4.2.3 organic synthesis

Question 1

distillation

Answer 1

primary alcohol > aldehyde

reagent: potassium dichromate (VI) solution and dilute H2SO4

conditions: warm gently and distil out aldehyde as it forms to prevent further oxidation to carboxylic acid

orange dichromate solution > green colour of Cr3+ ions

Question 2

reflux

Answer 2

prevents evaporation by condensing them back to liquids

primary alcohol > carboxylic acid

reagent: potassium dichromate (VI) solution and dilute H2SO4

use excess dichromate, heat under reflux

orange dichromate ions > green Cr3+ ions

anti-bumping granules to prevent vigorous, uneven boiling

Question 3

purifying organic liquid

Answer 3

put distillate of impure product into separating funnel

wash product by adding saturated sodium chloride solution

allow layers to separate in full, then run and discard the aqueous layer

run organic layer into clean, dry conical flask and add drying agent (CaCl2) to dry organic liquid

when dry, should appear clear

decant the liquid into distillation flask

distil to collect pure product