2.7 - Alcohols Flashcards
What can alcohols be grouped as?
Primary, secondary or tertiary
What is a primary alcohol?
1 carbon at functional group
What is a secondary alcohol?
2 carbons at functional group
What is a tertiary alcohol?
3 carbons at functional group
How is alcohol made by industrial production?
Hydration of alkenes in the presence of an acid catalyst, through electrophillic addition.
What conditions are needed to create an alcohol?
-phosphoric acid, 300* and 60 atm pressure
How can ethanol be produced?
Fermentation - yeast to turn glucose into ethanol
What is the equation for the fermentation of ethanol?
C6H12O6 - yeast/40 = 2C2H6O + 2CO2
ethanol is then separated by distilllation which can add cost
Why are biofuels cleaner than petrol?
They are renewable because you can grow more plants, they are carbon neutral (CO2 when burnt, aborbed when plants grow)
What are 2 issues with biofuels?
- car engines can’t run on biofuels
- land used for biofuel - food shortages
What do you get when you oxidise a primary alcohol?
Aldehyde
carbon - oxygen double bond and at least 1 carbon hydrogen bond
alkanal (no numbers as carbon must be on end)
What happens when you oxidise an aldehyde?
You get a carboxylic acid
c double bond o
carbon - oh double bond
What does oxidation do?
Breaks carbon hydrogen bonds but not carbon-carbon bonds
Means you can’t oxidise a tertiary group
What is the oxidising agent for alcohols?
acidified potassium dichromate (V)
What do you get if you oxidise a secondary alcohol?
Ketones
Double bond carbon to an oxygen atom, and 2 other c-c bonds
alkan-x-one (x= which carbon the ketone lies)
What methods are used to create aldehydes?
Distillation
Condenses any reacted aldehyde which forms a gas, into a new flask
What method is used to create carboxylic acids?
Reflux condensor
Condenses any gases and forces them back into the reaction vessel, aldehydes are returned to the flask to be oxidised again
What 2 methods can be used to test between aldehydes or carboxylic acids?
- fehlings solution
- tollens reagent
What is fehlings solution?
Cu2+ and is deep blue
Aldehyde - cu2+ oxidises and then reduced to CU+ (brick red)
ketone - no change
What is tollens reagent?
Diammine silver H ion (AG(NH3)2)+
clear solution
oxidises aldehyde, reduced to solid silver in test tube
does nothing to a ketone
What is the equation for the dehydration of alkenes?
CnH2n+1OH (H+)= CnH2n +H2O
