WO2010112222A1

WO2010112222A1 - Progressive emulsion crystallization

Info

Publication number: WO2010112222A1
Application number: PCT/EP2010/002078
Authority: WO
Inventors: Alen Kljajic; Rok Zupez
Original assignee: Krka, D.D., Novo Mesto
Priority date: 2009-03-31
Filing date: 2010-03-31
Publication date: 2010-10-07
Also published as: SI2413911T1; EP2413911B1; EP2413911A1

Abstract

The invention described herein is in the field of separation processes, more particularly, in the field of selective crystallization methods for purification of organic substances.

Description

PROGRESSIVE EMULSION CRYSTALLIZATION

FIELD OF THE INVENTION

BACKGROUND OF THE INVENTION

Solvent emulsion crystallization using two immiscible liquids and optionally surface active agents (surfactant)/co-surfactants forming emulsion (usually droplet type) is known in the art. In this type of crystallization systems, the mixture of chemical substances is dissolved mainly in one phase (dispersed phase), acting as a solvent phase and forming an emulsion with another immiscible liquid phase, anti-solvent phase. At higher temperatures, after the mixture of compounds has been dissolved, the emulsion is cooled to a targeted temperature where crystallization process takes place. After the crystallization is completed formed crystals are isolated from the emulsion (I. Holeci, Chem.Prumysl, 14, 145, 1964).

Instead of the solvent phase, the solute alone can present the immiscible phase in emulsion system (R. J. Davey, J. Garside, A. M. Hilton, D. McEwan, J. W. Morrison, Letters to Nature, 357, 1995).

Using emulsion media for crystallization (melt emulsions, solvent emulsions) as selective separation process is known in the art. The same emulsion can be used several times as recycled solvent/anti-solvent media. It means that after the crystallization out of emulsion is completed the emulsion can be heated again and additionally dissolve the mixture of chemical substance (with the desired compound) and perform the emulsion crystallization step again (US 6,855,176). Although, as the impurities concentrate in the emulsion the separation potential becomes lower in each additional use of the crystallization media. Furthermore, microemulsions have been used for isolating one or more enantiomer components from a mixture of enantiomers through co-crystallization (US 6,570,036; WO 97/32644).

Crystallization of substances using thermodynamically stable micro-emulsions as crystallization media (Gibbs free enthalpy of formation ΔG < 0) is known (WO 97/32644). The typical micro-emulsion region of a continuous isotropic liquid area can be presented in a ternary phase diagram and usually with fairly large amount of surfactants and a co-surfactant (P. Kumar, K. L. Mittal; Handbook of microemulsion science and technology).

These types of emulsion are not always suitable for industrial crystallization due to low capacity, low yields (separation of diastereisomers), long crystallization times and high surfactant content in the emulsion (US 6,855, 176; WO 97/32644).

As known in the art it is possible to operate with thermodynamically stable (micro)emulsions, dissolving the aggregate mixture at higher temperatures, cooling the emulsion to lower temperature and gaining a high level of super saturation. At this lower crystallization temperature, seeding is used to promote crystallization (WO 99/12623). This type of crystallization is characterized in seeding the desired component and seed crystals of at least one other substance. As the authors of WO 99/12623 have pointed out; it needs to be managed that no solid particles are in the crystallization container because they might promote crystallization of the impure substance in combination with consecutive or simultaneous seeding. This is the critical point of the process and can have serious drawbacks for the large-scale industrial crystallization process.

There is a need to have a productive purification process, including preparation, separation and isolation of pure materials, appropriate for large-scale production of pure organic molecules, starting from crude materials. Especially, whenever the crude materials include related impurities which have similar structure and properties as the parent material and are hard to purify using classical purification techniques. The need is most important in the field of synthesis of fine chemicals, more precisely chemicals, which are intermediates in the production of active pharmaceutical ingredients and the pharmaceutical ingredients themselves. There thus exists a need in the art for efficient emulsion crystallization as purifying process using any kind of emulsions not limited to emulsion stability and having easy and simple operating process with fast crystallization times, large capacity of process, high yields, efficient separation and low amount of surfactant needed. Also, there is a need in the art to manipulate the filtration properties of crystallized products from emulsion.

We have developed the Progressive Emulsion Crystallization (PEC) to overcome these difficulties. Its characteristics are high yields and good separation of related impurities which is used for obtaining a highly pure product with good filtration properties, appropriate for use with all types of droplet emulsions.

SUMMARY OF THE INVENTION

The present invention provides a benefit of progressive emulsion crystallization operating process in a batch, close to continuous or continuous operating way with the use of an appropriate homogenization system to keep suspension, and/or emulsion dispersed. Using the developed crystallization operating system enables the use of wide-range ratios of organic liquid/water/surfactant to control the process according to the properties of the impure substance and also to have a minimal amount of surfactant added and still have a good purification potential. This is needed especially when operating with active pharmaceutical ingredients and their intermediates.

The authors have developed an operating system, which enables efficient purification of chemical substances using droplet emulsions with unrestricted droplet size. The developed crystallization operating system in a reactor with appropriate homogenization enables the use of emulsions, characterized in Free Gibbs energy of droplet formation ΔG > 0, as shown in the examples. We developed two basic principles for the application of PEC:

a.) The principle of purification of impurities, in particular related impurities from crude products of preferably organic molecules. The process is characterized in that the mixture of compounds is dissolved at high temperatures, the prepared emulsion is preferably cooled to an optimized temperature between the temperature at which the mixture of compounds is dissolved in the emulsion and the temperature at which the crystallization is completed, and the seeds of the desired component are added. The temperature of the crystallization medium is cooled to the target temperature, preferably gradually, in particular with an optimized cooling ramp. After the targeted temperature is achieved, preferably the suspo-emulsion is continued to be homogenized for some period of time. Finally, the product formed is isolated. This emulsion purification processes have high overall yields and purification potentials and are appropriate for large-scale, industrial applications.

b.) The principle of design of physical properties of materials: After the crystallization out of emulsion is completed, particles of the product with good filtration properties and appropriate for large-scale production are required. The authors of the present invention have found out that the use of the processes of the present invention produces purified materials with good filtration properties, which are needed for large-scale production. This is mainly because of larger particles formed due to an optimized control of emulsion crystallization, PEC.

Also, the authors of the present invention have surprisingly found out that agglomeration of particles takes place, if, preferably at the end of the crystallization process, an additional amount of the emulsion is added to the crystallization mixture, said crystallization mixture being for example a suspo-emulsion formed after seeding and/or during crystallization, instead of additional amounts of the continuous or droplet phase from which the compound crystallizes. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows two photographs of ezetimibe crystals, prepared according to Example 1.

Fig. 2 shows two photographs of fipronil crystals, prepared according to Example 2.

Fig. 3 shows two photographs of fipronil crystals, prepared according to Comparative

Example 2.

Fig. 4 shows two photographs of montelukast acid crystals, prepared according to

Example 3.

Fig. 5 shows two photographs of orlistat crystals, prepared according to Example 4.

Fig. 6 shows two photographs of orlistat crystals, prepared according to Comparative

Example 4.

Fig. 7 shows two photographs of orlistat crystal agglomerates, prepared according to

Example 4/a with addition of emulsion to the crystal llization system after the crystallization is performed.

Fig. 8 shows two photographs of (3R,5R)-tert-butyl 7-(2-(4-fluorophenyl)-5-isopropyl-3- phenyl-4-(phenylcarbamoyl)-lH-pyrrol-l-yl)-3,5-dihydroxyheptanoate crystals, prepared according to Example 5.

Fig. 9 shows two photographs of trityl candesartan cilexetil crystals, prepared according to Example 7.

Fig. 10 shows two photographs of trityl candesartan cilexetil crystals, prepared according to Comparative Example 7.

Fig. 1 1 shows two photographs of orlistat crystals, prepared according to Example 10.

Fig. 12 shows two photographs of orlistat crystals, prepared according to Comparative

Example 10.

Fig. 13 shows two photographs of montelukast acid crystals, prepared according to

Example 1 1.

Fig. 14 shows two photographs of montelukast acid crystals, prepared according to

Comparative Example 1 1.

Fig.15 shows the particle size distribution (PSD) curve of materials, prepared in Example

1 1 and Comparative Example 1 1. Fig. 16 shows the particle size distribution (PSD) curve of materials, prepared in

Example 7 and Comparative Example 7.

Fig. 17 shows the particle size distribution (PSD) curve of materials, prepared in

Example 10 and Comparative example 10.

Fig. 18 shows the particle mean diameter, D lO, D50 and D90 diameter of materials in

Examples 7, 10 and 1 1.

DETAILED DESCRIPTION OF THE INVENTION

According to a first aspect, the present invention provides a crystallization process for the preparation of chemical compounds, in particular pure chemical compounds, in which an emulsion of droplets in a continuous phase is formed having Gibbs free enthalpy of formation ΔG>0, to effect crystallization and purification of the crude substance in the continuous or droplet phase, in which process seeding with crystals of the pure substance is carried out at a higher temperature than the temperature at which the crystallization is completed and in which process the emulsion comprises a surface active agent.

The term "crystallization process for the preparation of chemical compounds, in particular pure chemical compounds" may encompass in particular processes wherein the substance obtained after having carried out the crystallization process comprises an amount (percentage of weight) of the respective chemical compound being the target component, which amount (percentage of weight) is higher than the amount (percentage of weight) of the chemical compound being the target component present in the crude substance before carrying out the crystallization process.

The term "seeding with crystals of the pure substance" may encompass in particular a seeding with crystals comprising an amount (percentage of weight) of the respective chemical compound being the target component, which amount (percentage of weight) is higher than the amount (percentage of weight) of the respective chemical compound being the target component present in the crude substance. For example, the crystals used for seeding can have a purity of above 99 % (w/w), in particular of above 99.5 % (w/w), further in particular of at least 99.8 % (w/w), especially of 100 % (w/w).

The term "the temperature at which the crystallization is completed" may encompass for example the temperature at which no more or essentially no more crystals precipitate, or e.g. the temperature, at which the crystal precipitation is stopped or interrupted, in particular before starting the isolation of the crystals resulting from the crystallization process of the present invention. Preferably the crystal precipitation is stopped or interrupted when no more or essentially no more crystals precipitate.

The term "surface active agent" is known to a person skilled in the art and may encompass for example agents lowering the surface tension of a liquid and in particular may encompass agents lowering the surface tension of one or more of the components of the emulsion used during the crystallization process of the present invention.

Formation of emulsions is well-known in the art and is by definition "droplets" dispersed in a "continuous phase". Optionally, the emulsions contain additives such as surface active agents lowering the interfacial tension by adsorption of surfactants and stabilizing the emulsion droplets to a certain degree (Eli Ruckenstein, J. C. Chu; Stability of Microemulsions, J Chem Soc Faraday Trans II 1975;71 : 1690-1707). The droplet size is not limited and usually in the range between 0.2-100 μm.

Solvents which may be used in combination with water (in the droplets or in the continuous phase) are non-polar, lipophilic solvents as n-, i- or branched having formula C_nH_2n+2 (alkanes), C_nH_2n (alkenes), C_nH_2n-2 (alkynes), aromatics, halogenated hydrocarbons, ethers, aldehydes, natural or mineral oils, ketones, esters, amides, etc. An appropriate solvent can be any solvent which is at least partially immiscible with water and consequently capable of forming an emulsion with water. One, two or more solvents can be used with water simultaneously. Water insoluble solvents are all solvents which are not miscible with water or have very low solubility in water, and thus can form an emulsion with water. The dielectric constant of the solvent used as the organic phase is below 15 and is not limited for co-solvents, if the latter are used together with a first solvent.

One of the phases is thus comprised by water, to which other, water soluble polar solvents may be admixed, and the second phase is comprised by one or more unpolar solvents, which are not soluble in water or its mixtures with water soluble polar solvents. Usually the droplet is formed by the organic lipophilic solvent and the continuous phase comprises water.

All emulsions used are characterized by showing free Gibbs energy of droplet formation ΔG > 0, which means that if this emulsions are left to stand without homogenization, the liquid phases are separated after a certain period of time. Emulsions showing free Gibbs energy of droplet formation lower than 0, on the contrary, remain unchanged even if not constantly homogenized once they are formed.

The target component may theoretically crystallize or precipitate either from the droplet or the continuous phase but in most cases the first case occurs.

Usually the droplet phase of the emulsion will contain the aggregate mixture to be purified and may optionally contain one, two or more solvents. Surprisingly, it was found that the desired substance may also be practically insoluble in the dispersed "droplet" phase when compared to the continuous phase, leading to the precipitation or crystallization of the target component from the continuous phase.

Furthermore, the emulsion can contain a buffering agent and/or solubility adjusting agents, as known in the art.

The emulsion according to the present invention contains one or more surface active agents and/or dispersants which assist in forming an emulsion. The surface active agents can be non-ionic, cationic or anionic, as known in the art. For example, the surfactant can be or can comprise a di(C₆-Ci₂ alkyl) sodium sulfosuccinate said C₆-Ci₂ alkyl being a straight chain or being a branched C₆-Ci₂ alkyl, such as dioctyl sodium sulfosuccinate, an ethoxylated polyarylphenol phosphate based surfactant, a poly(ethylene g\yco\)-block- poly(propylene glycol)-£/øc£-poly(ethylene glycol) tri-block co-polymer or mixtures thereof.

The purification process of the present invention is appropriate for crude/aggregate substances which contain at least 30% by weight of the target component, preferably more than 50% by weight of the target component, more preferably more than 70 % by weight of the target component.

The "target component" is a chemical compound of interest as such, in particular any organic molecule, preferably a or the pure pharmaceutically active compound or its intermediate, is meant.

The term "aggregate mixture" or "crude substance" is used when unsatisfactorily pure target components are meant, which contain an elevated level of impurities, either synthetic, biosynthetic or degradation impurities by their origin. The term "pure substance" means a substance having less impurities than a crude substance, i.e. having a higher degree of purity than the crude substance.

"Targeted crystallization reactor temperature" is the lowest end temperature during the crystallization process. This is usually the temperature of suspo-emulsion immediately before the isolation process is performed.

In the examples the Reactor Temperature (RT) versus time during the cooling process is presented as a linear function, but is not limited thereto. It is used as an average cooling rate for describing the approximate time needed for cooling the mixture in the reactor to the desired temperature. The real function of the reactor temperature versus time of crystallization process can be represented by any other continuous function. The "temperature of seeding" is the temperature, at which the seeds of pure chemical substance are added.

This method of crystallization may be used for purifying any type of organic molecules, preferably prazoles (e.g. lansoprazole, pantaprazole, rabeprazole, omeprazole, esomeprazole), statins (e.g. rosuvastatin, fluvastatin, simvastatin, lovastatin, atorvastatin, and their intermediates, preferably the intermediates of atorvastatin, most preferably (3R,5R)-tert-butyl 7-(2-(4-fluorophenyl)-5-isopropyl-3-phenyl-4-(phenylcarbamoyl)-lH- pyrrol-l-yl)-3,5-dihydroxyheptanoate, ezetimibe, solifenacin or its pharmaceutically acceptable salts, orlistat or its intermediate lipstatin, fipronil, montelukast or its pharmaceutically acceptable salts, preferably alkaline or piperazine salts, most preferably montelukast sodium, montelukast trans-2,5-dimethylpiperazine and montelukast 2- methylpiperazine, saltans (such as valsartan, candesartan cilexetyl, olmesartan, telmisartan, irbesartan, eprosartan, preferably candesartan cilexetyl and trityl candesartan cilexetyl) and quetiapine. More preferably, the crystallization of the present invention is used for the purification of intermediates or crude drug products: ezetimibe, orlistat, fipronil, montelukast, atorvastatin, candesartan and pantoprazole.

The process can preferably be used for the purification of crude candesartan cilexetyl and its intermediates, most preferably trityl candesartan cilexetyl with a resulting purity more than 95 % in a single crystallization cycle, as well as for the purification of orlistat and montelukast acid with resulting purity more then 97% in a single crystallization cycle. Montelukast acid purified by the process of the present invention can e.g. be prepared by first forming a montelukast salt, preferably a montelukast piperazine salt and further converting it to montelukast free acid. Alternatively, montelukast salt, preferably montelukast piperazine salt, most preferably montelukast trans-2,5-dimethylpiperazine salt or montelukast 2-metylpiperazine salt, may also directly be purified by the process of the present invention. Montelukast free acid can eventually be converted to montelukast sodium salt, preferably with a purity of above 99.5 %. Most preferably, the crystallization in the case of ezetimibe and its derivates is performed with phase inversion, characterized in that purified ezetimibe is crystallized from the continuous and not from the droplet phase.

The emulsions comprising two immiscible liquids, surfactants, and optionally other additives yield in one single crystallization cycle at least 50%, preferably 70%, and more preferably more than 85% of the purified target component. The emulsion is heated and the mixture of substances (or crude substance or aggregate mixture) is dissolved, the emulsion is cooled to the desired temperature (which is higher than the crystallization temperature) where the seeding is performed (Seeding Reactor Temperature), to induce the crystallization. The crystallization takes place within the time period of further lowering the temperature to the targeted crystallization temperature. In the present invention best results have been observed when:

the final targeted crystallization reactor temperature at which the crystallization is completed, is 2 - 50°C below the seeding temperature, and the temperature of seeding was between 0 - 65 °C lower than the temperature at which all agglomerate mixture is dissolved. Preferably, the temperature of seeding was between 0.5 - 65 ⁰C lower, in particular 2 - 65 ⁰C lower than the temperature at which all agglomerate mixture is dissolved.

For efficient control of selectivity of emulsion crystallization processes characterized in having Gibbs free enthalpy of formation ΔG>0, preferably an optimized cooling ramp of crystallization media is used. Preferably the dynamics of cooling is less than 1.5 K/min, preferably less than 1 K/min, more preferably less than 0.5 K/min. The obtained product is preferably isolated and washed. If needed, the process is repeated. Instead of seeding any other method for forced nucleation can be used, as known in the art (ultrasound etc.).

The seed crystals applied in the process of the present invention may be prepared according to any process described in the prior art or known to the person skilled in the art. For ezetimibe seed crystals of ezetimibe may e.g. be prepared as described in WO 2008/089984; for fipronil, seed crystals may e.g. be prepared as described in WO 2007/069254 and WO 2008/055881 ; for montelukast acid, the seed crystals of montelukast acid used may be prepared as disclosed in US 2005/0187243; and e.g. for orlistat, seed crystals may be prepared as described in WO 2005/026140. For any compound to be purified by the present invention, any seed crystals of any polymorphic form can be used, preferably provided the seed crystals of the compound have a purity above 99.0 %, preferably above 99.5%. For pantoprazole the seed crystals can e.g. be prepared as disclosed in WO 2009/027533 and for (3R,5R)-tert-butyl 7-(2-(4- fluorophenyl)-5-isopropyl-3-phenyl-4-(phenylcarbamoyl)-lH-pyrrol-l-yl)-3,5- dihydroxyheptanoate as e.g. described in WO 2005/097742.

In a preferred embodiment of the invention, an emulsion with Free Gibbs energy of droplet formation ΔG>0 is formed, the aggregate mixture to be separated/ purified is dissolved at an elevated temperature, then the emulsion is cooled to the seeding reactor temperature, after which the temperature is still lowered to the target crystallization reactor temperature at which the crystallization is completed.

Using PEC results in high capacity of the crystallization process, high separation potential for related impurities, high yields of crystallization cycle, low amounts of surfactant needed and also produces large particles with improved filtration properties, which is needed especially in the "scale-up" development of an industrial process. There is a need in art for crystallization process characterized in effective and low-cost separation appropriate for large-scale production of pure organic substances.

Isolation of crystals from the emulsion can be carried out by any conventional means, such as filtration or centrifuge.

In particular the present invention provides the following items:

1.) A crystallization process for the preparation of chemical compounds, in particular of pure chemical compounds in which an emulsion of droplets in a continuous phase is formed having Gibbs free enthalpy of formation ΔG>0, to effect crystallization and purification of the crude substance in the continuous or droplet phase, characterized in that seeding with crystals of the pure substance is carried out at a higher temperature than the temperature at which the crystallization is completed and in that the emulsion comprises a surface active agent.

2.) A process according to item 1, characterized in that the purity of the crude substance is less than 90 %, preferably less than 80 %, most preferably less than 60% (w/w).

3.) A process according to any of items 1 or 2, where the final targeted temperature, at which the crystallization is completed, is 2-50 ⁰C below the temperature of seeding.

4.) A process according to any of items 1 to 3, where the temperature of seeding is 0-65

°C lower then the temperature, at which all of aggregate mixture is dissolved.

5.) A process according to any of items 1 to 4, where the average cooling rate for cooling the crystallization mixture from temperature, at which the seeding is done, to the targeted temperature is below 1 K/min, preferably below 0.5 K/min.

6.) A process according to any of items 1 to 5, where emulsion comprises an Ci-C₅ acetate ester as an organic phase.

7) A process according to any of items 1 to 6 characterized in that agglomeration of formed particles is induced by addition of the emulsion to the existing suspo-emulsion.

8.) The use of the process according to any of items 1 to 7 for the purification of a group of compounds, comprising statins like rosuvastatin, fluvastatin, simvastatin, lovastatin, atorvastatin, and their intermediates, like (3R,5R)-tert-butyl 7-(2-(4-fluorophenyl)-5- isopropyl-3-phenyl-4-(phenylcarbamoyl)-lH-pyrrol-l -yl)-3,5-dihydroxyheptanoate; sartans like valsartan. losartan, candesartan cilexetyl, olmesartan, telmisartan and irbesartan or their intermediates like trityl candesartan cilexetyl; prazoles like lansoprazole, pantoprazole, rabeprazole, omeprazole, or esomeprazole, ezetimibe, fipronil, montelukast acid or montelukast salts, like montelukast 2-methylpiperazine salt or 2-methylpiperazine salt; orlistat or its intermediate lipstatin, solifenacin base or solifenacin salts, and quetiapine; preferably orlistat, trityl candesartan cilexetyl and montelukast acid.

9.) The use of the process according to any of items 1 to 8 for the purification of crude candesartan cilexetyl, trityl candesartan cilexetyl or any intermediate of candesartan with a purity more than 95 % in a single crystallization step and a resulting purity more than

99 % after two crystallization steps. 10.) A process according to item 9 where purity of the starting material is below 90%, preferably below 50 %.

1 1.) A process according to any of items 1 to 8 for the purification of orlistat or its intermediate lipstatin with a resulting purity more then 97% in a single crystallization step and minimum resulting purity more than 98.5% after two consecutive crystallizations.

12.) A process according to item 1 1 where the purity of the starting material is below

95%, preferably below 87%.

13.) A process according to any of items 1 to 8 for the purification of montelukast acid with a resulting purity more than 97% in a single crystallization step and a resulting purity more then 99.0 % after three consecutive crystallizations.

14.) A process according to item 13 where the purity of the starting material is below

95%, preferably below 90%.

15.) A process according to any of items 13 and 14, characterized in that montelukast acid to be purified by the process is prepared by first forming a montelukast piperazine salt, preferably montelukast trans-2,5-dimethylpiperazine salt or montelukast 2- methylpiperazine salt and then converting it to montelukast acid.

16.) Montelukast sodium prepared according to any of items 13-15 with a chemical purity of above 99.5 %.

The term "Ci-C₅ acetate ester" encompasses for example Ci-C₅ alkyl acetate esters, in particular methyl acetate ester, ethyl acetate ester, and straight chain or branched C₃-C₅ alkyl acetate esters, and for example C₂-C₅ alkenyl acetate esters, e.g. straight chain C₂- C₅ alkenyl acetate esters and branched C₃-C₅ alkenyl acetate esters.

The present invention is illustrated by the following Examples without being limited thereto. With the examples we demonstrate the advantage of PEC with the concentrations of selected impurities, process yields and particle size distributions. Nevertheless, the invention is not limited to the selected impurities but is appropriate for the purification of any molecules and any related impurity. All emulsions used are characterized by showing free Gibbs energy of droplet formation ΔG > 0, which means that if this emulsions are left to stand without homogenization, the liquid phases are separated after a certain period of time. Emulsions showing free Gibbs energy of droplet formation lower than 0, on the contrary, remain unchanged even if not constantly homogenized.

In all examples mechanical stirring for appropriate homogenization of the (suspo-) emulsion was used during the described crystallization process in the reactor.

In all examples the mass of the starting material and the mass of the obtained purified product refers to the product, dried under vacuum and nitrogen flow and having loss on drying < 1 w/w %. If necessary, the drying time is prolonged until material having loss on drying < 1 w/w % is obtained.

In all examples the solvents used have a purity of more than 98.0 w/w %.

In all examples the given temperatures refer to the average temperature of the mixture in the reactor (RT) during the described step of the process.

The surface-active agents used in the examples are: i) Aerosol® OT-B (Cytec Industries Inc.), which consists of 85 w/w % dioctyl sodium sulfosuccinate and 15 w/w % sodium benzoate, ii) Pluronic® F 127 (Sigma Aldrich Co.), which is a poly(ethylene glycol)-WocΛ> poly(propylene glycol)-ό/oc£-poly(ethylene glycol) tri-block co-polymer, and iii) Soprophor® FL (Rhodia), which is an ethoxylated polyarylphenol phosphate based surfactant.

The purity or impurity content % is expressed as chromatographic purity (in area %). The assay is expressed as weight % and is determined by the use of the external standard method. The analytical methods for the chromatographic purity of target molecules were the following:

a.) FIPRONIL, HPLC method

Column: X Bridge C-8 75 x 4.6mm, 2.5μm,

Eluent A: 0.01 M (NH4)₂HPO₄ pH=6.0

Eluent B: acetonitrile

Eluent C: methanol

Gradient:

Post time: 3 min Flow-rate: 1.0 mL/min Detection: UV, wavelength 280 nm

Injection volume: 20 μl Column temperature: 25°C

Diluent: acetonitrile : methanol : water (40 : 30 : 30, V:V:V)

b.) MONTELUKAST, HPLC method

Column: Eclipse Plus C 18, 50 x 4.6 mm, 1.8 μm particles,

Eluent A: 0.005 M sodium dihydrogen phosphate : acetonitrile : triethylamine

= 65 : 35 : 0.2, pH=6.5 Eluent B: acetonitrile : water= 90 : 10 Gradient:

Post time: 3 min Flow-rate: 1.0 mL/min Detection: UV, 225 nm

Injection volume: 5 μl Column temperature: 25°C Diluent: methanol

c.) EZETIMIB, HPLC method for stereoisomeric purity Column: Chiralpak AD-H, 250 x 4.6 mm, 5 μm

Mobile phase: solvent A hexane solvent B: ethanol : methanol in the ratio 75:25 Isocratic elution: solvent A : solvent B in the ratio 90 : 10

Column temperature: 25°C

Flow rate: 1.5 ml/min

Detection: UV, 230 nm

Injection: 10 μl

Diluent: ethanol acidified with acetic acid (0.2 ml of acetic acid into 0.5 1 of ethanol, mix well)

d.) TRITYL CANDESARTAN CILEXETYL, HPLC method Column: Zorbax Eclipse Plus C 18, 50 x 4.6 mm, 1.8 μm particles, Eluent A: 0.01 M NaH₂PO₄, pH 2.5 Eluent B: acetonitrile Gradient:

Post time: 3 min Flow-rate: 1.0 mL/min Detection: UV, wavelength 225 nm Injection volume: 5 μl

Column temperature: 30⁰C

Diluent: acetonitrile : water (80 : 20, V:V)

e.) PANTOPRAZOLE, HPLC method

Column: Gemini C 18 150 x 4.6 mm i.d., 3 μm particles

Column temperature: 35°C

Mobile phase: gradient elution

A: 0.0 IM phosphate buffer solution pH 6.5

B: mixture of solvents (acetonitrile : methanol = 30 : 70) (V: V)

Post time: 2 minutes Flow: about 1.0 mL/min

Detection: UV, wavelength 280 nm

Injection: 20 μl

Temperature of samples: 8°C

Diluent: water : acetonitrile: TEA = 60 : 40 : (V/V/V), adjust the pH of the solvent to 10.0 with H₃PO₄.

f.) ORLISTAT, HPLC method

Column: Inertsil ODS3, 150 * 4.6 mm, 3 μm particles,

Eluent A: 0,1% phosphoric acid

EIuent B: acetonitrile

Gradient:

Post time: 4 min

Flow-rate: 1.2 mL/min

Detection: UV, 200 nm

Injection volume: 20 μl Column temperature: 45°C Diluent: acetonitrile

g.) (3R,5R)-tert-butyl 7-(2-(4-fluorophenyl)-5-isopropyl-3-phenyl-4- (phenylcarbamoyl)-l//-pyrrol-l-yl)-3,5-dihydroxyheptanoate, HPLC method Column: Luna PFP 10OA, 3 μm, 150 x 4.6 mm Mobile phase: solvent A 0.01 M ammonium acetate pH 3.8 solvent B: acetonitrile : tetrahydrofurane in the ratio 95:5

Post run: 3 min

Column temperature: 20⁰C

Flow rate: 1.0 mL/min

Detection: UV, 248 nm

Injection: 10 μl

Diluent: mixture of acetonitrile and water (70:30)

The term "particle size distribution" means a particle size frequency distribution that shows the percentage of particles (normalized in means of mass, volume or count) found in each size range and usually displayed in a histogram form.

The term "mean diameter", describes the arithmetic average volume particle diameter of the distribution.

The term "d90 value" means that at least 90% of the particles have a volume diameter less than the specified value. The same approach goes for the d50 and dlO. The term "d50 value" means that at least 50% of the particles have a volume diameter less than the specified value. The term "dlO value" means that at least 10% of the particles have a volume diameter less than the specified value. In the case of montelukast, the particle size was determined by laser light scattering on Malvern- Mastersizer Apparatus MS 2000 equipped with Hydro 2000S dispersion cell unit using vegetable oil as the dilution medium (RI=I, 469). Particle absorption index was set to 1.

In the case of trityl candesartan cilexetyl, the particle size was determined by laser light scattering on Malvern-Mastersizer Apparatus MS 2000 equipped with Hydro 2000S dispersion cell unit using Isopar L as the dilution medium (RI= 1,432). Particle absorption index was set to 1.

In the case of orlistat, the particle size was determined by laser light scattering on Malvern- Mastersizer Apparatus MS 2000 equipped with Hydro G dispersion cell unit using deionised water as the dilution medium (RI=I, 330). Particle absorption index was set to 1.

The invention is further illustrated by the following examples which demonstrate the used of PEC for the purification of certain organic compounds without being limited thereto. Parts or percentages are based on weight, unless specified otherwise.

EXAMPLES

EXAMPLE 1

Purification of ezetimibe by PEC

0.5 g of crude ezetimibe (enantiomeric purity 93.2 %) with 6.8 % of the impurity 1, (3R,4S)-l-(4-fluorophenyl)-3-((R)-3-(4-fluorophenyl)-3-hydroxypropyl)-4-(4- hydroxyphenyl)azetidin-2-one, was added to an emulsion consisting of 5 mL of chlorobenzene, 0.25 mL of water, 0.4 mL of methanol and 0.015 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate). The suspo- emulsion was heated from room temperature to 95 °C with average heating ramp 1 K/min and maintained for all solid to dissolve. The mixture was maintained at this temperature for 10 minutes and cooled to 50 ⁰C with average cooling ramp 1 K/min. At this point seeds of pure ezetimibe were added (10 mg) and the emulsion was slowly cooled to 35 ⁰C with average cooling ramp 0.05 K/min and maintained at this temperature for additional 5 hours to allow ezetimibe to fully crystallize. The formed product was isolated by filtration and washed with 0.5 mL of water. 0.36 g of ezetimibe with enantiomeric purity 98.3 %, with 1.4 % of the impurity 1, was obtained.

Table 1 : HPLC analysis of crystallized material .

EXAMPLE 2

Purification of fipronil by PEC

21g of crude fipronil (purity 94.2 %) with 4.4 % of the impurity 2, 5-amino-l-(2,6- dichloro^-CtrifluoromethyOphenyO^-CtrifluoromethylsulfonyO-lH-pyrazole-S- carbonitrile, and 1.1 % of the impurity 3, 5-amino-l-(2,6-dichloro-4- (trifluoromethyl)phenyl)-4-(trifluoromethylthio)-lH-pyrazole-3-carbonitrile, was completely dissolved in an emulsion consisting of 9 mL of isopropanol, 25 mL of ethyl acetate, 30 mL of water and 2 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate). The suspo-emulsion was heated from room temperature to reflux with average heating ramp 1 K/min and maintained at this temperature for 30 minutes for all solid to dissolve. Furthermore, the emulsion was cooled to 40 °C and the seeds of pure fipronil were added (200 mg) at this temperature. Then, the emulsion was cooled to 0 °C with average cooling ramp 0.20 K/min and maintained for additional 2 hours to allow fipronil to fully crystallize. The formed product was isolated by filtration and washed with 15 mL of water. 14.6 g of product with 2.5 % of the impurity 2 and 0.50 % of the impurity 3, with 96.9 % fipronil purity, was obtained. The microscope pictures of formed product are shown in Figure 2.

COMPARATIVE EXAMPLE 2

2 Ig of crude fipronil (purity 94.2 %) with 4.4 % of the impurity 2, 5-amino-l-(2,6- dichloro^^trifluoromethyOphenyO^^trifluoromethylsulfonyO-lH-pyrazole-S- carbonitrile, and 1.1 % of the impurity 3, 5-amino-l-(2,6-dichloro-4- (trifluoromethyl)phenyl)-4-(trifluoromethylthio)-lH-pyrazole-3-carbonitrile, was completely dissolved in an emulsion consisting of 9 mL of isopropanol, 25 mL of ethyl acetate, 30 mL of water and 2 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate). The suspo-emulsion was heated from room temperature to reflux with average heating ramp 1 K/min and maintained at this temperature for 30 minutes for all solid to dissolve. Furthermore, the emulsion was cooled to 0 °C and the seeds of pure fipronil were added (200 mg) at this temperature. The emulsion was maintained for additional 5 hours to allow fipronil to fully crystallize. The formed product was isolated by filtration and washed with 15 mL of water. The microscope pictures of formed product are presented in Figure 3.

14.3 g of 95,4 % fipronil product with 3.9 % of the impurity 2 and 0,6 % of the impurity 3 was obtained.

Table 2: ΗPLC analysis of crystallized materials in Example 2 and Comparative Example

2.

Impurity 2 Impurity Purity of Microscopic content (%) 3 content crystallized pictures of formed

(%) material (%) particles

EXAMPLE 2 2.5 0.5 96.9 Figure 2

COMPARATIVE 3.9 0.6 95.4 Figure 3 EXAMPLE 2 EXAMPLE 3

Purification of montelukast acid by PEC

3.15 g of crude montelukast acid (purity 93.5%) with 0.15 % of the impurity 4, (R₅E)- methyl 2-(l-((l-(3-(2-(7-chloroquinolin-2-yl)vinyl)phenyl)-3-(2-(2-hydroxypropan-2 yl)phenyl)propylthio)methyl)cyclopropyl)acetate, is completely dissolved in 9 mL of ethyl acetate at reflux conditions. 12 mL of warmed water and 0.35 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate) were added. Furthermore, the emulsion was cooled to 45 ⁰C with average cooling ramp 0.5 K/min and after that the emulsion was slowly cooled with the average cooling ramp 0.10 K/min to 15 °C. The seeds of pure montelukast acid were added (50 mg) at 30 ⁰C, during the slow cooling. Formed suspo-emulsion was homogenized at this temperature for the next 3 hours for montelukast acid to fully crystallize. The formed product is isolated by filtration and washed with 2 mL of water. 2.6 g of montelukast acid was obtained. The microscope pictures of formed product are presented in Figure 4. Montelukast acid with 97.9 % purity and with 0.02 % of the impurity 4 was obtained.

The steps of the crystallization were repeated using the product from the Example 3 (97.9 % purity with 0.02 % of the impurity 4). 2.3 g of 99.3% pure montelukast acid with < 0.01 % of the impurity 4, was obtained.

Table 3: HPLC analysis of crystallized materials in Example 3.

EXAMPLE 4

Purification of orlistat by PEC

13 g of crude orlistat (purity 84.3 %, 83.2 w/w %) was added to an emulsion consisting of 55 mL of heptan, 23.5 mL of water and 0.4 g of Aerosol® OT-B (85 w/w dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate) and 1.5 g of Pluronic F- 127 (poly(ethylene glycol)-6/øc£-poly(propylene glycol)-6/øcλ>poly(ethylene glycol) tri-block co-polymer). The suspo-emulsion was heated from room temperature to 40 ⁰C with average heating ramp 1 K/min and maintained at this temperature for 5 minutes for all solid to dissolve. Furthermore the emulsion was cooled to 21 °C with average cooling ramp 0.8 K/min and the seeds of pure orlistat were added (150 mg). Furthermore the temperature in reactor was cooled to 19 °C with average cooling ramp 0.02 K/min and maintained for the next 7 hours to allow orlistat to fully crystallize. The formed product was isolated by filtration and washed with 10 mL of water. 9.7 g of orlistat with purity of 97.2 % and 95.3 w/w % was isolated. The microscopic pictures of formed product are presented in Figure 5.

The process is repeated to obtain 8.6 g orlistat with 98.7 % purity.

COMPARATIVE EXAMPLE 4

13 g of crude orlistat (purity 84.3 %, 83.2 w/w % ) was added to an emulsion consisting of 55 mL of heptan, 23.5 mL of water and 0.4 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate) and 1.5 g of Pluronic® F-127 (poly(ethylene glycol)-ό/ocλ:-poly(propylene glycol)-ό/ocλ>poly(ethylene glycol) tri- block co-polymer). The suspo-emulsion was heated from room temperature to 40 ⁰C with average heating ramp 1 K/min and maintained at this temperature for 5 minutes for all solid to dissolve. Furthermore the emulsion was cooled to 19 °C with average cooling ramp 0.8 K/min and the seeds of pure orlistat were added (150 mg). The temperature was maintained for the next 8 hours to allow orlistat to fully crystallize. The formed product was isolated by filtration and washed with 10 mL of water. 9.6 g of orlistat with purity 94.7 % and 93.4 w/w % was obtained. The microscopic pictures of formed product are presented in Figure 6.

Table 4: HPLC analysis of crystallized materials.

EXAMPLE 4/a

After the first crystallization was completed (Example 4, after the suspo-emulsion is maintained at 19 ⁰C for 7 hours) emulsion consisting 20 mL of heptan, 10 mL of water and 0.8 g of Pluronic® F-127 (poly(ethylene glycol)-6/oc£-poly(propylene g\yco\)-block- poly(ethylene glycol) tri-block co-polymer) is added. The emulsion was prepared separately and homogenized for all F 127 to dissolve before the addition to the suspo- emulsion. Finally, the suspo-emulsion was homogenized for the next 45 minutes and the product was isolated with filtration. 9.3 g of orlistat was isolated without affecting the purity of the formed product (comparable to Example 4). The microscopic pictures of formed particles are presented in Figure 7.

EXAMPLE 5

Purification of atorvastatine intermediate by PEC

12g of crude atorvastatine intermediate (3R,5R)-tert-butyl 7-(2-(4-fluorophenyl)-5- isopropyl-3-phenyl-4-(phenylcarbamoyl)-lH-pyrrol-l-yl)-3,5-dihydroxyheptanoate (purity 98.8 %) with 0.22 % of the impurity 5 (MΗ+18, RRt = 1.03), was added to an emulsion consisting of 84 mL of ethyl acetate, 20 mL of water and 2.4 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate). The suspo- emulsion was heated from room temperature to 70 °C with average heating ramp 1 K/min and maintained at this temperature for 20 minutes for all solid to dissolve. Furthermore the emulsion was cooled to 15 ⁰C with average cooling ramp 0.6 K/min and the seeds of pure product were added (200 mg). Furthermore the temperature in reactor was cooled to 8 ⁰C with cooling ramp 0.04 K/min and maintained for the next 30 minutes to allow product to fully crystallize. Formed product was isolated by filtration and finally washed with 10 mL of water. 10.1 g of 99.4 % pure product with 0.14 % of the impurity 5 (MH+ 18, RRt = 1.03), was obtained. The microscope pictures of formed product are presented in Figure 8.

Table 5: HPLC analysis of crystallized atorvastatine intermediate.

EXAMPLE 6

Purification of pantoprazole acid by PEC

An emulsion consisting 4 mL ethyl acetate, 4 mL of water, 1 g of Soprophor® FL and 0.4 g of sodium hydroxide was prepared. Furthermore 4 g of crude pantoprazole in acid form was added and heated up to 65 °C with average heating ramp 1 K/min and maintained at this temperature for all solid to dissolve (10 minutes). The obtained emulsion was cooled to 20 ⁰C with cooling ramp 0.5 K/min and stirred with mechanical stirrer. The seeds of pure pantoprazole acid were added (50 mg) and further cooled to 5 °C with average cooling ramp 0.5 K/min and maintained at this temperature for 15 hours. The crystallized pantoprazole acid was filtered and washed with 2 mL of butyl methyl ether and with 2 mL of water. The product was dried in a vacuum dryer at 40 °C for 10 hours. 3.2 g of product was obtained.

The purity of the starting crude pantoprazole and the pantoprazole purified by PEC were analysed by HPLC and are given in the table below:

Table 6: HPLC analysis of crude pantoprazole acid and crystallized pantoprazole acid products.

Table 7: ΗPLC analysis of pantoprazole acid and the crystallized product after the crystallization (the steps of the described crystallization were preformed).

EXAMPLE 7

Purification of candesartan intermediate by PEC

5 g of crude l -(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-l-((2'-(l-trityl-lH-tetrazol-5- yl)biphenyl-4-yl)methyl)-lH-benzo[i/]imidazole-7-carboxylate (95.9 w/w %, purity 99.0 %) with 0.68 % of the impurity 10, 2-ethoxy-l-((2'-(l-trityl-lH-tetrazol-5-yl)biphenyl-4- yl)methyl)-lH-benzo[<^imidazole-7-carboxylic acid, and 0.04 % of the impurity 1 1, ethyl 2-ethoxy- 1 -((2'-( 1 -trity 1- 1 H-tetrazol-5-yl)biphenyl-4-yl)methyl)- 1 H-benzo[d] imidazole- 7-carboxylate, was added to 8.7 mL of dichloromethane and heated to reflux for all solid to dissolve (solution A). Separately the mixture of 23 mL of water, 28 mL of acetonitrile and 0.85 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate) was prepared and heated to 60 °C (mixture B). Then the mixture B was added to the solution A. The formed emulsion was cooled to 30 ⁰C with the average cooling ramp 0.6 K/min and the seed crystals of pure trityl candesartan cilexetil were added (150 mg). Furthermore the temperature in the reactor was slowly cooled to 20 °C with an average cooling ramp 0.05 K/min and maintained for the next 15 hours to allow the product to fully crystallize. The formed product is isolated by filtration and washed with 10 mL of acetonitrile. 4.5 g of the product with purity of 99.6 %, with 0.24 % of the impurity 10 and 0.02 % of the impurity 1 1, was isolated. The microscope pictures of formed product are presented in Figure 9.

COMPARATIVE EXAMPLE 7

Purification of candesartan intermediate by PEC

5 g of crude l -(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-l -((2'-(l-trityl-lH-tetrazol-5- yl)biphenyl-4-yl)methyl)-lH-benzo[(/]imidazole-7-carboxylate (95.9 w/w %, purity 99.0 %) with 0.68 % of the impurity 10, 2-ethoxy-l-((2'-(l-trityl-lH-tetrazol-5-yl)biphenyl-4- yl)methyl)-l H-benzo[d]imidazole-7-carboxylic acid, and 0.04 % of the impurity 1 1 , ethyl 2-ethoxy-l-((2'-(l-trityl-lH-tetrazol-5-yl)biphenyl-4-yl)methyl)-lH-benzo[i/]imidazole- 7-carboxylate, was added to 8.7 mL of dichloromethane and heated to reflux for all solid to dissolve (solution A). Separately the mixture of 23 mL of water, 28 mL of acetonitrile and 0.85 g of Aerosol® OT-B (85% w/w% dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate), was prepared and heated to 60 ⁰C (mixture B). Then the mixture B was added to the solution A. The formed emulsion was cooled to 30 °C with average cooling ramp 0.6 K/min and the seed crystals of pure trityl candesartan cilexetil were added (150 mg). Furthermore the temperature in reactor was slowly cooled to 20 °C with average cooling ramp 0.05 K/min and maintained at the final temperature for the next 15 hours to allow the product to fully crystallize. Formed product is isolated by filtration and washed with 10 mL of acetonitrile. 4.3 g of the product with purity of 99.5 %, with 0.27 % of the impurity 10 and 0.02 % of the impurity 1 1, was isolated The microscope pictures of formed product are presented in Figure 10.

Table 9: HPLC analysis of crystallized materials.

EXAMPLE 8

Purification of candesartan intermediate by PEC

24.0 g of crude l-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-l-((2'-(l-trityl-lH-tetrazol- 5-yl)biphenyl-4-yl)methyl)-lH-benzo[i/]imidazole-7-carboxylate (50.0 w/w %, purity 68.3 %) with 3.55 % of the impurity 10, 2-ethoxy-l -((2'-(l-trityl-lH-tetrazol-5- yl)biphenyl-4-yl)methyl)-lH-benzo[<i]imidazole-7-carboxylic acid, and 0.20 % of the impurity 1 1, ethyl 2-ethoxy-l-((2'-(l -trityl-lH-tetrazol-5-yl)biphenyl-4-yl)methyl)-lH- benzo[c/]imidazole-7-carboxylate, was added to 1 1 mL of dichloromethane and heated to reflux for all solid to dissolve (solution A). Separately the mixture of 43.6 mL of water, 83.7 mL of acetonitrile and 3.2 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate) was prepared and heated to 60 °C (mixture B). Then the mixture B was added to the solution A. The formed emulsion was cooled to 30 °C with average cooling ramp 0.6 K/min and the seed crystals of pure trityl candesartan cilexetil were added (350 mg). Furthermore the temperature in reactor was slowly cooled to 15 °C with average cooling ramp 0.05 K/min and maintained for the next 24 hours to allow the product to fully crystallize. Formed product is isolated by filtration and washed with 10 mL of acetonitrile. 10.9 g of the product with purity of 96.0 %, 94.0 w/w %, with 1.80 % of the impurity 10 and 0.08 % of the impurity 1 1, was isolated.

EXAMPLE 9

Purification of candesartan intermediate by PEC

7.0 g of crystallized l-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-l-((2'-(l-trityl-lH- tetrazol-5-yl)biphenyl-4-yl)methyl)-lH-benzo[</]imidazole-7-carboxylate, the product from Example 8 (purity 96.0 %, 94.0 w/w %) with 1.80 % of the impurity 10, 2-ethoxy- l -^'-Cl-trityl-lH-tetrazol-S-yObiphenyl^-yOmethyO-lH-benzofuQimidazole-?- carboxylic acid, and 0.08 % of the impurity 1 1, ethyl 2-ethoxy-l-((2'-(l-trityl-lH- tetrazol-5-yl)biphenyl-4-yl)methyl)-lH-benzo|//]imidazole-7-carboxylate, was added to 12.1 mL of dichloromethane and heated to reflux for all solid to dissolve (solution A). Separately the mixture of 32.6 mL of water, 37 mL of acetonitrile and 1.4 g of Aerosol® OT-B (85 w/w % dioctyl sodium sulfosuccinate, 15 w/w % sodium benzoate) was prepared and heated to 60 ⁰C (mixture B). Then the mixture B was added to the solution A. The formed emulsion was cooled to 30 ⁰C with average cooling ramp 0.6 K/min and the seed crystals of pure trityl candesartan cilexetil were added (200 mg). Furthermore the temperature in reactor was slowly cooled to 25 °C with average cooling ramp 0.05 K/min and maintained for the next 12 hours to allow the product to fully crystallize. Formed product is isolated by filtration and washed with 10 mL of acetonitrile. 6.0 g of the product with purity of 99.3 % (> 98.0 w/w %), with 0.45 % of the impurity 10 and 0,00 % of the impurity 1 1 , was isolated.

EXAMPLE 10

Purification of orlistat by PEC

10 g of crude orlistat (purity 95.3 %, 94.8 w/w %) with 0.37 % of the impurity 12, (S)- (3S,4R,6S)-3-hexyl-2-oxo-6-undecyltetrahydro-2H-pyran-4-yl 2-formamido-4- methylpentanoate, was added to an emulsion consisting of 39.5 mL of heptan, 17 mL of water and 0.57 g of Aerosol® OT-B (85 w/w % sodium dioctyl sulfosuccinate, 15 w/w % sodium benzoate). The suspo-emulsion was heated from room temperature to 40 ⁰C with average heating ramp 1 K/min and maintained at this temperature for 5 minutes for all solid to dissolve. Furthermore the emulsion was cooled to 20 °C with average cooling ramp 1 K/min and the seeds of pure orlistat were added (200 mg). Furthermore the temperature in reactor was cooled to 18 ⁰C with average cooling ramp 0.01 K/min and maintained for the next 7 hours to allow orlistat to fully crystallize. The formed product was isolated by filtration and washed with 15 mL of water. 8.4 g of orlistat with 98.5 % purity and 98.5 w/w %, with 0.18 % of the impurity 12, was isolated. The microscopic pictures of formed product are presented in Figure 1 1.

COMPARATIVE EXAMPLE 10

10 g of crude orlistat (purity 95.3 %, 94.8 w/w %) with 0.37 % of the impurity 12, (S)- (3S,4R,6S)-3-hexyl-2-oxo-6-undecyltetrahydro-2H-pyran-4-yl 2-formamido-4- methylpentanoate, was added to an emulsion consisting of 39.5 mL of heptan, 17 mL of water and 0.57 g of Aerosol® OT-B (85 w/w % sodium dioctyl sulfosuccinate, 15 w/w % sodium benzoate). The suspo-emulsion was heated from room temperature to 40 °C with average heating ramp 1 K/min and maintained at this temperature for 5 minutes for all solid to dissolve. Furthermore the emulsion was cooled to 18 ⁰C with average cooling ramp 1 K/min and the seeds of pure orlistat were added (200 mg). The suspo-emulsion was maintained at the temperature 18 ⁰C for the next 10 hours to allow orlistat to fully crystallize. The formed product was isolated by filtration and washed with 15 mL of water. 8.4 g of orlistat with 98.3 % purity and 97.5 w/w %, with 0.25 % of the impurity 12, was isolated. The microscopic pictures of formed product are presented in Figure 12.

Table 10: ΗPLC analysis of crystallized materials after the first crystallization.

EXAMPLE 11

Purification of montelukast acid by PEC

8.7 g of crude montelukast acid (purity 89.1 %, 87. 0 w/w %) with 0.32 % of the impurity 13, (R,E)-2-( 1 -((3-(2-acetylpheny I)- 1 -(3-(2-(7-chloroquinolin-2- yl)vinyl)phenyl)propylthio) methyl) cyclopropyl)acetic acid, is completely dissolved in 18 mL of ethyl acetate at reflux conditions. 26 mL of water and 1.0 g of Aerosol® OT-B (85% w/w % dioctyl sodium sulfosuccinate, 15% w/w % sodium benzoate) were added. Furthermore, the emulsion was cooled to 50 ⁰C and seeded with crystals of pure montelukast acid (150 mg). After that the emulsion was slowly cooled with the average cooling ramp 0.05 K/min to 10 ⁰C. Formed suspo-emulsion was homogenized at the final temperature 10 °C for the next 5 hours for montelukast acid to fully crystallize. The formed product is isolated with filtration and washed with 6 mL of water. 6.4 g of montelukast acid (purity 96.2 %, 95.3 w/w %), with 0.21 % of the impurity 13, was obtained. The microscope pictures of formed product are presented in Figure 13.

COMPARATIVE EXAMPLE 11

8.7 g of crude montelukast acid (purity 89.1 %, 87. 0 w/w %) with 0.32 % of the impurity 13, (R,E)-2-( 1 -((3-(2-acetylpheny I)- 1 -(3-(2-(7-chloroquinolin-2- yl)vinyl)phenyl)propylthio) methyl) cyclopropyl)acetic acid, is completely dissolved in 18 mL of ethyl acetate at reflux conditions. 26 mL of water and 1.0 g of Aerosol® OT-B (85% w/w % dioctyl sodium sulfosuccinate, 15% w/w % sodium benzoate) were added. Furthermore, the emulsion was cooled to 10 °C and seeded with crystals of pure montelukast acid (150 mg). Formed suspo-emulsion was homogenized at the temperature 10 °C for the next 17 hours for montelukast acid to fully crystallize. The formed product is isolated with filtration and washed with 6 mL of water.

6.2 g of montelukast acid (purity 95.7 %, 94.1 w/w %), with 0.26 % of the impurity 13, was obtained. The microscope pictures of formed product are presented in Figure 14.

Table 8: HPLC analysis of crystallized materials.

EXAMPLE 12

Purification of montelukast acid by PEC

i.) 1.9 g of crystallized montelukast acid - product from Example 1 1 (purity 96.2 %; 95.3 w/w %) with 0.21 % of the impurity 13, (R,E)-2-(l-((3-(2-acetylphenyl)-l-(3-(2-(7- chloroquinolin-2-yl)vinyl)phenyl)propylthio)methyl)cyclopropyl)acetic acid, was completely dissolved in 4.5 mL of ethyl acetate at reflux conditions. 6.5 mL of water and 0.25 g of Aerosol® OT-B (85% w/w dioctyl sodium sulfosuccinate, 15% w/w sodium benzoate) were added. Furthermore, the emulsion was cooled to 50 °C and seeded with crystals of pure montelukast acid (40 mg). After that the emulsion was slowly cooled with the average cooling ramp 0.05 K/min to 10 ⁰C. Formed suspo-emulsion was homogenized at the final temperature 10 °C for the next 5 hours for montelukast acid to fully crystallize. The formed product is isolated with filtration and washed with 2 mL of water.

1.6 g of montelukast acid (purity 97.8 %, 98.3 w/w %), with 0.15 % of the impurity 13, was obtained.

ii.) 1 g of crystallized montelukast acid - product from Example 12, i (purity 97.8 %, 98.3 w/w %) with 0.15 % of the impurity 13, (R,E)-2-(l-((3-(2-acetylphenyl)-l-(3-(2-(7- chloroquinolin-2-yl)vinyl)phenyl)propylthio)methyl)cyclopropyl)acetic acid, was completely dissolved in 4.5 mL of ethyl acetate at reflux conditions. 3.6 mL of water and 0.14 g of Aerosol® OT-B (85% w/w dioctyl sodium sulfosuccinate, 15% w/w sodium benzoate) were added. Furthermore, the emulsion was cooled to 50 ⁰C and seeded with crystals of pure montelukast acid (40 mg). After that the emulsion was slowly cooled with the average cooling ramp 0.05 K/min to 10 ⁰C. Formed suspo-emulsion was homogenized at the final temperature 10 °C for the next 5 hours for montelukast acid to fully crystallize. The formed product is isolated with filtration and washed with 2 mL of water.

0.8 g of montelukast acid (purity 99.0 %, 98.8 w/w %), with 0.09 % of the impurity 13, was obtained. EXAMPLE 13

Purification of montelukast acid by crystallization of l-rπT3-r(l E)-2-(7-chloroquinoline- 2-yl)ethenyllphenyll-3-r2-(l -hydroxy- l-methylethv0phenyl1propyl1thio]methyl1 cyclopropane acetic acid trans-2,5-dimethylpiperazine salt

To a 50 mL round-bottom flask equipped with a magnetic mixer, a reflux condenser and a nitrogen inlet 4.8 g of crude montelukast acid (purity 76.4 %, 62 w/w %), 33 mL of ethyl acetate and 0.30 g of trans-2,5-dimethylpiperazine were added. The mixture was heated to 70 °C and a clear solution was obtained. Then the mixture was cooled to 20 ⁰C and homogenized at this temperature for the next 15 hours.

The obtained product was isolated using filtration and washed with 50 mL of ethyl acetate/TBME mixture (50 v/v %).

2.70 g of montelukast-trans-2,5-dimethylpiperazine salt was obtained (purity 95.0 %).

2 g of obtained montelukast trans-2,5-dimethylpiperazine salt, 20 mL of ethylacetate and 20 mL of water was charged into a 50 mL round-bottom flask equipped with a magnetic mixer, a reflux condenser, a nitrogen inlet and an addition funnel. The mixture was heated to 70 ⁰C for solid particles to dissolve. The formed emulsion was cooled to 20 °C and 1.6 mL solution of acetic acid in water (2M solution) was added drop wise. The mixture was stirred for the next 10 minutes. The organic phase was separated and washed twice with 20 mL of water at room temperature. Finally, the ethyl acetate was evaporated and 1.7 g of montelukast free acid was isolated (purity 94.4 %, 93 w/w %).

Montelukast free acid as obtained by the process above may further be purified by the process of the present invention. Alternatively montelukast salts can also be purified by the process of the present invention. As another possibility montelukast acid is purified by the emulsion crystallization process of the present invention without previous formation of a montelukast salt, such as montelukast piperazine salts. EXAMPLE 14

Purification of montelukast acid by crystallization of l-f[|T3-[Yl E)-2-(7-chloroquinoline- 2-yl)ethenyl1phenyl1-3-r2-( 1 -hydroxy- 1 -methylethy Dphenyllpropy I]thio1methyl]cyclo propane acetic acid trans-2,5-dimethylpiperazine salt

To a 50 mL round-bottom flask equipped with a magnetic mixer, a reflux condenser and a nitrogen inlet 4.8 g of crude montelukast acid (purity 76.4 %, 62 w/w %), 33 mL of ethyl acetate and 0.33 g of trans-2,5-dimethylpiperazine were added. The mixture was heated to 70 °C and a clear solution was obtained. Then the mixture was cooled to 20 °C and homogenized at this temperature for the next 15 hours.

2.75 g of montelukast-trans-2,5-dimethylpiperazine salt was obtained (purity 95.7 %).

2 g of obtained montelukast-trans-2,5-dimethylpiperazine salt, 20 mL of ethylacetate and 20 mL of water was charged into a 50 mL round-bottom flask equipped with a magnetic mixer, a reflux condenser, a nitrogen inlet and an addition funnel. The mixture was heated to 70 ⁰C for solid particles to dissolve. The formed emulsion was cooled to 20 ⁰C and 2.8 mL solution of acetic acid in water (2M solution) was added drop wise. The mixture was stirred for the next 10 minutes. The organic phase was separated and washed twice with 20 mL of water at room temperature. Finally, the ethyl acetate phase was evaporated and 1.7 g of montelukast free acid was isolated (purity 95.0 %, 92.7 w/w %).

Montelukast free acid as obtained by the process above may further be purified by the process of the present invention. Alternatively montelukast salts can also be purified by the process of the present invention. As another possibility montelukast acid is purified by the emulsion crystallization process of the present invention without previous formation of a montelukast salt, such as montelukast piperazine salts. EXAMPLE 15

Purification of montelukast acid by crystallization of l-rπ^"(^"3-r(l E)-2-(7-chloroquinoline- 2-vDethenyπphenyl]-3-[2-(l -hydroxy- l-methylethyDphenyllpropyllthiolmethyll cyclopropane acetic acid 2-methylpiperazine salt

To a 50 mL round-bottom flask equipped with a magnetic mixer, a reflux condenser and a nitrogen inlet 3 g of crude montelukast acid (purity 78.3 %, w/w %), 32 mL of ethyl acetate and 0.27 g 2-methylpiperazine were added. The mixture was heated to 70 ⁰C and a clear solution was obtained. Then the mixture was cooled to 20 °C and homogenized at this temperature for the next 15 hours. The obtained product was isolated using filtration and washed with 50 mL of ethyl acetate/TBME mixture (50 v/v %). 1.60 g of dry montelukast-2-methylpiperazine salt was obtained (purity 97.9 %).

1 g of obtained montelukast-2-methylpiperazine salt, 10 mL of ethylacetate and 10 mL of water was charged into a 50 mL round-bottom flask equipped with a magnetic mixer, a reflux condenser, a nitrogen inlet and an addition funnel. The mixture was heated to 70 ⁰C for solid particles to dissolve. The formed emulsion was cooled to 20 °C and 1.4 mL solution of acetic acid in water (2M solution) was added drop wise. The mixture was stirred for the next 10 minutes and then stopped. The organic phase was separated and washed twice with 10 mL of water at room temperature. Finally, the ethyl acetate phase was evaporated and 0.8 g of montelukast free acid was isolated (purity 98.0 %, 97.8 w/w %).

Montelukast free acid as obtained by the process above may further be purified by the process of the present invention. Alternatively montelukast salts can also be purified by the process of the present invention. As another possibility montelukast acid is purified by the emulsion crystallization process of the present invention without previous formation of a montelukast salt, such as montelukast piperazine salts. Structures of molecules purified and related impurities:

-Ezetimibe (Example 1)

(3R,4S)-1-(4- Fluorophenyl)- 3-[(S)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4- hydroxyphenyl)azetidin-2-one

-Impurity 1 (Example 1)

(3R,4S)-1-(4-Fluorophenyl)-3-[(R)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4- hydroxyphenyl)azetidin-2-one

- Fipronil (Example 2, Comparative Example 2)

5-Amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-(trifluoromethylsulfinyl)-

1 H-pyrazole-3-carbonitrile

-Impurity 2 (Example 2, Comparative Example 2)

5-Amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-(trifluoromethylsulfonyl)-1 /-/- pyrazole-3-carbonitrile

-Impurity 3 (Example 2, Comparative Example 2)

5-Amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-(trifluoromethylthio)-1 H- pyrazole-3-carbonitrile -Montelukast acid (Example 3)

1 -[[[( 1 R)- 1 -[3-[( 1 E)-2-(7-Chloro-2-quinoliny l)ethenyl]phenyl]-3-[2-( 1-hydroxy- 1 - methylethyl)phenyl]propyl]thio]methyl]cyclopropaneacetic acid

-Impurity 4 (Example 3)

Methyl 1 -[[[( 1 R)- 1 -[3-[( 1 E)-2-(7-Chloro-2-quinolinyl)ethenyl]phenyl]-3-[2-( 1 -hydroxy- 1 - methylethyOphenyljpropyljthiolrnethyllcyclopropaneacetate -Orlistat (Example 4, Comparative Example 4)

Λ/-Formyl-L-leucine (1S)-1-[[(2S,3S)-3-hexyl-4-oxo-2-oxetanyl]methyl]dodecyl ester

-Atorvastatin intermediate (Example 5)

(3R,5R)-TerNbutyl 7-(2-(4-fluorophenyl)-5-isopropyl-3-phenyl- 4-(phenylcarbamoyl)-1H-pyrrol-1-yl)-3,5-dihydroxyheptanoate

-Impurity 5 (Example 5)

(3R,5R)-7erf-butyl 7-(2-(4-fluorophenyl)-5-isopropyl-3-phenyl-4-(phenylcarbamoyl)- lH-pyrrol-l-yl)-3,5-dihydroxyheptanoate MΗ+18 (RRt = 1.03) -Pantoprazole acid (Example 6)

5-(Difluoromethoxy)-2-[[(3,4-dimethoxy-2-pyridinyl)methyl]sulfinyl]-1/-/-benzimidazole

-Impurity 6 (Example 6)

2-[[Chloro(3,4-dimethoxypyridin-2-yl)methyl]sulfinyl]-5- (difluoromethoxy)-1 /-/-benzimidazole

-Impurity 7 (Example 6)

2-[[Chloro(3,4-dimethoxypyridin-2-yl)methyl]sulfinyl]-6- (difluoromethoxy)-1 /-/-benzimidazole

-Impurity 8 (Example 6)

5-Difluoromethoxy-2-[[(3,4-dimethoxy-2- pyridinyl)methyl]thio]-1H-benzimidazole

-Impurity 9 (Example 6)

5-(Difluoromethoxy)-2-[[(3,4-dimethoxypyridin-2-yl)methyl]sulfonyl]-1H-benzimidazole

-Trityl Candesartan cilexetil (Example 7)

1 -[[(Cyclohexyloxyjcarbonyljoxylethyl 2-ethoxy-1 -[[2'-(1 -trityl-1 W-tetrazol-5-yl)-[1 , 1 '-biphenyl]-4- yl]methyl]-1 H-benzimidazole-7-carboxylate

-Impurity 10 (Example 7)

2-Ethoxy-1 -((2'-(1 -trityl-1 H-tetrazol-5-yl)-[1 ,1 '-biphenyl]-4-yl)methyl)-1 H- benzo[d]imidazole-7-carboxylic acid -Impurity 11 (Example 7)

Ethyl 2-ethoxy- 1 -((2'-( 1 -trity 1-1 H-tetrazol-5-y l)-[ 1 , 1 '-bi phenyl]-4-y l)methyl)- 1 H- benzo[cφmidazole-7-carboxylate

- Impurity 12 (Example 15)

(S)-(3S,4R,6S)-3-Hexyl-2-oxo-6-undecyltetrahydrc>-2H-pyran-4-yl 2- formamido-4-methylpentanoate -Impurity 13

(R, E)-2-( 1 -((3-(2-Acetylphenyl)-1 -(3-(2-(7-chloroquinolin-2- yl)vinyl)phenyl)propylthio)methyl)cyclopropyl)acetic acid

Claims

What we claim is.

1.) A crystallization process for the preparation of chemical compounds, in particular of pure chemical compounds, in which an emulsion of droplets in a continuous phase is formed having Gibbs free enthalpy of formation ΔG>0, to effect crystallization and purification of the crude substance in the continuous or droplet phase, characterized in that seeding with crystals of the pure substance is carried out at a higher temperature than the temperature at which the crystallization is completed and in that the emulsion comprises a surface active agent.

2.) The process according to claim 1, characterized in that the purity of the crude substance is less than 90 %(w/w), preferably less than 80 %(w/w), most preferably less than 60% (w/w).

3.) The process according to any of claims 1 or 2, where the final targeted temperature, at which the crystallization is completed, is 2-50 ⁰C below the temperature of seeding.

4.) The process according to any of claims 1 to 3, where the temperature of seeding is 0-65 ⁰C lower, preferably 0.5-65 °C lower, preferably 2-65 ⁰C lower, than the temperature, at which all of aggregate mixture is dissolved.

5.) The process according to any of claims 1 to 4, where the average cooling rate for cooling the crystallization mixture from temperature, at which the seeding is done, to the targeted temperature is below 1 K/min, preferably below 0.5 K/min.

6.) The process according to any of claims 1 to 5, where emulsion comprises an Q-

C₅ acetate ester as an organic phase.

7) The process according to any of claims 1 to 6 characterized in that agglomeration of formed particles is induced by addition of an additional amount of the emulsion to the suspo-emulsion present after seeding and/or during crystallisation.

8.) The process according to any of claims 1 to 7 used for the purification of crude substance, said crude substance comprising one selected from the group consisting of statins like rosuvastatin, fluvastatin, simvastatin, lovastatin, atorvastatin, and their intermediates, like (3R,5R)-tert-butyl 7-(2-(4-fluorophenyl)-5-isopropyl-3-phenyl-4- (phenylcarbamoyl)-lH-pyrrol-l-yl)-3,5-dihydroxyheptanoate; saltans like valsartan, losartan, candesartan cilexetyl, olmesartan, telmisartan and irbesartan or their intermediates like trityl candesartan cilexetyl; prazoles like lansoprazole, pantoprazole, rabeprazole, omeprazole, or esomeprazole, ezetimibe, fipronil, montelukast acid or montelukast salts, like montelukast 2-methylpiperazine salt or 2- methylpiperazine salt; orlistat or its intermediate lipstatin, solifenacin base or solifenacin salts, and quetiapine; preferably one selected from the group consisting of orlistat, trityl candesartan cilexetyl and montelukast acid.

9.) The process according to any of claims 1 to 8 used for the purification of crude substance, said crude substance comprising one selected from the group consisting of candesartan cilexetyl, trityl candesartan cilexetyl and any intermediate of candesartan, with a purity of more than 95 % (w/w) in a single crystallization step and a resulting purity of more than 99 % (w/w) after two crystallization steps.

10.) The process according to claim 9 where the purity of the crude substance comprising one selected from the group consisting of candesartan cilexetyl, trityl candesartan cilexetyl and any intermediate of candesartan is below 90% (w/w), preferably below 50 % (w/w), and/or where the content of said one selected from the group consisting of candesartan cilexetyl, trityl candesartan cilexetyl and any intermediate of candesartan in the crude substance is below 90 wt.-%, preferably below 50 wt.-%, based on the total weight of the crude substance.

1 1.) The process according to any of claims 1 to 8 for the purification of crude substance, said crude substance comprising orlistat or its intermediate lipstatin, with a resulting purity of more then 97% (w/w) in a single crystallization step and minimum resulting purity of more than 98.5% (w/w) after two consecutive crystallizations.

12.) The process according to claim 1 1 where the purity of the crude substance comprising orlistat or its intermediate lipstatin is below 95% (w/w), preferably below 87% (w/w), and/or where the content of orlistat or lipstatin in the crude substance is below 95 wt.-%, preferably below 87 wt.-%, based on the total weight of the crude substance.

13.) The process according to any of claims 1 to 8 for the purification of crude substance comprising montelukast acid with a resulting purity of more than 97% (w/w) in a single crystallization step and a resulting purity of more then 99.0 % (w/w) after three consecutive crystallizations.

14.) The process according to claim 13 where the purity of the crude substance comprising montelukast acid is below 95% (w/w), preferably below 90% (w/w), and/or where the content of montelukast acid in the crude substance is below 95 wt.-%, preferably below 90 wt.-%, based on the total weight of the crude substance.

15.) The process according to any of claims 13 and 14, characterized in that montelukast acid to be purified by the process is prepared by first forming a montelukast piperazine salt, preferably montelukast trans-2,5-dimethylpiperazine salt or montelukast 2-methylpiperazine salt and then converting it to montelukast acid.

16.) Montelukast sodium prepared according to any of claims 13-15 with a purity of above 99.5 %(w/w).