A2 AQA CHEM4 3.4.10

3.4.10 Organic Synthesis and Analysis

Chemical tests

Alkenes

·         Alkenes decolourise bromine water

Haloalkanes

·         Add aqueous NaOH and heat, then add dilute HNO₃ and then aqueous AgNO₃

·          White ppt= chloride ions

o   soluble in dilute ammonia

·         Cream ppt=bromide ions

o   soluble in conc. ammonia

·         Yellow ppt=iodide ions

o   insoluble in conc. ammonia

Aldehydes and ketones

·         Tollen’s reagent

o   Aldehydes form a silver mirror

o   Ketones show no reaction

·         Fehling’s solution

o   Aldehydes form brick red ppt.

o   Ketones show no reaction

Carboxylic acids

·         Add NaHCO₃/Na₂CO₃ and a carboxylic acids produces effervescence

Acyl chlorides

·         Add H₂O to the sample slowly, white misty fumes of HCl are given off by an acyl chloride

Amines

·         Add universal indicator, if it turns blue/purple an amine is present since they are basic

Alcohols (general)

·         Add ethanoic acid and small amount of H₂SO₄ and heat. If a sweet, fruity smell is present, an ester has been produced so alcohol was present

OR

·         Add acidified potassium dichromate. 1^o and 2^o alcohols cause a colour change from orange to green but 3^o do not cause a colour change

Organic Synthesis

alkane à chloroalkane

mechanism:…