What are the raw material used to manufacture azo dyes

The azo dyes that are restricted for textile use have been so restricted because they cause skin hypersensitivity and allergies. Not all azo dyes are so restricted--there are eleven azo dyes that are approved for use in food.

An azo dye is any of a number of yellow to red synthetic dyes which contain an azo or diimide functional group.

restricted of azo dye means the use of azo dye is restricted by the authority/government/organisation.but there are eleven azo dyes are approved for use in food.

William Robert Waldron has written:

'The influence of sulphur on the color of azo dyes ..' -- subject(s): Sulphur, Dyes and dyeing, Chemistry, Azo compounds