US2478185A

US2478185A - Single bath chrome dyeing process

Info

Publication number: US2478185A
Authority: US
Publication date: 1949-08-09
Anticipated expiration: 1966-08-09

Description

Patented Aug. 9, 1949 UNITED STATES s-ATENT OFFICE.

SINGLE BATH CHROME DYEING PROESS USING ESTEREFIED AZO DYES' a Swiss firm No Drawing. Application February 18, 1947, Se-

rial No. 729,418. In Switzerland February 2'1,

12 Claims.

According to this invention valuable new dyestuffs capable of being chromed are made by treating an ortho: ortho' -dihydroxy-mcnoazo-dyestufi, which contains a single sulfcnic acid group, with an organic acylating agent.

The expression ortho:ortho dihydroxy-monoazo-dyestufis is; used herein to denote monoazodyestufis containing the atomic grouping As starting materials for the invention there come into consideration more especially those o-rthc:ortho"-dihydroxy-monoazo-dyestufis having a single sulfonic acid group. which contain at least once the residue of a component of the benzene or naphthalene series. Such monoazoedye stui fs can be obtained in known manner, for example, by coupling the diaao-compound of an aromatic ortho-amino-hydroxy-comp.ound contaming at the most two condensed rings, via, the (liaise-compound of an ortho-amino-hydroxybem zene or of an orthoamino-hydroxynaphthalene with an ace-component capable of coupling in ortho-positi'on with respect to an HO-group, and so selecting the two starting components that one of them contains a sulfonic acid group. The

ortho-amino-hydroxybenzenes or ortho-amino no-I-hydroxybenzene-d-sulfonic: acid, d-methyh 2-amino-l-hydroxy-benzcne-o-sulionic acid, 4- chloro-2-amino- 1 hydroinzbenzene a 6 sul'ionic acid, -nitro-2-amino-hydroxybenzeneefi sulfonio acid, 6 nitro-2-amino-li-hYdroxybenzene-4-sulionic acid, 5-nitro-2-amino-l-hydroxybenzenel sulfonic acid, 1-amino-2-hydrcxy-naphthalened-sulfonic acid, Z-amino-l-hydroxy-naphtha-- lene-4-sulfo11ic acid or 6 nitro-I-amino-2-hydroxy naphthalene-4-sulfonic acid; components coupled with azo-components containing a sulfonic acid group, namely 2-amino-1-hydroxybenzene, 4-chloro-2-aminc-1-hydroxybenzene, r6- dichloro-Z-amino-l-hydroxybenzene, 314:6 trichloro-2-amino-I-hydroxybenzene, 6 nitro 4 methyl-Z-amino-l-hyclroxybenzene, 4 nitro 2: amino-l-hydroxy-benzene, 5 nitro-Z-amino-lhydroxybenzene, 6-nitro-2-amino-1-hydroxyben zene, 5-nitro-4-ch1oro-2-amino 1 hydroxybenzene, 6-nitro-2-amino-4-chloro 1 hydroxybenzene, 4-nitro-6-chloro-2-amino 1 hydroxybenzene, 4:6-dinitro-2-amino-l-hydroxybenzene or 2-amino-1-hydroxybenzene-4-sulfonic acid diethylamide.

As and-components which come into consideration for making the starting materials used in the. present process there are suitable those which owe their coupling capacity to a phenolic hydroxyl group or to the presence of a reactive methylene group. As examples of such azo-components there may be mentioned:

Hydroxypyrene, hydroxybenzenes capable of coupling in ortho-position with respect to the hydroxyl group, such as 1-hydroxyAemethylbenzene, l-hydroxyi-tertiary amyl-benzene, l-hydroxy- 4-isobutyl-benzene; S-hydroxy-quinolines capabio of coupling in ortho-position with respect to the hydroxyl group, such as 5;-chl'oro-8hydroxyquinoline; acetoacetic acid arylides such as acetoacetic acid anilide or acetoacetic acid orthoanisidide; and also 2:4-dihydroXy-quinoline and the like. Especially good results can be obtained with hydroxynaphthalenes which couple in orthoposition with respect to a hydroxyl group or are capable ofcouplin in such a position, or with pyrazolones, especially I-aryl (for example, phenyl) -3-methyl-5-pyrazo1ones. As examples of such aZo-components there may be mentioned: l-hydroxy-naphthalene (in which case it is necessary to work under conditions such that coupling occurs in the 2-posi'tion, for example, in a medium rendered strongly alkaline with caustic alkali) 5-ch1oro-1-hydroxy-naphtha1ene, 5:55- dichloro 1 hydroxynaphthalene, l-hydroxy-emethoxynaphthalene, Z-hydroxy-naphthalene, 2- hydroxy-fi-methoxynaphthalene, 2 hydroxy-T- methoxynaphthalene, 2-hydroXy-naphtha1ene-6 sulfonic acid diethylamide, l-hydroxy-naphtha- 1ene-4-sulfonic acid, 1-hydroxynaphthalene5- sulfonic acid, Z-hydroxynaphthalene-4-sulionic acid, 2-hydroxynaphthalene-6-sulfonic acid, 2- hydroxynaphthal'ene-7-sulfonic acid, 1-hydroxynaphthalene-li-sulfonic acid-N-methylanilide-S- sulfonic acid; 3-methyl-5-pyrazolone, 1:3-difree from sulfonic acid groups which are to phenyl-S-pyrazolone, 1 phenyl-3-methyl-5-DY- razoline, 1- (3'-nitro) -phenyl-3-methyl-5-pyrazolone, 1-(2'-chloro) -phenyl-3-methyl pyrazolone, 1-(3'-sulfo) -phenyl-3-methyl-5-pyrazolone, 1- (2-chloro-5' -sulfo) -phenyl-3-methyl-4-pyrazolone, 1-(2-methyl-5'-sulfo)-pheny1-3-methyl- 5-pyrazolone.

As acylating agents for use in treating the ortho-ortho'-dihydroxy-monoazo-dyestufis containing a sulfonic acid group in accordance with the invention there may be mentioned, inter alia: benzene or toluene sulfonic acid chloride, maleic anhydride, terephthalic acid chloride. There are more especially suitable, however, acylating agents which contain as the sole acylating group a functionally converted carboxyl group, for example, carboxylic acid halides such as the acid bromides or chlorides, or carboxylic anhydrides. Among these compounds especially good results can be obtained with those which are free from groups imparting solubility and substituents conof a tertiary organic base, for example pyridine, p

it is also generally desirable to work in an anhydrous medium and in the absence of free alkalies. In the case of dyestufis which have been obtained by coupling a diazotized ortho-aminohydroxybenzene or ortho-amino-hydroxynaphthalene with a, compound coupling in ortho-position with respect to a phenolic hydroxyl group, for example, with a hydroxynaphthalene, the acylation may be carried out differently. However, it must be carried out in such a manner that at least one hydroxyl group in ortho-position with respect to the azo-group is acylated. The second hydroxyl group in ortho-position with respect to the azo-group may then remain unchanged depending on the kind and quantity of the acylating agent and on the conditions of the reaction, or it may be acylated in part of the dyestufi subjected to the acylation, or be acylated entirely. In the case of dyestuffs which are obtained by using 1-phenyl-3-methyl-5-pyrazolones as coupling components the enolized keto group in the 5-position of the pyrazolone residue is not easily esterified by the present process.

The monoazo-dyestufis obtainable by the present process are new and correspond to the formula in which the groups O- are in positions adjacent to the -N=N group, R1 and R2 each represent an organic residue, at least one aromatic bound O- group is attached by its free valency to the acyl group of an acyl residue, a remaining free valency is attached to hydrogen, and in which the residue contains a single sulfonic acid group.

Among the above dyestuffs there are especially valuable those of the general formula in which the groups -O are in positions adjacent to the -N=N- group, R1 represents an aromatic radical containing at the most two condensed rings, R2 represents a residue of a coupling component, at least one aromatic bound O- group is attached by its free valency to the CO group of a carboxylic acid which is free from substituents imparting solubility and in which the residue contains a single sulfonic acid group.

The mono-azo-dyestuffs obtainable by the invention are principally suitable for dyeing by the chroming process in which the dyeing is carried out by the single bath process with baths which contain the dyestuff and also an agent yielding chromium. A dyeing process of this kind is, for example, that in which dyeing baths are used which contain, in addition to the dyestuif, an alkali chromate such, for example, as sodium chromate or potassium chromate, and a buffer salt which prevents the bath becoming alkaline at a raised temperature, for example, at C. A salt of this kind, is, for example, ammonium sulfate. The method of dyeing by the single bath chroming process with baths which contain the dyestuif, an alkali chromate and ammonium sulfate is known under the name Synchromate process or Metachrome process. A special object of the invention is to convert chromable dyestuffs which are not suitable for dyeing by the aforesaid single bath chroming process into dyestuffs which are especially suitable for this dyeing process. In the dyeing process the complex chromium compound of the dyestufi is formed with the elimination of the acyl residue. The dyeings so obtained may be distinguished by very good properties of fastness, especially by very good properties of wet fastness. As fibers which may be dyed by the single bath chroming process, especially the so-called synchromate process, with the monoazo-dyestuffs obtainable by the invention, there may be mentioned principally fibers of animal origin such as silk, leather and principally Wool. Mixed fabrics, for example of wool and regenerated cellulose and also animalized cellulose, artificial fibers of casein, artificial fibers of superpolyamides or superpolyurethanes, can be dyed in this manner.

As compared with the process of French specification No. 914,640, in which is described the manufacture of ester-like derivatives of ortho:- ortho-dihydroxyazo-dyestufis which are sparingly soluble to insoluble in water which are derived from dyestuffs free from sulfonic acid groups and which contain in addition to the group which brings about acylation, an atomic grouping which determines the solubility of the acylation product, the process of the present invention for producing chromable dyestuffs is distinguished by the use of ortho:ortho-dihydroxyazo-dyestuffs containing a sulfonic acid group as starting materials, and by the use advantageously as acylating agents of compounds which are free from groups imparting solubility and substituents convertible into such groups.

The following examples illustrate the invention, the parts being by weight:

Example 1 12.6 parts of benzoyl chloride are introduced dropwise at room temperature into 280 parts of dry pyridine, while thoroughly stirring, and then there are introduced 40 parts of the pulverized and thoroughly dried dyestuff obtained by coupling diazotized 1-amino-2-hydroxy-naphthalene-4-su1fonic acid with l-hydroxy-naphthalene and, after coupling, freeing the product from any free alkali by acidification. The temperature of the esterification mixture is maintained for 2 hours at ill-45 0., and the greater part of the pyridine is then distilled under reduced pressure. The residue is stirred into about 400 parts of water, the dyestufl ester is separated by filtering with suction after the addition of 20-40 parts of sodium chloride, and dried under reduced pressure. 45 parts of a dark, water-soluble powder are obtained which dyes wool blue tints by the single bath process in the presence of an agent yielding chromium. A similar product is obtained when, instead of l-hydroxy-naphthalene, 2-hydroXy-naphthalene is coupled with the diazocompound of l-amino-2 hydroxynaphthalenelsulfonic acid to form the dyestuff to be esterified.

Example 2 11.2 parts of benzoyl chloride are introduced dropwise while thoroughly stirring in 280 parts of dry pyridine, and then there are introduced 44 parts of the finely pulverized and thoroughly dried dyestuff obtained by coupling diazotized 1-amino-6-nitro-2-hydroxy naphthalene-l-sulfonic acid with Z-hydroxy-naphthalene. The temperature of the esterification mixture is maintained for 2 hours at 40-45 C., and then the greater part of the pyridine is distilled under reduced pressure. The residue is stirred in about 400 parts of water, the dyestufi" ester is separated by filtering with suction after the addition of 20-40 parts of sodium chloride and dried under reduced pressure. 50 parts of a dark red, watersoluble powder are obtained, which dyes wool black tints by the single bath process in the presence of an agent yielding chromium.

Example 3 4:4 parts of the dry dyestuff, which has been obtained by coupling diazotized 5-nitro-4chloro- Z-aminophenol with l-hydroxy-naphthalene-5- sulfonic acid, are esterified at 60 i C. with 11 parts of benzoyl chloride in 200 parts of dry pyridine. After 1 hour the whole is diluted with 300 parts of water, and the pyridine is neutralized with 285 parts of hydrochloric acid of 30 per cent strength. The dyestuii ester is then removed by filtering with suction, washed and dried. There are obtained 52 parts of a dark powder which dissolves in hot water with a bordeaux red. coloration and dyes wool blue tints by the single bath process in the presence of an agent yielding chromium.

By using instead of the above mentioned dyestufi the dyestufi obtained by coupling diazotized l-nitro-2-aminophenol with l-hydroxy-naphthalene--sulfcnic acid there is obtained a dyesiuii ester which is similarly soluble in hot water, and which dyes wool violet brown tints by the single bath process in the presence of an agent yielding chromium.

Example 4 42.2 parts of the dried dyestufi, which is obtained by coupling diazotized 1-amino-2-hydroXy-napl1thalene-4-sulfonic acid with l-ph'enyl-3-methyl-5-pyrazolone and has finally been freed from alkali by washing and acidifying, are introduced into 280 parts of dry pyridine at 65-70 (3., and esterified by introducing 11.5 parts of benzoyl chloride dropwise. Withv a slight rise in temperature there is rapidly obtained a clear dark red solution. The whole is stirred for 1 hour, during which the temperature is not allowed to fall below 40-45 0., about 200 parts of pyridine are then distilled under reduced pressure, and the residue is taken up in 200 parts of water. By the addition of 20 parts of sodium chloride the dyestuff is completely precipitated, and then separated by filtering with suction and dried at 60 C. under reduced pressure.

There are obtained 50 parts of an orange powder which dissolves in warm water to give a clear solution. It dyes wool pure bluish red tints by the single bath process in the presence of an agent yielding chromium.

Example 5 16.8 parts of benzoyl chloride are introduced dropwise while thoroughly stirring into 280 parts of dry pyridine at room temperature, and then there are introduced 45.5 parts of the pulverized and dried dyestufi obtained by coupling diazotized l-hydroxy- 2 -amino-4=-nitro-6-chlorobenzene with 1-(4'-sulfophenyl)-3-methyl-5 pyrazoloned. The esterification is continued for 2 hours at 40-45 C., the greater part of the pyridine is then distilled under reduced pressure, the residue is introduced into 400 parts of water, the dyestufi ester is separated by filtering with suction, if desired, after the addition of 20-40 parts of sodium chloride, and dried under reduced pressure. About 55 parts of a red-brown water-soluble pov der are obtained which dyes wool orange tints by the single bath process in the presence of an agent yielding chromium.

Example 6 42 parts of the dried dyestuff which has been obtained by coupling diazotized 4-nitro-2-aminophenol-6-sulfonic acid with 1-phenyl-3-methyl- 5-pyrazolone, are dissolved at 60-70 C. in 280 parts of dry pyridine, and esterified by introducing dropwise 12.5 parts of benzoyl chloride while stirring. After 1 hour the suspension is stirred in 300400 parts of ice and the whole is rendered weakly acid to Congo by introducing dropwise about 350 parts of hydrochloric acid of 30 per cent. strength. The dyestufi is then separated b flitering with suction, washed with a solution of ;:odium chloride of 10 per cent. strength until neutral, and dried.

The dyestufi derivative i an orange powder which dissolves to give a clear solution in warm water, and dyes wool reddish orange tints by the single bath process in the presence of an yielding chromium.

Example 7 running in 280 parts of hydrochloric acid of 36) per cent. strength. The dyestuff is thus precipitated, separated by filtering with suction, washed 7 with cold water, and dried at 90 C. under reduced pressure.

There are obtained about 46 parts of a yelloworange powder, which dissolves in hot water to give a clear solution. It dyes wool fast borcleauxred tints by the single bath proces in the presence of an agent yielding chromium.

Example 8 46 parts of the pulverized and thoroughly dried dyestuff, obtained by' coupling diazotized 1- amino- 2 -hydroxynaphthalene- 4 -sulfonic acid with 1- (2'-chlorophenyl) 3-methyl-5-pyrazolone and washing and acidifying the product after coupling, to eliminate free alkali therefrom, are dissolved in 280 parts of dry pyridine to give a clear solution, and slowly esterified at 40-45" C. with 11.2 parts of benzoyl chloride while stirring. The initially clear solution becomes turbid in a short time, and the dyestufi ester partially precipitates. After stirring for 1 hour at 40-45 C. about 220 parts of pyridine are distilled under reduced pressure. The residue is stirred for a short time with 400 parts of water, 20 parts of sodium chloride are added, the dyestuff is separated by filtering with suction, and dried.

55 parts of an orange-red water-soluble powder are obtained, which dyes wool red tint by the single bath process in the presence of an agent yielding chromium.

Example 9 41 parts of the thoroughly dried dyestuff, obtained by coupling diazotized 4-chloro-2-aminophenol-G-sulfonic acid with 1-phenyl-3-methyl-5- pyrazolone, and, after coupling, acidifying the product to eliminate free alkali therefrom, are esterified in 280 parts of dry pyridine at 60-70" C. by introducing 11.2 parts of benzoyl chloride dropwise. After 1 hour the solution, in which the dyestuff ester i partially in suspension, is stirred in 300 parts of ice-water, and the whole is rendered weakly acid to Congo by adding dropwise about 350 parts of hydrochloric acid of 30 per cent. strength. The dyestufi ester i then separated by filtering with suction, Washed neutral with cold water, and dried.

The dyestufl? ester dissolves in boiling water to give a clear solution and dyes wool red tints by the single bath process in the presence of an agent yielding chromium.

Example 10 42.4 parts of the dry dyestufl, obtained by coupling diazotized 1-amino-2-hydroxynaphthalene-4-sulfonic acid with 1-phenyl-3-methyl-5- pyrazolone and finally washing and acidifying the product to eliminate free alkali therefrom, are introduced at 65-75 C. into 280 parts of dry pyridine, and esterified by introducing 12 parts of butyryl chloride dropwise. There is obtained a clear dark red solution, and after 1 hour about 200 parts .of pyridine are distilled under reduced pressure. The residue is taken up in 300 parts of water, the dyestufi ester is completely precipitated with 30 parts of sodium chloride, and it is then separated by filtering with suction, and dried. There are obtained 50 parts of an orange powder, which dissolves in hot water to give a clear solution. It dyes wool pure bluish-red tints by the single bath process in the presence of an agent yielding chromium.

Emample 11 47 parts of the dry dyestufl, obtained by coupling diazotized 1-amino-2-hydroxy-6-nitronaphthalenel-sulfonic acid with 1-phenyl-3-methyl- 5-pyrazolone and finally washing and acidifying the product to free it from excess alkali, are esterified in 280 parts of dry pyridine at 65-75" C. with 12 parts of benzoyl chloride. After 1 hour the whole is diluted with about 300 parts of cold water, the pyridine is neutralized with hydrochloric acid, and the precipitated dyestufl ester is separated by filtering with suction, washed and dried. There are obtained 60 parts of an orange powder which dissolves in boiling water to give a clear solution. It dyes wool strong yellowish red tints by the single bath process in the presence of an agent yielding chromium.

Example 12 44 parts of the dry dyestuff, obtained by coupling diazotized l-hydroxy-Z-aminobenzene-4- sulfonic acid-G-carboxylic acid with 1-phenyl-3- methyl-5-pyrazolone, are esterified in 200 parts of dry pyridine with 11 parts of benzoyl chloride at 60-70 C. After 1 hour the whole is diluted with 300 parts of water, and the pyridine is neutralized with 285 parts of hydrochloric acid of 30 per cent. strength. The dyestufi ester is then separated by filtering with suction, washed and dried. The dyestuff ester is obtained in a yield amounting to 53 parts. It dissolves in hot water and dyes wool .orange tints by the single bath process in the presence of an agent yielding chromium.

Example 13 42 parts of the dry dyestuif, obtained by coupling diazotized 4-nitro-2-amino-1-hydroxybenzene-6-sulfonic acid with 1-phenyl-3-methy1-5- pyrazolone, are esterified in 200 parts of dry pyridine with 9.5 parts of para-nitrobenzoyl chloride. After 1 hour the reaction mass is taken up in 300 parts of water, neutralized with 285 parts of hydrochloric acid of 30 per cent. strength, the dyestuff ester is separated by filtering with suction, washed with water, and dried. There are obtained 50 parts of an orange-yellow powder which dissolves in hot water with an orange-red coloration. The dyestufi ester dyes wool orange tints by the single bath process in the presence of an agent yielding chromium.

Example 14 40 parts of the dry dyestuff obtained by coupling 4-chloro-2-aminophenol with 2-hydroxynaphthalene-G-sulfonic acid, are esterified at -70 C. in 200 parts of dry pyridine with 23 parts of benzoylchloride. After 1 hour the reaction mass is diluted with 300 parts of water and the pyridine is neutralized with about 285 parts of hydrochloric acid of 30 per cent. strength; the dyestuff ester is separated by filtering, washed and dried. There are obtained 52 parts of an orange powder which dissolves in hot water with a red-orange coloration. The dyestuff dyes wool violet tints by the single bath process in the presence of an agent yielding chromium.

Example 15 parts of thoroughly wetted wool are entered at 60 C. into a dyebath which contains in 4000 parts of water 1.5 parts of dyestufi .obtainable as described in Example 4. 2.5 parts of ammonium sulfate, 2.5 parts of sodium chromate and also 20 parts of Glauber salt. The temperature is raised to the boil in the course of 30 minutes, and

dyeing is carried on for 2 hours at the boil. The goods are then rinsed and dried. The wool is dyed a pure bluish-red tint.

What we claim is:

1. Process for the production of fast dyeing on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, a buffer salt which prevents the bath becoming alkaline at a raised temperature and a monoazo dyestuff of the general formula ...0 O I t -N=N- 2 in which the groups O-- are in positions adjacent to the -N=N- group, R1 represents a naphthalene radical, R2 represents the radical of a coupling component, at least one aromatically bound -O-- group is attached by its free valency to the CO- group of the radical of a carboxylic acid which is free from substituents imparting solubility, a remaining free valency is attached to hydrogen, and in which the radical 1 1 -N=N1 l2 contains a single sulfonic acid group.

2. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, a buffer salt which prevents the bath becoming alkaline at a raised temperature and a monoazo dyestuff of the general formula 1 t1-N=N'R 2 in which the groups -O- are in positions adj acent to the N=N group, R1 .represents a naphthalene radical, R2 represents the radical of a coupling component, at least one aromatically bound O- group is attached by its free valency to the radical COR3, R3 standing for a benzene radical being free from groups imparting solubility, a remaining free valency is attached to hydrogen, and in which the radical cally bound -O- group is attached by its free valency to the radical a remaining free valency is attached to hydrogen, and in which the radical thirds-iii contains a single sulfonic acid group.

4. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, a bufier salt which prevents the bath becoming alkaline at a raised temperature and a monoazo dyestuff of the general formula I ti-N=NI t2 in which the groups =0..- are in positions adjacent to the -N=N-.- group, R1 and R2 each represents a naphthalene radical, at least one O- is attached by its free valency to the radical a remaining free valency is attached to hydrogen, and in which the radical I hN=N-1 h contains a single sulfonic acid group.

5. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, a buffer salt which prevents the bath becoming alkaline at a raised temperature and a monoazo dyestufi of the general formula R1N=1\]R2 in which R1 represents a naphthalene radical and bound to the N=N group in a position adjacent to the group, R2 represents the radical of a 1-phenyl-3- methyl-5-pyrazolone bound to the N=N- group in l-position, and in which the radical '7. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, ammonium sulfate and a m'onoazo dyestuif of the general formula in which the groups --O are in positions adjacent to the -N=N group, R1 represents a naphthalene radical, R2 represents the radical of a coupling component, at least one aromatically bound O-- group is attached by its free valency to the --CO- group of the radical of a carboxylic acid which is free from substituents imparting solubility, a remaining free valency is attached to hydrogen, and in which the radical 1N=NI i2 contains a single sulfonic acid group.

dyestulf of the general formula 1 l 8. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, ammonium sulfate and a monoazo in which the groups O- are in positions adjacent to the N=N group, R1 represents a naphthalene radical, R2 represents the radical of a coupling component, at least one aromatically bound O- group is attached by its free valency to the radical COR3, R3 standing for a henzene radical being free from groups imparting solubility, a remaining free valency is attached to hydrogen, and in which the radical to the radical a remaining free valency is attached to hydrogen, and in which the radical III1N=NA2 contains a single sulfonic acid group.

10. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, ammonium sulfate and a monoazo dyestuff of the general formula in which the groups O- are in positions adjacent to the N=N- group, R1 and R2 each represents a naphthalene radical at least one --O-.

is attached by its free valency to the radical a remaining-free valencyis attached to hydrogen, and in which the radical V t 1 N=N- I h contains a single sulfonic acid group.

11. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, ammonium sulfate and a monoazo dyestufi of the general formula in which 31 represents a naphthalene radical bound to the N=N group in a position adjacent to the group, R2 represents the radical of a 1-pheny1-3- methyl-5-pyrazolone bound to the N=N- group in 4-position, and in which the radical II{1-N=NII{2 contains a single sulfonic acid group.

12. Process for the production of fast dyeings on the fiber in which the material is dyed by the single bath process in a bath containing an alkali chromate, ammonium sulfate and the monoazo dyestufi of the formula SO H N it

so on FRIEDRICH FELIX. ALPHONSE HECKENDORN. W'ILLY WIDMIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,095,600 Graenacher Oct. 12, 1937 2,276,187 Graenacher Mar. 10, 1942 2,405,816 Conzetti Aug. 13, 1946 (Eertificate of Correction Patent N 0. 2,478,185 August 9, 1949 FRIEDRICH FELIX ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 3, lines 4 and 5, for -4-pyrazolone read -5-pyrazol0ne; column 6, lines 25 and 26, for pyrazoloned read pyrazolone;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 21st day of February, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gammz'ssz'oner of Patents.