Preparation of liquid formulations of basic azo dyes

Details Preparation of liquid formulations of basic azo dyes Preparation of liquid formulations of basic azo dyes

2003-04-10

2004-06-01

Powers, Rona T. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Azo

C534S614000, C534S688000

Reexamination Certificate

active

06743901

ABSTRACT:

DESCRIPTION
The present invention relates to a process for preparing liquid formulations of dyes of the general formula I
where
Y is chlorine or bromine,
Z is hydrogen, chlorine, bromine, sulfonic ester, nitro or optionally substituted sulfamoyl,
R is alkylene optionally interrupted by oxygen,
m is 1 or 2,
n is 0 or 1,
p is 0, 1 or 2,
An
⊖
is the equivalent of an anion,
R
1
and R
2
are independently hydrogen, optionally substituted alkyl, alkenyl, cycloalkyl, aralkyl or aryl or combine with the joining nitrogen to form a heterocycle,
R
3
is hydrogen or optionally substituted alkyl,
B is hydrogen or C
1
- to C
4
-alkyl,
B
1
is hydrogen, hydroxyl, C
1
- to C
4
-alkoxy or C
1
- to C
4
-alkyl, where
R
4
is optionally substituted alkyl and
R
5
is hydrogen or C
1
- to C
4
-alkyl, and the radical
may also be an optionally substituted piperazine radical, by diazotizing an amine of the formula II
and then coupling the diazonium salt onto a compound of the formula III
and also optionally adding solubilizing additives.
Basic azo dyes of the general formula I are known from EP-A-0 162 409. Liquid formulations with desired counterions such as acetate are prepared by dissolving the interveningly isolated dye in the desired acid such as acetic acid. The intervening isolation is necessary to free the dye of unwanted salt. However, intervening isolations are costly and inconvenient from a processing viewpoint, since they require additional crystallization, suction filtration and washing of the dye.
It is an object of the present invention to provide a process leading to stable dye solutions which can be used directly, without intervening isolation, as liquid formulations or as a basis therefor. Costly and inconvenient isolating operations of the dye shall be avoided. Moreover, the liquid formulations shall be minimally corrosive, if at all, with regard to alloyed steels.
We have found that this object is achieved by effecting said diazotizing at a pH set to an acidic value using pure methanesulfonic acid or at least 20 mol %, preferably ≧50 mol % and especially ≧80 mol % mixtures of methanesulfonic acid in monobasic acids.
Pure methanesulfonic acid is to be understood as meaning using methanesulfonic acid as sole acidifying agent. Monobasic acids can be monobasic mineral acids or carboxylic acids, such as hydrochloric acid, hydrogen bromide, formic acid, acetic acid, hydroxyacetic acid, aminoacetic acid, methoxyacetic acid, propionic acid, lactic acid, benzoic acid, benzenesulfonic acid and toluenesulfonic acid.
It is preferable to set the pH for the diazotization to an acidic value using pure methanesulfonic acid or at least 20 mol %, preferably ≧50 mol % and especially ≧80 mol % mixtures of methanesulfonic acid in monobasic carboxylic acids.
Preference is given to formic acid, acetic acid, propionic acid and lactic acid in particular. The pH for the diazotization is preferably set using a mixture of methanesulfonic acid in formic acid.
The acidifying is preferably carried out in such a way that the diazotization pH is in the range from 0 to 3, more preferably in the range from 1.0 to 2.5 and especially 2.
Preferably, the acidifying is effected using methanesulfonic acid alone. In this case, methanesulfonic acid is preferably used in a molar ratio in the range from 2.5/1 to 3.5/1 based on 1 mol of amine II. A larger methanesulfonic acid excess leads to an increased salt content and therefore is undesirable. Particular preference is given to using 2.8-3 mol of methanesulfonic acid per mole of amine II.
In general, the amine II will be dissolved in the mixture of water and methanesulfonic acid. Solubilizing additives often used in liquid formulations can, if desired, already be present in the reaction mixture. Solubilizing additives are specified hereinbelow and are water-miscible organic solvents and also ureas and lactams. Preferably, no solubilizing additives are used. Instead, it is preferable to use water as sole solvent for diazotizing and coupling for dye I.
The diazotization is effected using customary diazotizing agents such as nitrous acid which is formed from an alkali metal nitrite at an acidic pH. Useful diazotizing agents further include nitrosylsulfuric acid and the neopentylglycol ester of nitrous acid.
After excess nitrite has been destroyed, with sulfamic acid for example, the compound III is added, generally as an aqueous solution. This coupling is preferably carried out in the pH range from 3 to 6 and more preferably from 4 to 4.5. The pH should not exceed 7, since otherwise the dye will start to crystallize. However, if the solubilizing additives specified hereinbelow are added, the stability with regard to crystallization is distinctly increased.
The coupling pH is set using agents known to one skilled in the art. Useful bases for this include for example sodium acetate, aqueous sodium hydroxide solution, sodium carbonate, sodium bicarbonate and amines such as ethanolamine.
The diazotization is effected in a conventional manner at from −5 to 25° C. To carry out the coupling reaction, the reaction mixture is allowed to warm and is if necessary heated to 30° C. to complete the reaction.
The process is useful for preparing solutions of the dye of the general formula I.
Any alkyl and alkylene appearing in the abovementioned formula can be both straight-chain and branched. In substituted alkyl appearing in the abovementioned formula, possible substituents include for example hydroxyl and methoxy. The alkyl groups will then generally contain one or two substituents.
Useful anions An
⊖
include for example monomethylsulfate, ethylsulfate, aminosulfonate, chloride, bromide, formate, acetate, hydroxyacetate, aminoacetate, methoxyacetate, propionate, lactate, benzoate, benzenesulfonate and toluenesulfonate.
Useful Z radicals in addition to those already mentioned include C
1
-C
4
sulfonic esters whose alkyl radical is optionally substituted by mono- or di-(C
1
-C
6
)-alkylamino or morpholino, such as SO
2
OC
2
H
4
N(CH
3
)
2
, SO
2
OC
2
H
4
N(C
2
H
5
)
2
, SO
2
OC
2
H
4
N(C
3
H
7
)
2
, SO
2
OC
2
H
4
N(C
4
H
9
)
2
, SO
2
OC
2
H
4
N(CH
2
CH
2
)
2
O, SO
2
OCH(CH
3
)CH
2
N(CH
3
)
2
, SO
2
OCH(CH
3
)CH
2
N(C
2
H
5
)
2
, SO
2
OC
4
H
8
N(CH
3
)
2
or SO
2
OC
4
H
8
N(C
2
H
5
)
2
.
Further examples of Z are sulfamoyl, phenylsulfamoyl or mono- or di-(C
1
-C
4
)-sulfamoyl, whose alkyl radicals are optionally substituted by hydroxyl or methoxy, such as methylsulfamoyl, mono- or dimethylsulfamoyl, mono- or diethylsulfamoyl, mono- or dipropylsulfamoyl, mono- or dibutylsulfamoyl, mono- or dihydroxyethylsulfamoyl or N-methyl-N-hydroxyethylsulfamoyl.
Alkylene R has for example from 2 to 10 carbon atoms and is optionally interrupted from 1 to 3 times by oxygen, —NR
5
— or
Specific examples are:
C
2
H
4
, C
3
H
6
, CH(CH
3
)—CH
2
, CH
2
—CH(CH
3
)—, C
4
H
8
, CH(C
2
H
5
)—CH
2
, C
6
H
12
, CH
2
—C(CH
3
)
2
—CH
2
, —C(CH
3
)
2
—CH
2
—C(CH
3
)
2
—, C
2
H
4
OC
2
H
4
, C
3
H
6
OC
3
H
6
, C
3
H
6
OC
2
H
4
OC
3
H
6
, C
3
H
6
OC
4
H
8
OC
3
H
6
, C
3
H
6
OC
2
H
4
OC
2
H
4
OC
3
H
6
, C
2
H
4
NHC
2
H
4
, C
2
H
4
NHC
3
H
6
, C
3
H
6
NHC
3
H
6
, C
3
H
6
NHC
2
H
4
NHC
3
H
6
, C
3
H
6
NHC
6
H
12
NHC
3
H
6
,
R
1
and R
2
are independently for example C
1
-C
14
-alkyl, with or without hydroxyl, C
1
-C
8
-alkoxy, N—C
5
-C
8
-cycloalkylamino, N,N-di-(C
1
-C
4
-alkyl)amino substitution, C
2
-C
6
-alkenyl or C
5
-C
8
-cycloalkyl.
Specific examples of R
1
and R
2
in addition to those already mentioned include: methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, n-amyl, i-amyl, n-hexyl, i-hexyl, heptyl, octyl, 2-ethylhexyl, decyl, dodecyl, tridecyl, tetradecyl, 2-hydroxyethyl, 2- or 3-hydroxypropyl, hydroxybutyl, allyl, methallyl, cyclopentyl, cyclohexyl or cyclooctyl, N,N-dimethylaminoethyl, N,N-diethylaminoethyl, N,N-dipropylaminoethyl, N,N-dibutylaminoethyl, 3-(N,N-dimethylamino)-propyl, 3-(N,N-diethylamino)-propyl, 3-(N,N-dipropylamino)-propyl or 3-(N,N-dibutylamino)-propyl, N-cyclohexylaminoethyl, 3-(N-cyclohexylamino)-propyl, 3-(N-cyclooctylamino)-propyl, N-methyl-

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