As early as 1834, German chemist Michelrich used benzene and nitric acid to obtain nitrobenzene. The Russian chemist Qi Ning and the French chemist Hoffman discovered in 1842 that a new substance, called stupid amine, was formed in the reduction of nitrobenzene. In 1856, Parkin, an 18-year-old organic chemist in the UK, was conducting trials to produce quinine, a special drug for the treatment of malaria. He added potassium dichromate oxidant to the crude amine taken from the tar, and unexpectedly obtained a black sticky substance, which was obviously not what was originally intended. Disappointed, the young Parkin decided to come back. When he washed the test tube with alcohol, he produced a bright purple solution. He dipped the cloth in this purple solution, and the cloth was immediately dyed purple, washed with soap, and even exposed to sunlight. The purple of the cloth showed no signs of fading. We know that the purple solution obtained by Parkin is exactly a synthetic dye-stupid violet. Parkin applied for a patent for this achievement, and personally formulated a series of production procedures. It was officially put into production in 1857, marking the beginning of the synthetic dye industry.
In 1858, when Huffman treated aniline with carbon tetrachloride, he also obtained a dye, which was red and was called basic magenta. Two years later, he used stupid amine blue again. On the basis of aniline blue, Hoffman has prepared a variety of synthetic dyes, such as basic blue, aldehyde green, iodine green and so on. After the establishment of the stupid ring structure theory, it pointed out the direction for the further artificial synthesis of organic compounds such as dyes.
In 1868, the Germans Grebe and Lieberman synthesized the first element dye benzene by studying the structure of alizarin and using anthracene in explosive tar as a raw material.
In 1878, German chemists realized the reduction of indigo to indigo. During the same period, people also synthesized a knot of azo dyes. In 1858, Gris discovered the diazotization reaction. After 6 years, the diazonium salt was successfully coupled, which laid the foundation for the synthesis of a series of azo dyes.
Thus, in 1884, Portig synthesized the Congo red dye more smoothly. In this way, by the second half of the 19th century, the synthetic dye industry had become the “crown” of the organic synthesis industry. At the beginning of the 20th century, this industry developed even more.