GB1567691A - Process forthe preparation of chromium complex dyestuffs and cobalt complex dyestuffs - Google Patents

Abstract

Chromium or cobalt complex dyes are obtained in a rapid reaction, without the need for an excess of metallizing reagent and, if desired, directly in the form of a ready-to-use solution or a liquid concentrate, if a metallizable dye is reacted with an anhydrous chromium or cobalt compound in ethers containing hydroxyl groups. By heating hydrated chromium or cobalt salts in this ether, an anhydrous metallizing reagent is obtained, which is very effective and is a solvato-complex of the salt employed; the metallization can thereafter be carried out advantageously with this reagent.

Description

(54) PROCESS FOR THE PREPARATION OF CHROMIUM COMPLEX DYESTUFFS AND COBALT COMPLEX DYESTUFFS (71) We, PAYER AKTIENGESELL SCH~FT, a body corporate organised under the laws of Germany, of Leverkusen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The subject of the invention is a process for the preparation of chromium complex dyesnuffs and cobalt complex dyestuffs and of solutions of these dyestuffs in organic, watermiscible solvents. The dyestuffs and dyestuff solutions obtained according to the invention are substantially free from salts, for example chromium salts, cobalt salts or alkali metal salts.

The process according to the invention consists in dehydrating chromium salts or cobalt salts which contain water, such as CrCl, . 6H2.O or CoCI2 . 6H2O by heating in aliphatic ethers which contain hydroxyl groups, then reacting the dehydrated salts with metallisable, preferably azo or azo tnethine dyestuffs, and subsequently separating off, by filtration, any excess of the metallising agent which may be present and any electrolytes which may be present and optionally removing the solvent. The dyestuff solutions obtained in this way are substantially salt-free and can be used direct for the preparation of printing pastes and dye baths.

The dyestuff concentration of the solutions obtainable in this way is generally about lG40cZ by weight.

Ethers containing hydroxyl groups which can be used are, preferably, those of the formula RSO--Alkylene-OH ( I ) in which R=an aliphatic hydrocarbon radical with 1 to 6 carbon atoms, n=1 to 5 and Alkylene=an alkylene radical, especially C2-C,-alkylene, such as -CH2-CH2- and -CH,CH2CH2-.

Examples which may be mentioned are: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, triethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and triethylene glycol monomethyl ether.

Metallisable dyestuffs which are preferably used are monoazo, disazo or polyazo dyestuffs or azomethine dyestuffs, which, prior to metal lisation, contain, as groups which form metal complexes, o,o' - dihydroxy- o-hydroxy- o'- amino-, o- hydroxy - o' - alkoxy, o- hydro - o' - carboxy or 0 - all:oxy - 0'- amino-azo or azomethine groups.The dyestuffs can be free from acid groups or can carry one or more acid groups, preferably sulphonic acid groups or carboxylic acid groups; they can also contain sulphonamido or sulphone groups and be substituted by further non-ionic substituents customary in azo and azomethine dyestuffs, for example by fluorine, chlorine, nitro, cyano, alkyl, alkoxy, aryl and acylamino groups.Corresponding metal complexes have frequently been described in the patent literature, for example in German Patent Specifications and Offenlegungsschriften german Published Specifications) 870,305, 937,367, 940,483, 945,432, 953,827, 957,506, 960,485, 1,005,644, 1,047,340, 1,049,021, 1,072,338, 1,077,351, 1,191,058, 1,270,204, 1,254,785, 1,270,204, 1,444,635, 1,444,655, 1,444,658, 1,544,361, 2,119,830, 1,008,254, 1,012,007, 1,023,539, 1,079,247, 1,111,318, 1,133,846, 1,156.913, 1,265,324, 1,271,857, 1,444,605, 1,544,580, 1,619,649, 1,644,143, 1,902,867, 1,952,305 and 2,210,260, French Patent Specifications 1,353,364, 1,380,632, 950,916, 1,161,640, 1,269,496, 1,269,497, 1,272,728, 1,272,729, 1,273,542, 1,352,623, 1,376,128 and 1,518,833, and British Patent Specifications 553,658, 564,094, 553,480, 569,094 and 717,450.

In order to remove the water, the salts are preferably heated to temperatures of 100"C to 21O0C.

Metallisation is preferably carried out at temperatures of from about 70"C to 1400C.

When CiCla. 6H2O is dehydrated by azeotropic distillation in compounds of formula (I), compounds of the formula [CrC13 (HOAlkylene-O*R),] ('I) or mixtures of (II) with compounds of the formula [CrCl2 O+AlkyleneO+R] [HO- ( -Alkylene-O-),-R] J (III) wherein n and R and Alkylene have the meaning already mentioned above, are obtained, depending on the reaction conditions.

These reaction products, which, after all of the solvent has been distilled off, are in the form of oils, are extremely reactive chroming reagents which rapidly convert metallisable dyestuffs -- if appropriate with the exclusion of water and acid acceptors -- into the corresponding chromium 1:1 complex compounds.

Analogously, CoCI2. 6H2O can also be converted, by heating in ethers of the formula (I) and removing the water of crystallisation by distillation, into reactive Co compounds which rapidly react with metallisable dyestuffs to give the corresponding Co complexes.

The process according to the invention displays the following advantages: 1. the metallisation proceeds rapidly, 2. an excess of the metallising reagent is not required and 3. due to the high solubility of the starting components and of the metal complexes, the metallisation reaction can be carried out in small volumes.

It is also possible, in the solvents according to the invention, to convert dyestuffs which contain sulphonic acid groups which are usually in the form of their sodium salts and are capable of forming a metal complex into solutions of their metal complexes in high concentration.

In detail, chroming is, for example, so carried out that, after the CrCl,. 6H2O has been dehydrated in an ether of the formula (I), the equivalent amount of a metallisable dyestuff is added.

Heating under normal pressure gives a solution of the chromium 1:1 complex, which can now be converted into the symmetrical or unsymmetrical chromium 1:2 complex dye stuff by treatment with a basic agent and the equivalent amount of the same dyestuff or of a different dyestuff. Symmetrical chromium 1:2 complexes are also obtained when two equivalents of the dyestuff are allowed to act direct on the chroming reagent and, after the formation of the chromium 1:1 complex has ended, the product is warmed with a basic agent. The latter can also be added to the chroming agent at the same time as the two equivalents of the dyestuff.

Whilst the chromium 1:1 complex is formed mnst easily at temperatures which exceed 1000C - preferably under normal pressure at the boiling point of the ether of the formula (I) which is used - a low tem perature - preferably a temperature in the range from 4e-1200C - is adequate for the addition reaction of a second molecule of dyestuff with the chromium 1:1 complex dyestuff.

The dyestuffs to be metallised can be subjected to the chroming reaction not only in the dry state but also in the form of their moist pastes. For this purpose, the moist paste is dissolved in an ether of the formula (I), according to the invention, and the water present in the solution is removed by distillation. The amount of the ether-alcohol which distils over with the water as an azeotrope can be greatly reduced by adding a suitable third component. CrCl3. 6H2O can be dehydrated, in the manner already described, in the anhydrous solution of the dyestuff which is now obtained and, at the same time, chroming to give the 1:1 chromium complex dyestuff or, when an acid acceptor is present, chroming to give the 1:2 chromium complex dyestuff takes place.The anhydrous solution of the chromium 1:1 complex dyestuff in an ether of the formula (I) generally reacts readily not only with a dry dyestuff but also with a moist paste thereof to give the chromium 1:2 complex dyestuff.

Additions of water have a particularly advantageous effect on the solubility of dyestuffs which contain sulphonic acid groups. Because of the high concentration which is possible, the electrolytes precipitate virtually completely from the solution of the 1:2 chromium complex dyestuff, even in the presence of the water entrained in the paste.

Any excess of the chroming reagent which may be present is precipitated quantitatively, even in the presence of water, as chromium hydroxide, basic chromium carbonate or an alkaline earth metal chromate, depending on the choice of the basic agent.

Examples of agents having a basic action which can be used are alkali metal carbonate, bicarbonate or hydroxide or an alkaline earth ntetal carbonate, bicarbonate or hydroxide. In addition to the Na salts, the Li salts are, in particular, also used. It is also possible to use an alkali metal acetate, ammonia or amines as the basic agent but this is less advantageous since excess Cr compounds can partially remain in solution. However, the use of allranolamines is very advantageous.

In place of CrCl8 . 6H2O, it is also possible to use chromium hydroxide and hydrochloric add as the starting materials for the preparation of the chroming reagents. The use of other Crw compounds is also possible.

The Co complexes are prepared in the same way.

The insoluble inorganic salts can! be separated off by the customary methods of filtration, suction filtration or centrifuging.

The solutions, which, if necessary, are then also passed through an open clarifying filter, are virtually free from ionic chromium compounds and, depending on the water content, are salt-free or virtually free from salts. The clarified solutions can now be used as such for the preparation of dye baths or printing pasteL In this case, their storage stability can be considerably increased by adjusting the pH, with lithium salts which have an alkaline reaction, such as lithium hydroxide or lithium carbonate, or with alkanolamines, such as ethanolamine or 1,3-propanolamine, to the value which is advantageous for the metallisation reaction. The solutions which have been freed from solids can, however, also be worked up to dyestuff powders by one of the processes customary industrially, by separating off the solvents.It has proved to be economically advantageous to dry the solution in a paddle drier since, in this case, the ether employed is recovered. It is particularly advantageous in practice to mix the additives, which are necessary for application, into the solutions and only then to separate off the solvent. In this way, all mixing opera temps with solid substances are dispensed with.

Additives which can be used are dust suppressants, dispersing agents and other surfaceactive agents.

The dyestuff solutions or dyestuff powders according to the invention are suitable for the preparation of dye baths or printing pastes for dyeing and printing fibre materials which contain nitrogen, such as wool, silk and leather, and also synthetic polyamide or polyurethane fibres, as well as mixed fibres, tor example a mixture of wool and polyamide, by the customary processes.

The temperatures quoted in the examples which follow are in degrees centigrade, and the relationship between parts by weight and parts by volume is as grams to cc's.

Example 1.

26.6 parts by weight of CrCl, . 6H2O are introduced into 210 parts by volume of ethylene glycol monomethyl ether and azeotropically dehydrated by distillation through a 50 cm silver-coated column. When about 70 parts by volume of distillate have passed over, the mixture is cooled to 10(v110 , 42.4 parts by weight of the monoazo dyestuff of the formula

are introduced and the resulting mixture is stirred under reflux for 90 minutes. It is then diluted with 350 parts by volume of ethylene glycol monomethyl ether, 17.5 parts by weight of sodium bicarbonate are introduced and the mixture is stirred for 60 minutes at 800.

The dyestuff solution is then clarified by filtration to rernove inorganic salts and evaporated to dryness in a rotary evaporator.

The resulting dyestuff is a dark brown powder which is substantially free from chromium which is not bonded as a complex.

The dyestuff is soluble in water and dyes wool, from a bath containing sulphuric acid, in pink colour shades with good fastness properties.

Example 2.

37.3 parts by weight of the monoazo dyestuff of the formula

in 250 parts by volume of ethylene glycol monomethyl ether which contains 5.2 parts by weight of chromium in a compound formed from Cr(:ls . 6H O by azeotropic dehydration with ethylene glycol monomethyl ether are stirred under reflux for 120 minutes.

The mixture is then cooled to 70 , 34.5 parts by weight of sodium bicarbonate are introduced in the course of 5-10 minutes and 37.3 parts by weight of the monoazo dyestuff of the formula

are then introduced and the resulting mixture is stirred under reflux for 1 hour. It is then cooled to 80 , clarified by filtration and evaporated in a rotary evaporator.

The resulting dyestuff powder is substantially free from inorganic salts and free chromium (chromium which is not bonded in the complex dyestuff).

The dyestuff is readily soluble in water and dyes wool in orange shades with good fastness properties.

The dyestuff solution obtained after clarifying by filtration can also be used, in place of the dyestuff powder, for dyeing wool. The solution is also suitable for spray-dyeing on leather.

If, after the reaction has ended, 1 equivalent of 3-aminopropyl 2-ethylhexyl ether is added and the mixture is rendered neutral to slightly acid with hydrochloric acid and then filtered and evaporated, an orangecoloured lacquer dyestuff with good dyeing properties is obtained.

Example 3.

33.9 parts by weight of the monoazo dyestuff of the formula

are stirred in 200 parts by volume of ethylene glycol monomethyl ether which contains 5.2 g of chromium in a compound formed from CrCla . 6H2O by azeotropic dehydration with ethylene glycol monomethyl ether and the mixture is warmed under reflux for 3 hours.

The solution of the 1:1 chromium complex dyestuff is allowed to cool to 100--1050, 22 parts by weight of sodium bicarbonate are introduced in the course of 5-10 minutes, 41.9 parts by weight of the monoazo dyestuff of the formula

are then introduced and the mixture is stirred for 1 hour at 100--1050. It is allowed to cool to 80--90", clarified through 5 parts by weight of ';Celite" (a Trade Mark) and evaporated to dryness in a rotary evaporator.

The dyestuff is a dark red powder which is readily soluble in water, substantially free from chromium which is not bonded as a complex and dyes wool in red shades with good fastness properties.

Example 4.

26.6 parts by weight of CrCl, . 6H2O are introduced into 210 parts by volume of ethylene glycol monomethyl ether and dehydrated by distillation through a 50 cm silver-coated column. When about 70 parts by volume of distillate have passed over, the mixture is cooled to 100'-110' and 37.3 parts by weight of the monoazo dyestuff of the formula

are introduced and the mixture is stirred under reflux for 26--3 hours until the 1:1 chroming has ended.

The solution of the 1:1 Cr complex dyestuff is then allowed to cool to 7585 , 22.5 parts by weight of sodium bicarbonate are introduced in the course of 5-10 minutes, 32.2 parts by weight of the monoazo dyestuff of the formula

and 70 parts by volume of ethylene glycol monomethyl ether are then introduced and the mixture is stirred for 45-60 minutes under reflux. The formation of the mixed chromium complex has then ended and the mixture is cooled to 90 , clarified through a little "Celite" and rinsed with 27 parts by volume of ethylene glycol monomethyl ether.

The total filtrate is evaporated to dryness in a rotary evaporator.

A brown dyestuff powder which is substantially free from inorganic salts and contains virtually no free chromium (chromium which is not bonded in the complex dyestuff) is obtained.

The dyestuff dissolves readily in water and dyes wool in yellowish-tinged orange shades with good fastness properties.

Example 5.

37.3 parts by weight of the monoazo dyestuff of the formula

are introduced into 175 parts by volume of ethylene glycol monomethyl ether which contains 5.2 parts by weight of chromium in a compound formed from CrC1,.6H2O by azeotrople dehydration In ethylene glycol monomethyl ether. The mixture is stirred for 2* hours under reflux and cooled to 800 and 30 parts by weight of Na2CO3 and 34.3 parts by weight of the monoazo dyestuff of the formula

are introduced and the resulting mixture is stirred for 1 hour at 105 until the formation of the mixed chromium complex has ended.

The mixture is then cooled to 80 , the dyestuff solution is clarified by filtration to remove inorganic salts and evaporated to dryness in a rotary evaporator.

A dark brown powder which is substantially free from inorganic salts and contains virtually no free chromium (chromium which is not bonded in the complex dyestuff) is obtained.

The dyestuff dissolves readily in water and dyes wool in reddish-tinged brown shades with good fasmess properties.

The dyestuff solution clarified by filtration does not need to be concentrated to dryness; it can also be used direct, without separating off the solvent, for the preparation of dye baths for wool and polyamide or for spraydyeings on leather.

Example 6.

43.6 parts by weight of the monoazo dyestuff of the formula

are introduced into 350 parts by volume of ethylene glycol monoethyl ether which contains 5.2 parts by weight of chromium in a compound formed from CrCl3 . 6H2O by azeotropic dehydration in ethylene glycol monoethyl ether and the mixture is stirred under reflux at 135138 for 120 minutes.

The solution of the 1:1 Cr complex dyestuff is then allowed to cool to 80--900, 25 parts by weight of sodium bicarbonate are introduced in the course of about 5 minutes, 40.4 parts by weight of the monoazo dyestuff of the formula

are then introduced and the resulting mixture is stirred for 60 minutes at 100 .

After clarifying by filtration, the green dyestuff solution is evaporated in a rotary evaporator.

A black powder which dissolves readily in water and dyes wool in clear green shades with good fastness properties is obtained. The dyestuff is substantially salt-free and contains virtually no free chromium (chromium which is not bonded in the complex dyestuff).

Example 7.

42.2 parts by weight of the monoazo dyestuff of the formula

in 325 parts by volume of ethylene glycol monomethyl ether which contains 5.2 parts by weight of chromium in a compound formed from CrCl, . 6H2O by azeotropic dehydration in ethylene glycol monomethyl ether are stirred under reflux for 60 minutes. The mixture is then allowed to cool to 800 and 22 parts by weight of sodium bicarbonate and then 29 parts by weight of 8-hydroxyquinoline are introduced. In order to effect the reaction, the mixture is stirred for 120 minutes at 100--1050. The dyestuff solution is then clarified by filtration at 800 and evaporated to dryness in a rotary evaporator.

The black dyestuff powder, which is low in salts, dissolves readily in water and dyes wool from a weakly acid bath in bluishtinged green shades.

Apart from the chromium bonded in the dyestuff complex, the dyestuff contains no further chromium compounds.

Example 8.

34.3 parts by weight of the monoazo dyestuff of the formula

are converted, analogously to Example 2, into the 1:1 chromium complex and the reaction mixture is cooled to 80". 38.9 parts by weight of the monoazo dyestuff of the formula

in the form of a moist paste and 14.5 parts by weight of anhydrous sodium carbonate are then introduced and the mixture is stirred for 60 minutes at 100-1050 C. After cooling to 80 , the mixture is clarified by filtration through 8.5 parts by weight of "Celite" and the dyestuff solution is evaporated to dryness in a rotary evaporator.

The mixed chromium complex dyestuff is a black powder which dissolves readily in water and dyes wool in corinth shades with good fastness properties.

A black powder which has the same property is obtained when, in place of the 14.5 parts by weight of anhydrous sodium carbonate, an equivalent amount of another basic agent, such as sodium hydroxide, lithium hydroxide, ammonia, propylamine or 1,3propanolamine, is used and in other respects the procedure is as described under this example.

Example 9.

34.3 parts by weight of the monoazo dyestuff of the formula

are converted, analogously to Example 2, into the 1:1 Cr complex and the reaction mixture is cooled to 80".

37.3 parts by weight of the monoazo dyestuff of the formula

in the form of a moist paste are then introduced, 12.7 parts by weight of anhydrous sodium carbonate are added and the mixture is stirred for 60 minutes at 1050. After cooling, the mixture is clarified by filtration through 8.5 parts by weight of Celite and the dyestuff solution is evaporated to dryness in a rotary evaporator.

A black powder which dissolves readily in water and dyes wool from an organic-acid bath in fast reddish-tinged brown shades is obtained. The dyestuff powder is virtually free from chromium which is not bonded in the dyestuff complex.

Example 10.

42.4 parts by weight of the monoazo dyestuff of the formula

in the form of a moist paste are stirred in 515 parts by volume of ethylene glycol monomethyl ether with 26.65 parts by weight of CrCl, . 6H2O in a flask for 3 hours at 105--130"C and the water is distilled off azeotropically through a column. The solution of the 1:1 Cr complex dyestuff is then cooled to 80 , 22 parts by weight of NaHCO3 and 33.9 parts by weight of the monoazo dyestuff of the formula

are introduced and the mixture is stirred for 120 minutes at 1050 The solution of the mixed chromium complex dyestuff is then cooled to 80" and clarified through 8.6 parts by weight of "Celite". The filtrate is evaporated to dryness in a rotary evaporator.

A dark brown powder which dissolves readily in water, is substantially free from inorganic salts and contains virtually no chromium which is not bonded in the dyestuff complex is obtained.

The dyestuff dyes wool from an organicacid bath in bluish-tinged red shades with good fastness properties.

If the monoazo dyestuff of the formula II is replaced by an equivalent amount of the disazo dyestuff of the formula

a red dyestuff with similar properties is obtained.

Example 11.

33.9 parts by weight of the monoazo dyestuff of the formula (I)

in the form of a moist paste are stirred into 415 parts by volume of ethylene glycol mono methyl ether, 26.65 parts by weight of CrCl, . 6H2O are added and the mixture is stirred for 3 hours at 105129 , the water present in the reaction mixture being distilled off azeotropically through a column and the 1:1 Cr complex being formed at the same time.

The mixture is cooled to 800, 17.3 parts by weight of anhydrous sodium carbonate and then 33.9 parts by weight of the monoazo dyestuff of the formula (II)

are introduced and the resulting mixture is stirred for 60 minutes at 100-1050. After cooling to 80 , the dyestuff solution is clarified by filtration and evaporated to dryness in a rotary evaporator. A dark brown dyestuff powder which is virtually free from salts and contains virtually no chromium which is not bonded in the dyestuff complex is obtained.

The dyestuff dyes wool from an organic-acid bath in red colour shades with good fastness properties.

In the same way it is also possible to convert the dyestuff of the formula (II) which is in the form of its paste into the mixed complex. A water-containing dyestuff solution is then obtained and after clarification by filtration and concentrating to dryness this gives a dyestuff powder which has a somewhat greater salt content. However, this powder is also free from inorganic chromium salts. It is also possible to use ethylene glycol monoethyl ether in place of ethylene glycol monomethyl ether as the solvent.The red dyestuff solutions obtained from the dry powder or the moist paste of the dyestuff of the formula (II) and from ethylene glycol monomethyl ether or ethylene glycol monoethyl ether do not need to be concentrated to dryness but can be employed direct, after clarification by filtration, for dyeing wool, leather and polyamide. The solutions are particularly suitable for spray-dyeing leather.

Example 12.

44.9 parts by weight of the monoazo dyestuff of the formula

in the form of a moist paste are stirred in 260 parts by volume of ethylene glycol monomethyl ether and dehydrated by azeotropic distillation (final temperature at the top of the column: 1220). 63 parts by volume of an ethylene glycol monomethyl ether solution which contains 2.6 parts by weight of chromium in a compound formed from GCl5. 6H2O by azeotropic dehydration in ethylene glycol monomethyl ether are then added and the mixture is stirred under reflux at 122" for 90 minutes.The mixture is then cooled to 100-1050, 17.5 parts by weight of sodium bicarbonate are added in the course of 5-10 minutes and the resulting mixture is stirred for 60 minutes at 100--1050. After cooling to 80-900, the mixture is clarified by filtration to remove inorganic salts and evaporated in a rotary evaporator.

A dyestuff which has properties similar to those in Example 15 is obtained.

Example 13.

38.9 parts by weight of the monoazo dyestuff of the formula

and 38.9 parts by weight of the monoazo dyestuff of the formula

are introduced into 250 parts by volume of ethylene glycol monomethyl ether which contains 5.2 parts by weight of chromium in a compound formed from CrCl3. 6H20 by azeotropic dehydration in ethylene glycol monomethyl ether. The mixture is stirred under reflux for 180 minutes and then cooled to 80 , 22 parts by weight of sodium bicarbonate are introduced in the course of 5-10 minutes and chroming is completed by stirring for 2 hours at 100-1050.

In order to work up the dyestuff, the dyestuff solution is cooled to 800, clarified by filtration to remove inorganic salts and evaporated to dryness in a rotary evaporator.

A black powder is obtained which dissolves readily in water and dyes wool from an acid bath in navy blue colour shades.

Example 14.

30.9 parts by weight of each of the monoazo dyestuffs of the formulae

in 250 parts by volume of ethylene glycol monomethyl ether which contains 5.2 parts by weight of chromium in a compound formed from CrCl3 . 6H.2O by azeotropic dehydration in ethylene glycol monomethyl ether are stirred under reflux for 180 minutes. The mixture is then allowed to cool to 800, 22 parts by weight of sodium bicarbonate are introduced and the mixture is stirred for a further 120 minutes at 100--1050 After clarifying by filtration and evaporating in a rotary evaporator, a black powder is obtained which, in the form of a dispersion, dyes poly amide in black shades with good fastness properties.

The dyestuff is substantially salt-free and virtually free from chromium which is not bonded in the complex dyestuff.

The black dyestuff solution obtained after clarifying by filtration does not need to be evaporated in a vacuum rotary evaporator but can also be used direct for spray-dyeings on leather. If, for the preparation of the dyestuff solution, sodium bicarbonate is replaced by an equivalent amount of lithium hydroxide, the solution is miscible, even in high concentration, with water without dyestuff pre cipitating out and can thus dye wool, leather and polyamide from an aqueous dye bath.

The monoazo dyestuffs which follow can be converted into their chromium derivatives in an analogous manner. In the form of their powders or solutions, these derivatives dye wool, leather and polyamide in the shades indicated in the Table.

orange

red

grey

navy blue

brown Example 15.

410 parts by volume of ethylene glycol monomethyl ether which contains 2.6 parts by weight of chromium in a compound formed from CrCl, . 6H2O by azeotropic dehydration in ethylene glycol monomethyl ether are warmed to 80" and 27.6 parts by weight of sodium bicarbonate are added. 44.9 parts by weight of the monoazo dyestuff of the formula

are then introduced and the mixture is stirred for 1 hour at 100105 . It is clarified by filtration and evaporated to dryness in a rotary evaporator.

A black dyestuff powder which is substantially free from inorganic salts and contains virtually no free chromium (chromium which is not bonded in the complex dyestuff) is obtained.

The dyestuff dyes wool in grey shades with good fastness properties.

Example 16.

32.2 parts by weight of the monoazo dye stuff of the formula

are introduced into 200 parts by volume of ethylene glycol monomethyl ether which con tains 2.86 parts by weight of chromium in a compound formed from CrCl, . 6H2O by azeotropic dehydration in ethylene glycol monomethyl ether. 6.9 parts by weight of sodium bicarbonate are added and the mixture is stirred for 120 minutes at 100-1050. It is then allowed to cool to 80 , a further 6.9 parts by weight of sodium bicarbonate are introduced and the resulting mixture is stirred for a further 150 minutes at 100--105".

After the dyestuff solution has been clarified by filtration and evaporated in a rotary evaporator, a brown dyestuff powder which is virtually free from salts and is virtually free from chromium which is not bonded in the complex dyestuff is obtained.

Example 17.

32.2 parts by weight of the monoazo dye stuff of the formula

in 300 parts by volume of ethylene glycol monoethyl ether which contains 5.2 parts by weight of chromium in a compound formed from CrC13. 6H2O by azeotropic dehydration with ethylene glycol monoethyl ether are stirred under reflux at 135138 for 120 minutes.The solution of the 1:1 complex is allowed to cool to 80-900, a moist paste of 40.2 parts by weight of the monoazo dyestuff of the formula

and 22 parts by weight of sodium carbonate are introduced and the mixture is stirred for 60 minutes at 80"C. After clarifying by filtra tion and removing the solvent in a vacuum rotary evaporator, a powder which is readily soluble in water and dyes wool and polyamide in clear, greenish-tinged yellow shades with good fastness properties is obtained.

Example 18.

1 mol of CrCl3 . 6H2O is dissolved in 500 ml of ethyl-glycol. The solution is heated to the boil and the excess solvent is distilled off under normal pressure. Water and hydrogen chloride can be detected in the distillate.

The remaining oily residue is now stirred for one hour in a hot oil bath at 200 under the vacuum of a water pump. The initially readily mobile oil becomes increasingly more viscous and after one hour can hardly be stirred. On cooling, the residue solidifies to give a brittle crystalline mass. Elementary analysis agrees with the following ratio: C 5HI.ICIl,,,GO2.8 The product obtained is presumably a 1:1 mixture of CrCl (O-CH2-CH2-O-CH2-CHs ) and CrCl2 (O-CH2-CH2-O-CHCH,).

23 g of this chromium compound and 67.8 g of the monoazo dyestuff of the formula

in 250 ml of ethylglycol are heated under reflux for one hour. The mixture is allowed to cool to 80 , 34.5 g of sodium bicarbonate are introduced and the mixture is again stirred for one hour at 80-1000. The solution, which has now formed, of the 1:2 chromium complex dyestuff is clarified by filtration at 80" and evaporated to dryness in a vacuum rotary evaporator. The residue is a red powder which is virtually free from alkali metal salts and chromium salts and which dyes wool and polyamide in orange coloured shades.

WHAT WE CLAIM IS: 1. A process for the production of a chromium complex dyestuff or cobalt complex dyestuff, in which a water-containing chromium salt or cobalt salt is dehydrated in an aliphatic ether containing a hydroxyl group and is then reacted with a metallisable dyestuff.

2. A process according to Claim 1, in which equivalent amounts of a chromium salt or cobalt salt and a metallisable dyestuff are reacted.

3. A process according to Claim 1, in which two equivalents of a metallisable dyestuff are used per equivalent of chromium salt or cobalt salt, and in which the metallisation is carried out in the presence of an agent which has a basic action.

4. A process according to Claim 1, in which the reaction is carried out first in the absence of a basic agent with 1 equivalent of the metallisable dyestuff and then in the presence of a basic agent with a second equivalent of the same or a different metallisable dyestuff.

5. A process according to Claim 3 or 4 in which the agent which has a basic action is an alkali metal carbonate, bicarbonate or hydroxide or an alkaline earth metal carbonate, bicarbonate or hydroxide.

6. A process according to Claim 5, in which the agent which has a basic action is a sodium or lithium carbonate, bicarbonate or hydroxide.

7. A process according to any of the foregoing claims, in which the insoluble products are separated off after the reaction of the metallisable dyestuff in the presence of a basic agent, and the chromium complex dyestuff or cobalt complex dyestuff is subsequently isolated.

8. A chromium complex dyestuff or cobalt complex dyestuff when produced by the process of any of the foregoing claims.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. to cool to 80 , 34.5 g of sodium bicarbonate are introduced and the mixture is again stirred for one hour at 80-1000. The solution, which has now formed, of the 1:2 chromium complex dyestuff is clarified by filtration at 80" and evaporated to dryness in a vacuum rotary evaporator. The residue is a red powder which is virtually free from alkali metal salts and chromium salts and which dyes wool and polyamide in orange coloured shades. WHAT WE CLAIM IS:

1. A process for the production of a chromium complex dyestuff or cobalt complex dyestuff, in which a water-containing chromium salt or cobalt salt is dehydrated in an aliphatic ether containing a hydroxyl group and is then reacted with a metallisable dyestuff.

2. A process according to Claim 1, in which equivalent amounts of a chromium salt or cobalt salt and a metallisable dyestuff are reacted.

3. A process according to Claim 1, in which two equivalents of a metallisable dyestuff are used per equivalent of chromium salt or cobalt salt, and in which the metallisation is carried out in the presence of an agent which has a basic action.

4. A process according to Claim 1, in which the reaction is carried out first in the absence of a basic agent with 1 equivalent of the metallisable dyestuff and then in the presence of a basic agent with a second equivalent of the same or a different metallisable dyestuff.

5. A process according to Claim 3 or 4 in which the agent which has a basic action is an alkali metal carbonate, bicarbonate or hydroxide or an alkaline earth metal carbonate, bicarbonate or hydroxide.

6. A process according to Claim 5, in which the agent which has a basic action is a sodium or lithium carbonate, bicarbonate or hydroxide.

7. A process according to any of the foregoing claims, in which the insoluble products are separated off after the reaction of the metallisable dyestuff in the presence of a basic agent, and the chromium complex dyestuff or cobalt complex dyestuff is subsequently isolated.

8. A chromium complex dyestuff or cobalt complex dyestuff when produced by the process of any of the foregoing claims.