Organic Synthesis

In general used as separation technique to separate an organic product from its reacting mixture. Need to collect the distillate at the approximate boiling point range of the desired liquid.

Primary alcohol —> aldehyde

eragent: potassium dichromate (VI) solution and dilute sulfuric acid.

Limited amount of dicrhromate and warmly and gentyl distilled out the aldehyde as it forms preventing furter oxidation

Orange dichromate solution changes to green colour of Cr3+ ions

Reflux is used when heating organic reaction mixtures for long periods. The condenser prevents organic vapours from escaping by condensing them back to liquids. Never seal the end of the condenser as the build up of gas pressure could cause the apparatus to explode. This is true of any apparatus where volatile liquids are heated

Reagent: potassium dichromate(VI) solution and dilute sulfuric acid Conditions: use an excess of dichromate, and heat under reflux: (distil off product after the reaction has finished using distillation set up) Observation Orange dichromate solution changes to green colour of Cr3+ ions

• Put the distillate of impure product into a separating funnel • wash product by adding either - sodium hydrogencarbonate solution , shaking and releasing the pressure from CO2 produced. Or Saturated sodium chloride solution • Allow the layers to separate in the funnel, and then run and discard the aqueous layer. • Run the organic layer into a clean, dry conical flask and add three spatula loads of drying agent (e.g. anhydrous sodium sulfate, calcium chloride) to dry the organic liquid. When dry the organic liquid should appear clear. • Carefully decant the liquid into the distillation flask • Distil to collect pure product

Sodium hydrogencarbonate will neutralise any remaining reactant acid. Sodium chloride will help separate the organic layer from the aqueous layer

• be insoluble in the organic liquid • not react with the organic liquid

Sodium carbonate Effevecsence of co2 evolved

Warm with silver nitrate Slow formation of white precipitate of AgCl

Silver nitrate Vigorous reaction- steamy fumes of HCl- rapid white precipitate of AgCl

Sodium dichromate and sulfuric acid Orange to green colour change