Module 4: Chapter 14 Alcohols

• the -OH group attached to carbon atoms is called the hydroxyl group • an alcohol has a hydroxyl group attached to carbon chain or alicyclic ring • a hydroxyl attached to an aromatic ring is called a phenol and is different in its reaction to alcohols

(alkyl groups) longest carbon chain name (minus ‘e’ unless there’s more than one -OH) - position of alcohol group(s) - (di/tri/tetra) ol

the OH carbon joined to one other carbon or has 2 hydrogen atoms on it

the OH carbon is only directly joined to 2 other carbons or has 1 hydrogen atom attached to it

the OH carbon is directly joined to 3 other carbons or has no hydrogen atoms attached

• alcohols are polar molecules • alcohol molecules can form hydrogen bonds with each other • allows for alcohols to mix with water and gives alcohols much higher boiling points

• as the carbon chain gets longer the strength of London forces become more important and stronger • in all cases more energy is needed to overcome the additional hydrogen bondings in alcohols compared to corresponding alkane • as the carbon chain gets longer the solubility in water falls. H2O forms stronger attractions to other H2O’s than it can form to non-polar carbon chains

• Methanol can be used as a fuel, combusts efficiently and exists as a liquid at room temperature · however is toxic and engine corrosive · methanol is a feedstock for making polymers, paints and glues • Ethanol is the alcohol in drinks, it’s also used as a fuels (sometimes mixed with petrol), solvent and feedstock • Ethane-1,2-diol is used as antifreeze

• exothermic reaction - complete combustion

• the hydroxyl group of some alcohols can be oxidised using potassium dichromate (VI) solution (K2Cr2O7) acidified with dilute sulfuric acid (H2SO4) • orange to green as dichromate ions are reduced into chromium ions • oxidising agent represented by [O] • H2O is also a product

Primary alcohols: - aldehyde -COH (gentle heating with distillation) + H2O - carboxylic acid -COOH (high temperature under reflux, excess acidified K2Cr2O7) Secondary alcohols: - ketone (reflux) -C=O Tertiary alcohols: - not oxidised as tertiary alcohols don’t have a hydrogen atom bonded to the carbon atom carrying the -OH group

• a process that allows continuous heating of volatile reactants (vertical condenser) • vaporised reactants condense and drip back into the reaction vessel to continue reaction

Uses a side mounted condenser to separate liquids according to their boiling points

• dehydration reaction is when a water molecule is removed from the the starting material • heat alcohol under reflux in the presence of an acid catalyst (concentrated H2SO4/H3PO4) • forms an alkene and water

An elimination reaction is a reaction in which a small molecule is removed from a larger molecule leaving an unsaturated molecule (reverse addition reactions)

a reaction in which one atom or group (-OH) is replaced by another atom or group (-Br) - forms water