Qualitative Tests - Organic

(ii) To the other portion, add aqueous iron (III) chloride.

OBSERVATION

Compound E does not dissolve fully in water and has to be filtered, and the filtration is a slow process.

(i) The red litmus paper turned from red to pink

The blue litmus paper turned from blue to dark red / pink

(ii) The solution turned a dark purple colour

INFERENCE

(i) Shows the compound is an acidic solution

(ii) A phenol or phenoxide, coloured complex maybe formed with Fe3+

(C) METHOD

To E add 1 cm3 of methanol, 0.5 cm3 of concentrated sulphuric acid and warm this mixture. Cool the mixture and pour it into small quantity of aqueous sodium carbonate in a evaporating basin

OBSERVATION

No change observed when methanol added. A heated smell observed when sulphuric acid added. Some heat evolved and small crystals formed on heating

After cooling the mixture effervescence was observed and a yellowish colour was observed

INFERENCE

Carboxylic group maybe present because when methanol and sulphuric acid react together an ester was formed. Carbon dioxide may been given of when sodium carbonate was added, according to the following reaction:

CO32- + 2H+ --> CO2 + H2O

(D) METHOD

Place some of sample F on a inverted crucible lid and ignite it from above

OBSERVATION

No flame. Where ignited the powder turned yellow-brown colour

INFERENCE

Halogenated compound or hydroxo acid

(E) METHOD

Dissolve sample of F in 10cm3 of distilled water

(i) To 2 cm3 of the solution F add 1cm3 of aqueous sodium hydroxide followed by dilute hydrochloric acid

(ii) To 1 cm3 of solution F, add 3 cm3 of concentrated hydrochloric acid and 2cm2 of distilled water. Place thermometer in the solution and then stand the tube in ice-water mixture. Cool 1cm3 of aqueous sodium nitrate in the ice water mixture. Once the temperature is between 5 - 100C then add 10 drops of aqueous sodium nitrite to the solution F, ensure the temperature does not rise above 10 0C Add the resulting solution to a solution of a small amount of 2-naphtol in 7-8 cm3 of aqueous sodium hydroxide

(iii) To 2cm3 of the solution of F, add aqueous silver nitrate. Then add 1 cm3 of dilute nitric acid> Finally add an excess of aqueous ammonia

OBSERVATION

(i) F dissolves fully in water. The mixture turns slightly milky when sodium hydroxide is added. The mixture then becomes clear again when adding Hydrochloric acid

(ii) No change observed initially however, the tube heated on adding hydrochloric acid to approximately 220C. When 2-naphtol added thick reddish, precipitate is formed.

(iii) White precipitate formed on adding silver nitrate. The white precipitate remains after adding dilute nitric acid. The precipitate dissolved on adding aqueous ammonia.

INFERENCE

(i) Cannot be a phenol. Maybe a basic amine

(ii) Nitrous is formed in situ. (Azo dye formed) or aromatic primary amine

(iii) Cl - ion

E - Phenol derivative

F- aromatic primary amine with Cl attached to the benzene

(Benzonediazonium chloride)