4.2.1 - alcohols

• general formula of alcohols - Cn H2n+1 OH
• functional group of alcohols - OH
• alcohols have polar OH bonds so alcohols are polar and hydrogen bonds exist between the molecules
• strong hydrogen bonds between alcohol molecules result in relatively high melting and boiling points, and low volatilities compared to alkanes
• alcohols can form hydrogen bonds with water molecules so short chain alcohols are soluble in water
• solubility of alcohols decreases as chain length increases
• primary alcohols - OH group is bonded to one carbon atom
• secondary alcohols - OH group is bonded to two carbon atoms
• tertiary alcohols - OH group is bonded to three carbon atoms
• structural isomers can exist for alcohols with more than two carbon atoms
• primary alcohols can be oxidised to aldehydes (RCHO) and carboxylic acids (RCOOH)
• alcohols can be burnt to release energy: C2H5OH(l) +3O2(g) -> 2CO2(g) + 3H2O(l)
• primary and secondary alcohols can be oxidised by potassium dichromate: K2Cr2O7/H2SO4
• secondary alcohols can be oxidised to ketones (RCOR) when heated under reflux
• aldehydes and ketones contain the carbonyl group C=O
• primary alcohols are distilled to form aldehydes or heated under reflux to form carboxylic acids
• tertiary alcohols are not oxidised under reflux or distillation
• the chromium in potassium dichromate is oxidised and turns the solution orange to green