Apparatus for vacuum purification

Abstract

The present invention relates to a process for the vacuum purification of chemical compounds and to an apparatus for carrying out this process.

Claims

1. Apparatus for the sublimation of chemical compounds, comprising an oven (1), a sublimer unit (2), a condensation unit (3), which is in contact with the sublimer unit, a rotation drive (4) for rotation of the sublimer and condensation units, and a vacuum pump or vacuum-pump system (6), characterised in that the apparatus has, between the rotating part and the fixed part, a rotation coupling (5), which is selected from a rotary feedthrough with ferrofluidic seal or a double- or triple-acting mechanical face seal.

2. Apparatus according to claim 1, characterised in that the oven is a hot-air oven or a radiation oven.

3. Apparatus according to claim 1, characterised in that it has a plurality of condensation units, which can be heated to different temperatures.

4. Apparatus according to claim 1, characterised in that the rotation drive is integrated into the rotation coupling.

5. Apparatus according to claim 1, characterised in that the vacuum-pump system consists of a multistage system comprising a pre-pump, in particular an oil pump or a dry-running scroll pump, a rotary vane pump or a Roots pump, and a high-vacuum pump, in particular a turbomolecular pump or an oil diffusion pump.

6. Apparatus according to claim 1, characterised in that the sublimer unit (2) is connected to the condensation unit (3) in a vacuum-tight manner or in that the sublimer unit (2) and the condensation unit (3) are surrounded by a tube and the vacuum is applied to the surrounding tube.

7. Apparatus according to claim 1, characterised in that the sublimer unit and the condensation unit are arranged horizontally or in that the sublimer unit and condensation unit are tilted to the horizontal, where angles of 1 to 10 are preferred.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically illustrates an apparatus for carrying out the process according to the invention;

(2) FIG. 2 illustrates an apparatus with carrier-gas feed;

(3) FIG. 3 illustrates an apparatus for semi-continuous work;

(4) FIG. 4 illustrates an apparatus for carrying out the process according to the invention with a plurality of heating zones;

(5) FIG. 5 illustrates an apparatus with sublimer and condensation units with surrounding glass tube;

(6) FIG. 6 illustrates suitable vessel shapes for sublimer and condensation units which are permanently connected;

(7) FIG. 7 illustrates suitable vessel shapes for sublimer and condensation units which are not permanently connected; and

(8) FIG. 8 illustrates a complete design of the sublimation apparatus according to the invention.

(9) In the process according to the invention, the sublimation material is heated in the sublimer unit (2) in vacuo in the oven (1) and converted into the gas phase, with the sublimer unit rotating during the sublimation operation. The rotational speed here is preferably in the range from 0.5 to 100 min.sup.1, particularly preferably in the range from 1 to 20 min.sup.1, very particularly preferably in the range from 1.5 to 10 min.sup.1, in particular in the range from 2 to 5 min.sup.1. The rotation here is usually only switched on after the heating, but may also be switched on before the heating. The temperature here is adjusted via the sublimation or evaporation temperature given at the respective pressure until a technically useful evaporation rate is achieved. In general, it is preferred for the evaporation rate to be as high as possible. A technically useful evaporation rate is in the range between 10 and 1000 g/h, depending on the application and depending on the class of active compound. Depending on the class of compound, even an evaporation rate in the range between 1 and 10 g/h may also be technically useful. This is useful, in particular, in the case of organometallic compounds, as are employed for organic semiconductor components, since it is frequently difficult to sublime these compounds at all without decomposition. The evaporation here, as described above, can take place both from the solid and also from the melt.

(10) The sublimation or evaporation temperature of the compounds here at a pressure in the range from 10.sup.3 to 10.sup.6 mbar is frequently higher than 200 C. and frequently even higher than 250 C. This applies, in particular, to organic semiconductors, as are usually employed in electronic devices.

(11) The sublimation material is preferably converted into the gas phase at a temperature in the range from 200 C. to 500 C., particularly preferably in the range from 250 C. to 450 C., very particularly preferably in the range from 250 C. to 400 C. The sublimation temperature here depends on the material, where the lowest possible sublimation temperature and therefore the best possible vacuum is preferred in order to prevent thermal decomposition.

(12) The vacuum used is usually in the range from less than 10.sup.3 to 10.sup.8 mbar, preferably in the range from less than 10.sup.3 to 10.sup.8 mbar, particularly preferably in the range from 10.sup.4 to 10.sup.6mbar. These values apply, in particular, to processes which are carried out without injection of carrier gas. The pressure ranges used are preferably achieved by a multistage vacuum-pump system.

(13) In an embodiment of the invention, the process is carried cut as fractional sublimation, i.e. a plurality of fractions of the sublimed material are collected. A fractional sublimation of this type can also be used for the separation of mixtures, for example for the separation of stereoisomer mixtures.

(14) The process according to the invention is preferably carried out under dynamic vacuum. The apparatus is thus constantly connected to the vacuum-pump system while the process is carried out. This has the advantage over static vacuum that a better vacuum can thereby be achieved.

(15) In a further embodiment of the process according to the invention, the process is carried out using an inert carrier gas. If a carrier gas is used, the process according to the invention is preferably carried out in a pressure range from 10.sup.1 to 10.sup.4 mbar. This enables the conversion into the gas phase to be accelerated. In this way, it is possible to lower the effective evaporation/sublimation temperature in the case of sensitive substances in order to prevent decomposition. Alternatively, a higher sublimation rate can be achieved at the same temperature. The carrier gas used can generally be inert gases, for example nitrogen, helium, argon, krypton, xenon or sulfur hexafluoride. If the apparatus has a cold trap, use should be made of a carrier gas which does not condense in the cold trap and thus block the cold trap. If the cold trap is operated at the temperature of liquid nitrogen (196 C.), a suitable carrier gas is, in particular, helium.

(16) In a further embodiment of the invention, the process is carried out semicontinuously. To this end, fresh sublimation material is preferably fed into the sublimer unit in the melt. This has the advantage that only little sublimation material is always present in the sublimer unit, which thus means only low temperature stress for the material.

(17) The process according to the invention is preferably carried out as follows: the sublimation material, which should already be well dried, is initially introduced into the sublimer unit. The apparatus is closed, and a vacuum is applied. In an embodiment of the invention, the heating is initially carried out without rotation, and the rotation is only switched on when or just before the actual sublimation temperature is reached. This enables dusting of the material to be sublimed to be prevented or at least reduced. This applies, in particular, if the material is evaporated from the melt. It is preferred here during heating for material not to be heated directly to the sublimation temperature, but instead for the temperature to be increased stepwise in order firstly to remove the residual solvent which is usually still present from the product at relatively low temperature. In particular in the case of sublimation on a relatively large scale, it is appropriate firstly to determine the suitable sublimation temperature on a relatively small scale. If the sublimation material has melted or if the sublimation temperature has been reached or virtually reached in the case of sublimation from the solid state, the rotation is switched on. After completion of the sublimation, the sublimed material is removed from the condensation unit(s).

(18) The present invention likewise relates to an apparatus for carrying out the process according to the invention. The apparatus according to the invention is shown diagrammatically in FIG. 1.

(19) The invention therefore furthermore relates to an apparatus for the sublimation of chemical compounds, comprising an oven (1), a sublimer unit (2), a condensation unit (3), which is in contact with the sublimer unit, a rotation drive (4) for rotation of the sublimer and condensation units, and a vacuum pump or vacuum-pump system (6), characterised in that the apparatus has, between the rotating part and the fixed part, a rotation coupling (5), which is selected from a rotary feedthrough with ferrofluidic seal or a double- or triple-acting mechanical face seal.

(20) The apparatus according to the invention in which the process according to the invention can be carried out is described in detail below:

(21) The oven (1) in FIG. 1 is depicted in such a way that it surrounds both the sublimer unit (2) and the condensation unit (3). For this purpose, it is necessary for the oven to have various temperature zones, where the temperature of the sublimer unit is higher than that of the condensation unit. In an alternative embodiment of the present invention, the oven (1) may also only surround the sublimer unit (2), while the condensation unit (3) is arranged outside the oven.

(22) In general, all heating methods as are used in accordance with the prior art are suitable for the oven (1). The heating can take place either indirectly (vessel wall/jacket is heated, for example by hot air, heating bath, heating mantle, radiant heat, etc.) or directly (for example via IR or microwave coupling-in). It is also possible to mix the sublimation material with metal particles (beads) and to heat these metal particles inductively. In a preferred embodiment, the heating takes place by indirect heating, preferably by hot gas, so that the oven is preferably a hot-air oven. This method offers the advantage that a hot-air oven can be heated rapidly due to its low heat capacity and can be cooled again rapidly after completion of the purification operation. Furthermore, this method offers greater safety due to the absence of ignition sources. An active cooling operation by the introduction of air at room temperature is also possible in this way. It is preferred for an oven to be selected with which the desired temperature can be set selectively and regulated in a controlled manner. The thermal stress of the materials, some of which are heat-sensitive, and decomposition of the materials are thereby reduced. It is preferred for the temperature to be determined at various points in the oven in order to be able to control the process accurately.

(23) In a further preferred embodiment of the invention, the oven (1) can be divided into various heating zones, in each of which the temperature can be set selectively, i.e. the oven is preferably constructed in such a way that zonewise temperature setting is possible. This is possible, in particular, in the case of radiation ovens and hot-air ovens. Thus, for example, a plurality of radiation sources or hot-air sources can be used, and the individual heating zones in the oven can be insulated or at least screened off thermally from one another. This is depicted diagrammatically in FIG. 4, where (1) to (6) have the same meaning as described for FIGS. 1. (1a) to (1d) stand for separate heating sources, where the following applies to the temperatures: T.sub.(1a)>T.sub.(1b)>T.sub.(1c)>T.sub.(1d). (1e) represents the thermal screening-off of the heating zones from one another.

(24) This may have advantages since it also enables the condensation unit to be introduced into the oven, enabling fractional sublimation and thus still further purification of the material due to the various temperature zones of the oven.

(25) In a preferred embodiment of the invention, the hot air in the case of the use of a hot-air source is not passed directly to the sublimer unit in order to prevent overheating of the vessel wall and the associated risk of thermal decomposition of the sublimation material. Instead, the hot air is preferably deflected between the hot-air source and the sublimer unit, for example by a static plate (deflector plate, baffle plate) or metal fabric introduced in between, by rotating fan blades or another suitable deflection device. This enables uniform heating of the entire sublimer unit to be achieved.

(26) The sublimer unit (2) is the unit into which the sublimation material is introduced and from which the sublimation material is evaporated, while the condensation unit (3) is the unit on which the sublimed material is condensed. The condensation unit here may consist of one or more vessels.

(27) The sublimer unit (2) and the condensation unit (3) are described in greater detail below.

(28) In an embodiment of the invention, the sublimer unit (2) is connected to the condensation unit (3) in a vacuum-tight manner, for example by a flange, and the vacuum is applied directly to the sublimer and condensation units. This corresponds to the diagrammatic representation in FIG. 1

(29) In a further embodiment of the invention, the sublimer unit (2) and the condensation unit (3) are surrounded by a tube, for example a glass tube, and the vacuum is applied to the surrounding glass tube. This tube is connected to the remainder of the apparatus, for example by means of a ground-glass joint or a flat glass flange. The sublimer unit and the condensation unit are inserted into the surrounding tube. This embodiment has proven advantageous since loading of the apparatus with the sublimation material and removal of the sublimed material are thereby simpler. For this embodiment, it is furthermore sufficient for the surrounding tube to have adequate vacuum stability, while the sublimer and condensation units do not have to meet this requirement. This embodiment is depicted diagrammatically in FIG. 5, where units (1) to (6) have the same meaning as described for FIGS. 1, and (14) stands for the tube which surrounds the sublimer and condensation units. In this embodiment of the invention, the sublimer unit (2) and the condensation unit (3) are usually not connected to one another in a vacuum-tight manner, but instead are only placed loosely against one another or pushed into one another.

(30) The sublimer unit (2) is initially not restricted. Thus, for example, glass vessels, ceramic vessels, vessels made from corundum, boron nitride or graphite or also vessels made from various steel or metal variants are suitable. Graphite has the advantage that it can also be heated inductively. In a preferred embodiment of the invention, glass vessels are used. Preference is given to the use of quartz or Duran glass (borosilicate 3.3).

(31) The vessel geometry may vary (FIGS. 6 and 7). Thus, spheres, cylindrical vessels, but also tubes and further curved shapes are possible. In a preferred embodiment of the invention, the sublimer unit used is a cylindrical vessel having a rounded-off or outwardly curved base. This vessel shape has proven particularly suitable, since it has a larger surface area in relation to the volume than a round flask.

(32) In an embodiment of the invention, the apparatus with the sublimer unit and the condensation unit is arranged horizontally. In a further embodiment of the invention, the entire apparatus and thus also the sublimer unit and condensation unit are tilted to the horizontal, where angles of 1 to 10 are preferred, and the sublimer unit is arranged lower than the condensation unit. An apparatus tilt of this type has the advantage that the sublimer unit can accommodate relatively large amounts of material, and the same apparatus is thus suitable for the sublimation of relatively large amounts. A disadvantage does not arise through the tilt of the apparatus, since the sublimed material is usually formed either in solid form as glass or condenses in liquid form in the condensation unit and thus has a higher density than the material to be sublimed, which is usually introduced into the sublimer unit in powder form.

(33) In addition to the sublimation material, grinding bodies may also be added to the sublimer unit (2). These result in better mixing of the material and thus in more uniform temperature distribution and better sublimation rates. Furthermore, they result in comminution of the sublimation material, for example through grinding of crystals. A relatively large surface area of the sublimation material thus arises, which in turn results in faster sublimation. The grinding bodies used are preferably beads or approximately spherical bodies. These preferably have a diameter of 1 to 10 mm, particularly preferably 2 to 6 mm, where bead mixtures of various diameter have proven particularly suitable. Preferred materials for the grinding bodies are selected from glass or metal, particularly preferably from quartz or Duran glass. The grinding bodies are particularly preferably selected from the same material as the sublimation apparatus.

(34) The evaporated material is condensed on the condensation unit (3) in a less-hot zone within the oven or even outside the oven. The condensation unit usually rotates at the same speed as the sublimer unit. The condensation unit (3) may be permanently connected to the sublimer unit (2) (FIG. 6). The sublimer unit (2) and the condensation unit (3) may also be connected to one another, for example, by a flange, where, due to the high temperature requirement, this is sealed by means of a heat-stable seal, for example a Kalrez seal, a gold seal or a graphite seal. The connection between the sublimer unit (2) and the condensation unit (3) is preferably heated in order that material cannot sublime in this region and thus block the relatively narrow connection between the two vessels. In a preferred embodiment of the invention, however, the condensation unit is, as described above, not permanently connected to the sublimer unit (FIG. 7). This simplifies removal of the sublimed product and cleaning of the sublimer and condensation units. As described above, it is preferred for the sublimer and condensation units to be inserted into a tube, to which the vacuum is then applied.

(35) The condensation unit (3) may consist of various materials, for example glass, metal or ceramic, but also of surfaces having low surface energies, in particular having surface energies of less than 70 mN/m, for example PTFE, as described, for example, in DE 102005038211, where the same definition of surface energy as described therein applies. A condensation unit made from glass, metal or ceramic which is coated with a material having low surface energy, for example PTFE, is likewise suitable. In a preferred embodiment of the invention, the condensation unit consists of glass. This has the advantage that the transparency of the apparatus enables the sublimation and condensation process to be followed. It is also possible to construct the condensation unit from more than one corresponding material. This may take place in the sense of a composite material, but also in the sense of a coating.

(36) Various vessel geometries are suitable for the condensation unit (3), for example the same ones as described above for the sublimer unit, such as cylindrical or spherical units. The preferred geometry of the condensation unit also depends on whether the sublimed material condenses in the solid or liquid state.

(37) If the sublimed material condenses in the liquid state, the condensation unit is preferably cylindrical or spherical, in particular cylindrical, where it has a narrowing and an opening at both ends, at which it is connected loosely or by means of a seal to the sublimer unit on the one hand and optionally to the next condensation unit, if a plurality of condensation units are present, on the other hand, or to two condensation units if a plurality of condensation units are present. This is depicted diagrammatically in FIG. 6A. On further cooling, the material condensed in the liquid state solidifies, where the solid material is frequently obtained in the form of a glass. On solidification, the glass-like material frequently also detaches directly from the condensation unit and can thus be removed easily after completion of the sublimation. If the sublimed material does not detach of its own accord, it is detached mechanically from the condensation unit, for example by scraping, after completion of the sublimation.

(38) If the sublimed material condenses directly in the solid state, the condensation unit described above can likewise be used. Furthermore, cylindrical units which have a disc inside the cylinder ring on which the condensation of the sublimed material can take place have proven suitable for the condensation unit in the case of condensation in the solid state. This is depicted diagrammatically in FIG. 6B in plan view and in FIG. 6C in side view, in each case for a condensation unit. (3a) here stands for the outer cylinder ring, (3b) stands for the disc on which the condensation takes place and (3c) stands for the connections which stabilise the disc inside the cylinder ring. For fractional sublimation, a plurality of these units can be placed against one another, so that a plurality of such condensation units are present which can be heated to different temperatures. The removal of the sublimed material after completion of the sublimation is usually carried out mechanically, for example by scraping.

(39) The condensation unit (3) here is operated at a temperature which is sufficiently far below the sublimation or evaporation temperature (at a given pressure) in order to facilitate adequate condensation. The condensation here can take place into the liquid state or into the solid state. In the case of relatively small sublimation devices and in the case of low sublimation rates, even air cooling or cooling by a gas stream, for example an air or nitrogen stream, may be sufficient here. However, it may also be advantageous to bring all or part of the condensation unit to a (constantly) low temperature, for example by water cooling. Spherical condensation units in particular have the advantage that they can easily be cooled by dipping into a cooling bath, for example a water or ice bath. The entire unit is cooled uniformly by the rotation of the unit. The cooling temperature is preferably selected so that the sublimate is obtained in the glass-like state. This is achieved by cooling to below the glass-transition temperature. The sublimate can thus be removed from the apparatus more easily. In general, however, active cooling of the condensation unit is not necessary.

(40) Depending on the product specification, it may be appropriate or necessary, as already described above, instead of only one condensation unit, to use a plurality of condensation units, for example a plurality of flasks or cylinders arranged one behind the other or a plurality of the condensation units described in greater detail above which are heated to different temperatures in order in this way also to effect further purification through the separation of co-evaporated impurities. In this way, the separation of product mixtures which can otherwise only be separated with difficulty can likewise be facilitated, for example the separation of stereoisomers of a product. Thus, for example, the separation of diastereomers, for example atropisomers of a compound, by this process is facilitated, while the separation by processes in accordance with the prior art, for example by sublimation in accordance with the prior art, does not give satisfactory results here.

(41) The rotation coupling (5) is in accordance with the invention a rotary feed-through with ferrofluidic seal or a double- or triple-acting mechanical face seal.

(42) The rotation of the evaporator/sublimer unit can take place, for example, in such a way that the evaporator/sublimer unit is mounted on a hollow shaft made from metal or glass. This hollow shaft is driven by a variable motor via a toothed belt. In each case here, it should be possible both to regulate and control the rotational speed.

(43) FIG. 1 furthermore shows the rotation drive (4) and the rotation coupling (5) as separate elements. In an alternative embodiment of the invention, the rotation drive may also be integrated into the rotation coupling, so that this is a single element. In particular for the rotary feedthrough with ferrofluidic seal, such a combination of rotation drive and rotation coupling is commercially available.

(44) Since the process according to the invention is preferably carried out in a pressure range up to 10.sup.7 mbar, corresponding demands are made of the rotation coupling. In accordance with the invention, a double- or triple-acting mechanical face seal (for example U.S. Pat. No. 6,976,681) or a rotary feedthrough with ferrofluidic seal is used. These rotation couplings are generally already known in the prior art and are commercially available. Since heat is generated by the rotation of the coupling, it may be preferred to cool the coupling, in particular in the case of relatively large sublimation apparatuses. The cooling can be carried out, for example, by a gas stream or by water.

(45) The requisite pressure ranges are preferably achieved by a multistage vacuum-pump system (6), preferably by a two-stage vacuum-pump system. A pre-pump having a suction performance of 5-50 m.sup.3/h, for example an oil pump, a dry-running scroll pump, a rotary vane pump or a Roots pump, generates a pre-vacuum in the range from about 510.sup.2 to 510.sup.1 mbar. Connected thereto is a high-vacuum pump, for example a turbomolecular pump or an oil diffusion pump, with which a vacuum in the desired range can be achieved in each case. It may be appropriate to install a cold trap or a baffle, in which solvent residues present in the sublimation material and further volatile by-products are condensed, between the vacuum pump and the actual sublimation apparatus. This enables the pressure to be reduced further again. The cold trap or the baffle furthermore serves to protect the vacuum pump and prevent back-diffusion of pump constituents, such as, for example, oil, into the apparatus. The combination of a scroll pump with a turbomolecular pump offers the advantage that an absolutely oil-free vacuum can be generated thereby. This combination is therefore preferred. Furthermore, the apparatus can have a manometer for pressure measurement of the apparatus. This may also be appropriate in order to follow and control the sublimation process, since the beginning of the sublimation is indicated by a slight pressure increase and the end of the sublimation is indicated by a further pressure drop.

(46) The apparatus may also have further elements which are not absolutely necessary, but whose presence may be appropriate. Thus, for example, the presence of a thermometer and/or a manometer is appropriate for monitoring of the sublimation process. For large and thus heavy apparatuses, it may also be appropriate or necessary for the sublimer unit to be supported by a rotating bearing at its closed end. The use of a process control system may also be appropriate.

(47) An apparatus for carrying out a carrier-gas sublimation requires further elements, for example an inert-gas feed, as shown in FIG. 2. Constituents (1) to (6) of the apparatus in FIG. 2 have the same meaning as described for the apparatus in FIG. 1. This apparatus furthermore has the following elements: (7) gas feed tube; (8) rotation coupling; (9) metering valve; (10) gas source.

(48) The carrier gas is preferably fed coaxially into the sublimer unit. To this end, the evaporator unit is provided with a carrier-gas feed tube (7), which leaves the oven in coaxial form. It may be preferred to preheat the carrier gas before feeding into the sublimer unit. The coupling to the static metering valve (9), which is connected to the gas source (10), for example a gas bottle, can be carried out by means of a further rotation coupling (8). This is likewise preferably a rotary feedthrough with ferrofluidic seal or a double- or triple-acting mechanical face seal.

(49) An apparatus for semi-continuous work is shown in FIG. 3. Constituents (1) to (6) of the apparatus in FIG. 3 have the same meaning as described for the apparatus in FIG. 1. This apparatus furthermore has the following elements: (11) rotation coupling; (12) storage vessel; (13) metering device.

(50) The rotation coupling (11) here is likewise preferably a rotary feedthrough with ferrofluidic seal or a double- or triple-acting mechanical face seal.

(51) As for the carrier-gas supply, the apparatus for semi-continuous work also has a feed tube at one end of the sublimer unit. The feed into the sublimer unit here is in principle possible from both sides of the sublimer unit. This is connected via a further rotating seal (11) to the storage vessel (12), which contains the optionally heated material in the liquid or solid state. This can be metered into the sublimer unit via a stop cock or another metering device (13). It may be appropriate for the feed tube to be heated in order to facilitate the feed of the melt without solidification.

(52) Since high-purity materials are purified by the process according to the invention or using the apparatus according to the invention, the greatest possible cleanliness of the apparatus itself must be ensured. Thus, it is preferred for both the sublimer unit and also the condensation unit to be cleaned very well before carrying out a sublimation. For this purpose, cleaning of the corresponding sublimer unit and condensation unit by calcination or firing may also be preferred, causing impurities to be thermally decomposed.

(53) The process according to the invention and the apparatus according to the invention have the following surprising advantages over the prior art: 1. The process according to the invention enables significantly larger amounts of material to be sublimed per batch than is possible in accordance with the prior art. 2. The thermal load of the material to be sublimed is considerably lower than in the case of devices in accordance with the prior art. This enables losses of the material to be avoided. For some thermally sensitive materials which decompose completely on sublimation in accordance with the prior art, only the process according to the invention makes sublimation possible at all. Furthermore, the uniform input of heat means that no or at least significantly less ashing of the material is observed. 3. Due to the good mixing, the sublimation proceeds considerably more quickly than with apparatuses in accordance with the prior art, which represents a significant technical advantage. 4. The process according to the invention also offers considerable advantages for sublimation in which the evaporation takes place from the melt. Thus, apart from the advantages mentioned above, it should be emphasised that residual solvents in the melt are unproblematic here, since, due to the rotation, uniform evaporation is achieved and boiling delays due to evaporating solvent are avoided. Contamination of the sublimed material is thus avoided. Furthermore, it is unproblematic with the process according to the invention if the compound condenses in the liquid state and not in the solid state, since reflux of the purified material into the as yet unpurified material cannot occur here. 5. The process according to the invention can also be carried out using carrier gas, resulting in a further acceleration of the sublimation process and in addition a reduction in the sublimation temperal:ure. This process is therefore particularly suitable for thermally sensitive substances. 6. The process according to the invention can also be carried out semi-continuously, enabling sublimation on a still larger scale with simultaneous reduction of the thermal stress for the material to be sublimed.

(54) The present invention is explained in greater detail by the following examples, without wishing to restrict it thereto. The person skilled in the art will be able to find further embodiments from the description and the examples indicated without inventive step or naturally purify further materials using the process described. In particular, scaling of the apparatus and work on a larger scale are also possible without inventive step.

DESCRIPTION OF THE FIGURES

(55) The numbers indicated in the figures are explained in detail in the description above and in the working examples.

(56) FIG. 1: Apparatus for carrying out the process according to the invention

(57) FIG. 2: Apparatus with carrier-gas feed

(58) FIG. 3: Apparatus for semi-continuous work

(59) FIG. 4: Apparatus for carrying out the process according to the invention with a plurality of heating zones

(60) FIG. 5: Apparatus with sublimer and condensation units with surrounding glass tube

(61) FIG. 6: Suitable vessel shapes for permanently connected sublimer and condensation units: A) cylinder-cylinder; B) sphere-sphere; C) cylinder-sphere; D) cylinder-cylinder with carrier-gas feed or for semi-continuous work

(62) FIG. 7: Suitable vessel shapes for sublimer and condensation units which are not permanently connected: A) sublimer and condensation units for condensation in the liquid state; B) condensation unit for condensation in the solid state (plan view); C) condensation unit for condensation in the solid state (side view)

(63) FIG. 8: Overall view of the sublimation apparatus according to the invention, design drawing

EXAMPLES

Example 1

Structure of an Apparatus in Accordance with the Prior Art for Carrying Out the Sublimation (Comparison), Apparatus 1

(64) Components: 4 I single-necked glass flask made from Duran glass from Schott Mainz, provided with an NS 45 conical ground-glass joint socket, glass tube with a length of 1 m (internal diameter 40 mm), provided at one end with an NS 45 conical ground glass joint cone, provided at the other end with a flat flange, controllable heating hood, turbo drag pump stand, cold trap, can be filled with liquid nitrogen.

(65) A certain amount of compounds MAT1 to MAT6 to be sublimed is initially introduced in the 4 I single-necked glass flask (see Example 4, Table 2). The single-necked flask is provided with the glass tube, the NS 45 conical ground glass joint cone is sealed with Teflon rings. This unit is connected to the turbo drag pump stand via the flat flange and positioned in the controllable heating hood. The apparatus is evacuated until a vacuum has been achieved in the rest state (see Example 4, Table 2). The temperature is subsequently increased stepwise in 20 C. steps to the sublimation temperature indicated in Table 3 by means of the heating hood. When the sublimation is complete, the apparatus is allowed to cool to room temperature, the vacuum is released, the sublimate which has accumulated on the upper half of the flask is removed mechanically and sent for purity analysis by NMR or HPLC.

Example 2

Structure of an Apparatus According to the Invention for Carrying Out the Sublimation, Apparatus 2

(66) The sublimation apparatus according to the invention comprises the components depicted diagrammatically in FIG. 1. The complete design drawing is depicted in FIG. 8. The individual components have the following meanings here: A) pre-pump for generating a pre-vacuum B) turbomolecular pump for generating a high vacuum C) manometer for vacuum measurement D) cold trap, cooled using liquid nitrogen E) spool valve, for separation of sublimation space and pump stand F) rotary feedthrough with ferrofluidic seal and electric drive G) hot-air oven consisting of an insulated V2A tube (diameter 250 mm, length 450 mm), provided with four PT100 thermoelements for temperature control H) air heater for oven heating I) fan for air heater J) baffle for flow management in the oven K) air inlet into oven L) sublimation vessel consisting of sublimer unit and condensation unit

(67) A certain amount of compounds MAT1 to MAT6 to be sublimed is initially introduced in the sublimer unit (2) or (L) (see Example 4, Table 2). The sublimer unit according to the invention is assembled and evacuated to the base pressure (see Example 4, Table 2). The rotation is subsequently switched on (rotational speed 1.5 min.sup.1), and the temperature is increased stepwise in 50 C. steps to the sublimation temperature indicated in Table 2 by means of the hot-air oven. When the sublimation is complete, the apparatus is allowed to cool to room temperature, the vacuum is released, the sublimate which has accumulated in the condensation unit is removed mechanically and sent for purity analysis by NMR or HPLC.

Example 3

Structure of an Apparatus According to the Invention for Carrying Out the Carrier-Gas Sublimation, Apparatus 3

(68) The sublimation apparatus according to the invention consists of the components depicted in FIG. 2, which are arranged one after the other and are connected by commercially available corrugated vacuum hoses with O-ring flanges, analogously to FIG. 8.

(69) A certain amount of compounds MAT4 and MAT6 to be sublimed is initially introduced in the sublimer unit (2) (see Example 4, Table 2). The sublimer unit according to the invention is assembled and evacuated to the base pressure (see Example 4, Table 2), and the rotation is switched on (rotational speed 1 min.sup.1). The temperature is subsequently increased stepwise in 50 C. steps to the sublimation temperature indicated in Table 2 by means of the hot-air oven. When the sublimation temperature has been reached, the helium carrier-gas stream is adjusted so that the pressure indicated (see Example 4, Table 2) is achieved. When the sublimation is complete, the apparatus is allowed to cool to room temperature, the vacuum is released, the sublimate which has accumulated in the condensation unit is removed mechanically and sent for purity analysis by NMR or HPLC.

Example 4

Sublimations of Various Organic and Organometallic Substances

(70) The following organic substances MAT1 to MAT6 (overview Table 1) are evaporated in the above-mentioned apparatuses and thus purified:

(71) TABLE-US-00001 TABLE 1 Material overview Melting Molecular Purity point weight (acc. to Chemical name Literature [ C.] [g/mol] HPLC) MAT1 9,10-Bis-(2-spirobi- WO 04/58911 463 807.0 99.7% fluorenyl)anthracene MAT2 Bis-(2-spirobifluorenyl) WO 04/93207 384 658.8 99.98% ketone MAT3 2,2,7,7-Tetrakis-(bis-p- JP 03/124472 296 1097.5 99.95% tolylamino)spirobifluorene MAT4 Tris(4-(trimethylsilyl- DE 102005058543.4 768.3 99.5% phenylvinyl)phenyl)amine MAT5 fac-Tris[2-(2-pyridinyl- WO 02/060910 Decomp. 768.3 99.95% N)phenyl-C]- iridium(III) MAT6 fac-Tris[7,7-dimethyl-8- WO 05/033244 Decomp. 901.0 99.9% fluoro-4-methyldibenzo- [de,h]quinoline-C.sup.2,N]- iridium(III)

(72) An overview of the sublimation experiments carried out is reproduced in Table 2.

(73) TABLE-US-00002 TABLE 2 Sublimation overview Sublimation conditions Amount (T.sub.oven; p; phase; No. Material used [g] Sublimer addition) Observations 1 MAT1 200 App. 1 450 C.; Sublimation time: 8 h, (comparison) 4 10.sup.5 mbar; purity of sublimate: 99.4%, from the solid decomposition products: 0.3%. phase An ash layer forms over time at the glass flask/sublimation material interface. Crystals measuring up to several mm form on the surface of the sublimation material. Towards the end of the sublimation, ash is entrained, contaminating the sublimate. 2 MAT1 200 App. 2 400 C.; Sublimation time: 1 h 40 min, 3 10.sup.5 mbar; purity of sublimate: 99.7%, from the solid decomposition products: none. phase, Neither ash nor large crystals addition of 150 g form. The sublimation proceeds of glass beads completely and without problems. (diameter 5 mm) 3 MAT2 100 App. 1 390 C.; Sublimation time: 2 h 30 min, (comparison) 5 10.sup.5 mbar; purity of sublimate: 99.98%, from the solid decomposition products: none. phase Small amounts of an ash/ salts from the synthesis are entrained towards the end of the sublimation. 4 MAT2 300 App. 1 390 C.; Sublimation time: 7 h 30 min, (comparison) 5 10.sup.5 mbar; purity of sublimate: 99.98%, from the solid decomposition products: none. phase The sublimate preferentially deposits at the transition from the heated to the unheated zone. The interior of the flask slowly becomes blocked from the edge. After 5 h, there is a danger of blockage over the entire flask cross section. The sublima- tion has to be terminated. 5 MAT2 1000 App. 2 375 C.; Sublimation time: 6 h 30 min, 3 10.sup.5 mbar; purity of sublimate: 99.98%, from the solid decomposition products: none. phase; The sublimation proceeds addition of 500 g completely and without problems. of glass beads Little ash/salts from the (diameter 5 mm) synthesis remain in the sublimer unit. These are not entrained into the sublimate. 6 MAT3 50 App. 1 390 C.; Sublimation time: 7 h, (comparison) 3 10.sup.5 mbar; purity of sublimate: 99.75%, from liquid phase decomposition products: 0.2%. After melting at 305 C., solvent residues from the recrystallisation are liberated, These result in boiling delays and splashing. The condensation surface is contaminated by splashes. After sublimation of about 30 g, the transport of heat away at the condensation surface is so poor that the condensate no longer solidifies and runs back on the flask wall. 7 MAT3 500 App. 2 380 C.; Sublimation time: 3 h, 4 10.sup.5 mbar; purity of sublimate: 99.95%, from liquid phase decomposition products: none. At 305 C., the material melts. The pressure increases due to liberated residual solvent for 20 min. to 1 10.sup.2 mbar. However, no boiling delays and thus no splashing occur. The actual sublimation at 380 C. proceeds completely and without problems. 8 MAT4 50 App. 1 320 C.; Sublimation time: 7 h, (comparison) 3 10.sup.5 mbar; purity of sublimate: 96%, from liquid phase decomposition products: 4%. After melting at 220 C., solvent residues from the recrystallisation are liberated. These result in boiling delays and splashing. The condensation surface is contaminated by splashes. After sublimation of about 30 g, the transport of heat away at the condensation surface is so poor that the condensate no longer solidifies and runs back on the flask wall. Due to the high sublimation temperature and time, considerable decomposition occurs, with formation of, inter alia, 4,4- bis(trimethylsilyl)stilbene, which contaminates the sublimate. 9 MAT4 200 App. 3 240 C.; Sublimation time: 2 h 20 min, 2 10.sup.3 mbar; purity of sublimate: 99.5%, from liquid phase decomposition products: none. At 220 C., the material melts. The pressure increases due to liberated residual solvent for 15 min. to 5 10.sup.2 mbar and then drops back to 5 10.sup.5 mbar. No boiling delays and thus no splashing occur. The actual sublimation proceeds at 240 C. and with a helium carrier-gas stream which is adjusted so that the pressure remains constant at 8 10.sup.4 mbar. The sublimation proceeds completely and without problems. The formation of 4,4-bis(trimethylsilyl)- stilbene is not observed. 10 MAT5 50 App. 1 330 C.; Sublimation time: 5 h, (comparison) 5 10.sup.5 mbar; purity of sublimate: 98.6%, from the solid decomposition products: 2.3%. phase An ash layer forms over time at the glass flask/sublimation material interface. The temperature has to be increased from 330 C. successively to 360 C. in order to ensure an acceptable sublimation rate. Crystals measuring up to several mm form on the surface of the sublimation material. Ash is entrained, which contaminates the sublimate. After sublimation of about 35 g, the sublimation is terminated. 11 MAT5 150 App. 2 330 C.; Sublimation time: 1 h 40 min, 5 10.sup.5 mbar; purity of sublimate: 99.95%, from the solid decomposition products: none. phase; Neither ash nor large crystals addition of 100 g form. The sublimation proceeds of glass beads completely and without (diameter 5 mm) problems. 12 MAT6 10 App. 1 390 C.; Sublimation time: 5 h, (comparison) 5 10.sup.5 mbar; purity of sublimate: 97.2%, from the solid decomposition products: 2.7%. phase An ash layer forms over time at the glass flask/sublimation material interface. The temperature has to be increased from 390 C. successively to 420 C. in order to ensure an acceptable sublimation rate. Crystals measuring up to several mm form on the surface of the sublimation material. Ash is entrained, which contaminates the sublimate. After sublimation of about 6 g, the sublimation is terminated. The residue consists of an indium-containing ash. 13 MAT6 50 App. 3 350 C.; Sublimation time: 2 h 30 min, 7 10.sup.4 mbar; purity of sublimate: 99.9%, from the solid decomposition products: none. phase; The helium carrier-gas addition of 150 g stream is adjusted so that of glass beads the pressure remains constant (diameter 5 mm) at 7 10.sup.4 mbar. The sublimation proceeds completely and without problems.

(74) The experiments described show that the substances can be sublimed significantly more quickly, on a larger scale and with considerably less side reaction or decomposition with the process according to the invention. For some of the substances shown above, only the process according to the invention makes sublimation possible at all.

Example 5

Use of the Process According to the Invention for Isomer Separation

(75) The partial or complete separation of atropisorners of a compound can be carried out by the process according to the invention, as described below for the atropisomers of 9,10-bis(4-methylnaphth-1-yl)anthracene (WO 06/048268). 100 g of a 1:1 atropisomer mixture of 9,10-bis(4-methyl-naphth-1-yl)anthracene are sublimed from the solid phase in apparatus 3 at T=280 C. and p=910.sup.4 mbar with addition of 200 g of glass beads (diameter 5 mm). After a mass throughput of about 50%, corresponding to 50 g of sublimate and 50 g of residue, the sublimation is terminated. The atropisomer ratio in the sublimate is about 2.3:1.0 with respect to the more readily volatile atropisomer, that of the residue is about 1.0:2.3 with respect to the less volatile isomer. The determination of the atropisomer ratio of the sublimate and of the residue was carried out in accordance with WO 06/048268. By repeated sublimation of the sublimate and termination after a mass throughput of 50% in each case, the more readily volatile atropisomer can be considerably enriched in the sublimate. Ratios of greater than 20:1 can easily be produced in this way. The less volatile atropisomer can be considerably enriched in the residue by mass throughputs of 80% or more. Ratios of greater than 1:20 can easily be produced in this way.

Example 6

Use of the Process According to the Invention for Sublimation on a Large Scale

(76) The following examples show that the sublimation by the process according to the invention and in the apparatus according to the invention can also be carried out on a kilogram scale. To this end, the materials employed, the parameters of the sublimation process and the yield and purity after the sublimation are in each case indicated below. The rotation is switched on after the heating.

Example 6a

(77) Material: MATT (triarylmonoamine derivative having a molecular weight of about 670 g/mol); purity 99.83%

(78) Filling: 5000 g

(79) Temperature: 285 C.

(80) Final pressure: <10.sup.6 mbar

(81) Rotational speed: 1 min.sup.1

(82) Duration of the sublimation: 13.5 h

(83) Yield (purity): fraction 1: 4500 g (99.97%), fraction 2: 300 g (99.97%).

(84) A second sublimation increases the purity to >99.99%.

Example 6b

(85) Material: MAT8 (triarylmonoamine derivative having a molecular weight of about 670 g/mol); purity 99.88%

(86) Filling: 5500 g

(87) Temperature: 300 C.

(88) Final pressure: <10.sup.6 mbar

(89) Rotational speed: 2 min.sup.1

(90) Duration: 17 h

(91) Yield (purity): fraction 1: 4690 g (99.99%), fraction 2: 580 g (99.94%).

(92) A second sublimation of fraction 2 increases the purity to >99.99%.

Example 6c

(93) Material: MAT9 (2,4,6-triaryl-1,3,5-triazine derivative having a molecular weight of about 590 g/mol); purity 99.41%

(94) Filling: 5000 g

(95) Temperature: 310 C.

(96) Final pressure: <10.sup.6mbar

(97) Rotational speed: 4 min.sup.1

(98) Duration: 13 h

(99) Yield (purity): fraction 1: 4430 g (99.96%), fraction 2: 140 g (99.98%).

(100) A second sublimation increases the purity to >99.99%.