Organic compounds -- part of the class 532-570 series – Organic compounds – Chalcogen in the nitrogen containing substituent
Reexamination Certificate
2001-10-22
2003-09-16
Shah, Mukund J. (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Chalcogen in the nitrogen containing substituent
C008S506000, C008S648000
Reexamination Certificate
active
06620931
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to novel crystal polymorphs of methyl-substituted benzimidazolone-dioxazine pigment of the formula (1)
The compound of the formula (1) was first described in DE-A-44 42 291. An alternative synthesis of analogous compounds is described in EP-A-0 911 337.
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 crystal polymorphs frequently differ in rheology, color, and other coloristic properties. The different crystal polymorphs may be identified by means of X-ray powder diffractometry.
At the present time there are two known crystal polymorphs of the dioxazine pigment of the formula (1), which are referred to below as phase I and phase III and are distinguished by 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
):
2&THgr;
d
rel. intensity
Phase I:
5.00
17.68
28
6.08
14.53
14
(broad)
10.58
8.35
24
10.98
8.05
24
20.38
4.35
11
(broad)
22.20
4.00
10
(broad)
25.18
3.53
11
(broad)
27.16
3.28
100
Phase III:
5.22
16.92
23
broad
6.18
14.30
24
broad
10.92
8.09
17
broad
11.81
7.49
30
broad
12.34
7.17
35
broad
14.32
6.18
13
broad
17.07
5.19
10
broad
20.31
4.37
12
broad
23.16
3.84
14
broad
25.64
3.47
18
broad
26.99
3.30
100
The line positions noted as being “broad” are given to an accuracy of ±0.4°, all other line positions to an accuracy of ±0.2°.
Phases I and III develop during the synthesis of the dioxazine pigment of the formula (1) in accordance with DE-A-44 42 291 or EP-A-0 911 337.
SUMMARY OF THE INVENTION
It has now surprisingly been found that novel crystal polymorphs are formed if the pigment of the formula (1) is treated with certain organic solvents. This is all the more surprising since treating the analogous pigment of the formula (2) with organic solvents is not accompanied by the development of any new crystal phases.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The novel crystal polymorphs of the dioxazine pigment of the formula (1) are referred to as phases II, IV, V and VI.
They are distinguished by the following characteristic lines (Cu—K
&agr;
radiation, 2&THgr; in degrees, d in Å
−1
):
2&THgr;
d
rel. intensity
Phase II:
6.64
13.29
21
11.05
8.00
8
12.49
7.08
46
13.41
6.60
6
14.60
6.06
10
17.08
5.19
7
19.87
4.46
7
20.93
4.24
4
22.24
3.99
4
23.35
3.81
8
25.36
3.51
11
26.90
3.31
100
29.06
3.07
5
30.48
2.93
8
32.11
2.79
8
33.17
2.70
4
Phase IV:
6.51
13.56
96
11.15
7.93
100
13.09
6.76
24
14.49
6.11
41
19.63
4.52
27
22.40
3.97
28
23.67
3.76
23
25.34
3.51
23
27.47
3.24
95
29.49
3.03
18
Phase V:
5.04
17.51
13
7.53
11.73
12
7.95
11.12
13
9.38
9.42
15
10.32
8.57
14
10.94
8.08
15
12.33
7.17
10
13.49
6.56
9
14.94
5.92
8
16.51
5.36
9
17.04
5.20
8
18.27
4.85
9
19.75
4.49
9
21.08
4.21
8
22.26
3.99
9
24.12
3.69
7
25.17
3.53
7
27.25
3.27
100
30.44
2.93
6
Phase VI:
6.83
12.94
69
9.36
9.45
32
9.88
8.95
23
13.69
6.46
36
14.29
6.19
20
14.87
5.95
24
15.44
5.74
39
15.89
5.57
23
18.22
4.87
35
18.67
4.75
44
19.68
4.51
20
19.81
4.48
21
20.32
4.37
30
21.09
4.21
26
21.49
4.13
31
21.77
4.08
30
22.41
3.96
23
22.58
3.93
23
23.52
3.78
24
24.69
3.60
24
25.07
3.55
19
26.56
3.35
100
28.44
3.14
45
29.21
3.05
16
29.99
2.98
17
30.51
2.93
15
All of the line positions of phases II, IV, V and VI are given to an accuracy of ±0.2°.
The abovementioned phases are of extremely low solubility and feature good fastness properties and violet colorations.
The different phases exhibit different coloristic properties.
In the solid state, the compound of the formula (1) may also be present in a different tautomeric and/or isomeric form.
The invention provides a process for the phase conversion of a compound of the formula (1)
or of an isomer, tautomer or isomeric tautomer thereof, which comprises causing to act on the compound of the formula (1) an organic solvent selected from the group consisting of N-methylpyrrolidone, C
1
-C
20
-alcohol, e.g. methanol, ethanol, n-propanol, iso-propanol, n-, iso- or tert-butanol, 1,2,4-trichlorobenzene, dichloroacetic acid and trifluoroacetic acid, or a mixture of said solvents, or a mixture of 1,2-dichlorobenzene and trifluoroacetic acid, at a temperature of between 0 and 250° C., preferably between 20 and 210° C.
The process of the invention is appropriately conducted such that the compound of the formula (1) is suspended or fully or partly dissolved in the respective organic solvent and the mixture is held at the stated temperature for from 10 minutes to 48 hours, preferably from 30 minutes to 24 hours.
The starting material for preparing the phases of the invention is preferably the compound of the formula (1) in phase I, although it is also possible in each case to use the measures described to convert one or more of the novel crystal phases into one of the other said crystal phases.
Phase II is obtained, for example, by heating the pigment of the formula (1) to boiling with N-methylpyrrolidone.
Phase IV is obtained, for example, by dissolving the pigment of the formula (1) in trifluoroacetic acid and reprecipitating it by adding acetic acid.
Phase V is obtained, for example, by dissolving the pigment of the formula (1) in a mixture of trifluoroacetic acid and o-dichlorobenzene, preferably in a ratio of from 1:10 to 10:1, in particular from 1:2 to 2:1, and reprecipitating the pigment by evaporating the trifluoroacetic acid.
Phase VI is obtained, for example, by dissolving the pigment of the formula (1) in trifluoroacetic acid and reprecipitating the pigment by evaporating the trifluoroacetic acid.
Depending on the purity of the reactants, the concentrations, the temperatures and temperature programs employed, any aftertreatment, the pressure, the presence of impurities or additives, and the presence of seed crystals, it is possible for pure phase II, IV, V or VI, or a mixture comprising two or more of these phases to be formed.
The present invention therefore additionally provides a mixture of pigments of the formula (1) comprising at least 10%, preferably at least 25%, in particular at least 50%, with particular preference at least 75% and with very particular preference at least 90% of phase II, of phase IV, of phase V, of phase VI, or a mixture of two, three or four of these phases.
Depending on the desired field of application, it may be sensible to subject the resulting pigment to mechanical fine division. The fine division may be carried out by wet or dry grinding or by kneading. Grinding and/or kneading may be followed by treatment with a solvent, with water, or with a solvent/water mixture.
To facilitate the change of polymorph, to stabilize the polymorphs of the invention, to enhance the coloristic properties, and to achieve particular coloristic effects it is possible at any point in the process to add pigment dispersants, surface-active agents, defoamers, extenders or other additives. It is also possible to use mixtures of these additives. The additives may be added all at once or in two or more portions. The additives may be added at any point in the synthesis or in the various aftertreatments, or following the aftertreatments. The point in time that is best suited must be determined beforehand by means of rangefinding tests.
The dioxazine pigment of the formula (1) in phase II, IV, V or VI, or a mixture comprising these phases, is suitable for pigmenting coating materials, plastics, and cosmetics, for producing printing inks, for printing paper and textiles, for example, and pigment preparations, for the pulp dyeing of paper, and for coloring seed.
The abovementioned phases and phase mixtures of the dioxazine pigment of the formula (1) are suitable for use as colorants in electrophotographic toners and developers, such as one- or two-component powder toners (also called one- or two-c
Born Roland
Kempter Peter
Schmidt Martin U.
Bisulca Anthony A.
Clariant GmbH
McKenzie Thomas
Shah Mukund J.
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