Syntheses And Characterizations Of Azo Trichromatic Reactive Disperse Dyes In SCF-CO₂

Reactive disperse dye is one of the best choices to solve the dyeing limitations of natural fibers in supercritical CO₂.Therefore,actively developing reactive disperse dyes is of great significance for the water-free dyeing of natural fibers,and conforms to the current development concept of green production in printing and dyeing industries.The past few decades have witnessed the progress of reactive disperse dyes.For the broad application prospect of supercritical CO₂,the research and development of this dye with a special structure will become a research focus in future.To this end,azo three-primary colors reactive disperse dyes were designed and synthesized in this thesis,namely reactive disperse red SCFX-AYRL,reactive disperse yellow SCFX-AYYL and reactive disperse blue SCFX-AYBL.Among them,(A)the preparation of the red dye was based on the diazotization-coupling reaction in the organic solvent system,and the main factors such as the type of diazotization reaction solvent,the amount of protonic acid,the amount of sodium nitrite,the coupling reaction temperature,the type and amount of acid binding agent,the amount of cyanuric chloride and the reaction time were optimized.The recommended synthesis process was as follows,(a₁)preparation of diazonium salt:1,4-dioxane as solvent,2-chloro-4-nitroaniline 0.50 mmol,concentrated hydrochloric acid 5.00 mmol,sodium nitrite 0.55 mmol,diazotization reaction at 0?5?for 2 h;(a₂)preparation of the precursor:N-(2-aminoethyl)-N-ethyl m-toluidine 0.55 mmol,which was added dropwise to reaction(a₁)and maintained reaction system p H?6,0?5?coupling reaction for 3 h;(a₃)preparation of the target dyes:dioxane/water as solvent,dye precursor 1.0 mmol,sodium bicarbonate 2.0 mmol,cyanuric chloride 1.5 mmol,condensation reaction at 0?5?for 2 h.(B)During the preparation of the yellow dye,a coupling component intermediate was first synthesized,and then a diazotization-coupling reaction was performed based on a concentrated sulfuric acid system.The reaction process used was as follows,(b₁)preparation of the coupling components:2-bromoethylamine hydrobromide 5 mmol,aniline acetonitrile 6 mmol,5 m L DMF as solvent,and reaction at 120?for 16 h in a nitrogen environment;(b₂)preparation of the diazonium salt:a solution of nitrosylsulfuric acid with 50 mmol of concentrated sulfuric acid and 5 mmol of sodium nitrite was firstly prepared,and then 5mmol 2,6-dichloro-4-nitroaniline was put,diazotization reaction at 0?5?for 2 h;(b₃)preparation of the precursor:5.0 mmol of 2-[N-(2-aminoethyl)-N-phenyl]aminoacetonitrile was dissolved in water and a suitable amount of hydrochloric acid,and the corresponding diazonium salt was added dropwise to the coupling system,with p H=4?6,0?5?coupling reaction for 2 h;(b₄)preparation of the target dye:same as the red dye preparation process.(C)During the preparation of the blue dye,the coupling component intermediate was also synthesized first,and then the diazotization-coupling reaction was performed based on the concentrated sulfuric acid system.The reaction process used was as follows,(c₁)in the N mono-substitution of3-amino-4-methoxyacetanilide(AMA),the amount of AMA was 2.0 mmol,1-bromopropane 2.2 mmol,a small amount of potassium iodide,ethanol/water as the reaction system,nitrogen environment,reaction at 70?for 10 h;(c₂)Preparation of coupling components:3-(N-propyl)amino-4-methoxyacetanilide 2.0 mmol,2-bromoethylamine hydrobromate 2.2 mmol,DMF 10 ml,nitrogen environment,reaction at 110?for 6 h.The other reaction processes were similar to those of the yellow dye.Simultaneously,Fourier transform infrared spectroscopy,nuclear magnetic resonance spectroscopy,liquid chromatography-mass spectrometry,elemental analysis,ultraviolet-visible absorption(Uv-Vis)and other analytical testing methods were utilized to characterize the molecular structure and color characteristics of the products.The results show that the three reactive disperse dyes prepared in this paper conform to the expected structure,and their color characteristics also match the characteristics of three primary colors.In addition,the maximum absorption wavelengths of the red,yellow and blue dye in dichloromethane solution were 490 nm,380 nm and 583 nm,respectively.Moreover,the Uv-Vis spectroscopy further confirmed that the introduction of an alkyl chain into the bridge group can significantly reduce the inducing effect of the reactive group on the parent's color structure,and reduce the effect on the color characteristics of the dye precursor.It is also concluded that three dyes have similar solvation effects and exhibit good stability in acid-base effects.Finally,the supercritical CO₂ and water bath dyeing processes were used to explore the application characteristics of the reactive disperse dyes on natural fibers,and the color characteristics and various fastnesses of the dyed fabrics were investigated.The achieved results show that the dyeing effect of the three reactive disperse dyes on silk and wool fabrics was superior to that of cotton in supercritical CO₂ fluid media without fixation promoter.Under the condition of equal color matching of target dyes,the three dyes exhibit color matching compatibility in a water bath environment.