(C)CRYSTAL COMPOSITION (CC) COMPRISING 4,4'-DICHLORODIPHENYLSULFONE CRYSTALS (C)

Abstract

The invention relates to crystals (C) consisting of at least 98% by weight of 4,4′-dichlorodiphenylsulfone, 0 to 2% by weight of impurities and 0 to 2% by weight of at least one solvent (c). Moreover, the present invention relates to a crystal composition (CC) comprising crystals (C) and a process for the production of the crystal composition (CC) and the crystals (C).

Claims

1.-15. (canceled)

16. A crystal composition (CC) comprising crystals (C), wherein the crystals (C) consist of (a) at least 99.95% by weight of 4,4′-dichlorodiphenylsulfone, (b) 0 to 0.05% by weight of impurities, and (c) 0 to 0.05% by weight of at least one solvent, based on the total weight of the crystals (C) contained in the crystal composition (CC), wherein the crystal composition (CC) has a bulk density determined according to EN ISO 60:2000-01 in the range of 570 to 750 kg/m.sup.3.

17. The crystal composition (CC) according to claim 16, wherein the crystal composition (CC) comprises at least 95% by weight of crystals (C), based on the total weight of the crystal composition (CC).

18. The crystal composition (CC) according to claim 16, wherein the tapered density determined according to DIN ISO 787 part 11 of the crystal composition (CC) is in the range of 750 to 850 kg/m.sup.3.

19. The crystal composition (CC) according to claim 16, wherein the Hausner ratio of the crystal composition (CC) is in the range of 1.05 to 1.25.

20. The crystal composition (CC) according to claim 16, wherein the flowability (ff.sub.c) according to Jenike of the crystal composition (CC) is in the range of 10 to 50.

21. The crystal composition (CC) according to claim 16, wherein the average aspect ratio of the crystals (C) contained in the crystal composition (CC) is in the range of 0.2 to 1.

22. The crystal composition (CC) according to claim 16, wherein the average sphericity (SPHT.sub.3) of the crystals (C) contained in the crystal composition (CC) is in the range of 0.6 to 0.9.

23. The crystal composition (CC) according to claim 16, wherein the crystal composition (CC) has a d10x.sub.c min-value in the range of 30 to 120 μm, a d50x.sub.c min-value in the range of 150 to 350 μm and a d90x.sub.c min-value in the range of 300 to 600 μm.

24. The crystal composition (CC) according to claim 16 has an APHA-color number determined according to ASTM D1209 in the range of 0 to 50.

25. The crystal composition (CC) according to claim 16, wherein the impurities (b) comprise at least 90% by weight of one or more compounds selected from the group consisting of 2,4′-dichlorodiphenylsulfone, 3,4′-dichlorodiphenylsulfone, 4,4′-dichlorodiphenylsulfoxide, 2,4′-dichlorodiphenylsulfoxide and one or more carboxylic acid compound(s), in each case based on the total weight of the impurities (b) contained in the crystals (C).

26. The crystal composition (CC) according to claim 16, wherein the overall content of the isomers 2,4′-dichlorodiphenylsulfone and 3,4′-dichlorodiphenylsulfone, in the crystals (C) is in the range of 0 to 300 ppm by weight, based on the total weight of the crystals (C).

27. The crystal composition (CC) according to claim 16, wherein the content of monochlorobenzene in the crystals (C) is in the range of 0 to 50 ppm by weight, in each case based on the total weight of the crystals (C).

28. The crystal composition (CC) according to claim 16, wherein the content of toluene in the crystals (C) is in the range of 0 to 50 ppm by weight, in each case based on the total weight of the crystals (C).

29. The crystal composition (CC) according to claim 16, wherein the overall content of the isomers 4,4′-dichlorodiphenylsulfoxide and, 2,4′-dichlorodiphenylsulfoxide, in the crystals (C) is in the range of 0 to 50 ppm by weight, based on the total weight of the crystals (C).

30. The crystal composition (CC) according to claim 16, wherein the overall content of the carboxylic acid compound(s) in the crystals (C) is in the range of 0 to 200 ppm by weight, based on the total weight of the crystals (C).

Description

EXAMPLES

1. Inventive Example

Production of the Crystal Composition (CC)/the Crystals (C) According to the Invention

Step 1: Production of 4,4′-dichlorodiphenyl sulfoxide (DCDPSO)

[0077] 5.5 mol aluminum chloride and 40 mol monochlorobenzene were fed into a stirred tank reactor as first reactor. 5 mol thionyl chloride were added to the reaction mixture in 160 min. The reaction in a first reactor was carried out at 10° C. Hydrogen chloride produced in the reaction was withdrawn from the process. After finishing the addition of thionyl chloride the reaction mixture was heated to 60° C.

[0078] After finishing the reaction in the first reactor the resulting reaction mixture was fed into a second stirred tank reactor which contained 3400 g hydrochloric acid with a concentration of 11 wt-%. The second stirred tank reactor was heated to a temperature of 90° C. After 30 min the mixing was stopped and the mixture separated into an aqueous phase and an organic phase.

[0079] The aqueous phase was withdrawn and the organic phase was washed with 3000 g water while stirring at 90° C. After washing, stirring was stopped and the mixture separated into an aqueous phase and an organic phase.

[0080] The aqueous phase was removed and the organic phase was subjected to a distillation. Monochlorobenzene was distilled from the organic phase until saturation was reached at about 88° C. (monitored via a turbidity probe, distillation conditions: 200 mbar(abs)). The organic phase was cooled by reducing the pressure until the temperature reached 30° C.

[0081] By the cooling a suspension was obtained containing crystallized DCDPSO. The suspension then was filtrated to obtain a filter cake comprising crystallized DCDPSO, which was washed with 550 g monochlorobenzene.

[0082] The combined mother liquor and the monochlorobenzene which was used for washing were subjected to a distillation. In the distillation monochlorobenzene was removed until the amount of combined mother liquor and washing filtrate was reduced to 25 wt %. The distillation was operated at a bottom temperature of 90° C. and 200 mbar(abs).

[0083] While the distilled monochlorobenzene was reused in the next batch as starting material, 80 wt % of the obtained bottom product were transferred into the crystallization of the next batch.

[0084] After washing with monochlorobenzene, the thus obtained monochlorobenzene-wet filter cake comprising crystallized DCDPSO was washed with 300 g n-heptanoic acid and filtrated to obtain n-heptanoic acid wet DCDPSO as filter cake.

[0085] The filtrate was subjected to distillation yielding a top fraction of monochlorobenzene and a bottom fraction containing n-heptanoic acid and DCDPSO. The bottom fraction was topped up with fresh n-heptanoic acid and reused in the next filtration. The distillation was operated at a bottom temperature of 140° C. and 100 mbar(abs).

[0086] The 4,4′-dichlorodiphenyl sulfoxide yield in the steady state was 1232 g which corresponds to a yield of 91.3%.

[0087] The n-heptanoic acid wet DCDPSO had a purity of 89.7 wt %, containing 8.9 wt % n-heptanoic acid, 0.8 wt % monochlorobenzene, 0.3 wt % 4,4′-dichlorodiphenylsulfide and 0.3 wt % 2,4′-dichlorodiphenylsulfoxide.

Step 2: Production of 4,4′-dichlorodiphenyl sulfone (DCDPS)

[0088] 1113 g of the n-heptanoic acid wet 4,4′-dichlorodiphenyl sulfoxide obtained in step 1 were dissolved in 2900 g n-heptanoic acid and heated to 90° C. 7.2 g sulfuric acid were added to the solution. Over a period of 3 h and 10 min 143 ml H.sub.2O.sub.2 were added to the solution with a constant feed rate. During the reaction the temperature in the vessel was controlled to 90° C. by wall cooling, whereby the temperature in the reactor was determined to be 97 to 99° C. After finishing this step, the reactor was stirred for 15 minutes at a temperature of 97° C. Then, a second amount of 7 ml H.sub.2O.sub.2 was added within 10 minutes. After completing the H.sub.2O.sub.2 dosage the temperature of the solution was raised to 100° C. The reactor was stirred for 20 minutes at a temperature of 100° C.

[0089] To the resulting reaction mixture comprising DCDPS and n-heptanoic acid, 881 g water were added with a temperature of 97° C. The thus obtained mixture was cooled by reducing the pressure according to the cooling profile shown in table 1.

TABLE-US-00003 TABLE 1 cooling profile time [h] temperature [° C.] pressure [mbar] 0:00 97 760 0:50 81 380 01:15  90 580 1:45 90 580 2:45 81 370 3:40 61.5 175 4:35 43 70 6:00 18 980

[0090] A suspension comprising 2480 g n-heptanoic acid and DCDPS was obtained by this process.

[0091] The suspension then was filtered at ambient temperature to obtain a filter cake comprising about 80 wt % DCDPS, 16 wt % n-heptanoic acid and 4 wt % water. The mother liquor which was separated off the filter cake in the filtration process contained about 78 wt % n-heptanoic acid, 20 wt % water and about 2.5 wt % DCDPS. For filtering the suspension, a glass nutsche was used which was covered with a Sefar® Tetex DLW 17-80000-SK 020 Pharma filter cloth. For filtering, an absolute pressure of 500 mbar was set below the nutsche. After filtration, the filter cake was treated with dry air for 30 s.

Step 3: Washing the DCDPS with an Aqueous Base and Water

[0092] The filter cake obtained in step 2 then was washed with 2 kg of diluted NaOH 5%. For washing a pressure of 750 mbar(abs) were set to the filtrate side of the nutsche.

[0093] Washing with diluted NaOH was followed by washing with 1.5 kg water. For washing with water a pressure of 500 mbar(abs) were set to the filtrate side of the nutsche. Subsequently the filter cake was treated for 30 seconds with dried air.

[0094] After washing and treating with dried air, the filter cake contained about 20 wt % water and 0.24 wt % n-heptanoic acid. The final filter cake mass was 1369 g.

[0095] The mother liquor obtained in the filtration process was subjected to a phase separation. By phase separation, 482 g aqueous phase and 2712 g organic phase were obtained.

Step 4: Re-Crystallization of the DCDPS to Obtain the Crystal Composition (CC)/the Crystals (C)

[0096] 500.4 g of the filter cake obtained in step 3 containing 115 g water and containing about 0.24% n-heptanoic acid and about 240 ppm isomers of 4,4′-DCDPS were suspended into 1385 g methanol. This mixture was heated to a temperature of 100° C. in a closed vessel. The temperature was kept at 100° C. for 2 h and 20 min. Then the pressure in the vessel was reduced and methanol started to evaporate. Evaporation of methanol resulted in crystallization of the DCDPS (crystals (C)). The temperature in the vessel was reduced linearly with a rate of 10 Kelvin per hour until a temperature of 10° C. was reached. After this temperature was reached, the vessel was vented until ambient pressure was achieved. The thus obtained mixture of crystallized DCDPS (crystals (C)) and methanol was filtered in a filter nutsche. By this filtration a wet filter cake which weighted 613.5 g was obtained. The wet filter cake was washed with 400 g fresh methanol. Afterwards, the washed wet filter cake was dried for 5 hours in a Rotavapor® rotary evaporator with a wall temperature of 130° C. The thus obtained product (crystal composition (CC)) had given in the below table 2.

[0097] The particle analysis of the crystal composition (CC) obtained in step 4 gives the following result:

[0098] d10x.sub.c min-value: 46 μm,

[0099] d50x.sub.c min-value: 181 μm,

[0100] d90x.sub.c min-value: 354 μm

[0101] Sphericity (Spht3): 0.822

[0102] Aspect ratio (b/l3): 0.636

[0103] The crystal composition (CC) obtained in step 4 had a bulk density of 706 kg/m.sup.3, a tapered density (1250 lifts) of 819 kg/m.sup.3, a Hausner ratio of 1.16, a flowability according to Jenike of 24 and an APHA number of 24.

[0104] Analytical Methods

[0105] The d10x.sub.c min-values, the d50x.sub.c min-values and the d90x.sub.c min-values, sphericity (Spht3) and aspect ratio (b/l3) are determined as described above using a Camsizer®.

[0106] GC analysis was performed to determine any impurity (DCDPS Isomers, DCDPSO, monochlorobenzene, water), solvent (Methanol) and the purity of the 4,4′-dichlorodiphenylsulfone. Samples were diluted in dimethylformamide (DMF) and the internal standard tridecane was added to quantify the components based on calibration curves. GC analysis was performed using a RTx5 Amine column (0.25 μm) from Restek® using the following temperature ramp: holding 50° C. for 2 minutes, heating 15° C. per minute until 250° C. is reached, holding 250° C. for 15 minutes. The column has a length of 30 m, an internal diameter of 250 μm and a film thickness of 0.25 μm. Helium is used as carrier gas with 1 ml/min (constant flow). The split ratio is 200:1. The injection and detector temperature are 300° C. The injection volume is 1 μl.

[0107] APHA numbers were measured (as described above) on a Hach Lange LICO 500 instrument; 2.5 g 4,4′-dichlorodiphenylsulfone were dissolved in 20 mL N-methyl-2-pyrrolidone (NMP) and measured against pure NMP.

[0108] The flowability according to Jenike, the Hausner ratio, the bulk density and the tapered density (1250 lifts) were determined as described above.

2. Storage Tests

[0109] Storage tests were conducted at 25° C. and 50% relative humidity (condition i) and at 40° C. and 90% relative humidity (condition ii). The crystal composition (CC) of the inventive example was stored under the above mentioned conditions. The sample was examined after 2 and 4 weeks.

[0110] After 2 weeks and after 4 weeks of storage the sample of the inventive example under condition i as well as under condition ii was still free flowing.

TABLE-US-00004 TABLE 2 BASF Aldrich Alfa Aeser TCI 4,4′-DCDPS 99.978 wt % 99.92 wt % 99.82 wt % 99.69 wt % DCDPS Isomers* 90 ppm 170 ppm 370 ppm 40 ppm DCDPSO** 0 40 ppm 190 ppm 780 ppm Methanol 120 ppm 0 0 0 Monochlorbenzene 0 0 0 0 Toluene 0 520 ppm 690 ppm 110 ppm n-Heptanoic acid <20 ppm 0 0 0 *total amount of 2,4′-dichlorodiphenylsulfone and 3,4′-dichlorodiphenylsulfone **total amount of 2,4′-dichlorodiphenylsulfoxide and 4,4′-dichlorodiphenylsulfoxide 0 means not detectable via GC ppm refer to weight ppm w missing amounts to 100 wt % are other impurities

[0111] Moreover, samples of 4,4′-dichlorodiphenylsulfone (4,4′-DCDPS) were obtained from the commercial suppliers Sigma Aldrich, Alfa Aesar and TCI. The compositions of the commercial available 4,4′-dichlorodiphenylsulfone samples are given above in table 2. The bulk density, the tapered density, the Hausner ratio and the flowability according to Jenike for the commercial samples are given below in table 3.

TABLE-US-00005 TABLE 3 Tapered Hausner Bulk density density ratio Supplier kg/m3 1250 kg/m3 1250 ffc Aldrich 684 838 1.23 11 TCI 837 974 1.16 242 Alfa Aesar 579 759 1.31 6

[0112] Example 2 of CN 106588719 was repeated. The purity of the obtained 4,4′-dichlorodiphenylsulfone was determined via GC analysis as described above. The purity was 99.69 wt %.

[0113] As can be seen from the examples above, the crystal composition (CC) according to the invention show high purity combined with a low bulk density and a good flowability. Moreover, the crystal composition (CC) according to the invention has a good storability.

[0114] The 4,4′-dichlorodiphenylsulfone compositions known in the state of the art show a higher amount of impurities as well as a higher amount solvents. To improve the purity of the commercial 4,4′-dichlorodiphenylsulfone samples these samples are dissolved in acetone and recrystallized. The recrystallization from acetone leads to a higher purity. However, after the recrystallization of the commercial samples they show a higher bulk density and a poor flowability.

FIGURES

[0115] FIG. 1A illustrates the measurement of X.sub.c min

[0116] FIG. 1B illustrates the measurement of X.sub.Fe max