Alcohols Flashcards
(45 cards)
How to specifically name an alcohol?
The ending of the name will be “ol”
For positioning put the C number where it occurs in-between the longest C chain ie Butan and the ol ending
If there’s more than one alcohol put di or tri in front of ol
As you increase the C chain in alcohols what happens to the boiling points?
The boiling points increase
Due to the molecules becoming bigger, so have more electrons
Fluctuations in their electron clouds become more likely and the strength of London forces increase.
More energy is required to separate the molecules
Why do alcohols have a higher boiling points than alkanes?
Alcohols can hydrogen bond, with other alcohol molecules
Hydrogen bonding is stronger than London forces
So more energy required to break them
What’s the maximum amount of water molecules a molecule of ethanol can bond to?
3, 2 hydrogens with the oxygen, and 1 oxygen with the hydrogen
Why does water solubility of the alcohols decrease as the chain length increases?
The OH group is the only part that interacts with the water.
As the chain length increases the effect of the OH group decreases, and that of the non polar (water insoluble) carbon chain becomes more important
Solvent a large alcohol would be able to dissolve in?
Any non polar solvent eg hexane
What does the combustion of an alcohol produce?
CO2 and H2O
Advantages of using ethanol as a fuel?
Much cleaner, undergoes more complete combustion
Has reduced amounts of greenhouse gases produced
Conditions required for dehydration of alcohols?
Heat under reflux
Catalyst of conc sulfuric acid or conc phosphoric acid
What does elimination mean?
Removal of atoms or groups from neighbouring C atoms to form an alkene, releasing a small molecule
How do you recognise an elimination reaction?
Goes from 1 molecule to 2 molecules
Increase in number of double bonds
Why can the elimination of alcohols also been known as a dehydration reaction?
Because the small molecule that is released is water
Example of a dehydration reaction?
CH3CH2OH = H2O + CH2=CH2
What are the 2 chemicals required to make an oxidising agent for alcohols?
Sodium dichromate solution or potassium dichromate solution
And dilute sulphuric acid
What’s the observation if a successful oxidising agent is created?
Reaction turns from orange to green
What determines what happens when an alcohol is oxidised?
The conditions employed
And whether the alcohol is primary, secondary or tertiary
What does reflux mean?
The continuous boiling and condensing of a reaction mixture, to prevent the loss of volatile components
What are the 3 possible products of oxidising an alcohol?
Aldehydye, ketone or carboxylic acid
What’s a primary alcohol?
When you remove the OH group, if the carbon it was bonded to is only bonded to one other Carbon
What conditions are required to create an aldehyde from a primary alcohol?
Add oxidising agent, and gentle heating with distillation
What process is used to separate out the aldehyde from the reaction mixture?
Distillation
When an aldehyde is formed, what do you put at the very end of the name?
“al”
Equation for ethanol oxidising to ethanol?
CH3CHOH + [O] = H2O + CH3CHO
Aldehyde structure?
Carbon double bonded to an oxygen and single bonded to a hydrogen it’s the bonded to a carbon chain
