Synthetic Dyes Based on Environmental Considerations

Abstract

We have described the synthesis of some novel 1:2 Fe complexed azo dyes and compared their properties with 1:2 Cr and 1:2 Co commercial analogs. We also report the interesting FAB mass spectroscopy analysis of 1:2 metallized azo dyes resulting in the formation of 1:1 complexed dyes and their unmetallized precursors. Results from light- and rubbing-fastness evaluations of these 1:2 Fe metallized dyes show the black dyes to be strong candidates for use on wool and nylon in applications requiring high lightfastness.

DFT and MP2 study of isomery scheme in Formazan and intermolecular and intramolecular proton transfer between its tautomers

“…Moreover, the hybridations of N2 and N4 in all tautomers are sp 2 , so that the value of N1AN2AC3 and C3AN4AN5 bond lies between 110. 7 and 120.2 . This is interesting that when the hydrogen is connected to the nitrogen as central atom, because of higher mobility of hydrogen atom versus nitrogen or carbon, the angle will be smaller (the lone pair of central atom press the apart atoms to be closer together).…”

“…Preparation of formazan was done by various methods such as reduction of tetrazolium salts and coupling diazonium salts [4,5]. Interestingly, the reduction of nitrotetrazolium blue to formazan is one of the current test methods for the estimation of anti-and pro-oxidant activity of different compounds [6,7]. Another method described is reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide to formazan by the mitochondrial succinate dehydrogenase [4].…”

“…The practical application of formazans as dyes was initially described by Ciba in 1946 [14]. Moreover, formazan and their derivatives were used in colorimetric methods [15] study of mutagenicity [16], preparation of colored polyamide and protein fibers [7], detection of low NADH concentrations [17] prevention of hemoglobin interference [18], and determination of manganese by stripping voltammetry [19].…”

Iron Complexed Acid Mordant Dyes and Their Application on Nylon 6 and Wool

“…The metallized dyes Fe(II)dye1±3 and Cr(III)dye1±3 were prepared from their corresponding dihydroxyazo dyes1±3 in a similar manner to the method described for 1:2 metal complexed azo dyes in a quantitative yield [10]. The commercial 1:2 chromium complexes were prepared for comparison with 1:2 iron complexes.…”

“…An increasing interest has developed in replacing the abovementioned metals by less toxic ones and to prepare environmentally friendly iron complex dyes [7±9]. Iron analogues of some 1:2 Cr and Co commercial azo dyes, as well as formazan dyes, were used for dyeing wool and nylon with better fastness properties [10,11]. Iron complexes of disazo resorcinol based dyes have also been used for the dyeing of leather to a brown color and are described in [12].…”