摘要：This study presents the experimental synthesis of a polymeric indigoid used as a colouring agent for foodstuff .The resulting additive, due to a high molecular mass, will have a low migration tendency and it can safely be used to prepare foodstuff with a much better texture and consistency. The synthesis of the polymeric indigoid was conducted by means of two methods: the first one starting from anthranilic acid and the second one starting from the nitrobenzaldehyde. This is a presentation of the advantages and the disadvantages of the two methods. The alternative synthesis eliminates the disadvantage which the known method presents and which consists of the fact that the product of chlorine- methylation of the ester of the acid o-carboxyl-phenyl- glycin carboxylic, by reacting with the formic aldeyde, leads to secondary products which end up generating polymers that are different from the synthesized polymeric indigoid. The spectro-chemical analysis of the two polymeric compounds with indigoid structure shows that their spectrochemical behaviour is similar. The synthesis method of from o- nitrobenzaldehyde (using the Bayer-Drewsen method as an alternative of generating the chromophore), presents the advantage of obtaining the indigoid polymer under a pure form, without any secondary compounds which might alter its colour. The Baeyer – Drewsen synthesis is superior to the other variant studied due to its small number of technological phases, convenient handling, high conversion level (85-90%), resulting products that are free from mechanical ions, etc. The sulphonation of the polymers has proved to be an alternative for obtaining coloring agents with a high molecular mass, low migration capacity, presumably of interest for the food industry.=(di
