Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2001-09-13
2003-01-07
Killos, Paul J. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C534S550000, C534S558000, C534S561000, C534S564000, C534S579000, C534S748000, C534S575000, C524S190000, C562S019000, C562S047000
Reexamination Certificate
active
06504045
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to novel crystal polymorphs (alpha, beta, gamma, delta, zeta and eta) of a yellow disazo colorant having the chemical structure (I), to their preparation and use as pigment.
The majority of organic pigments exist in a plurality of different crystal forms, also called polymorphs. Crystal polymorphs have the same chemical composition but a different arrangement of the building blocks (molecules) in the crystal. The crystal structure determines the chemical and physical properties; consequently, the individual polymorphs frequently differ in rheology, color and other coloristic properties. The different crystal polymorphs may be identified by means of X-ray powder diffractometry.
The compound of the formula (I) is formed by coupling one equivalent of 2-chloro-N,N′-1,4-diacetoacetylphenylenediamine (II) with two equivalents of diazotized dimethyl aminoterephthalate (III), and is described in DE-A-2 058 849.
CS-A-266 632 describes the treatment of amorphous N,N′-1,4-diacetoacetylphenylenediamine azo pigments in C
1-3
alcohols or in water at increased pressures of up to 6 bar and 100-150° C. The compound of the formula (I) is not mentioned in the examples there.
The process described in DE-A-2 058 849 gives the compound of the formula (I) as amorphous product to which no crystal phase can be assigned by X-ray powder diffractometry. Amorphous crude pigment obtained in accordance with DE-A-2 058 849 possesses a cloudy reddish yellow hue, inadequate color strength, poor rheological properties, and inadequate solvent resistance, light stability and weathering stability, and in this form is of no interest from an applications standpoint.
If the pigment of the formula (I) is subjected to a solvent treatment by the process described in CS-A-266 632, the resulting product is still substantially amorphous; no crystal polymorph can be assigned to it, and it differs markedly from the phases of the invention described below. The hue and properties of the pigment thus treated also remain virtually unchanged, and render the product of no interest from an applications standpoint.
SUMMARY OF THE INVENTION
It is an object of the present invention to convert the compound of the formula (I) into a form which is useful from an applications standpoint.
It has surprisingly been found that, by treatment in certain organic solvents, it is possible to produce a total of six defined, pure crystal phases of (I). The polymorphs are called &agr; (alpha), &bgr; (beta), &ggr; (gamma), &dgr; (delta), &zgr; (zeta), and &eegr; (eta). They feature the following characteristic lines in the X-ray powder diagram (Cu—K
&agr;
radiation, double the Bragg angle 2&THgr; in degrees, interplanar spacings d in Å
−1
):
relative
&agr;: 2&THgr;
d
intensity
6.1
14.6
100
8.2
10.8
34
9.0
9.9
13
14.1
6.3
15
15.2
5.8
6
15.8
5.6
12
17.0
5.2
6
22.1
4.0
8
23.6
3.8
8
24.0
3.7
15
24.8
3.6
8
25.3
3.5
52
26.1
3.4
29
27.3
3.3
40
28.8
3.1
17
relative
&bgr;: 2&THgr;
d
intensity
9.0
21.6
44
10.6
8.3
7
15.1
5.8
8
16.0
5.5
6
16.5
5.4
9
19.5
4.5
8
22.1
4.0
11
26.9
3.3
100
27.7
3.2
17
relative
&ggr;: 2&THgr;
d
intensity
5.9
14.9
98
8.0
11.1
25
8.7
10.1
9
9.6
9.2
9
11.8
7.5
11
13.8
6.4
14
14.9
5.9
7
15.5
5.7
13
16.6
5.3
11
17.6
5.0
8
18.3
4.9
7
22.8
3.9
9
24.1
3.7
17
24.4
3.6
24
25.5
3.5
100
26.1
3.4
17
26.4
3.4
30
27.2
3.3
32
27.4
3.2
47
29.0
3.1
20
relative
&dgr;: 2&THgr;
d
intensity
5.8
15.2
63
7.9
11.2
12
9.4
9.4
6
11.6
7.6
16
13.4
6.6
6
15.1
5.9
9
16.4
5.4
9
17.2
5.2
8
18.0
4.9
8
23.2
3.8
5
23.4
3.8
5
23.7
3.8
7
24.3
3.7
17
24.6
3.6
13
25.5
3.5
100
25.8
3.4
21
26.4
3.4
22
26.9
3.3
22
27.3
3.3
41
28.6
3.1
7
28.8
3.1
11
relative
&zgr;: 2&THgr;
d
intensity
7.0
12.6
7
8.9
9.9
23
11.2
7.9
10
11.9
7.4
48
13.2
6.7
6
14.0
6.3
7
15.1
5.9
26
17.2
5.1
37
18.0
4.9
14
18.2
4.9
27
21.5
4.1
33
21.8
4.1
27
22.6
3.9
13
23.9
3.7
100
24.7
3.6
13
25.2
3.5
17
25.9
3.4
7
26.9
3.3
76
27.1
3.3
92
27.8
3.2
7
29.9
3.0
6
31.1
2.9
7
31.7
2.8
9
32.3
2.8
7
33.0
2.7
8
relative
&eegr;: 2&THgr;
d
intensity
9.0
9.9
60
11.5
7.7
6
14.1
6.3
6
16.0
5.5
23
20.1
4.4
7
21.5
4.1
16
26.8
3.3
100
27.5
3.2
7
27.9
3.2
12
All of the line positions are given to an accuracy of ±0.2°.
In the solid state, the compound of the formula (I) may also exist in a different tautomeric and/or cis/trans-isomeric form.
All of the polymorphs differ in their X-ray diffraction diagrams and in terms of their properties from the products obtained in accordance with the known processes of DE-A-2 058 849 and CS-A-266 632. The novel polymorphs are of low solubility, are strongly colored and are notable for good fastness properties and brilliant yellow colorations.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a process for preparing crystal polymorphs of a disazo colorant of the formula (I), which comprises causing one or more solvents from the group consisting of dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, C
4
-C
20
alcohol, 1,2-dichlorobenzene, pyridine, and nitrobenzene, or combinations of these solvents with water, the water content being from 0 to 90% by weight, to act on a compound of the formula (I) or on a tautomer, cis/trans isomer or a tautomeric cis/trans isomer of the compound of the formula (I) at a temperature of at least 100° C.; this procedure is referred to below as “solvent treatment”.
To obtain a novel crystalline phase of the compound of the formula (I), it is possible to use amorphous crude pigment, another of said crystal polymorphs, or a mixture of two or more crystal polymorphs. The compound of the formula (I) may be present in the form, for example, of dry pigment, presscakes, or an aqueous suspension.
The solvent treatment takes place preferably at from 135 to 250° C., with particular preference at from 150 to 200° C. The duration of the solvent treatment is appropriately from 1 minute to 24 hours, preferably from 5 minutes to 10 hours, in particular from 10 minutes to 5 hours. It is appropriate to cool the pigment to room temperature before isolating it.
The yellow alpha (&agr;) polymorph is obtained, for example, by dissolving pigment of the formula (I) as the beta (&bgr;) polymorph in pyridine at from 110 to 130° C. and reprecipitating it by cooling.
The beta (&bgr;) polymorph is formed, for example, by heating crude pigment of the formula (I) to from 135 to 160° C. in dimethylformamide (DMF), N-methylpyrrolidone (NMP), or a mixture of DMF or NMP with water. The crystalline, greenish yellow pigment obtained possesses a brilliant hue, high opacity and color strength, very good solvent resistance, and excellent light and weather fastness.
The yellow gamma (&ggr;) polymorph is obtained, for example, by dissolving a pigment of the formula (I) as the beta (&bgr;) polymorph in o-dichlorobenzene at from 170 to 190° C. and reprecipitating it by cooling.
The yellow delta (&dgr;) polymorph is obtained, for example, by dissolving pigment of the formula (I) in the beta phase in dimethyl sulfoxide at from 180 to 200° C. and causing it to crystallize slowly by cooling. The delta polymorph is also formed if nitrobenzene at from 140 to 210° C. is used as solvent instead of dimethyl sulfoxide.
The zeta (&zgr;) polymorph is obtained, for example, by dissolving pigment of the formula (I) in the form of the beta phase in dimethylformamide at from 135 to 160° C., cooling the solution to below 50° C., and overlaying it with methanol. Yellow pigment crystallizes as the zeta (&zgr;) polymorph.
The eta (&eegr;) polymorph is obtained, for example, by heating amorphous crude pigment of the formula (I) to from 170 to 190° C. in o-dichlorobenzene, without dissolving it completely, and then cooling it again. The pigment possesses a brilliant greenish yellow hue, high opacity and color strength, and very good solvent, light and weather fastness.
Depending on the purity of the starting materials, the concentrations, the applied temperatures and temperature programs, any aftertreatment, the pressure, the presence of impurities or additives, and the presence of seed crystals, the cryst
Jung Ruediger
Metz Hans-Joachim
Schmidt Martin U.
Schupp Olaf
Wacker Andreas
Bisulca Anthony A.
Clariant GmbH
Killos Paul J.
Reyes Hector M
LandOfFree
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