TO PREPARE PHENYL AZO-2 NAPHTHAL FROM ANILINE AND DETERMINE IT'S MELTING POINT

Phenyl azo - B napthol

 Apparatus REQUIRED:

• Conical flask

• beakers

•  glass rod

• measuring cyliInders

•  funnels

• filter papers

• Thiele's tube.

• capilliary tube.

Chemical Required 

• Aniline (3ml)

• B-naphthol (3gm)

• conc. HCl (8ml)

• Sod. nitrile (2gm)

• Sod. hydroxide (2gm)

THEORY

Phenyl azo - B napthol is a Common example of Azo dye. It is prepared by the coupling reaction. In the lab, it is prepared by the action of sodium nitrile and conc. hydrochloric acid with alkaline B napthol at ice cold temp.

PROCEDURE:

• First we took a conical flask containing 16ml of water then added 8ml conc. HCL and 3 ml of aniline
• cooled the sol" in on ice bathbath 0°-5°c
• Added a soln of 2gm sodium nitrite in 10ml water dropwise with continuous shaking and Controlling tempt below 5°C.
•  Took another flask to dissolve 3gm Beta napthal in a soln of 2gm sod. hydroxide in 25ml of water. Heat was provided to dissolve the mix of water. Heat was provided to dissolve the mix On get pure clear soln then cooled in ice bathbath
• Then we mixed the two cold soln slowly dropioise with continuous stirring at least for 15-20 min without allowing temp. to rise above o°c.
•  An orange colour azo dye called 2-napthal aniline was separated out.
• Filtered the crude sample and washed it with cold water.
•  Then was dried and little sample was recrystallised from ethyl alcohol and its melting point was noted.

RESULT

•  Appearonie. deep chinning red crystals.

• The melting point: 181°C

• Observe Meking point: 130°c

• Yield: 8g