Question

give the chemical test to differentiate black catechu and pale catechu

Answer 1

Hi there,

1. Black catechu

Chemical test of black catechu:

1. Black catechu with ferric chloride gives bluish-black color.

2. Black catechu with vanillin or Hydrochloric acid gives red or pink color.

3. An aqueous solution of black catechu with lime water gives the brown color

2. Pale catechu

Chemical test of pale catechu:

1. Test for Gambier fluorescein

An alcoholic solution of powdered drug and filter it. Add NaOH to the filtrate and shake well. Add a few drops of light petroleum to give green fluorescence.

Note: Black catechu gives the negative gambier fluorescein test. On the other hand, Pale catechu gives the positive result for gambier fluorescein test.

Hope it helped.