Fun With Textile Dye - Azo Dye | English
Channel: Arvind Gupta
Date: 15/08/2016

In today’s experiment we will prepare a compound – a DYE. Dyes are important because they give us colorful fabrics. We need some chemicals – 2-Napthol, Sodium hydroxide, Aniline, Sodium Nitrate and also concentrated Hydrochloric Acid. First pour out 4-ml of Aniline in a measuring cylinder. Then add this Aniline to10-ml of concentrated Hydrochloric Acid in the beaker. A lot of fumes will be formed. Then add 20-ml of water to the mixture. This mixture will become very hot. Before using it we will have to cool it in a bucket of ice, to 5 degree centigrade. So place the solution in a jar full of ice for at least 10-minutes to reduce the temperature to 5 degree centigrade or below.
For the second solution add a few crystals of Sodium Nitrate to 20-ml of water in the beaker. Stir it well. This is also an exothermic reaction and the solution will become hot. Cool it down to less than 5 degree centigrade by placing it in an ice bath. For the third solution I add 2-napthol to the solution of Sodium Hydroxide. To get a clear solution you will have to stir this mixture for a long time until all the napthol is dissolved. Once again you have to cool this solution to less than 5 degree centigrade by placing it in a cold bath. 
Now there are 3 solutions. First - Aniline in Hydrochloric Acid; Second – Sodium Nitrate solution; and the Third solution is 2-napthol in Sodium Hydroxide. 
Now pour the First Aniline Solution into the second solution of Sodium Nitrate. Finally, pour the two solutions in a bigger beaker. In the end the 2-napthol solution is added. You will see a beautiful red colored precipitate. A DYE has been created. This is called AZO DYE. The Azo dye is formed between Aniline and beta napthol. To get the DYE we will have to filter this solution. This AZO DYE is usually used to color fabrics. When you pour this solution on a piece of filter paper you will see a brilliant red. On dipping the filter paper in the solution the paper will be dyed. This dye is used to color clothes. On filtering this solution we will get this kind of powdered DYE or Azo Dye. This will color our clothes ORANGE. On touching my fingers become orange too.

This work is supported by IUCAA (www.iucaa.in) and TATA Trust (http://www.tatatrusts.org/) and (www.tata.com/aboutus/sub_index/Tata-trusts)

TATA Trust: Education is one of the key focus areas for Tata Trusts, aiming towards enabling access of quality education to the underprivileged population in India. To facilitate quality in teaching and learning of Science education through workshops, capacity building and resource creation, Tata Trusts have been supporting Muktangan Vigyan Shodhika (MVS), IUCAA's Children’s Science Centre, since inception. To know more about other initiatives of Tata Trusts, please visit www.tatatrusts.org

Credits:,Ashok Rupner, Manish Jain, Pradnya Pujari, Shivaji Mane, Jyoti Hiremath, Arvind Gupta, Pankaj kumar Boruah