KR820000566B1 - Azo coupling process - Google Patents

Abstract

Aq. suspensions of H2O-insol. azo dyes are continuously manufd. by rapidly mixing a stream of a heterocyclic or weakly basic benzenoid amine in H2SO4 contg. nitrosylsulfuric acid or the daizotizing agent with a stream of coupling component in aq. MeOH and removing the formed dye.

Description

AZO Coupling Method

The accompanying drawings are schematic views of the tubular reactor used to carry out Example 4.

The present invention relates to a process for the preparation of an aqueous slurry of a water insoluble azo compound, and more particularly to such a process carried out continuously.

The present invention provides a reaction for preparing a first stream (hereinafter referred to as a diazo component) and a water insoluble azo compound containing a diazonium compound resulting from the diazotization of a heterocycle or a weakly basic benzenoid amine in an acidic medium. A number consisting of continuously removing the resulting slurry by continuously mixing together a second stream (hereinafter referred to as a coupling component) containing a compound capable of coupling with the diazo component under conditions present in the zone. It provides a method for producing an aqueous slurry of insoluble azo compound.

Continuous means that the diazo component and the coupling component are mixed in an equivalent ratio, preferably in a slight excess of coupling components, so that the mixing and reaction are complete and added to either component or one of the streams as the slurry leaves the reaction zone. No residual excess in the slurry above any predetermined excess.

The coupling reaction is preferably carried out in one or more steps by completely mixing the streams together under conditions that can cause the reaction to produce the desired azo compound in a short time, in particular under conditions that minimize the decomposition of the diazo component.

Incomplete reactions may occur when the product formed is not in the same phase as the reactants, especially when the solid product is produced by mixing the two solutions and the unreacted material may be absorbed and adsorbed in the product. Therefore, to avoid this absorption, it is desirable to intensify the mixing, which promotes the formation of products with smaller and more uniform particle distribution.

Heterocycles and weakly basic benzenoid amines are usually diazotized in a concentrated sulfuric acid medium, ie in a medium containing at least 50% by weight sulfuric acid based on the total weight of water and sulfuric acid in the medium and the first stream is subjected to the diazotization process. It may also contain a direct product of.

Thus, acidic media may contain other acids such as acetic acid or phosphoric acid, but sulfuric acid media containing at least 50% by weight sulfuric acid based on the total weight of water and sulfuric acid are suitable.

However, weakly basic benzenoidamines such as, for example, 2,4-dinitroaniline and halomononitroaniline can be diazotized under more dilute acid conditions and contain the diazo compound in a more dilute acid medium composed of 25% by weight sulfuric acid. The product of the process may form a first stream.

The lowest concentration of acid in the first stream is preferably such a concentration that the diazonium compound is degraded to 5% or less, in particular 1% or less, before mixing with the second stream. The range of degradation and lowest concentrations that can be tolerated in successive diazotization and coupling coupling systems depends, in part, on the time between diazotization and coupling. If the acid concentration in the product stream at the end of the diazolation is such a concentration at which the diazonium compound is unstable therein, decomposition of the diazonium compound can be maintained within the above-mentioned range by moderate reduction during the period between the diazoation and the coupling.

In order to achieve coupling under appropriate conditions, a small, high speed stirring vessel may be used, which is equipped with a device for feeding a metered feed of the bicomponent stream. Alternatively, a tubular mixer may be used that promotes good mixing of the shape and fluid velocity of the tubes used. A tubular mixer is a device in which reactants are held in a tube or outlet and mixed together quickly and completely, and a mixed reactant stream is a device in which the reaction is complete and exits the outlet tube or pipe.

In contrast, the reaction zone is a recirculation system with at least one mixing zone where the reactants are mixed, a recirculation loop connecting the inlet to the mixing zone and the outlet from the mixing zone, and a device for circulating the reaction mixture through the loop. It can consist of. The product stream is conveniently removed from the reaction zone through the outlet from the recycle loop.

When the reaction zone is contained in a stirring vessel, the stirrer is a high-speed shear type such as Turax to minimize the condensation formation of the azo compound containing the reactants absorbed by the high shear rate during mixing and reaction. Commercially available under the trade names of Turrax and Silverson.

However, rapid and thorough mixing in a relatively small reaction zone is sufficient to make the product pulverized, so it is not necessary to crush or crush the particles of the product. The presence of the surfactant in the reaction zone during coupling helps to keep the product in the pulverized state by inhibiting the condensation of the primary particles.

The tubular mixer may contain concentric arrays of tubes, multi-jet clusters or tangential spray mixers, for example as T-junction or Y-junction pipes. In the case of a T-junction, the reactants are preferably mutually approached along opposing arms of T and the reaction mixture is removed at right angles to the direction of approach.

Mixing can be enhanced by installing a static mixer such as a set of baffles supplied under the trade names kenics and Sulzer in the reaction zone extending along the tube from which the reaction mixture is removed from the mixer.

50%)인 경우는 점성이 크므로, 제2스트림과의 혼합을 용이하게 하기 위하여 제2스트림과 혼합시키기 직전에 상술한 디아조화 공정의 직접 생성물을 물과 혼합시킴으로서 보다 묽은 매체로 전환시킬수 있다. 물과의 이러한 혼합은 이후부터 예비 희석이라 칭하며 커플링 반응 대역의 바로 위의 혼합대역내에서 바람직하게 수행된다.The first stream is concentrated sulfuric acid medium (

50%), it is highly viscous, so it can be converted to a thinner medium by mixing the direct product of the above diazotization process with water just before mixing with the second stream to facilitate mixing with the second stream. . This mixing with water is hereinafter referred to as preliminary dilution and is preferably carried out in the mixing zone just above the coupling reaction zone.

The range of preliminary dilutions is such that the concentration of acid in the first stream is reduced to a range of 2-15% by weight, particularly 5-10% by weight, relative to the total weight of water and acid in the stream so that the viscosity of the first stream is reduced. Is preferred. This prediluted stream is usually more easily and effectively mixed with the second stream.

Another advantage of the preliminary dilution is that the diluted first stream contains two less stable reactants, and although the second stream is somewhat viscous, it tends to reduce the development of the diazo component retention, which leads to coupling. It happens more effectively.

Since the diazo component is usually unstable under such dilute acidic conditions, the preliminary dilution of the first stream is preferably carried out as late as possible before mixing with the second stream and within a time sufficient to minimize degradation of the diazo component. Such time typically ranges from 1 second to 1 millisecond.

Preliminary dilution is preferably carried out in a tubular reactor equipped with a static mixer, in which case water is less likely to form unstable diluted diazo components which lead to decomposition of the diazo components. The difference in viscosity between and agricultural is not very important.

Suitable coupling components are those which can be coupled with the diazonium salt of a heterocycle or weakly basic benzenoid amine to produce products in the form of disperse dyes and pigments.

When the derived azo compound is represented by the structural formula DN = NE (where D is a residue of the diazo component), the residue of the coupling component represented by (E) is the residue of any series of coupling components that bind to the diazo component. For example, acyl acetarylamide, pyrazolone, aminopyrazolone, phenol, naphthol, 2,6-diaminopyridine or residues of coupling components from 2,6-dihydroxypyridines. In particular, E is a residue of an aromatic coupling component which binds by the presence of an optionally substituted amino group, such as a residue of a coupling component of 1-naphthyl amines, in particular a coupling of an aniline, which binds at the para position with respect to an optionally substituted amino group. Residues of components.

The residue of the coupling component represented by E is preferably of the following general formula.

Wherein Z ¹ and Z ² each form a cyclic structure comprising a hydrogen atom or an optionally substituted hydrocarbon group, in particular an optionally substituted lower alkyl group or comprising a nitrogen atom attached to ring B, wherein the benzene ring B is It may form part of a naphthalene or quinoline ring containing additional substituents or optionally further substitution.

E especially represents a group of the following general formula.

Wherein W is hydrogen, lower alkyl or lower alkoxy; V is hydrogen, lower alkyl, lower alkoxy, chlorine, bromine or acyl amino, in particular general-NHCOT ² or -NHSO ₂ T ³ , wherein T ² is hydrogen, alkyl especially lower alkyl, aryl, amino or aminoalkyl, T ³ is an acylamino group of optionally substituted lower alkyl or aryl; Z ³ is hydrogen or optionally substituted alkyl especially lower alkyl group; Z ⁴ is hydrogen. Optionally substituted alkyl, especially lower alkyl, or optionally substituted aryl or cycloalkyl, Z ³ and Z ⁴ together may form a cyclic structure.

Examples of optionally substituted lower alkyl groups represented by Z ¹ , Z ² , Z ³ and Z ⁴ are β-hydroxyethyl, α-methyl-β-hydroxyethyl, β- or γ-hydroxypropyl and δ-hydroxy Hydroxy lower alkyl such as oxybutyl; lower alkoxy lower alkyl such as β- (methoxy or ethoxy) ethyl and γ-methoxypropyl; cyano lower alkyl such as β-cyanoethyl; Phenyl lower alkyl such as benzyl and β-phenyl ethyl; acyloxy lower alkyl such as β-acetoxyethyl and 1-acetoxy-2-propyl; carboxylower alkyl such as β-carboxyethyl and δ-carboxybutyl; lower alkoxy carbonylalkyl, such as β-methoxycarbonylethyl; hydroxy lower alkoxy lower alkyl, such as β- (β'-hydroxy ethoxy) ethyl; lower alkoxy lower alkoxy lower alkyl, such as β- (β'-methoxy ethoxy) ethyl; lower alkoxy lower alkoxycarbonyl lower alkyl, such as β- (β'-methoxy ethoxy carbonyl) ethyl; acyloxy lower alkyl, especially lower alkylcarbonyloxy lower alkyl, such as β-acetoxyethyl and δ-acetoxybutyl; chloro lower alkyl, such as γ-chloropropyl, and lower alkoxycarbonyloxy lower alkyl, such as β-ethoxy carbonyl oxy ethyl, may be mentioned, provided that Z ¹ and Z ² or Z ³ and Z ⁴ form a cyclic structure The -NZ ¹ Z ² or -NZ ³ Z ⁴ -group may be a morpholine, piperidine or pyrrolidine group.

Examples of such coupling components include acylacetarylamides such as aceto acet anilide and aceto acet-2,5-dimethoxyanilide; Aminopyrazoles such as 1-phenyl-3-methyl-5-aminopyrazole; 1,3-dimethyl-5-pyrazolone, in particular 1-phenyl-3- (methyl, carbon, in which a phenyl group is optionally substituted by methyl, methoxy, ethoxy, chlorine, bromine, nitro, sulfonamido or acetylamino Pyrazolone 3-cyano-4-methyl-2,6-dihydroxypyridine and 1-ethyl-3-cyano-4-methyl-6-hydroxy, such as amido or carbomethoxy) -5-pyrazolone 2,6-dihydroxypyridine, such as cipyrid-2-one; 2,6-diaminopyridine, such as 3-cyano-4-methyl-2,6-di (N-2-methoxyethylamino) pyridine; Phenols such as O-cresol, resorcinol and 3-acetylaminophenol; naphthol, such as β-naphthol; Arylamines of naphthylamines, such as 1-naphthyl amine, in particular 2,5-dimethoxyaniline, N, N-diethylaniline, N, N-di (β-hydroxyethyl) -m-toluidine, N, N -Di (β-dicyanoethyl) aniline, N-ethyl-N- (β-ethoxyethyl) aniline, N, N-di (β-carbomethoxyethyl) -m-toluidine, 2-methoxy-5 -Methyl-N- (β-acetoxy-α-methylethyl) aniline, N- (β- (β'-methoxyethoxycarbonyl) ethylaniline, N, N-di (β-acetoxyethyl)- m-toluidine, N-ethyl-N- (β-cyanoethyl) aniline, N-ethyl-N- (δ-acetoxybutyl) aniline, N-ethyl-N-benzyl-m-toluidine, N, N- Diethyl-m-acetamidoaniline, 2-methoxy-5-acetylamino-N- (2-methoxyethoxycarbonylethyl) aniline, 2-methoxy-5-acetylamino-N, N-bis -(2-methoxycarbonylethyl) aniline, 2-methoxy-5-acetylamino-N-ethyl-N- (2-methoxyethoxycarbonylethyl) aniline, 2-methoxy-5-acetylamino -N, N-bis- (2-acetoxyethyl) aniline, and 2- Mention may be made of anilines such as oxy-5-acetylamino-N, N-bis- (2-acetoxyethyl) aniline.

A convenient index for the basicity of amines is the pka value published by JohnSon, entitled “Temperature Changes of Ho Acidity Function in Sulfuric Acid Aqueous Solutions” (JACS 91 1969, pages 6654-6652). The pka value of the base is defined as follows.

Wherein ^f B, ^f H ⁺ and ^f BH ⁺ are the activity coefficients of the base, hydrogen ion and conjugate acid, respectively.

Preferred benzenoidamines for preparing diazo components used in the present invention have pka values in the range of 1.5- to -10.5, in particular in the range of -3.5 to -7.0.

Particularly suitable amines from benzenes contain at least two nuclear substituents selected from nitro and cyano or at least one nuclear substituent selected from nitro and cyano and at least two other substituents selected from halogen and sulfone.

Examples of such amines belonging to benzenes include 2,4-dinitroaniline, 2-chloro-4,6-dinitroaniline, 2-bromo-4,6-dinitroaniline, 2-cyano-4, 6-dinitroaniline, 1-amino-2,4-dinitrobenzene-6-methylsulfone, 2,6-dicyano-4-nitroaniline, 2-cyano-4-nitroaniline, 2-chloro-4 -Nitro-6-cyano aniline, 2-bromo-4-nitro-6-cyanoaniline, 2-cyano-4-nitro-6-methylaniline, 2-bromo-6-chloro-4-nitro Aniline, and 2,6-dichloro-4-nitro aniline.

It is particularly preferred that the benzenoid amine contains at least two nuclear substituents selected from nitro and cyano and additionally one other substituent selected from nitro, halogen or sulfone groups.

Heterocycle amines may be derived from imidazole, thiazole, triazole, pyridine, pyrazole, benzthiazole, thiadiazole, thiophene, isothiazole, benzisothiazole or benztriazole.

Examples of heterocycle amines are 2-amino thiazole, 2-amino-5-nitrothiazole, 2-amino-5-methylsulfonylthiazole, 2-amino-5-cyanothiazole, 2-amino-4 -Methyl-5-nitrothiazole, 2-amino-4-methylthiazole, 2-amino-4-phenylthiazole, 2-amino-4- (4'-chlorophenyl) thiazole, 2-amino-4 -(4'-nitrophenyl) thiazole, 3-aminopyridine, 3-aminoquinoline, 3-aminopyrazole, 5-imino-1-phenylpyrazole, 3-aminoindazole, 3-amino-2- Methyl-5,7-dinitroidazole, 3-amino-1,2,4-triazole, 5- (methyl-, ethyl-, phenyl-, or benzyl) -1,2,4-triazole, 3 -Amino-1- (4'-methoxyphenyl) pyrazole, 2-aminobenzthiazole, 2-amino-6-methylbenzthiazole, 2-amino-6-methoxybenzthiazole, 2-amino- 6-cyanobenzthiazole, 2-amino-6-nitrobenzthiazole, 2-amino-6-carboethoxybenzthiazole, 2-amino-6-thiocyanatobenzthiazole, 2-amino -6-methylsulfonyl Zthiazole, 2-amino-1,3,4-thiadiazole, 2-amino-1,3,5-thiadiazole, 2-amino-4-phenyl or 4-methyl-1,3,5- Thiadiazole, 2-amino-5-phenyl-1,3,4-thiadiazole, 2-amino-3-nitro-5-methylsulfonylthiophene 2-amino-3,5-dinitrothiophene, 2 -Amino-3-alkoxycarbonyl-5-nitrothiophene (alkoxy = C ₁ -C ₅ ), 2-amino-3-cyano-5-nitrothiophene, 5-amino-3-methyl-4 -Nitroisothiazole, 3-amino-5-nitro-2,1-benzisothiazole, 3-amino-7-bromo-5-nitro-2,1-benzisothiazole, 3-amino-7 -Bromo-5-nitro-2,1-benzoisothiazole, 5-amino-4-nitro-1-methylimidazole, 4-amino-5-bromo-7-nitrobenzisothiazole and 4 -Amino-7-nitrobenztriazole.

Preferred heterocycle amines are benzthiazole, triazole and thiophenes, especially 2-amino-6-methoxybenzthiazole, 2-amino-6-thiocyanatobenzthiazole, 3-amino-1,2, 4-triazole and 2-amino-3,5-dinitrothiophene and the like.

The physical form of the azo compound is that the second stream is introduced into the reaction zone simultaneously with either the first and second streams or with both or the other two streams, although the second stream is preferably introduced with the coupling component. It can be modified by carrying out a coupling reaction in the presence of a surfactant introduced into the third stream.

Surfactants can be cationic, anionic or nonionic, depending on the nature of the azo compound and the desired crystal form of the azo compound. In addition, the presence of the surfactant helps to prevent contamination of the surface of the product by tar or the like or to prevent azo compounds from accumulating on the walls of the reactor including the reaction zone.

In the case of the anionic form, the ratio of the surfactant to the azo compound present during the coupling reaction varies widely, for example from 0.01: 1-0.5: 1. However, the fraction used is preferably a small portion of the above-mentioned range, i.e. 0.02: 1-0.15: 1, with the additional interface required to maintain the fluidity of the slurry during and after the concentration process or to prevent re-condensation after grinding. The activator is added to the slurry after leaving the reaction zone.

Since cationic surfactants are not normally compatible with the anionic dispersants used in the preparation of the disperse dyes, smaller proportions of such surfactants, i.e. 0.01: 1-0.05: 1, are preferably used.

Cationic surfactants are particularly useful for protecting the walls of the reaction zone from accumulation of newly formed azo compounds because of their detergency.

More or less than the above ratio may be used, but generally does not provide the same amount of technical effect, satisfactory economic advantages do not provide.

Suitable surfactants are those described in British Patent Specification No. 1,425,337 as dispersants or wetting agents. In addition to these, modified starch, methyl and hydroxy propyl methyl cellulose as described in “Water-Soluble Resins” by water-soluble polymers such as Davidson and Sittig (Reinhold) as nonionic surfactants. Derivatives, hydroxyethyl cellulose, carboxymethyl cellulose polyvinyl alcohol, polyvinylpyrrolidone, poly (acrylic acid) and analogs thereof, polyacrylamide, ethylene oxide polymer (polyox water soluble resin), polyethyleneimine, hydrolyzed styrene Poloxamine and its sulfated derivatives of the following general formula sold under the trademark of maleic anhydride copolymer and “Tetronic”, and

Wherein (Y is-(C ₃ H ₆ O) _6- (C ₂ H ₄ O) ₆ -H) Anionic surfactant wherein at least one of the alkyl chains has 12-15 carbon atoms Mention may be made of quaternary alkylammonium halides.

Preferred anionic surfactants are alkyl sulfonates, lignin sulfonates and naphthalenes and / or condensation products of benzene sulfonic acid with formaldehyde. Preferred nonionic surfactants are alkylphenols, especially nonylphenols and long chain alkanols having 12-25 carbon atoms, especially ethylene oxide condensates of alkylphenols, alkanol condensates containing 5-50 ethylene oxide units and polyglycerides of long chain fatty acids. Aryl esters such as polyglyceryl ricinoleate. Preferred cationic surfactants are quaternary alkylammonium halides and long chain alkyl pyridinium halides comprising at least one long chain alkyl group having 12-25 carbon atoms.

If the end use of the azo compound requires a more pulverized state than can be obtained during the coupling reaction, the process of the present invention is carried out in a bead or ball mill to reduce the particles to the desired size. Can be crushed. However, it has been found that when the azo compound is prepared by a known batch coupling process, less grinding is required in order to achieve a dispersion which is generally satisfactory for the end use.

Formation of azo compounds in the moving stream, especially in the presence of surfactants, has been shown to increase the production of stable small particles. This means that the heat treatment and separation techniques that are commonly required for azo compounds in the form present when formed in a batch coupling process can be avoided.

The use of an ultrasonic vibrator in contact with the walls of the reaction zone or the reaction medium helps to reduce the tendency for newly formed products to accumulate in the walls and to promote the formation of azo compounds in the pulverized state.

Another advantage of the continuous coupling reaction is the high yield and high purity of the product which can be achieved by quickly and well mixing the reactants in a relatively limited space. Because of the rapid mixing of the reactants and the short residence time in the reaction and reaction zones, there is no need to cool the reaction zones, thus avoiding the use of ice or other cooling devices as is typically required in batch processes.

When the coupling reaction is felt under acidic conditions, it is desirable to raise the pH in the reaction zone to optimize the selectivity and / or reaction rate of the reaction. The pH can be raised to any desired value by adding the appropriate basic material to the reaction zone simultaneously with or after the first and second stream so that the reaction between the diazo component and the coupling component is achieved in the medium at the optimum pH. . The basic substance is an alkaline buffer.

Although the diazo component is generally unstable in a dilute acidic medium, it is preferable that the diazo component and the coupling component are well mixed together before raising the pH because the grinding is further promoted under alkaline conditions.

Although it is not necessary to raise the pH in the reaction zone to promote coupling, it is appropriate to further treat the slurry of azo compound in neutral medium, for example to concentrate, separate or grind. Therefore, after the reaction is completed, it is preferable to raise the pH of the slurry to within the range of pH 5-9, in particular pH 6-8 by addition of a basic substance.

The addition of basic material in the product stream is preferably controlled by a pH meter, which adjusts the rate of addition of the basic material to monitor the pH of the medium after neutralization and to maintain the pH at or near the desired value.

Especially in the case of continuous couplings under turbulent conditions, it is advisable to avoid high temperatures in the reaction zone, although temperature control is not very important. If the temperature rises too high depending on the nature of the diazo component, the rate of decomposition may exceed the rate of mixing and coupling. Therefore, it is advisable to precool the reactant stream before mixing them, especially when the diazo components are less stable. This cools the reaction zone because the coupling reaction occurs so quickly that the heat of reaction cannot be removed quickly enough to prevent excessive rise in temperature. In general, the temperature in the reaction zone preferably does not exceed 55 ° C., in particular 40 ° C., and the degree of preliminary cooling can be adjusted in consideration of the heat of reaction, the flow rate of the stream and the heat capacity of the system.

The concentration of reactants and product stream is generally limited by the physical properties of the product stream. At product concentrations above 10% the product stream is rather thick and tends to inhibit sufficient mixing in the reaction zone. Since this may promote harmful side reactions such as diazo decomposition, the concentration of the reactant stream is preferably adjusted to provide a product stream that is sufficiently rugged to minimize the harmful side reactions. The introduction of dispersants into the reaction zone often increases the fluidity of the product strip and in some cases can raise the concentration of the product by 20% depending on the nature of the product and the dispersant used. Since it is commercially and technically preferable to prepare a concentrated slurry containing at least 50% of the azo compound, the coupling reaction is preferably carried out after the concentration process.

Preferred concentration processes are those which do not adversely affect the physical form of the azo compound under the desired conditions and a suitable process for this purpose is membrane separation treatment. Although conventional separation and cleaning techniques using, for example, filter presses can be used, they are generally less economically advantageous than concentration techniques that can operate continuously, such as membrane separation.

"Membrane Separation" means ultrafiltration, electrodialysis, reverse osmosis, or a combination thereof. Ultrafiltration is due to the size of the pores, allowing the dispersion to pass through a semipermeable membrane that allows the passage of only those molecules expressed as the molecular weight of the largest molecule that can permeate the membrane at the so-called “cut off” level or below. It refers to a process that can separate low molecular weight substances from insoluble high molecular weight substances. Of course, the smaller the molecules, the easier and faster they pass through the membrane. If an attempt is made to remove inorganic materials such as salts and water from dispersions containing complexes or polymeric organic materials such as surfactants, some compromise must be made between the rapid removal rate of the inorganic materials and the prevention of any loss of organic materials.

Although a film having a blocking level within 1,000-50,000 is suitable, it is preferable to use a blocking level in the range of 1,000-120,000 depending on the molecular weight of the organic material.

It has been found that satisfactory separation can be achieved by using a membrane having a blocking level in the range of 50,000-20,000 when the molecular weight of the organic material is in the range of 500-2,500, especially when the organic material is a nonionic surfactant. Even low molecular weight anionic and cationic surfactants, membranes with blocking levels in the range of 5,000-50,000 can be used to achieve satisfactory separation.

This can lead to loose aggregations containing several or many molecules with significantly larger molecular weight than a single dispersion, since surfactant materials, especially nonionic surfactants, often form micelle structures. Iii) to some extent due to the chemical nature of the organic molecules, the relative shape of the organic molecules, the pores of the membrane and the mutual attraction of the organic material and the membrane. These factors can make the membrane less permeable to organic materials than indicated by the membrane's nominal molecular blocking level.

The choice of membrane is determined by the ratio of the rate of permeation of the membrane by the substance to be removed from the dispersion to the rate of permeation of the membrane by the substance to be retained in the dispersion, preferably at least 5-1.

For economic reasons, it is desirable to select the membrane so that the concentration of surfactant in the permeate is less than 50% in the concentrated dispersion.

Reverse osmosis refers to a membrane separation process in which the membrane has holes small enough to restrict the passage of low molecular weight materials. In conclusion, osmotic pressure occurs in a membrane that can withstand the pressure used before permeation proceeds, which in other respects is similar to ultrafiltration.

Electrodialysis refers to the passage of ionic material through a selective membrane under the influence of the electric field supplied to the membrane. However, this treatment cannot remove a significant amount of water from the dispersion, so in addition to the removal of inorganic ions, it is also necessary to use ultrafiltration if the dispersion is to be concentrated. If only ultrafiltration is used, it is often necessary to add water to the slurry to prevent the total solids in the concentrate from rising too high before removing all minerals. Electrodialysis can assist in the concentration process for the removal of inorganic ions.

If the inorganic content of the dispersion is particularly high or the end use of the azo compound requires a particularly low level inorganic material, it is necessary to add water during the membrane separation treatment to maintain proper fluidity. Some parts of soluble organics, usually surfactants used in the coupling step, tend to be lost during ultrafiltration, which is dependent on the nature of the surfactant and dispersion and the addition of extra surfactant before, during and after ultrafiltration. Can be supplemented by

The present invention will be described based on the examples as follows, where the percentages are by weight unless otherwise indicated.

Example 1

In this example, the diazotized 2-bromo-4,6-dinitroaniline is coupled with 2-methoxy-5-acetylamino-N- (2-methoxyethoxycarbonylethyl) aniline to azo dye. To prepare. The diazo component is soluble in concentrated sulfuric acid and is prepared by mixing with an amine solution in 95% sulfuric acid and a solution of nitrosyl equivalent in 100% sulfuric acid. The diazo solution obtained is stable at 20 ° C. and contains 0.8665 gram moles of diazonium salt per kilogram of solution. The coupling component is soluble in acetic acid / water and a solution containing 0.120 gram moles of coupling component per liter of 3.7% acetic acid / mole is prepared.

When the diazonium salt solution is uniformly injected at a rate of 166 g per minute into a branch pipe of a pipe in which all branch pipes are joined in the form of a T-section having a 2 mm inner diameter, and water is injected into the other pipe at a speed of 1100 ml per minute, The solutions are joined at 90 °. The mixed solution passes 10 cm along the outlet tube toward the second T-junction. The inner diameter of both inlet pipes of this joint is 2 mm and the outlet pipe that is 90 ° to the inlet is 25 cm in length and 3 mm in diameter. The solution of the coupling component is injected into the other inlet branch of the second T-part at a uniform rate of 1200 ml per minute and joined with the diazo solution at 180 °. Couplings occur so rapidly that unreacted diazonium salts cannot be detected in the solution exiting the outlet tube. The flow is controlled such that the reactants are molar equilibrium or the coupling component is slightly excess (<5%). The dye slurry exiting the tubular reactor is led to a stirred tank where it is continuously neutralized to pH 4.5 using an aqueous solution of sodium hydroxide. The dye slurry from the neutralization reactor contains 2.8% of pigment and about 5.1% of inorganic salts. The dye slurry may be treated by conventional methods, ie by filtration and washing to liberate the salt, or alternatively by concentration and washing by ultrafiltration.

Example 2

In this example, the diazotized 2-bromo-4,6-dinitroaniline is coupled with 2-methoxy-5-acetylamino-N- (2-methoxyethoxycarbonylethyl) aniline to azo dyes. To prepare. The diazo component is soluble in concentrated sulfuric acid and is prepared by mixing a solution of amine in 95% sulfuric acid with a solution of nitrosyl sulfuric acid in 100% sulfuric acid. The resulting diazo solution is stable at 20 ° C. and contains 0.8665 gram moles of diazonium heat per kilo of solution. The coupling component is soluble in acetic acid / water, producing a solution containing 0.120 gram moles of coupling component per liter of 3.7% acetic acid / water.

The diazonium salt and coupling component solution was fed at a rate of 166 grams per minute and 2310 ml per minute in a reactor equipped with a Silverson immersion agitator (Silverson is a registered trademark) by a pipe ending directly below the rotor of the mixer. Inject evenly. The average residence time in the reactor is 6 seconds. The rotor is 3 cm in diameter and rotates at 8,000 r.p.m. The dye slurry is allowed to overflow into the reactor and into a second stirred reactor hole where it is continuously neutralized with aqueous sodium hydroxide solution. The neutralized dye slurry contains 2.8% of pigment and about 5.1% of inorganic salts. The dye slurry may be treated in a conventional manner, i.e., by filtration and washing to remove salts, or alternatively, the slurry may be concentrated and washed by ultrafiltration.

Example 3

In this example, 2,4-dinitroaniline diazotized at pH 3.5 with 20% sodium acetate solution was used to control the neutralization of 5-acetylamino-2-methoxy-N, N-bis (2-meth). Azo dyes are prepared by coupling with oxycarbonylethyl) aniline. The diazo component is soluble in concentrated sulfuric acid and is prepared by mixing a solution of amine in 95% sulfuric acid with a solution of nitrosyl sulfuric acid in 100% sulfuric acid. The resulting diazo solution is stable at 20 ° C. and contains 0.942 gram moles of diazonium salt per kilo of solution. The coupling component is soluble in sulfuric acid / water, producing a solution containing 0.104 gram moles of coupling component per liter of 1.0% sulfuric acid / water.

Diazonium salts, coupling components, and sodium acetate solutions may be prepared by high speed shear immersion stirrers (Ultra-Turrax mixers) by pipes terminated immediately below the rotor of the mixer; Ultra Turax® is a uniformly injected reactor at 6.05 g / min, 48.96 g / min and 47.17 g / min, respectively. The average residence time in the reactor is 13 seconds. The rotor is 1.2 cm in diameter and rotates at 10,000 r.p.m. The neutralized dye slurry contains 2.7% of pigment and about 5% of inorganic salts.

The dye slurry may be subjected to conventional methods, i.e., washing to liberate filtration and salts, or alternatively to concentration and washing of the slurry by ultrafiltration.

Example 4

As shown in the accompanying drawings, a tubular reactor was used. In the figure, the L-shaped outer pipe 11 having a 4 mm inner diameter has an inlet 13 and an outlet 15. The inner pipe 17 having an inner diameter of 1 mm is sealed to the inner surface of the outer pipe 11 at the joint 19 below the curved portion 21 to form an annular space 23 between the main pipes 11, 17. do. The side arms 25 in the outer pipe 11 extend from the junction 19 to the annular space 23.

The inner and outer pipes extend 50 mm and 250 mm downward from the junction 19, respectively.

The feedstock solution is the same as used in Example 2. The diazonium salt solution is fed from the inlet 13 of the outer pipe 11 to the inner pipe 17 at a constant rate of 166 g per minute, and the coupling component solution is annular from the side arm 25 at a constant rate of 2310 ml per minute. Supply to (23). From their initial contact point, the reactants flow up to a distance of 200 mm below the outer pipe and into a 10 mm diameter and 1 m long tube leading to the stirred tank reactor, where the dye slurry obtained is neutralized with aqueous sodium hydroxide solution. The neutralized slurry contains 2.8% dye and about 5.1% inorganic salt.

Example 5

In this example, 2,4-dinitroaniline diazotized at pH 3.5 using 20% W / W sodium acetate solution to neutralize 5-acetylamino-2-methoxy-N, N-bis (2 Azo dye is prepared by coupling with -methoxy-carbonylethyl) aniline.

The diazo component is soluble in concentrated sulfuric acid and is prepared by mixing an amine solution in 95% sulfuric acid with a nitrosyl sulfuric acid solution in 100% sulfuric acid. The resulting diazo solution is stable at 20 ° C. and contains 0.94 gram moles of diazonium salt per kilo of solution. The coupling component is soluble in molar sulfuric acid and a solution containing 0.104 gram molar coupling component per liter of 1.0% sulfuric acid / water is prepared.

The diazonium salt, coupling component and sodium acetate solution are each 6.05g per minute, 48.96g per minute, in a reactor equipped with a silver hand immersion stirrer (Silverson is an iso trademark) by each pipe terminating just below the rotor of the mixer. And uniformly at a rate of 47.17 g per minute. The average residence time in the reactor is 13 seconds. The rotor is 1.2 cm in diameter and rotates at 10,000 r.p.m. The neutralized dye slurry contains 2.7% of pigment and about 5% of inorganic salts. The dye slurry may be treated by conventional methods, i.e., by filtration and washing to remove salts, or alternatively, the slurry may be concentrated and washed by ultrafiltration.

Example 6

In this example, diazotized 2-bromo-6-chloro-4-nitroaniline is converted to N, N-bis (2-meth) at pH 2.9-3.2 using 30% W / W sodium acetate solution to neutralize. Azo dyes are prepared by coupling with oxycarbonylethyl) aniline. The diazo component is soluble in concentrated sulfuric acid and is prepared by mixing an amine solution in 96% sulfuric acid with a nitrosyl sulfuric acid solution in 100% sulfuric acid. The resulting diazo solution is stable at 20 ° C. and contains 0.892 grams of diazonium salt per kilo of solution. The coupling component is soluble in sulfuric acid / water, producing a solution containing 0.333 gram moles of coupling component per liter of 5% sulfuric acid / water.

The diazonium salt, coupling component and sodium acetate solution are uniformly fed to the tubular recycle loop reactor at a rate of 12.23 g per minute, 32.10 g per minute, and 109.60 g per minute, respectively, by means of each pipe entering the turbulent mixing zone in the reactor. . The recycle flow is about 4 liters per minute and is maintained by a Stuart-Turner centrifugal pump (Stuart-Tuner is a registered trademark).

The dye slurry overflows from the reactor through the lute and contains 3.4% of pigment and about 5% of inorganic salts. Separation of the dye may be by conventional methods, ie by filtration and washing to remove salts, or alternatively the slurry may be concentrated and washed by ultrafiltration.

Claims (1)

Reaction for preparing a first stream containing a diazonium compound obtained from the diazotization of a heterocycle or a weakly basic benzenoid amine in an acidic medium, as detailed above and shown in the figures, for preparing a water-insoluble azo compound. A process for preparing an aqueous slurry of a water insoluble azo compound consisting of continuously removing a slurry produced by continuously mixing together a second stream containing a compound capable of coupling with a diazo component under conditions existing in a zone. .

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