Indigo has been revered as a dye for three thousands of years. Indigo could be obtained from aniline, through its conversion into N-phenylglycine. The N-phenylglycine(produced by the reaction of chloroacetic acid with aniline) gave indoxyl on fusion with alkali, and the indoxyl readily formed indigo by air oxidation. Due to the limitations of the technology and production process is difficult to avoid waste residue, waste water problems, serious environmental pollution, China indigo production and developme...