Systematic Carbon Chemistry

• Compounds containing only single carbon–carbon bonds are described as saturated
• Compounds containing at least one carbon–carbon double bond are described as unsaturated
• Compounds containing carbon–carbon double bonds can take part in addition reactions
• In an addition reaction, two molecules combine to form a single molecule
• It is possible to distinguish an unsaturated compound from a saturated compound using bromine solution
• Unsaturated compounds quickly decolourise bromine solution
• Isomers are compounds with the same molecular formula but different structural formulae
• Isomers may belong to different homologous series and usually have different physical properties
• The functional group in an alcohol is the hydroxyl group (-OH)
• The general formula for the alcohol homologous series is CnH2n+1OH
• In straight chain alcohols with more than 3 carbon atoms, the position of the hydroxyl group is indicated in the name
• In branched chain alcohols, the main chain is the longest chain which includes the hydroxyl group
• In a primary alcohol, no more than one carbon atom is joined directly to the carbon bonded to the hydroxyl group
• In a secondary alcohol, there are two carbon atoms attached to the carbon bonded to the hydroxyl group
• In a tertiary alcohol, there are three carbon atoms attached to the carbon bonded to the hydroxyl group
• All alcohols have similar chemical properties
• As the size of the molecule increases, the boiling points increase
• Smaller alcohols are soluble in water because the hydroxyl group can form hydrogen bonds with water
• Larger alcohols are insoluble due to the influence of the non-polar hydrocarbon chain
• Some alcohols contain more than one hydroxyl group in the molecule
• e.g. antifreeze contains ethane-1,2-diol (ethylene glycol)
• fats and oils can be hydrolysed to produce propane-1,2,3-triol (glycerol)
• Alcohols with a greater number of hydroxyl groups have even higher boiling points
• The greater degree of hydrogen bonding also accounts for the increase in viscosity as the number of hydroxyl groups increases
• The functional group in a carboxylic acid is the carboxyl group (-COOH)
• In branched chain carboxylic acids, the main chain is the longest chain which includes the carboxyl group
• In aqueous solution, carboxylic acids behave as typical acids and form salts when reacted with metals and bases
• Reaction of methanoic acid with magnesium:

  2HCOOH + Mg → Mg(HCOO)2 + H2

  The salt formed in this case is magnesium methanoate
• Reaction of ethanoic acid with copper(II) carbonate:

  2CH3COOH + CuCO3 → Cu(CH3COO)2 + CO2 + H2O

  The salt formed in this case is copper(II) ethanoate