APPARATUS REQUIRED:
1) Aniline: 3 m
2) Sodium nitrite: 2g
3) Sodium hydroxide: 2g
4) Conc HCL : 8ML
5) B- naphthol : 3g
6) Ice
THEORY:
Phenyl a20-B-hapthol is a common example of a20 dye. It is prepared by the coupling reaction. In the laboratory, it is prepared by the action of sodium nitrite & concentration hydrochloric acid with alkaline B- naphthol at ice cold temperature.
PROCEDERE:
3 ml of aniline in a mixture of 8 ml conC. HCL was dissolved & 16 ml of water was added. The solution was cooled in ice at 0.5°C & then added to a solution of 2gm sodium nitrite in 10 ml water dropwise with continuous shaking. In another flask 3gm of B-naphthol was dissolved in a solution of 2gm sodium hydroxide in 25 ml of water & was cooled at 0.5ºc. Finally, the filtered product was washed with cold water & dried & recrystallized from ethyl alcohol.
RESULT:
Appearance: Deep shining red crystal
Yield: 7.8gm
Melting point: 131°C
CONCLUSION:
Hence, preparation of phenyl a20-B-naphthol was done in the laboratory from aniline.
PRECAUTION:
1) All the apparatus should be dried & cleaned.
2) The temperature should be maintained at the required level.