2.7 Alcohols and Carboxylic Acids

Alcohol general information

• high mp/bp

• soluble

• C_nH_2n+1OH

Fermentation

• glucose + yeast → ethanol + carbon dioxide

• remove yeast by distillation

Biofuels

• bioethanol - fermentation

• biodiesel - oils/fats in seeds

Biofuels advantages

• renewable

• produce less greenhouse gases

• less dependent on changes of prices

Biofuels disadvantages

• lots of land needed

• large quantities of water/fertiliser

Alcohol → alkene

• dehydration (-H₂O)

• 360°C

• Al₂O₃ catalyst

Primary alcohol → carboxylic acid

• oxidation

• acidified potassium dichromate

• reflux

• orange > green

Primary alcohol → aldehyde

• oxidation

• acidified potassium dichromate

• distillation

• orange > green

Secondary alcohol → ketone

• oxidation

• acidified potassium dichromate

• reflux

• orange > green

Alcohol + carboxylic acid → ester

• esterification

• H₂SO₄ catalyst

Test for primary/secondary alcohols

• acidified potassium dichromate (VI)

• reflux

• orange/yellow > green

Carboxylic acid general information

• high mp/bp

• soluble

• C_nH_2nO₂

Carboxylic acid + base →

salt + water

Carboxylic acid + carbonate →

salt + water + carbon dioxide

Carboxylic acid → alkane

• elimination (-CO₂)

• lose carbon from chain

• heated

• soda lime

Test for carboxylic acids

• sodium carbonate/hydrogencarbonate

• effervescence as CO₂ produced