Organic Chemistry Reactions Reactions Hydrolysis of a polysaccharide polysaccharide + water → disaccharide Example: 2(C6H10O5)n + nH2O → nC12H22O11 Hydrolysis of a disaccharide disaccharide + water → monosaccharide Example: C12H22O11 + H2O → 2C6H12O6 Reactions Fermentation of glucose C6H12O6 → 2C2H5OH + 2CO2 Special conditions for fermentation: • optimum temperature range between 20°C and 30°C • little or no oxygen present • enzymes (catalyst) e.g. in yeast Reactions Oxidation of a primary alcohol primary alcohol + oxidising agent → aldehyde (there will be more reactants and products depending on the oxidising agent) Note: if the aldehyde is not immediately removed it will be further oxidised to a carboxylic acid Example: ethanol + acidified dichromate → ethanal + chromium ions CH3CH2OH + Cr2O72- + 12H+ → CH3CHO + 2Cr3+ + 7H2O (For definitions of primary and secondary alcohols, see notes, Subtopic 5.2) Reactions Oxidation of a secondary alcohol secondary alcohol + oxidising agent → ketone (there will be more reactants and products depending on the oxidising agent) Example: propan-2-ol + acidified dichromate → propanone + chromium ions CH3CH(OH)CH3 + Cr2O72- + 12H+ → CH3COCH3 + 2Cr3+ + 7H2O (For definitions of primary and secondary alcohols, see notes, Subtopic 5.2) Reactions Oxidation of an aldehyde under acidic conditions aldehyde + oxidising agent + H+ → carboxylic acid (there will be more reactants or products depending on the oxidising agent) Example: ethanal + acidified dichromate → ethanoic acid + chromium ions CH3CHO + Cr2O72- + 12H+ → CH3COOH + 2Cr3+ + 6H2O Reactions Oxidation of an aldehyde by Tollens’ reagent aldehyde + Tollens’ reagent → carboxylate anion + silver metal + ammonia (there will be more reactants or products depending on half-reactions) Example: methanal + Tollens’ reagent → methanoic acid + silver + ammonia CH2O + Ag(NH3)2+ + H2O → CHOOH + Ag + 2NH3 + 2H+ Since an obvious silver ‘mirror’ forms on the flask if a reaction occurs, this is commonly used to test whether a substance is a ketone or an aldehyde. A ketone cannot be oxidised, so no silver mirror would form. Tollens’ reagent is ammoniacal silver nitrate solution, Ag(NH3)2NO3 (aq) Usually we wouldn’t write the nitrate, since it is a spectator. And many more… See “Organic_reactiontypes” in the Notes folder for a full list. Some are detailed further in other notes files or the textbook.