Synthesis and characterization of novel reactive dyes with simultaneous insect-repellent and anti-bacterial properties

N,N-Diethyl-m-toluamide (DEET) is widely used as an insect-repellent. Sulfonamides are an important class of anti-bacterial drugs. In order to combine the strength of anti-bacterial activities of sulfonamides and insect-repellent property of DEET, three azo reactive dyes were designed and synthesized. To do this, the diazoniom salts of sulfonamides viz. 4-amino-N-(4-methyl-2-pyrimidinyl) benzene sulfonamide, 4-amino-N-(4-dimethyl-2-pyrimidinyl) benzene sulfonamide and 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzene sulfonamide were prepared using HCl and NaNO₂. The resulting diazoniom salts were then coupled to the coupling component containing N,N-diethyl-m-toluamide to produce the novel dyes. The synthesized dyes were filtered off and then purified. To investigate and analyze the dyes, analytical methods such as ¹H-NMR, FTIR, UV-visible spectroscopy, and elemental analysis were used. Consequently, the anti-bacterial activities of dyes were measured with E. coli and P. aeruginosa as a Gram-negative strain and S. aureus and S. mutans as a Gram-positive strain according to MIC method. The insect-repellent efficacy of the dyes was studied using standard methods for Anophle mosquito repellent. The results confirmed anti-bacterial and insect-repellent activity of the dyes.     

Application of liquid organic salt to cotton dyeing process with reactive dyes

Reactive dyes are used widely in cotton dyeing process. Reactive dyeing uses high amounts of inorganic salts to accelerate dye exhaustion. These salts are then discharged to the effluent, leading to serious environmental problems. Biodegradable organic salts can alternatively be used in the dyeing process. In this paper, a new liquid organic salt was synthesized by acid-base neutralization, which was used to replace inorganic salts in reactive dyeing. Dye exhaustion in organic salt dyeing was similar to the values in conventional dyeing. However, dye fixations were slightly lower in organic salt dyeing than in conventional dyeing. The washing fastness of dyed fabrics with organic salt was excellent. Experimental results showed that dye exhaustion reached the maximum value when the concentration range of organic salt was from 20 g/l to 40 g/l. In addition, the optimal alkali concentration in organic salt dyeing was found to be about 30 g/l. These parameters suggested organic salt could replace inorganic salt in reactive dyeing process.     

Dyeing properties of bi-functional reactive dyes on a novel regenerated cellulosic fiber

Three bi-functional reactive dyes such as Bis(vinylsulphone) type, Bis(monochlorotriazine) type and Bis(mononicotinotriazine) type were applied to regular viscose rayon and new regenerated cellulosic fiber (enVix®) which was prepared from cellulose acetate fiber by the hydrolysis of acetyl groups, and their dyeing properties and fastness properties were compared.enVix exhibited better dyeability and fastness than regular viscose rayon and these results were also explained by the differences in the supramolecular structure of these two fibers.     

Adsorption behavior of reactive orange 5 and reactive red 2 on ramie fabric and their quantum chemical calculations

The adsorption behavior of Reactive Orange 5 and Reactive Red 2 on ramie fabric is studied, and their structures are investigated by using density function theory (DFT) and time-dependent DFT (TD-DFT) calculations. The results indicate that Reactive Red 2 reaches a saturation adsorption state more quickly than Reactive Orange 5. With the increase of temperature from 30 to 50 °C, the equilibrium adsorption amount of Reactive Red 2 and Reactive Orange 5 increases correspondingly, and at the same temperature the former presents a larger adsorption amount than the latter. In addition, the chlorine atom and the conjoint carbon atom of Reactive Red 2 produces a weaker binding force than those of Reactive Orange 5, which implies the nucleophilic attack of hydroxyl groups of ramie fabric to the corresponding carbon atoms occurs more easily in Reactive Red 2 than in Reactive Orange 5. The energy band gap (translation from HOMO to LUMO) of Reactive Red 2 is lower than that of Reactive Orange 5, and this indicates Reactive Red 2 has a higher chemical activity. The LUMO of Reactive Red 2 (?3.05 eV) is lower than that of Reactive Orange 5 (?2.93 eV), which indicates that Reactive Red 2 presents a stronger ability to accept electrons than Reactive Orange 5. The conclusion that Reactive Red 2 has stronger adsorption activity than Reactive Orange 5 is supported and explained by the results of these quantum chemical calculations.     

Effects of infrared heating on phenolic compounds and Maillard reaction products in maize flour

Maize grains were heated by infrared radiation for 50–100 s, than flaked and milled. The output was set to 110, 115, 120 and 140 °C to determine the effect of temperature on the formation of acrylamide, 5-hydroxymethylfurfural (HMF) and furosine, as well as the level of phenolic compounds in maize flour and its total antioxidant capacity (TAC). Acrylamide and HMF levels were increased as the load of the heat treatment was increased in grains, while furosine concentration was rapidly increased to an apparent maximum (34.96 μg/g) followed by decrease during heating. Acrylamide, as well as HMF variables correlated very well with TAC of heat-treated flour (r² = 0.98 and 0.86). The process of infrared heating had a great influence on the reduction of phenolic compound contents. However, new antioxidants that were formed as a result of the Maillard reaction increased the total antioxidant capacity of heat-treated maize flour.     

Study on the dyeing of wool fabrics with Phytolacca berry natural dyes

Dyeing of wool fabrics with natural dyes from Phytolacca berries has been studied. The effect of dye concentration, dye bath pH, dyeing time and temperature were discussed. The influence of chitosan application on the dyeing properties of wool fabrics was investigated. The SEM photographs of chitosan treated wool fabrics clearly depict the deposition of chitosan on the fibers. The effect of chitosan concentration, dye bath pH, dyeing time and temperature has been studied by orthogonal experiment. It has been proved that the dyed wool samples pretreated by chitosan have higher color fastness, faster dyeing rate, and better antibacterial properties compared with untreated ones.     

Colorimetric studies of benzoquinoline based hot brand monoazo reactive dyes and their dyeing performance on various fibers

A series of hot brand monoazo reactive dyes (9a-l) were obtained by the coupling of diazotized 1Hbenzo[ g]pyrazolo[3,4-b]quinoline-3-ylamine (5) with various cyanurated coupling components (8a-l) in good yield. Synthesized dyes were characterized by various spectroscopic techniques. Their dyeing performances as reactive dyes have been assessed on silk, wool, and cotton fabrics. The percentage dye bath exhaustion and fixation on different fibers were found to be very good. The dyed fabric showed moderate to very good light fastness and good to excellent washing and rubbing fastness properties. Spectral properties and colorimetric data of synthesized dyes have also been studied in detail.     

紫化和黄化茶树品种叶色色差研究

对24个叶色紫化、黄化以及绿色叶片茶树品系(种)的叶片色泽进行感官分类赋值,并用色差计测定供试品系芽下第二叶的色差参数,分析叶片色差参数与色泽赋值之间的关系。结果显示,叶色赋值与Hunter E(r=0.96,P<0.01)、L(r=0.96,P<0.01)、a(r=-0.57,P<0.01)和b (r=0.87,P<0.01)存在极显著相关性。用E和L值可以作为紫化和黄化茶树品种选育的筛选指标,a和b值可以作为紫化茶树筛选的参考指标。     

Adsorption and dyeing characteristics of reactive dyes onto cotton fiber in nonionic Triton X-100 reverse micelles

The nonionic reverse micelles used for dyeing cotton fiber were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The adsorption capacity of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fiber was investigated. The Langmuir and Freundlich isothermals were employed to model the adsorption data. In addition, the color strength and fixation rate of cotton fabrics dyed in the reverse micelles and bulk water were examined and compared. The salt and alkali as influencing factors were also discussed. The FT-IR spectra were employed to study the polarity of water added in reverse micelles. The results indicated that the adsorption of the dyes onto cotton showed better agreement with Langmuir model. The adsorption process was monolayer adsorption. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity. The fixation percentage and color strength of the cotton fiber dyed in TX-100 reverse micelles was higher than those in bulk water. The polarity of water in TX-100 reverse micelles was lower than that in bulk water.     

Synthesis of temporarily solubilized reactive disperse dyes and their application to the polyester/cotton blend fabric

Five temporarily solubilized reactive disperse dyes were synthesized and characterized. They were applied to polyester/cotton blend fabric using one-bath dyeing method without dispersing agent. The dye that has azonaphthalene chromophore seemed to not only be exhausted on polyester but also react with cotton. But other dyes were selectively dyed on polyester and showed limited uptake on cotton. Good levelling as well as moderate to good colour fastness was obtained with the dyes on P/C blend fabric.