldehyde produced?
• 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.
How is just carboxylic acids produced?
• 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
Name the reflux apparatus
• Round bottomed flask • Heat • Anti-bumping granules to provide a surface area to make boiling smoother • Liebig condenser
How are secondary alcohols oxidised to produce ketones
Reflux
How can aldehydes and ketones be distinguished
• 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
What process is the oxidation of an alcohol (separation)
FRACTIONAL DISTILLATION
Suggest why anti-bumping granules prevent bumping
They form smaller bubbles
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
Check physical flashcards for answers
Give two ways of maximising the yield of propanal obtained by distillation of the reaction mixture.
• Keep the temperature of the reaction mixture below the boiling point of propan-1-ol/below 97 °C • Cool the distillate / collecting vesse