AS Chemistry Alchols Mind Map
- Created by: E
- Created on: 22-04-15 11:08
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- Alcohols
- Ethanol Production
- Fermentation C6H12O6 -------->2CH3CH2OH+2CO2
- Slow
- Batch process
- Renewable raw materials
- Makes impure copper (purified by fractional distillation)
- Normal pressure
- 30-40'C
- Micro-organisms (yest) to supply enzyme in absence of oxygen
- Made from sugar, maize, or corn
- Anaerobic conditions (without oxygen)
- Direct Hydration CH2=CH2+H20-------->CH3CH2OH
- Fast
- Continuous process
- Non-renewable raw materials
- Makes pure ethanol
- High pressure
- 300'C
- Concentrated phosphoric acid catalyst
- Made from crude oil
- ***CARBON NEUTRAL*** The CO2 used in photosynthesis when growing plants for sugar is the same amount of combustion of alcohol and fermentation.
- Fermentation C6H12O6 -------->2CH3CH2OH+2CO2
- Introduction and Classification of Alcohols
- The Basics
- Have the function group -OH
- Have the suffix -ol
- Have the prefix hydroxy-
- Classification
- Primary
- The carbon attached to the OH is attached to only one other carbon.
- eg Propan-1-ol CH2CH2CH2OH
- Secondary
- eg Propan-2-ol CH3CH(OH)CH3
- The carbon attached to the OH is attached to 2 other carbons.
- Tertiary
- eg 2-Methyl propan-2-ol CH3C(CH3)(OH)CH3
- The carbon attached to the OH is attached to 3 other carbons.
- Primary
- The Basics
- Oxidation of Alchols
- Primary Alcohols
- Oxidised to aldehyde and then to carboxylic acid.
- Oxidation of primary alcohol to an aldehyde (distillation) CH3CH2CH2OH+[o]---->CH3CH2H-C=O+H20
- [o] is distill potassium dichromate. (H+/K2Cr2O7)
- Oxidation of aldehyde to carboxylic acid (reflux) CH3CH2H-C=O+[o]---------->CH3CH2OH-C=O
- Secondary Alcohols
- Oxidised to a ketone only.
- Don't need to distil/reflux, simply heat.
- Oxidation of secondary alcohol to ketone. CH3CH(OH)CH3---->CH3C(=O)CH3+H2O
- Uses acidified potassium dichromate. (H+/K2Cr2O7)
- Tertiary Alcohols
- CAN'T BE OXIDISED.
- There are no hydrogen atoms attached to the carbon bearing the hydroxyl group and so no oxidation can occur.
- There is no reaction between tertiary alcohols and acidified potassium dichromate.
- Chemical Test for Alcohols
- H+/K2Cr2O7 (potassium dichromate) is orange. It is reduced to Cr^3+ which is green.
- Primary and secondary alcohols react with potassium dichromate so would go from orange to green.
- Tertiary alcohols DON'T react with potassium dichromate so no colour change would occur.
- Primary Alcohols
- Chemical Test for Aldehydes
- Test 1-Tollens Reagent
- 2).Used to identify an aldehyde.
- 3).Aldehyde is oxidised to carboxylic acid.
- 4).Ag+ ions reduced to Ag which creates a 'silver mirror'.
- 5).Ketone can't be oxidised so there is no change.
- 6).So if silver mirror is produced it was an aldehyde. If not, it was a ketone.
- 1).Silver nitrate dissolved in dilute aqueous ammonia.
- Fehling's Solution
- 2).Used to identify an aldehyde.
- 3).Cu2+ in fehlings is reduced to Cu2O which produces a red precipitate.
- 4).Ketone can't be oxidised so there is no change.
- 5).So if there is a red precipitate it was an aldehyde, if not it was a ketone.
- 1).Blue solution containing copper(II) ions in an alkaline solution (NaOH)
- Test 1-Tollens Reagent
- Ethanol Production
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