2b) - Alcohols

An alcohol is a molecule containing a hydroxyl functional group (-OH)

CnH2n+1OH

The basic rules of naming apply: the position of the hydroxyl group is indicated before the “ol” part

Miscible liquids are ones that can mix together

Immiscible liquids are ones that cannot mix together

• solvents • steriliser • fuels

Alcohols are used as fuels as they are highly flammable and burn with very clean flames

Step 1 - name the longest chain that contains the hydroxyl group Step 2 - number the chain from end closest to the OH Step 3 - name the branches and number according to step 2 Step 4 - if multiple branches use di - tri - etc if different types of branch name alphabetically

Alcohols can be classed as primary secondary or tertiary

A primary alcohol is one in which the hydroxyl group (–OH) is attached to a carbon atom with at least two hydrogen atoms. This will only occur when the hydroxyl group is at the end of the molecule chain.

A secondary alcohol is one in which the hydroxyl group (-OH) is attached to a carbon with only one hydrogen atom attached.

A tertiary alcohol is one in which the hydroxyl group is attached to a carbon with no hydrogen atoms attached. This will normally mean that the hydroxyl group is joined to the same carbon atom as a branch.

Alcohols containing two hydroxyl groups are called diols

Alcohols containing three hydroxyl groups are called triols

Hydroxyl groups make alcohols polar which gives rise to hydrogen bonding

Methanol, ethanol and propanol are miscible with water, thereafter the solubility decreases as size increases

As alcohols increase in size their melting and boiling points increase due to the increasing strength of intermolecular forces

Yes The smaller the molecule the more soluble the smaller the molecule the more volatile