alcohols Flashcards
(12 cards)
What is a primary alcohol?
An alcohol where the OH group is attached to a carbon with only one alkyl group.
What is a secondary alcohol?
An alcohol where the OH group is attached to a carbon with two alkyl groups.
What is a tertiary alcohol?
An alcohol where the OH group is attached to a carbon with three alkyl groups.
What is the industrial production of alcohol?
Hydration of ethene: CH₂=CH₂ + H₂O → CH₃CH₂OH. Conditions: steam, H₃PO₄ catalyst, 300°C, 60 atm. Continuous, fast, high yield, pure product.
What is the fermentation process?
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Conditions: 30–40°C, yeast, anaerobic. Batch process, slower, impure product (needs distillation).
What is the oxidation of alcohols using acidified potassium dichromate?
Primary: → aldehyde (distil) → carboxylic acid (reflux)
Secondary: → ketone
Tertiary: No reaction
Describe the colour change in potassium dichromate when oxidising alcohols.
Orange solution turns green due to reduction of Cr⁶⁺ to Cr³⁺.
How can aldehydes and ketones be distinguished?
Tollens’ reagent: Aldehyde forms silver mirror; ketone does not.
Fehling’s solution: Aldehyde forms red ppt; ketone does not.
What is the dehydration of alcohols?
Alcohol → alkene + water. Conditions: Conc. H₂SO₄ or Al₂O₃ catalyst. Elimination reaction.
What is the test for alcohols?
Primary/Secondary: Acidified K₂Cr₂O₇ turns orange → green.
Tertiary: No colour change.
What are the uses of ethanol as a biofuel?
Renewable, carbon-neutral (ideally), made from fermentation. Can be blended with petrol to reduce fossil fuel use.
Why is ethanol considered carbon-neutral?
CO₂ released on combustion = CO₂ absorbed during photosynthesis to grow the crops.
