M4 B5 Alcohols
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What is the Functional Group of alcohols and their General Formula?
Functional Group- OH General Formula - CnH2n+1 OH
What is another name for the alcohol functional group?
Hydroxy
How do you classify Alcohols?
It depends on how many Carbons the Carbon with the OH group on it is connected to
Why is the OH bond a polar bond?
Oxygen is more electronegative than Hydrogen
What happens to the solubility of an alcohol as the carbon chain length increases?
Solubility decreases (becomes less)
What is the link between the number of OH groups and the solubility of an alcohol? Why?
The more OH groups an alcohol has, the greater its solubility because it can form more hydrogen bonds with water, increasing solubility
What does it mean if a liquid is volatile?
It turns from a liquid to a gas easily by the breaking of intermolecular forces between molecules.
Why do alcohols have a higher MPT and BPT than alkanes of comparable Mr’s?
OH groups form hydrogen bonding which require more energy to break as they’re stronger than induced dipole dipole forces.
Why do alcohols burn more cleanly than other compounds?
They contain oxygen, so they produce less carbon monoxide e.g C2H5OH + 3O2 —> 2CO2 + 3H2O
What is the main oxidising agent used in oxidation reactions of alcohols?
Acidified Potassium Dichromate
What is the observation for the oxidation reactions? Why is this?
Orange to Green because the Dichromate ion is Orange and the Chromium ion is Green
What are the 2 products formed when oxidising a primary alcohol and how can you determine which one is formed?
• Aldehyde and Carboxylic Acid • Aldehyde is produced under Distillation conditions and with 1 mole of the oxidising agent • Carboxylic Acid is produced under Reflux conditions and with 2 moles of the oxidising agent
How do we show the oxidising agent in the equations?
[O] or 2[O] for reflux
What is distillation used for?
Provide heat energy for the reaction to occur To remove the product from the oxidising mixture to prevent further oxidation To remove the aldehyde from the mixture as it has a lower boiling point
What type of Intermolecular Force (IMF) is in an aldehyde?
Permanent dipole dipole (C=O)
How do you make an aldehyde from a primary alcohol?
Use acidified Potassium Dichromate as the oxidising agent under Distillation conditions
What is reflux used for?
The continuous evaporation and condensation of a reactant
How do you make a carboxylic acid from a primary alcohol?
Use acidified potassium dichromate as the oxidising agent (2 MOLES) under reflux conditions
How can you make a carboxylic acid from an aldehyde?
Oxidise it in reflux conditions
What is the product formed when oxidising a secondary alcohol and what are the conditions?
Ketone is formed under reflux conditions
What is the colour change observed in ALL the oxidation reactions of alcohols?
Orange to Green
What happens during an oxidation reaction of tertiary alcohols?
Nothing happens :) The potassium dichromate remains orange
What is the elimination of Water and what is it also known as?
It involves the removal of a water molecule to form an alkene. Also known as dehydration
What is the conditions and catalyst for the elimination of water reaction?
Reflux conditions with an acid catalyst such as concentrated Sulphuric Acid