Preparation of quaternized azo dyes

Quaternized azo dyes whose diazo components are derived from a five-membered nitrogen-containing aromatic aminoheterocycle and whose coupling components are derived from the aniline series are prepared by reacting to corresponding neutral dye-bases with an alkylating agent in .gamma.-butyrolactone as inert diluent.

The present invention relates to a novel process for preparing quaternized 
azo dyes whose diazo components are derived from a five-membered 
nitrogen-containing aromatic amino heterocycle and whose coupling 
components are derived from the aniline series by reacting the 
corresponding neutral dyebases with an alkylating agent in an inert 
diluent. 
The preparation of basic dyes is known per se and is customarily effected 
by reacting a neutral, quaternizable chromophore, the so-called dyebase, 
with an alkylating agent. 
The diluents used are in general N,N-dimethylformamide, toluene, chloroform 
and 1,1,1-trichloroethane. 
However, these diluents have the disadvantage of incomplete 
biodegradability. Moreover, they are not suitable for use as medium for 
the quaternized azo dyes or they are unsuitable from an applicational 
hygiene point of view. 
It is an object of the present invention to make available a novel process 
for preparing quaternized azo dyes by reacting the corresponding neutral, 
quaternizable dyebases with an alkylating agent using a diluent which on 
the one hand shall be readily biodegradable and on the other shall be 
suitable for use as medium for the resulting quaternized dye. 
We have found that this object is achieved by a process for preparing a 
quaternized azo dye of the formula I 
##STR1## 
where 
An.sup..crclbar. is one equivalent of an anion, 
L is C.sub.1 -C.sub.4 -alkyl, 
Het is a five-membered aromatic heterocycle which may be benzofused and 
contains at least one nitrogen atom and 1 or 2 further hetero atoms 
selected from the group consisting of nitrogen, oxygen and sulfur and to 
which the radical L is attached at a nitrogen atom, and 
K is the radical of a coupling component of the aniline series, by reacting 
the neutral dyebase of formula II 
EQU Het--N.dbd.N--K (II) 
where Het and K are each as defined above, with an alkylating agent of the 
formula III 
EQU L--X (III) 
where L is as defined above and X is a leaving group, in 
.gamma.-butyrolactone as inert diluent. 
Suitable diazo components Het-NH.sub.2 from which the radical Het in the 
formula II is derived are for example the basic structures aminopyrazole, 
aminoimidazole, aminooxazole, aminoisoxazole, aminothiazole, 
aminoisothiazole, amino-1,2,4-triazole, amino-1,2,4-oxadiazole, 
amino-1,3,4-oxadiazole, amino-1,2,4-thiadiazole, amino-1,3,4-thiadiazole 
or benzofused derivatives thereof, such as aminoindazole, 
aminobenzimidazole, aminobenzoxazole, aminobenzisoxazole, 
aminobenzothiazole and aminobenzisothiazole. 
If allowed by the substitution pattern, the aminoheterocycles mentioned may 
contain further substituents, for example C.sub.1 -C.sub.4 -alkyl, phenyl, 
C.sub.1 -C.sub.4 -alkoxy, halogen, in particular chlorine and bromine, or 
mono- or di-C.sub.1 -C.sub.4 -alkylamino. 
Of particular suitability are heterocycles of the aminoisothiazole, 
aminoindazole or aminobenzothiazole series. 
Of very particular suitability are for example 
5-amino-3-methyl-4-chloroisothiazole, 5-amino-3-methyl- 
5-bromoisothiazole, 3-aminoindazole, 3-amino-1-methylindazole, 
2-aminobenzothiazole and 2-amino-6-methoxybenzothiazole. 
The radical K of the coupling component is derived for example from 
anilines KH of the formula IV 
##STR2## 
where 
R.sup.1 and R.sup.2 are identical or different and each is independently of 
the other hydrogen, C.sub.1 -C.sub.8 -alkyl, which may be interrupted by 
one or two oxygen atoms in ether function and may be C.sub.1 -C.sub.8 
-alkoxycarbonyl-, cyano-, hydroxyl-, C.sub.1 -C.sub.4 -alkyloxy-, 
benzoyloxy- or phenoxy-substituted, C.sub.3 -C.sub.5 -alkenyl, C.sub.5 
-C.sub.7 -cycloalkyl or phenyl, which may be monosubstituted or 
disubstituted by chlorine, methyl, ethoxy, dimethylamino or acetylamino, 
R.sup.3 is hydrogen, C.sub.1 -C.sub.4 -alkyl C.sub.1 -C.sub.4 -alkoxy, 
chlorine, C.sub.1 -C.sub.4 -alkanoylamino, ureido, mono- or di-C.sub.1 
-C.sub.4 -alkylureido or C.sub.1 -C.sub.4 -alkylsulfonylamino, and 
R.sup.4 is hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy or 
chlorine. 
Examples of suitable radicals R.sup.1 and R.sup.2 are hydrogen, methyl, 
ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, neopentyl, 
isopentyl, tertpentyl, hexyl, heptyl, octyl, 2-ethylhexyl, allyl, 
methallyl, cyclopentyl, cyclohexyl, cycloheptyl, benzyl, 1- or 
2-phenylethyl, 2-hydroxyethyl, 2-cyanoethyl, 2- or 3-hydroxypropyl, 2- or 
3-cyanopropyl, 1-methyl-2-hydroxyethyl, 2-hydroxybutyl, 
1-ethyl-2-hydroxyethyl, 4-hydroxybutyl, 2-acetoxyethyl, 
2-propionyloxyethyl, 2-acetoxybutyl, 4-acetoxybutyl, 2-propionyloxybutyl, 
2-benzoyloxyethyl, 3-acetoxypropyl, 2-(4-methylbenzoyloxy)ethyl), 
2-(3-methylbenzoyloxy)ethyl, 2- or 3-benzoyloxypropyl, 2- or 
4-benzoyloxybutyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, 
propoxycarbonylmethyl, butoxycarbonylmethyl, 2-methoxycarbonylethyl, 
2-ethoxycarbonylethyl, 2-propoxycarbonylethyl, 2-butoxycarbonylethyl, 
2-secbutoxycarbonylethyl, 2-(2-ethylhexyloxycarbonyl)ethyl, 
2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-butoxyethyl, 
2-phenoxyethyl, 2-(4-acetoxybutoxy)ethyl, 2-methoxypropyl, 2-ethoxypropyl, 
2-propoxypropyl, 1-methyl-2-methoxyethyl, 3-methoxypropyl, 3-ethoxypropyl, 
2-butoxypropyl, 6-phenoxy-4-oxahexyl, 2-ethoxy-4-oxahexyl, 
3-benzyloxypropyl, 2-, 3- or 4-chlorophenyl, 2-, 3- or 4-methylphenyl, 2-, 
3- or 4-methoxyphenyl, 
2-ethoxyphenyl,2,4-dichlorophenyl,4-dimethylaminophenyl and 
4-acetylaminophenyl. 
R.sup.3 and R.sup.4 are each for example hydrogen, chlorine, methyl, ethyl, 
propyl, isopropyl, butyl, isobutyl, secbutyl, methoxy, ethoxy, propoxy, 
isopropoxy, butoxy or sec-butoxy. 
R.sup.3 may also be for example acetylamino, propionylamino, butyrylamino, 
isobutyrylamino, benzoylamino, methylureido, butylureido, 
N,N-dimethylureido, methylsulfonylamino, ethylsulfonylamino, 
propylsulfonylamino or butylsulfonylamino. 
L is for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl or 
sec-butyl. 
Suitable leaving groups X are for example halogens, chloride, bromide or 
iodide, methosulfate, ethosulfate, methanesulfonate, benzenesulfonate and 
o- or p-toluenesulfonate. 
Suitable anions A.sup..crclbar. are for example the anions mentioned above 
under X and also acetate, sulfate and hydrogensulfate. 
The use of dimethyl sulfate or diethyl sulfate as alkylating agent is 
preferred, dimethyl sulfate being particularly preferred. 
Particular preference is given to a process where the quaternizable dyes 
used are those of the formula V 
##STR3## 
where 
Het is isothiazolyl, indazolyl or benzothiazolyl, which may each be 
substituted by C.sub.1 -C.sub.4 -alkoxy or halogen, and 
L.sup.1 and L.sup.2 are identical or different and each is independently of 
the other C.sub.1 -C.sub.6 -alkyl, which may be substituted by hydroxyl or 
cyano. 
Of particular suitability here are those dyes of formula V where Het is a 
radical of the formula 
##STR4## 
where L.sup.3 is hydrogen or C.sub.1 -C.sub.4 -alkyl, L.sup.4 is hydrogen 
or C.sub.1 -C.sub.4 -alkyl, L.sup.5 is hydrogen, C.sub.1 -C.sub.4 -alkyl 
or C.sub.1 -C.sub.4 -alkoxy, and Hal is chlorine or bromine. 
The process of the present invention is advantageously carried out by first 
introducing the .gamma.-butyrolactone as diluent into a stirred apparatus, 
then adding the neutral dyebase of the abovementioned formula II at from 
75.degree. to 100.degree. C, and finally, at from 80.degree. to 90.degree. 
C., with stirring, starting with the addition of the alkylating agent of 
the formula III, which will in general take from 0.5 to 1.5 hours. This is 
followed, at from 80.degree. to 90.degree. C., by a post addition stirring 
phase which in general takes from 3 to 7 hours. 
The molar ratio of alkylating agent III to dyebase II is in general 1:2.5, 
preferably 1:1.9. 
For each part by weight of dyebase II there will in general be used from 
0.3 to 0.9 part by weight of .gamma.-butyrolactone. 
After the reaction has ended, the reaction mixture is admixed at 
40.degree.-60.degree. C. with from 50 to 100% by weight of water, based on 
the weight of the reaction mixture, and heated with stirring at from 
50.degree. to 100.degree. C. for from 0.5 to 1 hour. This serves to 
destroy excess alkylating agent. 
The resulting solution of quaternized dye I in .gamma.-butyrolactone is 
already usable. However, it may be adjusted to specific color strength 
values by further diluting it, for example with water or acetic acid. 
The process of the present invention gives the target products in high 
yield and purity. The diluent employed in the process is readily 
biodegradable and, what is more, has the advantage that it is highly 
suitable for use as medium for the quaternized dyes; i.e., the reaction 
solutions obtained in the process of the present invention are directly 
ready-to-use. There is no need for diluent exchange. 
The quaternized dyes of the formula I are useful for dyeing polyamide or 
polyacrylonitrile fabric. 
The invention will now be more particularly described by way of example.

EXAMPLE 1 
147 g of .gamma.-butyrolactone were heated to 85.degree.-90.degree. C. and 
during the heating-up phase 335 g (1 mol) of the dye of the formula 
##STR5## 
were added. Then 238 g (1.88 mol) of dimethyl sulfate were added dropwise 
at 80.degree.-90.degree. C. in the course of one hour, and the mixture was 
subsequently -stirred at the stated temperature for 5 hours. 
The mixture was then cooled down to 50.degree. C., admixed with 500 ml of 
water and subsequently stirred at 70.degree. C. for 45 minutes to destroy 
excess dimethyl sulfate. Then 35 g of active charcoal were added and the 
mixture was filtered. 
The resulting solution of the dye of the formula 
##STR6## 
is ready-to-use. To adjust it to a specific color strength it was diluted 
with 317 g of acetic acid and 387 g of water. The resulting solution dyes 
polyacrylonitrile fabric in a blue shade. 
The same method gives the following dyes: 
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Hue on 
Example polyacrylonitrile 
No. Dye fabric 
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##STR7## CH.sub.3 SO.sub.4.sup..crclbar. 
violet 
3 
##STR8## CH.sub.3 SO.sub.4.sup..crclbar. 
blue 
4 
##STR9## CH.sub.3 SO.sub.4.sup..crclbar. 
blue 
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