Triazinyl Reactive Dyes Research Articles

Study into the cold pad‐batch application of monochloro‐s‐triazinyl and m‐carboxypyridinium‐s‐triazinyl reactive dyes bearing various “second‐leg” N‐substituents

AbstractA series of monochloro‐s‐triazinyl (MCT) and related m‐carboxypyridinium‐s‐triazinyl (nicotinic acid [NTR]) reactive dyes based on the same red chromophore and bearing –NHCN, –OCH3, –N(CH3)SO2CH3, –N‐methylphenyl and –OH “second‐leg” substituents were evaluated in cold pad‐batch dyeing. It was found that both the MCT and NTR dyes containing a cyanoamino second‐leg substituent displayed a superior technical performance to the dyes bearing methoxy, N‐methyl(methylsulphonyl)amino, hydroxyl and N‐methylaniline substituents. The results suggest that these technical benefits of dyeing are derived from the smaller molecule size and electronic effect of the cyanoamino group compared with the other second‐leg substituents commonly used in both MCT and NTR reactive dye synthesis. Indeed, the use of the cyanoamino second leg on the studied red NTR reactive dyes offered a combination of short batch time, high fixation efficiency, good build‐up properties and good wet fastness properties.

Synthesis and kinetic study of a series of chloro- and m-carboxypyridium triazinyl reactive dyes

Five monochloro-s-triazinyl reactive dyes (MCT) and five m-carboxypyridium-s-triazinyl reactive dyes (NTR) were synthesised with the same red chromophore bearing an –NHCN, –OCH3, –CH3NSO2CH3, –N-methyl phenyl or –OH group as ‘second-leg’ substituents. A kinetic study of the hydrolysis of these dyes was conducted, and the rate constant (kobs) and half-life time values were determined. The kobs of the MCT and NTR dyes was found to follow the order –OCH3 > –CH3NSO2CH3 > –N-methyl phenyl > –NHCN > –OH, which was approximately in agreement with the values obtained for the Hammett substituent constants. Overall, the higher the electron-donating property of the substituent on meta-position to the leaving group in the triazine ring, the lower the hydrolysis rate constant.

Liquid ammonia dyeing of cationic ramie yarn with triazinyl reactive dyes

Cationic ramie yarn was prepared using a 2,3-epoxypropytrimethylammonium chloride agent. Subsequently, original and cationic ramie yarns were dyed in liquid ammonia with triazinyl reactive dyes (C.I. reactive orange 5, C.I. reactive red 2, and C.I. reactive green 19). The dyeing time was varied from 10 to 600 s with 10 % dye on mass of fabric (o.m.f) and dyeing concentration ranged from 1 to 100 % dye o.m.f for 600 s dyeing time at −35 °C at a liquor ratio of 35:1 were evaluated. After dyeing, the samples were baked at 100 °C for 10 min. The results indicated that the time taken to attain equilibrium for the original ramie yarn was 60 s and was 300 s for the cationic yarn. The cationic treatment increased the dye exhaustion and fixation and improved the wash fastness, but decreased the degree of rub staining. Pseudo first-order and second-order kinetic models were used to describe the kinetic data. The adsorption process of the liquid ammonia dyeing followed the second-order kinetics. The Langmuir and Freundlich adsorption models were applied to describe the experimental isotherms. The experimental data for dyeing untreated ramie yarn fitted the Freundlich model, but the kinetics of the cationic ramie yarn was found to fit the Langmuir isotherm.

Novel cationic softener containing MCT reactive dyes for cotton: Synthesis and characterization

Two novel cationic softener containing mono-s-chloro triazinyl reactive dyes together with their analogues were designed. The dyes were synthesized via reacting an N,N-dimethyldodecylamine with p-nitrobenzyl bromide. The resultant was reduced using stannous chloride and hydrochloric acid to produce the primary amine. The quaternary ammonium salt containing primary amine was then diazotized to produce diazonium salt part of azo dye. The diazonium salt was then coupled to H-acid/J-acid reacted with cyanuric chloride and sulfanilic acid. The analogue dyes were prepared via the same route without quaternary ammonium salt making stage. The chemical structures of the novel dyes were characterized by FTIR, 1H-NMR, and elemental analysis. The spectroscopic properties of the dyes were determined in terms of λ max and ɛ max in aqueous solution.

The synthesis and application of novel 2-chloro-4-alkylthio triazinyl reactive dyes

Abstract Two hetero bi-functional reactive dyes (red and yellow) each containing both a sulphatoethylsulphonyl and 2-chloro-4-alkylthio-s-triazinyl reactive group have been synthesised and their dyeing properties including exhaustion, colour strength on fabric (visual colour yield), fixation and wash fastness compared with market leading products. Under the alkaline application conditions employed, both the dyes, a yellow and a red, having a novel bridging group, exhibited good build-up, fixation and wet fastness properties being essentially comparable with leading commercial products. The concept of synthesising a substituent that can be introduced into a dye as a linking group to impart increased reactivity to a chlorotriazine has been demonstrated to be viable and effective.

Protection of lyocell fibres against fibrillation; influence of dyeing with bis‐monochloro‐s‐triazinyl reactive dyes

Four bis‐monochlorotriazinyl (bis‐MCT) reactive dyes, including Procion Orange H‐ER, together with Remazol Black B, were applied, in turn, to lyocell fibres and their wet abrasion resistance (Nass‐Scheuer‐Festigkeit) measured. The bis‐MCT dyes performed poorly, showing that little cross‐linking had occurred and all were inferior to Remazol Black B. The cross‐linking propensity of Procion Orange H‐ER was not superior to the other bis‐MCT dyes evaluated. A possible explanation for the apparent superiority of Procion Orange H‐ER in a recent paper published in this journal may lie with fabric construction but not with the suppression of fibrillation once it has occurred.

Influence of dichloro‐s‐triazinyl reactive dyes on the fibrillation propensity of lyocell fibres

Four dichloro‐s‐triazinyl dyes and 2,4‐dichloro‐6‐p‐sulphoanilino‐1,3,5‐triazine have been applied by exhaustion methods to dried lyocell fibres. The method of application, of both dyes and agent, influenced the cross‐linking performance and, in turn, the wet abrasion resistance of the treated fibre. However, dyeing alone, with any of the MX dyes used in this study, was insufficient to protect the fibre from wet abrasion problems during laundering. A comparison between one of the MX dyes, Chloranyl Orange MX‐2R, and 2,4‐dichloro‐6‐p‐sulphoanilino‐1,3,5‐triazine on a mol‐for‐mol fixed basis, showed 2,4‐dichloro‐6‐p‐sulphoanilino‐1,3,5‐triazine to be greatly superior at protecting lyocell against wet abrasion.

Triazinyl reactive dyes for the exhaust dyeing of cotton: Influence of the oxido group on the reactivity of chloro and m-carboxypyridinium leaving groups

A series of four triazinyl reactive dyes have been applied to cotton by exhaust dyeing in alkaline media. Two of the dyes employed o-toluidine as the reactivity modifying group, with either a chlorine or a nicotinic acid leaving group, and the other two used the same leaving groups but with an oxido group as the reactivity modifier. The dye containing the combination of a chlorine leaving group and an oxido reactivity modifying group (dye IV) proved greatly inferior in dyeing performance to that of the other combinations studied in the series. Dyeing at a higher salt level, to correct for the low substantivity of dye ( IV), and at a higher temperature, furnished only a marginal improvement in visual colour yield indicating lack of reactivity to be the problem. The low reactivity of dye ( IV) was confirmed by computational analysis.

Acid-catalysed methanolysis reaction of non-polar triazinyl reactive dyes in supercritical carbon dioxide

An extensive study of the reaction mechanism of the methanolysis reaction of triazinyl systems of non-polar reactive dyes has been done in a neutral, moderately acidic and strongly acidic medium. In a neutral reaction medium, dichlorotriazines are more reactive than the monochlorotriazines. However, in a moderately acidic medium, as supercritical carbon dioxide, an inversion in the reactivity pattern of monochlorotriazines was observed, which is related to the dye structure. Amines as substituent group attached to the triazinyl ring showed the largest conversion and k values, approaching those values of dichlorotriazine. Protonation of the ring, and stabilization of the positive charge in the triazinyl ring due to the mesomeric effect, explain the reactivity increased of monochlorotriazines. When acids were added to the reaction medium, resulting in an increase of the acid concentration, the reactivity of monochlorotriazinyl dyes was surprisingly much larger than dichlorotriazine; k values increased up to a factor of 54. The largest k was measured for the monochlorotriazinyl dye, S1Cl–NH 2, showing a value of 3.0 × 10 −3 s −1, while a value of 3.2 × 10 −4 s −1 was measured in supercritical carbon dioxide. In a strongly acidic medium, the reactivity of triazinyl reactive dyes is substantially influenced by the basicity of the substituted groups in the reactive group, and in the chromophore. Based on this kinetic study, the dyeing of cotton in supercritical carbon dioxide under acidic conditions seems to be very promising when triazinyl dyes are used.

A study on the relationship between steric effects and performance of some triazinyl reactive dyes

A series of model compounds of triazinyl reactive dyes was synthesized. The dihedral angles between the phenyl and triazinyl ring were calculated using PC Model software (Serena Software Co., USA). and the pseudo first order rate constants of hydrolysis were determined by HPLC. The relationship between steric effects and the reactivity of triazinyl reactive dyes are discussed.

Neutral‐fixing reactive dyes for cotton. Part 1 —synthesis and application of quaternised S ‐triazinyl reactive dyes

A number of different tertiary amines have been employed to prepare the corresponding quaternised triazines from a selected monochloro-s-triazine reactive dye. Preparation conditions have been established along with suitable analytical methods. The reactivity of the quaternised dyes with cellulose has been determined, special attention being paid to neutral fixation at high temperatures (100°C). Good neutral fixation was achieved with all the tertiary amine derivatives studied. In the case of the nicotinamide derivative an anomalous hydrolysis reaction involving ring opening was noted; this reaction led to the formation of aminotriazine rather than the expected hydroxytriazine.

Reactive dyes for cellulose. An unexpected hydrolysis product of a triazinyl reactive dye with a 3–carboxypyridine (nicotinic acid) leaving group

During a recent investigation into the relative rates of hydrolysis of a series of triazinyl reactive dyes bearing various leaving groups, an unexpected reaction was observed in the case of a nicotinic acid derivative. In model studies in dilute aqueous sodium carbonate solution none of the expected hydroxytriazine was detected; instead the aminotriazine was formed cleanly and rapidly (pseudo–first–order rate constant k = 1. 60 times 10‐1min‐1). The nicotinamide derivative behaved similarly. Other pyridinium derivatives examined all behaved as expected, yielding the hydroxytriazine, but at much slower rates (e. g. k = 1. 28 times 10–3 min‐1for the unsubstituted pyridinium salt). A possible mechanism to account for the rapid generation of aminotriazine is proposed and the significance of this observation to the dyeing of cotton with quaternised nicotinic acid dyes under basic and neutral conditions is discussed.

Reactive dyes for cellulose. Concurrent methoxide‐hydroxide reactions of triazinyl reactive systems: a model system for assessment of potential fixation efficiency

A series of triazinyl reactive dyes, identical in all respects but for the leaving group, has been synthesised. The rate of hydrolysis of each member of the series, i.e. fluoro, chloro, sulpho and DABCO derivatives, has been determined. The corresponding nicotinic acid compound could not be included in the study as it did not yield the expected hydroxytriazine in dilute sodium carbonate solution. Each dye has been added, in turn, to a methanol‐water solution in the presence of base and the chemical selectivity to methoxide attack determined from the product ratio. Measurements were made at 40°C and under conditions of equal reactivity to hydroxide ion, as determined from Arrhenius plots. The selectivity results are in agreement with empirical observations, made over more than 30 years, for the fixation efficiency to cellulose of dyes carrying these reactive groups.

Further Studies of the Acid‐catalysed Hydrolysis of Type 3 Dye‐Fibre Bonds between Cellulose and Triazinyl Reactive Dyes

Improved experimental methods have shown that the conclusions drawn in earlier work [1, 2] are only partially correct. The kinetics of hydrolysis of Type 3 dye-fibre bonds have been shown to be complex and not first-order as believed. The reason lies in the variation of the internal pH of the fibre as dye is removed. Redetermined bimolecular hydrolysis constants for H-acid derivatives show that the more ready hydrolysis of Type 3 dyeings from red H-acid dyes is associated with the formation of a highly active species in the internal pH region 3-3.5. The problems these findings pose for the establishment of a ‘bleaching’ test are raised.

Acid‐catalysed Hydrolysis of Type 3 Dye‐Fibre Bonds between Cellulose and Triazinyl Reactive Dyes

The kinetics of the acid hydrolysis of Type 3 dyeings produced by the reaction of dichlorotriazinyl aminoazo dyes with cellulose have been studied at 40°C. A marked effect has been observed owing to what are believed to be localised pH effects, i.e. a non‐uniform distribution of hydrogen ions within the fibre phase owing to the localised charges on the dye molecules attached to the fibre. Variation of the ionic strength in the reaction medium does not affect the bimolecular rate constants for the hydrolysis, but brings about changes that can also be ascribed to pH effects in the fibre phase. There is evidence for two kinds of Type 3 dye‐fibre bonding, giving a very rapidly hydrolysed species, present in relatively low concentration, and a more stable species.