Design,Synthesis And Structure-Activity Relationship Of Isolated Mannich Reactive Dyes

At present,among the most commonly used dyes for dyeing silk,acidic dyes and silk are bonded by van der Waals force,ionic bond and hydrogen bond,and the color fastness to wet treatment of dyed silk fabric is poor.Although reactive dyes and silk are bonded by covalent bonds,the color fastness to wet treatment is good,but the utilization rate of dyes is reduced easily due to hydrolysis,and alkali fixation will damage the silk.The dyeing process of these two dyes requires a large amount of salt to promote the dyeing,causing environmental pollution.The previous work of this research group proposed a dyeing method that uses the Mannich reaction between aromatic primary amine dyes,aldehyde components and tyrosine residues to selectively modify tyrosine residues in silk and form C-C-N covalent bond with the silk,so as to obtain high color fastness to wet treatment.At present,there are not many arylamine dyes used for Mannich reaction dyeing of silk,and its light resistance is not ideal.Moreover,the position and amount of amino group of arylamine dyes and the water solubility of dyes have great influence on the Mannich reaction efficiency.Therefore,the structure design,synthesis and structure-activity relationship of aromatic primary amine dyes capable of Mannich reaction with silk were studied in this paper,which provided a strong theoretical basis for the development of dye structure design for Mannich reaction dyeing of silk.In this paper,9 Mannich reactive dyes were designed and synthesized,the UV-visible absorption spectra of the aqueous solution of aromatic primary amine dye D1～D9 were tested and analyzed,and the silk fabric was dyed by conventional acid dye and Mannich reaction dyeing with dye D1～D9.The structure-activity relationship between the number and position of substituents in the structure of Mannich reactive dyes on the Mannich reactive dyeing of silk fabrics was investigated,and the influence of the position and number of amino groups and the water solubility of dyes on the Mannich reactive dyeing properties of silk fabrics was revealed.The results showed that the introduction of appropriate amount of water-soluble groups in the aromatic primary amine dye increased the water solubility of the dye,improved the chance of dye entering the fiber and reaction,and helped to obtain excellent dyeing effect in the Mannich reaction dyeing of silk fabric.On the premise of ensuring good water solubility of the dyes,the dyeing efficiency of Mannich reaction on silk can be improved by increasing the number of arylamine reactive groups in the dye structure.In the chemical structure of aromatic primary amine dye using sulfonyl groups as bridge groups to isolate aromatic primary amine reactive groups and dye chromophore,but also promote the separation of two reactive groups,which can further reduce the electron cloud density of aromatic primary amine reactive groups,making it easier to dye silk;The silk fabrics were dyed by dye D1～D9 according to Mannich reaction dyeing process,and the color fastness to soap washing and friction of the dyed silk fabrics could reach above grade 4.At the same time,in order to solve the problem that the direct introduction of the primary amine group into the chromophore conjugated system has adverse effects on the light resistance of the arylamine dyes,this paper studied the light resistance of the isolated Mannich reactive dyes.By exposing isolated Mannich dye solution to XPA series photochemical reaction apparatus for illumination,the photofading mechanism of isolated Mannich dye solution was investigated.The light fastness of D1～D9 Mannich reaction dyed silk fabric and blue standard wool was tested respectively.The light fastness of isolated Mannich reaction dyes was revealed by combining the fading of blue standard wool and Mannich reaction dyed silk fabric after light exposure.The results show that the isolated Mannich reaction dyes mainly undergo photooxidation and photofading under the condition of light.The light fastness of isolated Mannich reaction dyes is better,and the light fastness of dye D5 is the best,and the color fastness of dye D5 can reach grade 5.By isolating the arylamine group in the structure of arylamine dye from the parent structure of dye hair color with appropriate bridge base,the density of arylamine group electron cloud is reduced,the antioxidant capacity of arylamine group is improved,and the discoloration of dye caused by photooxidation reaction by the amino group directly connected with the hair color system is inhibited,so as to improve the light resistance of the silk fabric dyed by arylamine dye Mannich reaction can be improved.In summary,9 Mannich reactive dyes were designed and synthesized,and the Mannich reactive dyeing properties and light fastness of the dyes on the silk fabric were systematically studied.It was found that the synthesized dyes could obtain excellent dyeing effect after dyeing the silk fabric with Mannich reaction,and the isolated Mannich reactive dyes had better light fastness.The research in this paper can provide an idea for the structure design of aromatic amine dyes for the dyeing of silk fabrics by Mannich reaction,and has innovative significance for the research and development of the dyeing technology of high light fastness and high wet fastness.