14
Reactive Dyes
Classification of Reactive Dyes
Reactive dyes can be classified into different groups as follows:
I. Reactive dyes containing a cyanuric chloride nucleus.
a. Procion H.
Cibacron
Monochlorotriazine reactive dye
x = aromatic or aliphatic amine, or dye with a free amino group attached to the chlorine, or a heterocyclic residue.
II. Reactive dyes containing a chloro pyrimidine nucleus.
III. The vinyl sulfone reactive type.
Remazol -SO2 - CH = CH2
-SO2 - CH2-CH2-SO3H
Vinyl sulfone reactive dyes.
IV. Reactive dye containing an epoxy group.
V. The most widely useful of these systems remains, however, the b-Sulphatoethylsulphonyl system. A manufacturing disadvantage to this type of dye is the need to synthesis an intermediate containing the reactive group and then use this in the dye preparation rather than simply to attach the reactive system to one of the wide variety of chromophores containing an amino group, as can be done in the case of the chloroheterocyclic dyes.
VI. Pyridazone
VII. Dichloroquinoxaline
Levafix
VIII. Acrylamide
D - NH - CO - CH2 = CH2
primazine.
IX. Methylolated Nitrogen
D - NH - CH2 - OH
Calcobond.
Most of the newer systems have lower reactivity than the dichlorotriazinyl amono dyes. The other reactive groups are as follows:
1. 1,4-Dichlorophthalazine-6-Carbonyl.
2. b-Chloroethylsulphonyl.
3. b-Sulphatopropionamid.
Reactive systems based on nucleophilic substitution and/or addition. Chlorotriazinyl dyes and most of above groups react with cellulose by a process of nucleophilic substitution while vinyl sulphone dyes react with cellulose by nucleophilic addition.
X. Reactive dyes containing a Cyanuric Chloride nucleus
Cyanuric chloride contains three labile chlorine atoms which can be replaced in sucession to an amine salt or a hydroxy compound. A simple dye containing a cyanuric chloride can be represented as follows:
Dye represents a chromopore or a colouring molecule such as Azo, Anthraquinone or phthalocyanine with a solubilising group SO3H.
X represents a chlorine atom or some other inactive radical which may confirm a solubilising group.
If x is chlorine then two chlorine atoms are free for reaction with cellulose, wool and other natural and synthetics fibres. The ordinary procion of I.C.I. contains two chlorine atoms of sufficient reactivity to combine with hydroxyl or amino groups of polymers. The dichloro triazine dyes have sufficient reactivity with water, and must be applied from a cold bath and mild alkali. So dyes if this class are known as cold dyeing type.
If x is something else other than chlorine then it is a monochlorotriazine type. The Cibacron dyes of Ciba and the Procion H dyes of I.C.I. belong to this type. They have only one chlorine atom available for reaction with the fibre. The mono chloro triazines are less reactive towards water and can be applied from a bath at higher temperatures without undergoing hydrolysis. However, above 60°C they are found to hydrolyse. In addition these dyestuffs require a more alkaline solution before reaction. They can be applied as cold bath dyeing but careful conditions are required. Otherwise they are unstable.
Both the mono chloro and dichlorotriazine reactive dyes can be applied by the padding or exhaustive methods. However the drawback of these dyes is that they are not fast to bleaching as well as resin finishing. Fibres dyed with reactive dyes cannot be employed on a finishing bath.
Examples
Cibacron Brilliant Orange CL.
Procion Brilliant Orange HARS.
The structure of these dyes have been investigated by Pancherstik et-al. Cyanuric chloride reactive dyes with a metal complex are useful and they give a fast shade. The metal is held on to the dye by coordinate covalent bonds.
Monochlorotriazinyl dyes are sufficiently stable to withstand long periods of storage, but dichlorotriazinyl dyes are liable to hydrolyse with loss of hydrogen chloride. It was found that the stability of dichlorotriazinyl dyes in dry storage can be greatly improved by addition of a buffer such as a mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate; hydrolysis is evidently accelerated by presence of acid.
The highly reactive dichlorotriazinyl dyes are usually more suitable for dyeing and less reactive monolchorotriazinyl dyes for printing.
Procion dyes are highly soluble in water and the solubility is conferred on the molecule by the presence of sulphonic acid groups. If cotton is padded or printed with a neutral solution of a Procion dye and then dried, the colour can be removed almost completely from the fabric by water washing. If however, the impregnated fabric is treated, with alkali a large proportion of the dye is fixed and is resistant to soap boiling.
Vinyl Sulfone Reactive Dyes
Reactive dyes having a vinyl sulfone group have good fastness and were first introduced by Bayer in Germany. They form a bond with the fibre.
Substituted aromatic compounds having b sulfate ethyl sulphonyl group can easily be prepared by esterification of the corresponding sulfone with H2SO4.
H2SO4
R — SO2 (CH2)2 OH —---—® R — SO2
(CH2)2 ——— O —— SO3H
On neutralisation they become water soluble. Excess alkali gives quantitative formation of vinyl sulfonyl compound.
R — SO2 — (CH2)2 —— OSO3 + OH —® R — SO2
— CH — CH2 — OSO3 RSO2 — CH — CH2
The vinyl sulfone formation can be explained by assuming that the weakly basic sulphate ion is formed easily, once a proton is removed the a-methylene group.
At high temperatures the vinyl sulfones hydrolysis to form hydroxy vinyl sulfones. This can react further giving the ether and the vinyl sulfonyl ether undergoes cleavage giving b-hydroxy-ethyl sulfones.
R—SO2(CH2)2
O``H
O + H2O ——® 2RSO2 — (CH2)2 OH
heat
R—SO2(CH2)2
The hydroxy compound can react with primary, secondary and teritary amines. They also react with protein which are good photographic gelatine coatings.
Wool treated with 3’,4-dichlorophenyl b-sulfato ethyl sulfone in a neutral bath at the boil absorbs quantitatively. The fixation is fast to washing.
Fixation on cotton of diazo amino compounds containing a b-sulfato ethyl sulfonyl groups occurs at 80-85° from a weak sodium alkali bath in the presence of sodium sulphate. The diazo amino compound attached to the fibre can be cleaved to get a diazo compound with a small amount of mineral acid and azo dyes may then be produced on the fibre with various coupling agents. The fastness of these dyes is very good.
This process is known as sulfo ethylation. The ether bond formed is stable to acid and alkali, vinyl sulfone with additional substitutents is used for cellulose acetate polyamide and polyester fibres. In alkali a very fine suspension is obtained, which adheres to the fibre and is fast to wet and light. They also dye wool.
2:2’ dihydroxy phenyl azo dyes with vinyl sulfonyl or b-sulfato ethyl groups are good as chrome and metal complex azo dyes. The characteristics formation of Remazol dyes are:
R3
|
D—SO2—CH—CH—OZ
| |
R1 R2
where d is dyestuff.
R1 = R2 = R3 = hydrogen or low mol. wt. hydrocarbons.
OZ is the residue of an acid.
In neutral aqueous solutions, the Remazol dyes do not undergo chemical reaction and can so be boiled without hydrolysing. Neutral solutions are stable at room temperatures. Vinyl sulfone forms a covalent bond with cellulose.
F——SO2——CH==CH2
| Cell
¯ alkali
F—SO2—(CH2)2—O—O—cell.
The bond in Remazol is an ether linkage, stable to acid and neutral bath but cleave with alkalies. They can be used to materials which are resin treated which is a unique thing.
Vinyl sulphone dyes are suited to the dyeing of either nitrogenous or cellulosic fibres.
In commercial dyes, the vinyl sulphonyl group rarely used, because the vinyl sulphone is normally made from the sulphato compound, so that its use in the dye would add an extra step in manufacture. Secondly the higher solubility of the sulphato esters is advantageous in dyeing and printing applications.
Tetrachloro Pyrimidine Dyes
Sandoz and Geigy Ltd. independently found a new reactive nucleus in tetrachloropyrimidine. It is different from cyanuric chloride in that one of the nitrogen is replaced by C - Cl and so all the carbon atoms are not equal. It has also been established that the 4th or the sixth carbon atom reacts first. So dyes with a free amino group react with it giving rise to a reactive dye.
N1 —— C6 —— Cl
|| ||
Cl—— C2 C5 —— Cl
| |
N3 ==== C4 —— Cl
Sandoz claim that their dyes (Drimarene Z) have the following advantages.
1. Stability to alkali at low temperature.
2. High stability and low salt sensitivity. They can be stored without deterioration.
3. Reactivity at high temperature. A system of low reactivity is required for printing dyes to ensure good paste stability but it should also be reactive enough for maximum yield to be obtained with reasonable steaming time. With Drimarene Z dyestuffs the steaming time is 8-12 minutes which is about the same as that for vat dyes.
4. Stable chemical link with the fibre. The reactive system should be such that the dye fibre linkage should be stable at the boil. This is exactly the case with Drimarene Z dyes.
5. Removal of unreacted dye. This is important for not all the dye reacts with the fibre. The removal of the dye unreacted is easy.
6. High brilliancy is also found in these dyes.
7. They have a very good wet fast because of the stable chemical linkage. The wet fastness to print and stability to resins differ from individual to individual.
Chemistry of tetrachloropyrimidines
Tetrachloropyrimidine contains reactive halogen atoms in the 2,4-& 6 positions. The chlorine in the 5 position is very stable and cannot be exchanged with other groups easily. The most reactive of the other 3 is exchanged for the chromophore. It is the chlorine in the 4 or 6 position which is equivalent.
In these dyes, two reactive halogen atoms are available, but under the fixation conditions generally only one of them is believed to react with cellulose. It is generally assumed that the chlorine in the 2 position is involved.
Reactive Dyes based on Epoxides
Epoxides are used to form a permanent bond with the cellulose polymers in resin finishes. An epoxide as part of the dyestuff molecule would render the combination with certain polymers possible. They are catalysed by acid or bases.
A typical epoxide molecule would be
CH ——— CH2
O
An epoxide with phthalocyanine would give a good epoxide phthalocyanine reactive dye. These have excellent fastness for cellulose, wool and synthetics.
Other types of Reactive Dyes
There are quite a number of other kinds of reactive dyes which form stable linkages with polymers etc. They are the chlorinated pyridines, chlorosulfanamides, and other chloro compounds. A reactive dye with the hydroxy alkyl group are the roter dyes.
Hence it is seen that reactive dyes have given us many kinds of combinations and many more are yet to come.
Major Factors Influencing the Dyeing behaviour of Reactive Dyes are:-
(i) The chemical reactivity of reactive dyes.
(ii) Influence of diffusion and affinity in reactive dyeing of cellulose.
(iii) Reaction between reactive dyes and cellulose.
(iv) Variation of reactive system in reactive dyes.
Reactivity of different types of Reactive Dyes
Procion M dyes, which have as the reactive centre a dichloro-S-triazine group, are the most reactive and therefore the dyeings can be carried out at room temperature. Only one of the two chlorine atoms of the cyanuric chloride nucleus can be replaced at room temperature while the other requires temperatures above 60°C for the reaction. It can be seen therefore that dyes based upon monochloro-S-triazine reactive group (Procion H.Cibacrons) would require higher temperature for fixation. These dyes are quite stable under alkaline conditions at room temperature and are therefore admirably suited for printing, and for dyeing by the pad-bake and pad-steam methods. In contrast, the highly reactive Procion M dyes are amenable to easy cold pad-batch method of dyeing; they are unsuitable for printing.
An ideal reactive dye will be on which has high reactivity with cellulose and at the same time having good stability in alkaline solutions or pastes. Generally, the greater the reactivity of the dye, the greater is its instability in alkaline media. Levafix E dyes, which are based on halogenated quinoxaline ring (2-3-dichloroquinoxaline-6-carboxylamide). combine in them these opposing properties well. They are almost as reactive as Procion M dyes, and are quite stable under alkaline conditions.
Drimarenes, which are based on tetrachloropyrimidine are excellent for printing as they have high storage stability under alkaline at room temperature, but react rapidly with cellulose during steaming.
The reactivity of vinyl sulphone dye lies between those of monochloro and dichlorotriazinyl dyes. Vinyl sulphone dyes have good stability under neutral and acidic conditions but poor stability under alkaline conditions.
Application
Reactive dyes are possessing high moderate or low reactivity. A highly reactive dye which combines with the fibre rapidly or hydrolyse in water in a short period of time requires only weak alkali such as sodium bicarbonate. A low reactivity product requires a strong alkali like sodium hydroxide. A moderately reactive dye requires an alkali such as soda ash.
Purification of Reactive Dyes
Reactive Dyes of the tetrachloropyrimidine and cyanuric chloride have registered a steady increase. Production of these dyes were not fully investigated. Normal purifying with salt and polar solvents affect the reactive group. The method by Rose also does not come handy as the use of polar solvents and fairly high temperature are involved. C.D. Mehta et. al. have independently applied a method for the purification of these dyes. They employed a mixture of solvents. Generally the dye was dissolved in Dimethyl formamide and brought out with chloroform. They successfully purified reaction red 2B of the tetrachloropyrimidine and Procion Brilliant red H.7 G.S. of the cyanuric chloride type. They could also purify other similar dyes.
Advantage and Limitations of Reactive Dyes
The reactive dyes give even a better performance than most of the nonreactive dyes. Their advantages over the other dyes are as follows:-
(1) Their advantages over vats.
(i) improved surface appearance and penetration;
(ii) avoidance of reduction and oxidation processes, and
(iii) Lower cost.
(iv) better range of shades
(2) Their advantages over azoics are:
(i) Better rubbing fastness; and
(ii) reproducibility of matchings.
(iii) better range of shades
(3) Their advantages over pigments are:
(i) better workability and less scumming of reserved portions;
(ii) much better penetrations and much better rubbing fastness even at higher concentrations; and
(iii) absence of adverse effect in final handle.
(4) Their advantages over rapid fasts and rapidiogens in printing are:
(i) Brighter prints and better (softer) handle.
(ii) No acid - steaming for fixation
Fabric preparation
Reactives are generally used on higher value cloths which are normally mercerised. The colour build-up of reactives depends on the degree and efficiency of mercerisation. Thus the same strength of dyes used on differently mercerised cloth will give different depths and variations in shade. This impairs reproducibility of matchings.
Washing Off
A large quantity of reactive dyestuff (10-40%) gets hydrolysed and hence remains unfixed and the difficulties associated with this residual dye which if not removed completely will tend to run during subsequent washing and will cause a lot of consumer dissatisfaction and/or possibly stain the while portions. Hence a thorough washing and soaping is absolutely necessary. This leads to a higher level of water consumption. The vinyl sulphone group gives much less difficulty. In the first place the quantum of unfixed dye is in the region of 10-15%; as against 30-40% in the case of cold brands. Also the unfixed dye does not stain the adjoining portions during washing.
Some of the other disadvantages are:
(1) poor chlorine fastness,
(2) high printing cost and
(3) limited stability of printing paste (with alkali).
New Developments of Reactive Dyes
Reactive dyes, the newest addition to the existing, dyes are the centre of attraction in dyestuff research. Many reviews have been published so far. They form a bond with the fibre. First came the cyanuric chloride reactive dyes. Then the vinyl sulphone and the tetrachloropyrimidine reactive dyes. The cyanuric chloride and the tetrachloro pyrimidine dye cotton mainly whereas the vinyl-sulfone dyes acetetes, polyamines, polyesters and wool. The hydrolysis of reactive dyeing, has been studied recently by Benz.
The Remazol dyes (vinyl sulfone) form a ether bondage with the fibre whereas the Ciba-cron and Procion form an ester linkage. The Remazol are stable to acid but they cleave at a hot alkali bath. They are stable to resin finishes which is not the case with both the cyanuric chloride and tetra-chloropyrimidine dyes. The tetrachloro-pyrimidines are most stable to alkali and storage than the cyanuric chloride dyes. The reaction of a cyanuric chloride or tetrachloropyrimidine to the fibre is a substitution reaction whereas in vinyl-sulfone it is an additional reaction through a covalent bond.
Reactive groups are generally found to combine with dyes that are not substantial (i.e.) acid dyes, phthalocyanine dyes. It is found that about 50% of the reactive dyes have a phthalocyanine groups.
Lately Sumifix Supra Dyes marketed by Sumitomo Company of Japan are bifunctional reactive dyes having two different reactive groups vinyl sulfone and monochlorotriazine groups. The main advantages of these dyes are as follows:
(1) Good Reproducibility.
(2) Good levelling properties.
(3) High fastness to perspiration, light, chlorinated water and peroxide washing etc.
(4) High degree of exhaustion and fixation.
Kayacelon Reaction Dyes
Nippon Kayaku of Japan developed these dyes which react with cellulose at high temperature of 130°C at neutral pH without the need of alkali. The leaving group in the reaction with cellulose is 3-carboxy pyridine.
The advantage of these dye are as follows
1. Simplified dyeing process.
2. Reduction in processing time.
3. Increase in productivity.
Cibacron C Dyes
Ciba-Geigy marketed Cibacron C Dyes which are bifunctional reactive dyes having a monofluorotriazine reactive group linked to the vinyl sulfone reactive group by an aliphatic bridge. Sumfix Supra Bi-functional reactive dyes are mainly for exhaust dyeing. While Cibacron C dyes are mainly for pad batch and continuous dyeing.
Procion Supra Dyes of (I.C.I.)
Reactive dyes are capable of giving high fixation when applied to cellulosic fabric. Procion Supra Dyes are intended primarily for use in textile printing applications but may also be employed in continuous dyeing processes.
Procion HEXL Dyes
Procion HEXL Dyes was introduced by ICI for better technical performance over some bismonochlorotriazinyl HE dyes in their levelness and shade reproductibility.
Prociline N Dyes
Prociline N Dyes range is a combination of matched shades from Dispersal PC dyes and selected Procion P monochlorotriazinyl reactive dyes.
Lately Sumitomo Chemical Co., Japan have put up ‘Hot type’ products under trade name ‘Sumifix’ and ‘Sumifix Supra’, which can be applied to cellulose silk, etc.
Table 14.5
No. Commercial Name C.I. Generic Name
1. Sumifix Supra Reactive Y-145
Yellow 3RF
2. Sumifix Supra Reactive R-194
Brill. Red 2BF
3. Sumifix Supra Reactive R-195
Brill. Red 3BF
4. Supra Navy Reactive B-194
Blue 2GF
5. Yellow FGS Reactive Y-115
6. Yellow GNS Reactive Y-115
7. Yellow GR Special Reactive Y-116
8. Brill. Scarlet R Reactive R-113
9. Brill. Red G Reactive R-112
10. Brill. Red BS Reactive R-111
11. Navy Blue GS 15% Reactive B-147
12. Turquoise Blue BF Reactive B-148
Manufacturing Processes
Reactive Red
Structural Formula:
Add 190 kg of finely powdered cyanuric chloride to a well stirred mixture of crushed ice and ice-cold water. Then gradually add a 1500 litres neutral solution of H acid and maintain the temperature below 5°C. Simultaneously add 20% (w/v) of sodium carbonate solution in small lots to maintain the pH between 6.2 and 6.8. The reaction mixture is stirred for 20-25 minutes and the pH is adjusted between 6.2 and 6.8 till the reaction is complete. This is indicated by the complete solubility of the reaction mixture. Absence of free diazotisable amino group also indicates the completion of the reaction.
Aniline is diazotised by the conventional method as follows:
260 litres (2.52 mole) of concentrated hydrochloric acid is added to a stirred mixture of 500 kg of ice and 300 litres of water and this is followed by the addition of 94 kg (1.01 mole) aniline. When aniline goes completely in the solution, add 70 kg (1.01 mole) sodium nitrite as 20% solution (w/v) to diazotise aniline. The temperature is maintained below 5°C and the completion of diazotisation is tested with starch iodide paper.
Then gradually add the diazo solution in a thin stream to the cyanurated H-acid. Simultaneously add 20% (w/v) sodium carbonate solution in lots to maintain the pH between 6.2 and 6.8. The completion of the coupling is indicated by the absence of the coupling component (here cyanurated H-acid) which is tested by spolting the reaction mixture and diazotised aniline side by side on a filter paper. The reaction is complete when there is no colour developed at the junction of the two run-outs of the spots. The temperature during coupling is maintained below 10°C.
Add a mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate as a buffer. The reactive dye is then salted out with common salt. Filter it and wash it with chilled saturated brine containing the buffer. Dry below 45°C under vacuum.
Reactive Rose Red
Structural Formula:
The procedure for this dye was generally the same as Reactive Red. The molar proportions of the reactants are similar to those used in the case of Reactive Red.
Some difficulties were encountered in salting out of the dye, in stirring the mixture during coupling and in the final filtration.
A dispersion of cyanuric chloride is prepared not by adding powdered cyanuric chloride to ice water mixture, but first cyanuric chloride is dissolved in acetone to make a 20% solution and this solution is then added to ice water mixture.
Another important modification is to add salt before the addition of the diazo solution. The cyanurated H-acid was thus salted out first and then coupled with diazotised O-anisidine.
Reactive Violet
Structural Formula:
The procedure and the molar proportions of the reactants remains the same as that in the case of Reactive Red. The only difficulty experienced was in the diazotisation of a-naphthylamine hydrochloride because of the low solubility of a-naphythlamine hydrochloride. The method described in BIOS 1661 was found to be suitable for diazotisation of a-naphthylamine.
Reactive Orange
Structural Formula:
This dye is obtained by coupling diazotised meta-anilic acid with cyanurated J-acid. The molar proportions are the same as in the case of Reactive Red. The cyanuration of J-acid is carried out in the same manner as the cyanuration of H-acid in the case of Reactive Red.
The diazotisation of meta-anilic acid is carried out by conventional method and coupling is carried out at pH 6.2 to 6.8 and temperature is maintained below 10°C.
Reactive Yellow
Structural Formula:
This dye is obtained by preparing the azo dye from diazotised C-acid and m-toluidine first and then cyanurating it in presence of acetone.
The diazotisation of C-acid (1-mole) is carried out by the conventional method and the coupling with m-toluidine (0.99 mole) is carried out in acidic medium. The pH of the reaction mixture during coupling is found to have an appreciable effect on the colour yield of the product. Since the diazonium salt of C-acid has a very low solubility in highly acidic conditions, so either increase the volume for smooth and complete coupling or raise the pH to about 5.5 to 6.0. Raising the pH increases the solubility of the diazonium salt, coupling is more smooth and yield of the final dye is also increased.
The cyanuration of the dye is carried out first by preparing a slurry of cyanuric chloride by using acetone as in the case of Reactive Rose Red. Use of acetone reduces the time of cyanuration.
The rest of the operations are similar to the ones used in the above dyes.
Reactive Red M8B
Acetylation of H Acid
Charge water 300 litre H Acid 88 kg under stirring and prepare clear solution to pH 7.0 by adding caustic soda solution (13 kg (100%)). Bring temperature to 15-16°C by ice. Add 44 kg acetic anhydride stir for two hours, at the end of reaction pH - 3.5 to 3.7.
Diazotisation of Tobias Acid
Charge 250 litre water 15 kg sodium hydroxide heat to 50°C add 61 kg Tobias acid bring pH to 9.0.
Note: Do not increase temperature more than 55 to 60°C and also do not increase pH above 9.0.
In diazo vat, charge ice and water and 125 kg HCl acid. Cool to 5°C. Add small quantity of sodium nitrite to start reaction. Then start addition of Tobias acid and sodium nitrite solution simultaneously. (21 kg sodium nitrite as 5% solution) and slowly keeping the temperature of diazo below 10°C destroy excess of nitrous acid by adding sulfamic acid. Cool diazo to 7°C.
Coupling Start coupling by adding above acetylated H-acid into Tobias acid diazo in 2 hours at 8-10°C. At the end of reaction red-rose colour develops pH should be 7.0 adjust with soda ash solution. Stir overnight.
Hydrolysis Check up pH and coupler pH 7 to 7.5. Heat to 90 to 95°C. Maintain at 95°C for 4 hours (try to control) volume during heating as it affects the yield.
Take chromatography test on circular paper, develop with 1% sodium hydroxide and finally with water, there should be main reddish orange band with no brown band at perifery. If chromatograph indicates unhydrolyse dye, maintain at 90-95°C for 1 hour more and test again. Then cool to 60-65°C, add HCl to bring pH 6.5 (about 200 kg). Stir for half an hour more. Add 10% salt (about 240 kg vacuum salt) stir overnight and filter at room temperature suck, dry, with air and discharge the press.
Cyanuration Charge 400 to 500 litre water to kettle, heat to 60-65°C add acid wet cake to get clear solution.
In another vessel charge water and ice, add dispersing agent add 40 kg cyanuric chloride and stir for 30 minutes. Add above dye solution 3 to 4 hours. Temperature 0-5°C addition must be done slowly otherwise cross condensation take place. Stir for 3 hours. There should not be any violet band on nitrite exposure.
Add soda solution, bring pH 6.8 in 2½ hours. Then increase pH to 7 stir for one hour and then salt out with 15 to 20% salt on W/V basis (300-400 kg salt).
Stir for 3 hours, filter the cake, press with air to remove maximum moisture. Dry at 50-55°C.
Reactive Dyes with Trichloropyrimidine As Reactive Group
Structural Formula:
It is dark blue powder which gives a blue solution in water. It dyes brilliant blue shades on wool with very good fastness to light, washing, miling, water, perspiration, crocking and dry cleaning.
Preparation
Dissolve 98 litres of 3-aminobenzyl alcohol in 1200 litres water and then add 336 kg of caustic soda (30%). Cool the solution to 2°C by adding ice. Add a solution of 146 kg of 2,4,6-trichloropyrimidine in 176 litres of toluene, dropwise over 3 hours, while stirring, maintain the temperature at 0-3°C. Stir the mixture for 10-15 hours at 0-3°C and then add 284 litres of 30% hydrochloric acid. Filter and wash the residue with a common salt solution and vacuum dry at 35-40°C.
Add 349 litre of 100% 1-amino-4-(2,4,6’-trimethyl)-phenylamino anthraquinone-2-sulfonic acid, at 20-30°C to 2160 litres of chlorosulphonic acid. Then add 640 litres of sulfuryl chloride, drop by drop and heat the mixture in about 30 minutes to 50°C. Cool the mixture after 16 hours at 50-55°C and pour it into a mixture of ice and water and 1600 kg of sodium chloride. Suck the precipitate and wash with 10% sodium chloride solution and paste it up with 4000 litre of water.
Adjust the suspension to pH 7 and sprinkle 264 kg of finely pulverised 3-amino-(1-dichloropyrimidyl hydroxymethyl)-benzene. Stir the mixture at 20-30°C and maintain the pH at 7.0-7.5 by adding of dilute sodium carbonate solution. After complete condensation, acidify the mixture with hydrochloric acid. Suction off the dye stuff, wash with 1% hydrochloric acid to remove slight excess of 3-amino-1-(dichloropyrimidyl hydroxy-methyl) benzene.
Neutralize the dyestuff paste with sodium carbonate and vacuum dry at 50°C.
Reactive Dyes with 2,3-Dichloroquinoxaline-6-Carbonyl Chloride As Reactive Group
Structural Formula:
Preparation
Add 94 kg 2,4-diamino-benzene sulfonic acid and 50 kg of 30% sodium hydroxide to 250 ml water. Stir the slurry and cool to 25°C and dilute with 700 litre water. To this solution add at once 56 kg of acetic anhydride. Continue stirring for one hour. Adjust the pH to 8 and add 34.5 kg of a 31% sodium nitrite solution. Add this solution over half on hour to a solution of 250 litre of water and 250 kg ice and 60 kg of 30% hydrochloric acid. Stir the slurry for half an hour before excess nitrite is destroyed with sulfonic acid as shown by a negative test on starch iodide paper.
Add this diazo slurry with stirring at 5-15°C over one hour to a solution of 250 litres of water, 162 kg of 1-(2’,5’-dichloro-4’sulfophenyl)-3-methyl-5-pyrazolone, 36 kg of 30% sodium hydroxide, 50 kg of sodium acetate and 250 kg of ice. To this yellow-brown solution add 60 kg of hydrochloric acid. Raise the temperature to 90°C over 1 hour. Maintain this temperature for 2 hours. Cool to 40°C.F ilter the precipitated solid dye-base and wash with a dilute hydrochloric acid solution.
Dissolve this dye base cake in a solution of 2500 litre of water and 83 kg of sodium hydroxide. Stir the solution at 30-35°C. To this solution add 115 kg of 2,3-dichloro-6-quinoaxaline carboxyl chloride dissolve in 50 kg of xylene. Stir the mixture for 3 hours at 35-40°C and maintain the pH at 3.5-8.0 by adding sodium hydroxide solution. Filter the reaction mass. Add to it 75 kg of potassium chloride in 1000 litres of water over one hour. Filter out the precipitated insoluble potassium salt and dry below 60°C.
Reactive Dyes with Chloroacetyl As Reactive Group
Structural Formula:
It is a red dye which dyes wool and nylon in shades fast to light and wet treatments.
Dissolve the red dye 108 parts obtained by acid coupling of diazotized 1-aminobenzene-2-sulphonic acid with 2-(2’,4’,6’ trimethylphenylamino)-8 hydroxy naphthalene-6-sulphonic acid in 300 parts 96% sulphuric acid at 15-20°c, cool to 0-5°c, add 50 parts N-hydroxymethyl chloroacetamide in portions and increase temperature to 20°C in one hour. Discharge the mass into 2400 parts ice and stir until the temperature decreases to 10°C. Filter the precipitated dye, dissolve in water and reprecipitate with 800 parts common salt. Filter, wash with 20% common salt solution, dry under vacuum.
Reactive Dyes with 6-Amino-2-Chlorobenzothiazole-5-Sulphonic Acid As Reactive Group
Formula:
It gives bright blue shades on cotton with very good wet fastness properties in the presence of basic agents.
Preparations
Take 80 parts sodium salt of 1-amino-4-bromoanthraquinone-2-sulphonic acid in 800 parts water. Add a solution of 54 parts 2-chloro-6-aminobenzothiazole in 100 parts dioxane and then 48 parts sodium hydrogen carbonate and 6 part copper chloride. Heat the mixture for about 9 hours at 55-60°C filter, wash and dry the product.
Dissolve 75 parts of new dyestuff, which crystallizes in blue needles at 5-10°C in 1 hour in 500 parts of oleum. Stir the mixture for two hours at room temperature. Discharge the mass on ice, filter wash and dry the product.
Reactive Turquoise Blue
Reactive system b-chloro ethylamine hydrochloride.
Manufacturing process
Charge 200 kgs chlorosulfonic acid in glass line kettle, charge 20 kgs of copper phthalocyanineblue at such a rate that temperature does not go above 40°C. It should be added in about 2 hours. Stir for 1 hour. Heat the chlorosulfonation mass to a temperature of 137-140°C and maintain for 4 hours. Cool the reaction mass to room temperature (i.e. 28-30°C).
In the meantime charge water and ice in rubber line kettle. Charge chlorosulfonation mass to rubber line kettle at such a rate that the temperature of the material remain about 0°C. Stir for one hour. Filter the precipitated sulfonyl chloride in filter press. After the filtration is completed, unload the press into wooden tray containing ice pieces.
Control Test
The quality of chlorosulfonated product can be roughly checked here.
Take wet cake + water — make alkaline by sodium carbonate solution, and small amount is poured on a filter paper to see the solubility of the product. If the chlorosulfonation is proper, the product is completely insoluble and the runout is very clear. If the chlorosulfonation has not taken place properly the run out is deep blue in colour.
To the brick line wooden vat charge water and ice. Charge wet cake of copper phthalosulfonyl chloride and stir for one hour at 0°C. Charge the slurry of b-chloroethylamine hydrochloride (11 kgs of 100%). Stir for half an hour. Charge soda ash solution to raise the pH to 8-8.5 at 0°C. Stir for two hours at 0°C. Raise the temperature to 20-25°C by maintaining the pH to 8-8.5. After that raise the pH to 8.7 by adding soda ash solution.
(Note: The blue solid suspension goes into solution and clear blue solution is obtained).
Maintain the reaction at 20-25°C for 14 hours for completion of condensation. Charge hydrochloric acid, charge vacuum salt in one hour and stirs for one hour. Filter the product in filter press and suck, dry at 50-55°C.
Notes
(1) The tone of the dye can be changed by adding phosphorous trichloride thionylchloride during sulfonation.
(2) For maintaining pH, buffer solution can be used.
(3) For getting good product, correct concentration of chlorosulfonic should be used.
Properties of Cyanuric Chloride
1. Cyanuric Chloride is a white solid of m.p. 146°C to b.p. 198°C possessing a pungent odour of mouse excrement. It is best purified by crystallisation from anhydrous organic solvents such as light petroleum. Solubilities in various organic solvents at 25°C are stated to be as follows:
Table 14.6
No. Organic Solvent Solubility date gms/
100 gms solvent
1. Acetone 25
2. Acrylonitrile 19
3. Benzene 19
4. Carbon Tetrachloride 7.5
5. Chloroform 20
6. Dioxan 55
7. Nitrobenzene 18 per 100 g of solvent
2. Cyanuric Chloride is only very slightly soluble in cold water.
Table 14.7
No. Temperature Solubility (g/100 ml)
1. 0°C 0.032
2. 5°C 0.035
3. 10°C 0.038
4. 15°C 0.041
5. 20°C 0.044
6. 25°C 0.049
The increase in solubility which occurs when increasing amounts of acetone are added to the water.
Cyanuric Chloride is readily hydrolysed by liquid water and by water vapour, and must therefore be stored in airtight containers. Under such conditions it may be kept for a long time without change; the presence of iron rust is said to catalyst the decomposition that occurs in the presence of moisture.
Chlorosulfonic Acid
It is a clear, colourless to straw-coloured liquid that fumes strongly on contact with air. It is reacts violently with liquid water to form hydrogen chloride vapour and sulphuric acid. The liquid form of the compound is highly corrosive to body tissues, acting as both as strong acid and a dehydrating agent. The vapour is also hazardous since its hydrolysis products, hydrochloric and sulphuric acids, are strong irritants to the eyes, lungs and mucous membrances.
Commercial Grades and Specifications of Chlorosulfonic Acid
The commercial product offered in both bulk and laboratory quantities contains a minimum of 98.5% CISO3H (62.3° Be, heavy) and has the following typical analysis:
Total CISO3H 98.8%
Total sulphur as SO3 69.0%
Total chloride as HCl 30.9%
Free sulphuric acid as H2SO4 0.7%
Free sulphur trioxide as SO3 0.6%
Colour colourless to straw
Odour Pungent
Boiling point, °C
at 765 torr 151-152
Melting point, °C -81 to -80
Specific gravity 20/4°C 1.753
Specific heat,
15-80°C, cal/g 0.282
Refractive index, 1.437
Vapour pressure, p
(T in °K), torr 10g p = 9.371
(2752/T)
Heat of vaporization,
at bp, cal/g 109
Identification of Reactive Dyes
In order to distinguish these dyes from other classes which color wool in the polyfiber test, an individual dyeing on mercerized cotton is necessary.
Procedure
Dissolve 150mg of the dye sample in a 200-ml neutral dyebath at room temperature. Add 10g of sodium sulfate, 5g of mercerized cotton, and 0.5g of sodium carbonate. Bring to a boil within 10 min and continue boiling for 10 min. Rinse, then boil with synthetic detergent for 2 min. Only reactive and direct dyes remain on the fabric.
Dry the fabric and treat it with dimethylformamide. Direct dyes will be stripped; reactive dyes remain on the fabric.
The following black reactive dyes can be identified by spotting with cold concentrated nitric acid and by steeping in cold concentrated sulfuric acid.
Table 14.8
C.I. Name Color after Color of Color on
spotting with extract dilution
cold concentrated
nitric acid
Reactive Black 1 Khaki blue red
Reactive Black 5 bluish green greenish black bluish green
Reactive Black 7 reddish brown purple gray
Reactive Black 15 violet red - brown purple
Reactive Black 16 green blue - green brown
Paper and thin - layer chromatography is very useful in the identification of reactive dyes. |