Organics 2 - 5th

• organic molecules containing an -OH functional group

each alcohol has a name, in which: - the start of the name shows how many carbon atoms it has - the end of the name is -ol to show it is an alcohol

methanol

ethanol

propanol

butanol

in this method, ethene (C2H4) gas is mixed with steam (H2O) under the following conditions: - 300 degrees celcius - 65 atm pressure - phosphoric acid catalyst

• crude oil provides the ethene

• makes pure ethanol • can run continuously

• conditions require a lot of energy • non-renewable raw material used

• yeast - provides enzymes • 30 degrees celcius - enzymes optimum temperature • anaerobic - prevents oxidation

• sugar cane provides the glucose

• renewable raw material used • conditions not energy-intensive

• makes impure ethanol • must be done in individual batches

• depends mostly on the availability of crude oil or sugar cane in different parts of the world

• combustion • microbial oxidation • chemical oxidation

• ethanol tends to combust completely because of the oxygen atom in the -OH group • this results in a non-luminous, blue flame • C2H5OH + 3O2 -> 2CO2 + 2H2O

• many micro-organisms, such as bacteria and fungi, can use the oxygen in the air to oxidise ethanol into ethanoic acid • this can only happen if anaerobically, ie if the micro-organism is growing in the presence of air • we can represent the microbial use of oxygen in an equation using the ‘O’ symbol • C2H5OH + 2 [O] -> CH3COOH + H2O

• when we want to deliberately oxidise ethanol in the lab, we heat it with a mixture of: - potassium dichromate (VI) (K2Cr2O7) - dilute sulfuric acid (H2SO4) • this forms ethanoic acid and we use the symbol [O] to write an equation for the reaction • C2H5OH + 2[O] -> CH3COOH + H2O • as this occurs, the orange dichromate ions are turned into green chromium ions • this means the reaction is always accompanied by the same colour change • CrO7 2- -> Cr 3+ • orange to green

• organic molecules containing an -COOH functional group

• the start of the name shows how many carbon atoms it has • the end of the name is ‘-oic’ acid to show its a carboxylic acid

methanoic acid

ethanoic acid

propanoic acid