AZO DYE FOR WATERLESS DYEING OF NATURAL FIBERS IN SUPERCRITICAL CO2 FLUID, AND PREPARATION METHOD THEREOF

Abstract

The invention discloses a special-purpose reactive disperse dye for waterless dyeing of natural fibers in supercritical CO.sub.2 fluid and an intermediate thereof. The reactive disperse dye has a longer alkane-chain bridging group between a chromophoric parent structure and an active group of the dye, which effectively promotes the donating-withdrawing effect on the electron cloud in the conjugated system, enhances the hyperchromic effect, effectively reduce the influence of the active group itself and its reaction on the dye coloring system, improves the color and stability against acid and alkali of the dye, and facilitate the improvement of the compatibility of the dye with supercritical fluid and the dyeing performance for natural fibers as well. The invention also discloses an intermediate of the reactive disperse dye, and a method for preparing the reactive disperse dye.

Claims

1. An intermediate of a reactive disperse dye, having a structure of Formula (I): ##STR00005## wherein R.sub.1 is Cl or Br; and 1≤m≤6, and 1≤n≤6.

2. A reactive disperse dye, having a structure of Formula (II): ##STR00006## wherein R.sub.1 is Cl or Br; and 1≤m≤6, and 1≤n≤6.

3. The reactive disperse dye according to claim 2, wherein R.sub.1 is Cl, m=2, and n=1.

4. A method for preparing an intermediate of a reactive disperse dye according to claim 1, comprising steps of: (1) under an acidic condition, diazotizing 2-chloro-4-nitroaniline or 2-bromo-4-nitroaniline to obtain a diazotized product; (2) coupling the diazotized product with a coupling component at pH 5-7, to obtain a dye intermediate of Formula (I), wherein the coupling component has a structure of Formula (III): ##STR00007## wherein 1≤m≤6 and 1≤n≤6.

5. The method for preparing an intermediate of a reactive disperse dye according to claim 4, wherein Step (1) specifically comprises dissolving 2-chloro-4-nitroaniline or 2-bromo-4-nitroaniline in a mixed solvent of an organic solvent with water, controlling the resulting solution to be acidic by adding concentrated hydrochloric acid, and then adding sodium nitrite for diazotization, to obtain the diazotized product.

6. The method for preparing an intermediate of a reactive disperse dye according to claim 5, wherein the organic solvent is selected from the group consisting of N, N-dimethylformamide, 1, 4-dioxane, acetic acid and any combination thereof.

7. The method for preparing an intermediate of a reactive disperse dye according to claim 5, wherein in Step (2), before the coupling reaction the method also comprises adding an aqueous urea solution to remove excess nitrous acid.

8. The method for preparing an intermediate of a reactive disperse dye according to claim 4, wherein in Step (2), the method also comprises purifying the dye intermediate by column chromatography on silica gel, a eluent for column chromatography is petroleum ether, dichloromethane and acetone, and the volume ratio of petroleum ether to dichloromethane being 0-3:1-4, and the volume ratio of acetone to dichloromethane being 0-4:1-4.

9. A method for preparing a reactive disperse dye according to claim 2, comprising reacting the dye intermediate of Formula (I) with cyanuric chloride in a solvent in the presence of an acid binding agent, to obtain a reactive disperse dye of Formula (II), ##STR00008## wherein R.sub.1 is Cl or Br; and 1≤m≤6, and 1≤n≤6.

10. The method for preparing a reactive disperse dye according to claim 9, wherein the acid binding agent is sodium carbonate and/or sodium bicarbonate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 is a Fourier-transform infrared spectrum of a purified intermediate of a reactive disperse dye according to an embodiment of the invention;

[0039] FIG. 2 is a Fourier-transform infrared spectrum of a purified reactive disperse dye according to an embodiment of the invention; and

[0040] FIG. 3 is a UV-Vis absorption spectrum of a dye intermediate and a reactive disperse dye according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] The invention will be further illustrated in more detail with reference to the accompanying drawings and embodiments. It is noted that, the following embodiments only are intended for purposes of illustration, but are not intended to limit the scope of the present invention.

Embodiment 1

[0042] Preparation of Dye Intermediate

[0043] (1) 0.5 mmol of 2-chloro-4-nitroaniline was weighed and placed into a 100 ml three-neck flask, added with 10 ml of N, N-dimethylformamide and 5 ml of deionized water, and ultrasonically dispersed and dissolved. The three-neck flask was placed on a low temperature magnetic stirrer, and stirred evenly at a temperature controlled as 0-5° C. Then, 5 mmol of concentrated hydrochloric acid was added to the system. After the reaction system reached a predetermined temperature range, 5 ml of 0.11 mmol/ml sodium nitrite aqueous solution was slowly added to the system dropwise, and the reaction was continued for 2 h. Then, 5 ml of 0.01 mmol/mL urea solution was added, and fully reacted for 10 min. The reaction product was traced by TLC.

[0044] (2) The pH of the diazonium salt reaction system in Step (1) was adjusted to about 6 with a sodium hydroxide solution. 0.55 mmol of a N-(2-aminoethyl)-N-ethyl-m-toluidine solution was taken, dissolved in 5 ml of N, N-dimethylformamide, and then slowly added dropwise to the above diazonium salt solution. The reaction was continued at 0-5° C. for 3 h, and the reaction was traced by TLC. After the reaction was completed, the reaction system was diluted with deionized water, filtered under suction, and washed. The filtrate was extracted with dichloromethane, concentrated by rotary evaporation, and mixed with the filtered product. The mixed product was separated and purified by column chromatography on silica gel to obtain a dye intermediate. The yield is 93.58% and the purity of the product is 99%.

Embodiment 2

[0045] Preparation of Dye Intermediate

[0046] (1) 0.5 mmol of 2-chloro-4-nitroaniline was weighed and placed into a 100 ml three-neck flask, added with 10 ml of 1, 4-dioxane and 5 ml of deionized water, and ultrasonically dispersed and dissolved. The three-neck flask was placed on a low temperature magnetic stirrer, and stirred evenly at a temperature controlled as 0-5° C. Then, 5 mmol of concentrated hydrochloric acid was added to the system. After the reaction system reached a predetermined temperature range, 5 ml of 0.11 mmol/ml sodium nitrite aqueous solution was slowly added to the system dropwise, and the reaction was continued for 2 h. Then, 5 ml of 0.01 mmol/mL urea solution was added, and fully reacted for 10 min. The reaction product was traced by TLC.

[0047] (2) The pH of the diazonium salt reaction system in Step (1) was adjusted to about 6 with a sodium hydroxide solution. 0.55 mmol of a N-(2-aminoethyl)-N-ethyl-m-toluidine solution was taken, dissolved in 5 ml of 1, 4-dioxane, and then slowly added dropwise to the above diazonium salt solution. The reaction was continued at 0-5° C. for 3 h, and the reaction was traced by TLC. After the reaction was completed, the reaction system was diluted with deionized water, filtered under suction, and washed. The filtrate was extracted with dichloromethane, concentrated by rotary evaporation, and mixed with the filtered product. The mixed product was separated and purified by column chromatography on silica gel to obtain a dye intermediate. The yield is 94.19% and the purity of the product is 98%.

Embodiment 3

[0048] Preparation of Reactive Disperse Dye

[0049] (1) 0.05 g (0.138 mmol) of the purified target dye intermediate was weighed and placed into a 100 ml three-neck flask, and ultrasonically dispersed and dissolved in 5 ml of 1, 4-dioxane and 5 ml of deionized water. The three-neck flask was placed on a low temperature magnetic stirrer, and stirred evenly at a temperature controlled as 0-5° C. 0.207 mmol of cyanuric chloride and 0.276 mmol of sodium carbonate were dissolved respectively in 5 ml of 1, 4-dioxane and 5 ml of deionized water, and then slowly added dropwise to the three-neck flask at the same time. The reaction was continued for 2 h. After the reaction was completed, the reaction system was diluted with deionized water, filtered under suction, and washed. The filtrate was extracted with dichloromethane, concentrated by rotary evaporation, and mixed with the filtered product. The mixed product was separated and purified by column chromatography on silica gel to obtain a dye intermediate. The yield of the final reactive disperse dye is 71.56% and the purity of the product is 99%.

Embodiment 4

[0050] Preparation of Reactive Disperse Dye

[0051] (1) 0.05 g (0.138 mmol) of the purified target dye intermediate was weighed and placed into a 100 ml three-neck flask, and ultrasonically dispersed and dissolved in 5 ml of 1, 4-dioxane and 5 ml of deionized water. The three-neck flask was placed on a low temperature magnetic stirrer, and stirred evenly at a temperature controlled as 0-5° C. 0.207 mmol of cyanuric chloride and 0.276 mmol of sodium bicarbonate were dissolved respectively in 5 ml of 1, 4-dioxane and 5 ml of deionized water, and then slowly added dropwise to the three-neck flask at the same time. The reaction was continued for 2 h. After the reaction was completed, the reaction system was diluted with deionized water, filtered under suction, and washed. The filtrate was extracted with dichloromethane, concentrated by rotary evaporation, and mixed with the filtered product. The mixed product was separated and purified by column chromatography on silica gel to obtain a dye intermediate. The yield of the final reactive disperse dye is 74.40% and the purity of the product is 99%.

Embodiment 5

[0052] Characterization and Performance Test

[0053] The purified dye intermediates and reactive disperse dyes obtained in embodiments 1-4 were structurally characterized by Fourier transform IR spectroscopy and UV-Vis absorption spectroscopy. The results are shown in FIGS. 1, 2 and 3.

[0054] The test results by Fourier transform IR spectroscopy of the dye intermediates in FIG. 1 show that the absorption peaks at 3444.37 cm.sup.−1 and 3421.78 cm.sup.−1 are respectively attributed to the —NH.sub.2 anti-symmetric stretching vibration and symmetric stretching vibration, the absorption peak at 3099.35 cm.sup.−1 is attributed to the C—H stretching vibration on the aryl ring, the absorption peaks at 2969.31 cm.sup.−1 and 2923.82 cm.sup.−1 are respectively attributed to the C—H anti-symmetric stretching vibration and symmetric stretching vibration in an alkyl group, the absorption peak at 1601.11 cm.sup.−1 is attributed to the N═N stretching vibration, the absorption peaks at 1512.70 cm.sup.−1 and 1338.05 cm.sup.−1 are respectively attributed to the Ar—NO.sub.2 anti-symmetric stretching vibration and symmetric stretching vibration, and the absorption peak at 1104.40 cm.sup.−1 is attributed to the C—Cl stretching vibration on the aryl ring.

[0055] The test results by Fourier transform IR spectroscopy of the reactive disperse dyes in FIG. 2 show that the absorption peak at 3419.87 cm.sup.−1 is attributed to the N—H stretching vibration, the absorption peak at 3259.67 cm.sup.−1 is attributed to the C—H stretching vibration on the aryl ring, the absorption peaks at 2963.82 cm.sup.−1 and 2926.19 cm.sup.−1 are respectively attributed to the C—H anti-symmetric stretching vibration and symmetric stretching vibration in an alkyl group, the absorption peak at 1597.90 cm.sup.−1 is attributed to the N═N stretching vibration, the absorption peak at 1551.99 cm.sup.−1 is attributed to the C═N stretching vibration, the absorption peaks at 1512.98 cm.sup.−1 and 1333.58 cm.sup.−1 are respectively attributed to the Ar—NO.sub.2 anti-symmetric stretching vibration and symmetric stretching vibration, the absorption peak at 1101.15 cm.sup.−1 is attributed to the C—Cl stretching vibration on the aryl ring, and the absorption peak at 798.76 cm.sup.−1 is attributed to the C—Cl stretching vibration on the triazine ring.

[0056] Comparison of the test results of FIGS. 1 and 2 shows that, the cyanuric chloride reactive group is successfully introduced into the parent structure of the reactive disperse dyes prepared by the present invention.

[0057] FIG. 3 is a UV-Vis absorption spectrum of a dye intermediate and a reactive disperse dye in a dichloromethane solution, where curve a is the dye intermediate (in which the maximum absorption wavelength is 496 nm, and the corresponding molar absorption coefficient ε.sub.max=8.86×10.sup.3 L/(mol.Math.cm)), and curve b is the reactive disperse dye (in which the maximum absorption wavelength is 505 nm, and the corresponding molar absorption coefficient ε.sub.max=5.91×10.sup.3 L/(mol.Math.cm)). It can be seen from curves a and b that the variation in the maximum absorption wavelength between the active disperse dye and the dye intermediate in the embodiments of the invention is Δλ.sub.max=505−496=9 nm, which is much smaller than the change in the maximum absorption wavelength, Δλ.sub.max=395−326=69 nm, described in “Synthesis and characterization of special reactive disperse dyes applicable in supercritical carbon dioxide fluid”. The above results indicate that the alkyl bridging group between the reactive group and the parent structure of the dye significantly reduces the influence of the introduced cyanuric cyanide reactive group on the chromophoric parent structure of the dye, and avoid the appreciable change of the main color of the dye caused by the cyanuric cyanide reactive group.

[0058] The above description is only preferred embodiments of the present invention and not intended to limit the present invention, it should be noted that those of ordinary skill in the art can further make various modifications and variations without departing from the technical principles of the present invention, and these modifications and variations also should be considered to be within the scope of protection of the present invention.