Alizarin, indigo, and blue dye-indanthrine were synthesized.
1. In 1868, German chemists Grebe and Liebermann synthesized alizarin.
2. In 1880, German chemist Bayer registered a patent for the synthesis of indigo.
3. In 1901, the German chemist Born synthesized the blue dye-indanthrene. These three compounds are three milestone inventions in the development of the synthetic dye industry.
Synthetic dyes refer to organic substances that can color fibers and other materials. They are divided into two categories: natural and synthetic. Natural dyes are divided into plant dyes, such as alizarin, etc., and animal dyes, such as cochineal.