Process for obtaining crystalline hexyl diethylaminohydroxybenzoylbenzoate

Abstract

Disclosed is a process for obtaining crystalline diethylaminohydroxybenzoylhexyl benzoate (I), the process comprising the steps (a) to (d), (a) providing a feed comprising diethylaminohydroxybenzoylhexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution, wherein the diethylaminohydroxybenzoylhexyl benzoate (I) has i) a dihexyl phthalate (PSDHE) (II) content of up to 100,000 ppm, based on the weight of the diethylaminohydroxybenzoylhexyl benzoate (I); and wherein the amount of diethylaminohydroxybenzoylhexyl benzoate (I) in the feed is in the range of from 15.0 wt% to 65.0 wt% based on the total weight of the feed; (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of hexyl diethylaminohydroxybenzoylbenzoate (I); (c) seeding the supersaturated solution obtained in the step (b) by using a seed crystal of diethylaminohydroxybenzoyl hexyl benzoate (I); wherein the amount of the seed crystals is in the range of 0.01 wt% to 15.0 wt% based on the weight of hexyl diethylaminohydroxybenzoylbenzoate (I) in the solution; and (d) cooling the solution obtained in step (c) to a temperature in the range of-20 DEG C to 17 DEG C to obtain a suspension comprising crystalline hexyl diethylaminohydroxybenzoylbenzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) and washing the isolated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent at least a first and a second time; and (e) optionally recrystallizing the hexyl diethylaminohydroxybenzoylbenzoate (I) obtained in step (d), involving mixing the hexyl diethylaminohydroxybenzoylbenzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d); wherein the amount of washing solvent in each of the at least first and second washing in at least one of step (d) of the crystallization or step (d) of the recrystallization (e) is at least 63 wt.% based on the weight of the diethylaminohydroxybenzoylbenzoic acid hexyl ester (I) in the corresponding solution in step (b). Furthermore, the present invention discloses a crystalline diethylaminohydroxybenzoyl hexyl benzoate obtained by the process of the present invention, the present invention relates to a purified diethylaminohydroxybenzoylhexyl benzoate obtained by the process of the present invention and to a cosmetic composition comprising a purified diethylaminohydroxybenzoylhexyl benzoate according to the present invention.

Description

Technical Field

[0001] The invention claimed herein relates to a process for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate. Furthermore, the invention claimed herein relates to crystalline diethylaminohydroxybenzoyl hexyl benzoate obtained by the process of the present invention, purified diethylaminohydroxybenzoyl hexyl benzoate obtained by the process of the present invention, and a cosmetic composition comprising purified diethylaminohydroxybenzoyl hexyl benzoate according to the present invention. Background Art

[0002] UV radiation causes harmful effects on human skin, such as sunburn, phototoxicity and photosensitization, accelerates skin aging, and increases the risk of skin cancer. To protect human skin from UV radiation, sunscreen or cosmetic compositions containing UV filters (also called UV absorbers) are used.

[0003] Typically, UV light can be divided into UV-A radiation (320-400 nm) and UV-B radiation (280-320 nm). Since 2006, the European Commission has recommended that all sunscreen or cosmetic compositions should have a UV-A protection factor that is at least one third of the indicated sun protection factor (SPF), where the SPF refers primarily to UV-B protection.

[0004] 2-(4'-diethylamino-2'-hydroxybenzoyl)hexyl benzoate (DHHB) is an effective UV-A filter. It is represented by formula (I).

[0005]

[0006] The preparation of hexyl 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoate (I) is known, for example, from DE 10011317, EP 2155660 and WO 2003097578.

[0007] However, the products obtained from the known processes are associated with several disadvantages.

[0008] Typically, 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I) is obtained as a melt after the synthesis process is completed and stored in the same form. After about six weeks at room temperature, crystal growth occurs in the melt. When in use, the user is required to heat the entire package to a temperature above the melting point of (I) in order to be able to remove the product from the storage container.

[0009] The product contains phthalic acid dihexyl ester (II) (also called PSDHE, or dihexylphthalate, or di-n-hexyl phthalate) as an impurity. The PSDHE content should be as low as possible because the substance is toxic; it may impair fertility and may have harmful effects on the unborn child. According to the Harmonized Classification and Labelling (ATP05), the permitted amount of PSDHE (II) in the final product is up to 150 ppm.

[0010]

[0011] Furthermore, the products obtained by the known processes contain rhodamine-type dyes (e.g. [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenyl]-diethylammonium salt) (III) and the corresponding esters (IV) as impurities, which lead to undesirable discoloration of the final product.

[0012]

[0013] Furthermore, the products obtained by the known methods may contain a potential intermediate 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V).

[0014]

[0015]

[0016] Due to these challenges, there is a continuing need for rapid and efficient methods for obtaining crystalline 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester (I) and for obtaining crystalline (I) with low amounts of (II) and low amounts of (III), (IV) and (V).

[0017] Therefore, the object of the present invention is to provide a method for obtaining crystalline 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I). In addition, the object is to provide a method for obtaining crystalline 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I) with a low amount of dihexyl phthalate (II). In addition, it is expected that the method provides crystalline 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester with a low amount of rhodamine-based impurities (III) and (IV) and a low amount of 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid (V). Summary of the invention

[0018] Surprisingly, it was found that at least one of the above objects is achieved by a method according to the invention claimed herein.

[0019] In a first aspect, the present invention relates to a process for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), the process comprising steps (a) to (d),

[0020] (a) providing a feed comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution,

[0021] Wherein the diethylaminohydroxybenzoyl hexyl benzoate (I) has

[0022] i) a content of dihexyl phthalate (PSDHE) (II) of up to 100,000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0023] and

[0024] wherein the amount of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the feed is in the range of 15.0 wt % to 65.0 wt % based on the total weight of the feed;

[0025] (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0026] (c) seeding the supersaturated solution obtained in step (b) with crystals of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0027] wherein the amount of the seed crystal is in the range of 0.01 wt % to 15.0 wt % based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the solution; and

[0028] (d) cooling the solution obtained in step (c) to a temperature in the range of -20°C to 17°C to obtain a suspension containing crystalline diethylaminohydroxybenzoyl hexyl benzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), and washing the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent at least a first time and a second time;

[0029] as well as

[0030] (e) optionally recrystallizing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d), which involves mixing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d);

[0031] wherein the amount of washing solvent in each of the at least first and second washing in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 63 wt.% based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b), wherein the first crystallization solvent comprises at least one C4-C8 alcohol.

[0032] In a second aspect, the present invention relates to a process for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), the process comprising steps (a) to (d),

[0033] (a) providing a feed comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution,

[0034] Wherein the diethylaminohydroxybenzoyl hexyl benzoate (I) has

[0035] i) a content of dihexyl phthalate (PSDHE) (II) of up to 100,000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0036] and

[0037] wherein the amount of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the feed is in the range of 15.0 wt % to 65.0 wt % based on the total weight of the feed;

[0038] (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0039] (c) seeding the supersaturated solution obtained in step (b) with crystals of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0040] wherein the amount of the seed crystal is in the range of 0.01 wt % to 15.0 wt % based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the solution; and

[0041] (d) cooling the solution obtained in step (c) to a temperature in the range of -20°C to 17°C to obtain a suspension containing crystalline diethylaminohydroxybenzoyl hexyl benzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), and washing the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent;

[0042] as well as

[0043] (e) optionally recrystallizing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d), which involves mixing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d);

[0044] wherein the amount of the washing solvent in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 130 wt.% based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b), wherein the first crystallization solvent comprises at least one C4-C8 alcohol.

[0045] In a third aspect, the present invention relates to a crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by one of the processes according to the invention, having

[0046] i) less than 250 ppm of dihexyl phthalate (PSDHE)(II);

[0047] ii) a rhodamine (III) content of less than 150 ppm; and

[0048] A content of rhodamine hexyl ester (IV) of less than 150 ppm; each based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0049] In a fourth aspect, the present invention relates to a purified diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by one of the processes according to the invention, having

[0050] i) less than 250 ppm of dihexyl phthalate (PSDHE)(II);

[0051] ii) a rhodamine (III) content of less than 10 ppm; and

[0052] A content of rhodamine hexyl ester (IV) of less than 10 ppm; each based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0053] In a fifth aspect, the present invention relates to a cosmetic composition comprising the purified diethylaminohydroxybenzoyl hexyl benzoate (I) of the present invention. DETAILED DESCRIPTION

[0054] Before describing the present compositions and formulations of the invention claimed herein, it should be understood that the invention is not limited to the specific compositions and formulations described, as such compositions and formulations may, of course, vary. It should also be understood that the terminology used herein is not intended to be limiting, as the scope of the invention claimed herein will be limited only by the appended claims.

[0055] If a group is defined as including at least a certain number of embodiments hereinafter, this means that it also includes a group preferably consisting only of these embodiments. In addition, the terms 'first', 'second', 'third' or 'a', 'b', 'c', etc. in the specification and claims are used to distinguish similar elements, and are not necessarily used to describe sequential or chronological order. It should be understood that the terms used in this way are interchangeable where appropriate, and the embodiments of the invention claimed herein described herein can operate in other sequences except as described or shown herein. In the case of the steps of the methods or uses or tests of the terms 'first', 'second', 'third' or '(A)', '(B)' and '(C)' or '(a)', '(b)', '(c)', '(d)', 'i', 'ii', etc., unless otherwise indicated in the application as described above or below, there is no time or time interval coherence between these steps, that is, these steps can be performed simultaneously or there can be a time interval of seconds, minutes, hours, days, weeks, months or even years between such steps.

[0056] Furthermore, ranges defined throughout this specification also include the endpoints, ie, a range of 1 to 10 means that both 1 and 10 are included in the range. For the avoidance of doubt, the applicant is entitled to any equivalents under applicable law.

[0057] In the following paragraphs, different aspects of the invention claimed herein are defined in more detail. Unless explicitly indicated to the contrary, each aspect so defined may be combined with any one or more other aspects. In particular, any feature indicated as preferred or advantageous may be combined with any one or more other features indicated as preferred or advantageous.

[0058] References throughout this specification to 'one embodiment' or 'an embodiment' mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention claimed herein. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0059] In addition, in one or more embodiments, specific features, structures or characteristics may be combined in any suitable manner, as will be apparent to those skilled in the art from this disclosure. In addition, although some embodiments described herein include some features (in addition to other features included in other embodiments), the combination of features of different embodiments is also intended to be within the scope of the invention claimed herein and to form different embodiments, which will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0060] As used herein, the term "ultraviolet filter" or "UV filter" refers to an organic or inorganic compound that can absorb and / or reflect UV radiation caused by sunlight. UV filters can be classified as UV-A, UV-B or broadband filters based on their UV protection curves. In the context of the present application, broadband filters can be listed as UV-A filters because they also provide UV-A protection. In other words, preferred UV-A filters also include broadband filters.

[0061] The definition of "broadband" protection (also called broad spectrum or extensive protection) is based on a "critical wavelength". For broadband coverage, both UV-B and UV-A protection must be provided. According to US requirements, a critical wavelength of at least 370 nm is required to achieve broad spectrum protection. In addition, the European Commission recommends that all sunscreen or cosmetic compositions should have a UVA protection factor that is at least one third of the indicated sun protection factor (SPF), e.g. if a sunscreen composition has an SPF of 30, the UVA protection factor must be at least 10.

[0062] The term "sunscreen composition" or "sunblock" or "skin care product" refers to any topical product that reflects and / or absorbs some portion of the UV radiation. Thus, the term "sunscreen composition" is to be understood as including not only sunscreen compositions, but also any cosmetic composition that provides UV protection. The term "topical product" refers to a product that is applied to the skin and may refer to, for example, a spray, a lotion, a cream, an oil, a foam, a powder or a gel. According to the present invention, the sunscreen composition may comprise one or more active agents, for example, an organic UV filter, and other ingredients or additives, for example, an emulsifier, an emollient, a viscosity regulator, a stabilizer, a preservative, or a fragrance.

[0063] The terms "diethylaminohydroxybenzoyl hexyl benzoate" and "DHHB" and "compound (I)" or "(I)" are used synonymously in the present invention. They all refer to the compound of formula (I) depicted above.

[0064] The term "crystallization solvent" refers to a solvent used for the crystallization of a material. The crystallization solvent provides a certain threshold solubility at certain temperatures or concentrations for the material to be crystallized. Thus, the material may be soluble in the crystallization solvent at certain temperatures and / or concentrations, but once the temperature is lowered or the concentration of the material in the crystallization solvent is increased, crystallization may begin.

[0065] The term "wash solvent" refers to a solvent used to wash the solid material. Typically, the wash solvent should not dissolve the solid material during washing so that only impurities and by-products are removed from the solid material.

[0066] The term "solvent" is to be understood as a substance that can dissolve a solute thereby producing a solution.

[0067] The terms "n-hexanol" and "1-hexanol" are used synonymously in the present invention.

[0068] The term "C1-C8 alcohol" or "C4-C8 alcohol" and the like refers to a compound comprising at least one hydroxyl functional group "-OH" and a carbon chain comprising the number of carbon atoms in the subscript, i.e. C3 contains three carbon atoms. The alcohol may be a primary alcohol (RCH2OH), a secondary alcohol (R2CHOH) or a tertiary alcohol (R3COH). In addition, the carbon chain of the alcohol may be linear (as in n-propanol or n-hexanol), it may be branched (as in isobutanol), it may be cyclic (as in cyclohexanol), and it may be saturated or unsaturated.

[0069] These alcohols may have one hydroxyl functional group (monohydric alcohol) or multiple hydroxyl functional groups (polyhydric alcohol). In addition, these alcohols may have other functional groups at different positions of the molecule. Those skilled in the art are aware of other functional groups that may be present in C1-C8 or C4-C8 alcohols.

[0070] Surprisingly, it was found that the process according to the invention claimed herein provides crystalline 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester (I) with low PSDHE (II) content and low content of rhodamine-based impurities (III) and (IV). The process of the invention claimed herein is rapid and efficient.

[0071] The method of the invention claimed herein improves the quality and purity of crystals (I) and reduces the time required for crystallization by selecting appropriate crystallization process parameters (such as crystallization solvent, supersaturation, seed amount of (I), seeding temperature, process temperature, amount of washing solvent, and time of each process step).

[0072] According to a first aspect of the present invention, the present invention relates to a method for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), the method comprising steps (a) to (d),

[0073] (a) providing a feed comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution,

[0074] Wherein the diethylaminohydroxybenzoyl hexyl benzoate (I) has

[0075] i) a content of dihexyl phthalate (PSDHE) (II) of up to 100,000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0076] and

[0077] wherein the amount of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the feed is in the range of 15.0 wt % to 65.0 wt % based on the total weight of the feed;

[0078] (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0079] (c) seeding the supersaturated solution obtained in step (b) with crystals of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0080] wherein the amount of the seed crystal is in the range of 0.01 wt % to 15.0 wt % based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the solution; and

[0081] (d) cooling the solution obtained in step (c) to a temperature in the range of -20°C to 17°C to obtain a suspension containing crystalline diethylaminohydroxybenzoyl hexyl benzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), and washing the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent at least a first time and a second time;

[0082] as well as

[0083] (e) optionally recrystallizing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d), which involves mixing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d);

[0084] wherein the amount of washing solvent in each of the at least first and second washing in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 63 wt.% based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b), wherein the first crystallization solvent comprises at least one C4-C8 alcohol.

[0085] Thus, according to one aspect of the present invention, washing of the isolated crystalline DHHB with a washing solvent occurs at least a first and a second time, wherein the amount of washing solvent in each of the at least first and second washings in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 63 wt.% based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b). In this method, additional washing steps may be added by washing the isolated crystalline DHHB a third, fourth, fifth, sixth, etc.

[0086] According to a preferred embodiment of the first aspect of the present invention, the amount of washing solvent in each of at least the first and second washing in at least one of the step (d) of crystallization or the step (d) of recrystallization (e) is at least 65 wt.%, preferably at least 68 wt.%, more preferably at least 70 wt.% and most preferably at least 74 wt.% based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b).

[0087] According to a second aspect of the present invention, the present invention relates to a method for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), the method comprising steps (a) to (d),

[0088] (a) providing a feed comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution,

[0089] Wherein the diethylaminohydroxybenzoyl hexyl benzoate (I) has

[0090] i) a content of dihexyl phthalate (PSDHE) (II) of up to 100,000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0091] as well as

[0092] wherein the amount of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the feed is in the range of 15.0 wt % to 65.0 wt % based on the total weight of the feed;

[0093] (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0094] (c) seeding the supersaturated solution obtained in step (b) with crystals of diethylaminohydroxybenzoyl hexyl benzoate (I);

[0095] wherein the amount of the seed crystal is in the range of 0.01 wt % to 15.0 wt % based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the solution; and

[0096] (d) cooling the solution obtained in step (c) to a temperature in the range of -20°C to 17°C to obtain a suspension containing crystalline diethylaminohydroxybenzoyl hexyl benzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), and washing the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent;

[0097] as well as

[0098] (e) optionally recrystallizing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d), which involves mixing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d);

[0099] wherein the amount of the washing solvent in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 130 wt.% based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b), wherein the first crystallization solvent comprises at least one C4-C8 alcohol.

[0100] In a second aspect of the present invention, the separated crystalline DHHB is washed with a washing solvent, wherein the amount of the washing solvent in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is based on the weight of the diethylaminohydroxybenzoyl benzoic acid hexyl ester (I) in the corresponding solution in step (b) is at least 130wt.%. In this aspect of the present invention, the mandatory total amount of the washing solvent for the washing step is defined. The washing solvent of the whole amount can be used to wash by washing the crystalline DHHB once. However, the total amount of the washing solvent used can be dispersed in several washings, such as washing the separated crystalline DHHB at least for the first and second time, or washing the separated crystalline DHHB at least for the first, second and third time, or washing the separated crystalline DHHB at least for the first, second, third and fourth time. Generally, there is no restriction on the number of washings of the separated crystalline DHHB. It has been found that washing twice to six times, particularly washing the separated crystalline DHHB twice to three times allows the best balance between process efficiency and product purity.

[0101] The following examples relate to the methods of the first and second aspects of the invention.

[0102] In the case of washing of the crystalline DHHB separated by washing the crystalline DHHB at least for the first and second time, the amount of the washing solvent can be the same in both the first washing and the second washing. However, it is also possible that the amount of the washing solvent used in the first and second washings is different. For example, the amount of the washing solvent used in the first washing can be greater than the amount of the washing solvent used in the second washing. Alternatively, the amount of the washing solvent used in the second washing can be greater than the amount of the washing solvent used in the first washing.

[0103] Where the crystalline DHHB is washed a third, fourth, fifth, sixth, etc., time, the amount with which the DHHB is washed each of these times can be independently selected from the amount of wash solvent used in the first and second washes.

[0104] According to a preferred embodiment of the present invention, the total amount of washing solvent used for washing the separated crystalline DHHB is at least 132 wt.%, more preferably at least 135 wt.%, even more preferably at least 140 wt.% or at least 145 wt.%, particularly preferably at least 150 wt.% and most preferably at least 160 wt.%, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b).

[0105] According to a preferred embodiment of the present invention, the diethylaminohydroxybenzoyl hexyl benzoate (I) in step (a) has

[0106] i) a rhodamine (III) content of less than 15000 ppm; and / or

[0107] ii) a rhodamine hexyl ester (IV) content of less than 15000 ppm;

[0108] Each is based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I). DHHB having such an impurity profile with respect to rhodamine (III) and rhodamine hexyl ester (IV) can be completely and efficiently purified using the crystallization method of the present invention.

[0109] According to another preferred embodiment of the present invention, the diethylaminohydroxybenzoyl hexyl benzoate (I) in step (a) has a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 5000 ppm based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I).

[0110] According to a preferred embodiment of the present invention, the solution in step (b) is cooled to a certain temperature so that the concentration c of the dissolved diethylaminohydroxybenzoyl hexyl benzoate (I) is equal to the equilibrium solubility c of diethylaminohydroxybenzoyl hexyl benzoate (I) at the temperature. * The ratio c:c * In the range of from 1.1:1.0 to 9.0:1.0. Further preferably, c:c * The ratio of c:c is in the range of 1.5:1.0 to 7.0:1.0 and even more preferably in the range of 2.0:1.0 to 6.0:1.0. * The temperatures when the ratio of c:c is 3.8:1.0, 4.0:1.0 and 4.1:1.0 are the most preferred. * The crystallization process finds the best balance between the crystallization rate and the purity of the obtained product at a certain temperature.

[0111] According to another preferred embodiment, the diethylaminohydroxybenzoyl hexyl benzoate (I) (DHHB) in step (a) has a dihexyl phthalate (PSDHE) (II) content of 10 to 70000 ppm, in particular from 500 to 50000 ppm or from 5000 to 40000 ppm or from 7000 to 30000 ppm, based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I). It was found that DHHB with such a PSDHE content can be purified particularly quickly and effectively using the method of the invention.

[0112] The method of the present invention uses a first crystallization solvent in step (a). According to a preferred embodiment, the first crystallization solvent comprises or consists of at least one selected from the group consisting of C1-C8 alcohols. It was found that C1-C8 alcohols are excellent crystallization solvents for DHHB in the method of the present invention. They only show low solubility for DHHB at low temperatures, while allowing good solubility at higher temperatures, thus allowing efficient crystallization of DHHB when cooling the supersaturated solution of DHHB in step (b).

[0113] C4-C8 alcohols have been found to be particularly preferred as the first crystallization solvent. Therefore, according to a particularly preferred embodiment, the first crystallization solvent comprises or consists of a C4-C8 alcohol.

[0114] In the case of performing the recrystallization step (e), a second crystallization solvent is used. In this case, it is preferred if the second crystallization solvent comprises or consists of at least one selected from the group consisting of C1-C8 alcohols. It has been found that C1-C8 alcohols are excellent crystallization solvents for DHHB in the process of the present invention. They only show low solubility for DHHB at low temperatures, while allowing good solubility at higher temperatures, thus allowing efficient crystallization of DHHB when cooling the supersaturated solution of DHHB in step (b). It has been found that C4-C8 alcohols are particularly preferred as the second crystallization solvent. Therefore, according to a particularly preferred embodiment, the second crystallization solvent comprises or consists of C4-C8 alcohols.

[0115] In the case of performing the recrystallization step (e), the first crystallization solvent and the second crystallization solvent are preferably both C1-C8 alcohols. According to a preferred embodiment, the first crystallization solvent and the second crystallization solvent can be the same, for example, the first crystallization solvent and the second crystallization solvent can both be 1-hexanol. This method allows an effective and resource-saving method. However, according to the present invention, the first crystallization solvent and the second crystallization solvent can also be different, for example, the first crystallization solvent is 1-hexanol, and the second crystallization solvent is isopropanol. This method allows optimal fine-tuning between the crystallization step and the recrystallization step to allow a particularly pure crystallized DHHB product.

[0116] It was found that in case a recrystallization step (e) takes place, it is preferred that the first crystallization solvent is selected from the group consisting of C4-C8 alcohols and the second crystallization solvent is selected from the group consisting of C1-C8 alcohols. It is particularly preferred that the first crystallization solvent comprises or consists of 1-hexanol and the second crystallization solvent comprises or consists of an alcohol selected from methanol, ethanol, n-propanol and isopropanol. By such a combination of the first crystallization solvent and the second crystallization solvent, all relevant by-products and impurities can be removed particularly effectively with the process of the invention.

[0117] According to a particularly preferred embodiment, the first crystallization solvent comprises or consists of 1-hexanol.

[0118] If the last step in the synthesis of diethylaminohydroxybenzoyl benzoic acid hexyl ester (I) is the esterification of diethylaminohydroxybenzoyl benzoic acid with 1-hexanol, the product obtained from the esterification step comprises a mixture of diethylaminohydroxybenzoyl benzoic acid hexyl ester (I) and 1-hexanol. In this case, a preferred embodiment is to use the feed leaving the esterification reaction directly in the crystallization method of the present invention.

[0119] In a preferred embodiment, the product obtained from the esterification comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and 1-hexanol is used directly as feed for the crystallization.

[0120] According to another preferred embodiment of the present invention, the second crystallization solvent comprises or consists of 1-hexanol.

[0121] In step (d) of the method of the present invention, the separated crystallized DHHB is washed with a washing solvent. According to a preferred embodiment of the present invention, the washing solvent comprises an alcohol (particularly a C1-C8 alcohol) or consists of it. Particularly preferably in the present invention, the washing solvent comprises an alcohol selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, isobutanol, the tert-butyl alcohol, n-butyl alcohol, n-pentanol, sec-pentanol, cyclopentanol, n-hexanol, sec-hexanol, cyclohexanol, n-heptanol, sec-heptanol, n-octanol, sec-octanol. It is found that alcohol and the specifically listed alcohols are very suitable as washing solvents in the method of the present invention. They effectively remove impurities from the crystallized DHHB. Particularly preferably, the washing solvent is 1-hexanol.

[0122] In the case of carrying out the recrystallization step (e), the washing solvent used in the recrystallization can be the same as in the crystallization. However, the washing solvent used in the recrystallization step (e) can also be different from the washing solvent used in the crystallization. For example, the washing solvent used in the crystallization can include or consist of 1-hexanol, and the washing solvent used in the recrystallization can include or consist of isopropanol. Therefore, the first crystallization solvent, the second crystallization solvent, the washing solvent in the crystallization and the washing solvent in the recrystallization can all be independently selected from the preferred solvents determined herein.

[0123] Preferably, washing of the isolated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) is carried out with a washing solvent having a temperature within ±5° C. of the temperature to which the solution was cooled in step (d). In this way, it is ensured that the washing solvent does not dissolve DHHB and only removes impurities.

[0124] In another preferred embodiment, the first wash solvent and / or the second wash solvent is cooled to a temperature in the range of -5° C. to 5° C. In this way, it is ensured that the wash solvent does not dissolve DHHB and only removes impurities.

[0125] The crystallized DHHB of step d is isolated in any technically reasonable manner. The skilled person is aware of different techniques for filtering the crystallized material in a chemical process, for example by using a nutsche filter or agitated nutsche filter or a centrifuge, such as a pusher centrifuge, a decanter centrifuge, a sieve decanter centrifuge, a peeler centrifuge or a drum filter, such as a rotary or vacuum drum filter or a belt filter, etc. For example, the filtration can be done by suction or by pressure.

[0126] Typically, washing the separated crystalline DHHB with a washing solvent can be carried out in any technically reasonable manner. The technician is aware of different techniques for washing crystalline materials in chemical processes. However, it is particularly preferred that washing is carried out by displacement washing or by reslurry / suspension washing.

[0127] In displacement washing, the washing solvent is passed through the filtered crystallized DHHB and the first crystallization solvent or the second crystallization solvent. The displacement washing can be accomplished by suction, pressure or by gravity.

[0128] In contrast, in reslurry / suspension washing, a suspension of isolated crystalline DHHB in a washing solvent is first prepared and preferably stirred for a period of, for example, 2 to 50 minutes, more preferably 10 to 30 minutes. Next, the suspension is filtered to obtain the crystalline DHHB. Passing through the filter can again be done by suction, pressure or by gravity. For reslurry / suspension washing, an agitated nutsche filter is particularly preferred.

[0129] According to a particularly preferred embodiment of the present invention, the first and / or second crystallization solvent and / or washing solvent are recycled after use. It was found that in the present invention, the first and / or second crystallization solvent as well as the washing solvent can be effectively reused via recycling. This results in an ecological and resource-saving process.

[0130] In the case where the first and / or second crystallization solvent and / or washing solvent are recycled after use, according to one embodiment, it is preferred that the first and / or second crystallization solution and / or washing solvent are purified for recycling after use. In the case where the starting material DHHB has a high impurity content, this is preferred. However, according to another embodiment, it is also preferred that the first and / or second crystallization solvent and / or washing solvent are not purified for recycling after use. This allows for more efficient and less complicated recycling of solvents. In addition, it saves additional resources and reduces costs.

[0131] In a preferred embodiment, in step (a), the feed is heated to a temperature in the range of 25° C. to 80° C. In a more preferred embodiment, in step (a), the feed is heated to a temperature in the range of 35° C. to 80° C., most preferably in the range of 40° C. to 60° C. and particularly preferably in the range of 43° C. to 52° C. These were found to be ideal temperatures to obtain complete dissolution of DHHB in the crystallization solvent without wasting energy.

[0132] In a preferred embodiment, in step (b), the solution is cooled to a temperature in the range of 18° C. to 35° C., more preferably in the range of 18° C. to 32° C., and most preferably in the range of 23° C. to 30° C. It has been found through extensive experiments that this is the ideal temperature range for obtaining a supersaturated solution of DHHB, which forms the basis for the crystallization of DHHB.

[0133] Due to the highly metastable nature of the liquid (I), the crystallization of (I) itself is very slow. Seeding of the supersaturated solution is an important step during the crystallization of the invention claimed herein. Due to seeding, crystallization starts earlier compared to crystallization without seeding. Therefore, the overall method of the invention claimed herein provides crystallized (I) faster than methods not involving a seeding step.

[0134] In addition to other process parameters, seeding with the proper amount of crystals of (I) followed by stirring at the seeding temperature is important to the success of the invention claimed herein.

[0135] The quality of the crystals (I) obtained during the crystallization depends on the temperature at which the seeding is carried out and on the amount of seed crystals.

[0136] In a preferred embodiment, in step (c), seeding is performed at a temperature in the range of 18 to 35°C, more preferably in the range of 18 to 32°C and most preferably in the range of 23 to 30°C.

[0137] In a preferred embodiment, the seed crystals of diethylaminohydroxybenzoyl hexyl benzoate (I) are used in step (c) in at least one form selected from a solid crystalline mass and a suspension in a solvent.

[0138] In a preferred embodiment, seed crystals of diethylaminohydroxybenzoyl hexyl benzoate (I) are employed in step (c) in the form of a suspension in the crystallization solvent of step (a).

[0139] In a more preferred embodiment, seeds of diethylaminohydroxybenzoyl hexyl benzoate (I) are employed in step (c) in the form of a suspension in 1-hexanol.

[0140] In a preferred embodiment, the amount of seed crystals is in the range of 0.01 wt% to 15.0 wt%, more preferably in the range of 0.5 wt% to 10.0 wt%, even more preferably in the range of 1.0 wt% to 5.0 wt%, and most preferably in the range of 1.5 wt% to 4.5 wt%, based on the weight of diethylaminohydroxybenzoylhexyl benzoate (I). This amount of seed crystals has been found to be particularly effective in promoting rapid crystallization.

[0141] It is further preferred that after the supersaturated solution obtained in step (b) is seeded with crystals of diethylaminohydroxybenzoyl benzoic acid hexyl ester (I) and before cooling in step (d), the supersaturated solution containing the seed is stirred for up to 8 hours, in particular 20 minutes to 7 hours. It was found that stirring the supersaturated solution of DHHB after the introduction of the seed of DHHB leads to a good size distribution of crystals and ensures rapid crystal formation. The stirring rate is selected so that it is suitable for crystal formation, for example the stirring rate is high enough to allow a good distribution and flow of dissolved particles without adversely affecting the formation of crystals.

[0142] In a preferred embodiment, step (d) involves cooling the solution obtained in step (c) to -10°C to 15°C; more preferably to -5°C to 10°C and most preferably to 0°C to 5°C. In this way, crystallization of DHHB present in the supersaturated solution of step (b) is achieved in high yield in an energy efficient manner.

[0143] In a preferred embodiment, step (d) involves cooling the solution obtained in step (c) at a cooling rate of 1 to 15 K / h, more preferably 3 to 10 K / h and most preferably 4.5 to 8 K / h. These cooling rates have been found to be particularly beneficial for the crystallization process of DHHB.

[0144] For the cooling in step (d), different cooling methods can be used. The skilled person is aware of a variety of different cooling methods. Preferably, the solution is cooled in one of the following ways: in a linear manner, with a piecewise linear cooling profile, with a parabolic cooling profile as the cooling rate increases, with a dynamic cooling profile to maintain a relatively constant supersaturation in the crystallizer, or with a vacuum cooling method.

[0145] According to a preferred embodiment of the present invention, the suspension obtained in step (d) is stirred at the cooling temperature of step (d) for up to 12 hours, preferably for up to 2 hours and most preferably for up to one hour before isolating the crystalline DHHB.

[0146] In a preferred embodiment, in step (d), the separation of the crystals is performed by filtration while maintaining the temperature of the solution within ±5° C. of the temperature to which the solution is cooled in step (d). In this way, it is ensured that DHHB does not dissolve during this step.

[0147] Preferably, the filter cake (i.e. the solid components remaining in the filter after filtering the suspension) is dried after filtering. This is preferably done by suction or by passing a drying gas, such as air or nitrogen, in particular nitrogen. In the production method, it is preferred to dry the filter cake by passing nitrogen through the filter cake. The filter cake is preferably dried for a period of up to 5 hours, more preferably up to 1 hour and most preferably from 5 to 30 minutes.

[0148] In a preferred embodiment, the method of the invention claimed herein further comprises the following steps,

[0149] i. dissolving the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) or step (e) in a purified solvent;

[0150] ii. contacting the solution obtained in step (i) with an adsorbent; and

[0151] iii. removing the adsorbent and the purification solvent from the solution obtained in step (ii) to obtain purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0152] In a preferred embodiment, the purification solvent is selected from toluene, cyclohexane, and combinations thereof.

[0153] In a preferred embodiment, the adsorbent is selected from the group consisting of silica, charcoal, and combinations thereof.

[0154] In a preferred embodiment, the purified diethylamino hydroxybenzoyl hexyl benzoate is subsequently solidified, particularly granulated. The method of solidifying the purified diethylamino hydroxybenzoyl hexyl benzoate is known to the technician. Melt crystallization with a specific shear rate with or without seeding is the preferred way to solidify DHHB. According to a particularly preferred embodiment, the purified diethylamino hydroxybenzoyl hexyl benzoate is solidified according to at least one of the solidification methods described in WO 2008 / 135360A1, PCT application PCT / EP 2022 / 055088, and PCT application PCT / EP 2022 / 055089. Preferably, the solidified DHHB is further processed into pourable / flowable particles, lozenges or flakes. The method of preparing such particles, lozenges or flakes by solidified materials is known to those skilled in the art.

[0155] The crystallization and stirring of the material according to the present invention can be carried out in any suitable crystallization and agitator equipment. The technician is aware of the common process equipment for crystallization and stirring of the material. In a preferred embodiment, the crystallization is carried out in a crystallizer selected from the following: a stirred vessel with baffles, a forced circulation crystallizer, a guide tube crystallizer, a guide tube baffle crystallizer and an Oslo type crystallizer. Any type of agitator can be used. Preferred agitators are, for example, single-stage or multi-stage inclined or non-inclined cross-blade agitators, impeller agitators or propeller agitators. Particularly preferred are anchor agitators or inclined anchor agitators.

[0156] The process of the invention claimed herein provides crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) in a yield of 75.0% to 99.5%, more preferably 90.0% to 99.0%, based on the total amount of (I) in the feed.

[0157] Another aspect of the present invention is crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the process of the present invention. The crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) according to the present invention has

[0158] i) less than 250 ppm of dihexyl phthalate (PSDHE)(II);

[0159] ii) a rhodamine (III) content of less than 150 ppm; and

[0160] iii) a rhodamine hexyl ester (IV) content of less than 150 ppm;

[0161] Each is based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0162] In a preferred embodiment of the present invention, the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) has a PSDHE (II) content of less than 120 ppm, preferably less than 60 ppm, more preferably less than 20 ppm, even more preferably less than 5 ppm and most preferably less than 1 ppm, based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0163] In a preferred embodiment of the present invention, the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) has a rhodamine (III) content of less than 80 ppm, preferably less than 40 ppm, more preferably less than 20 ppm, even more preferably less than 10 ppm and most preferably less than 5 ppm, based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0164] In a preferred embodiment of the present invention, the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) has a rhodamine hexyl ester (IV) content of less than 120 ppm, preferably less than 100 ppm, more preferably less than 50 ppm, even more preferably less than 10 ppm and most preferably less than 5 ppm, based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0165] According to one embodiment of the present invention, the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) has a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 250 ppm based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0166] In a preferred embodiment of the present invention, the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) has a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 100 ppm, preferably less than 60 ppm, more preferably less than 15 ppm, even more preferably less than 5 ppm and most preferably less than 1 ppm, based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0167] Certain combinations of by-products in the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the process of the present invention are particularly preferred. In particular, it is preferred that the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) of the present invention has a PSDHE (II) content of less than 120 ppm, a rhodamine (III) content of less than 150 ppm and a rhodamine hexyl ester (IV) content of less than 150 ppm; more preferably a PSDHE (II) content of less than 90 ppm, a rhodamine (III) content of less than 80 ppm and a rhodamine hexyl ester (IV) content of less than 120 ppm; even more preferably a PSDHE (II) content of less than 5 ppm, a rhodamine (III) content of less than 10 ppm and a rhodamine hexyl ester (IV) content of less than 10 ppm; and most preferably a PSDHE (II) content of less than 1 ppm, a rhodamine (III) content of less than 5 ppm and a rhodamine hexyl ester (IV) content of less than 5 ppm; each based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0168] Certain other combinations of by-products in the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the process of the present invention are also particularly preferred. In particular, it is preferred that the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) of the present invention has a PSDHE (II) content of less than 120 ppm, a rhodamine (III) content of less than 150 ppm, a rhodamine hexyl ester (IV) content of less than 150 ppm and a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 100 ppm; more preferably a PSDHE (II) content of less than 90 ppm, a rhodamine (III) content of less than 80 ppm, a rhodamine hexyl ester (IV) content of less than 120 ppm and a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 60 ppm. ) content; even more preferably less than 5 ppm of PSDHE (II) content, less than 10 ppm of rhodamine (III) content, less than 10 ppm of rhodamine hexyl ester (IV) content and less than 10 ppm of 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content; and most preferably less than 1 ppm of PSDHE (II) content, less than 5 ppm of rhodamine (III) content, less than 5 ppm of rhodamine hexyl ester (IV) content and less than 1 ppm of 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content; each based on the weight of the crystalline diethylaminohydroxybenzoyl benzoic acid hexyl ester (I).

[0169] Crystalline DHHB with such high purity and low amounts of problematic by-products was not obtainable via previous crystallization methods.

[0170] Another aspect of the present invention relates to purified diethylaminohydroxybenzoyl hexyl benzoate (I) having

[0171] i) less than 250 ppm of dihexyl phthalate (PSDHE)(II);

[0172] ii) a rhodamine (III) content of less than 10 ppm; and

[0173] iii) a rhodamine hexyl ester (IV) content of less than 10 ppm;

[0174] Each is based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I). Purified DHHB is obtained by the process of the present invention when crystalline DHHB is dissolved in a purification solvent and contacted with an adsorbent which is subsequently removed.

[0175] According to a preferred embodiment of the present invention, the purified DHHB of the present invention is solid. Particularly preferably, the purified DHHB is in the form of pourable / flowable granules, lozenges or flakes.

[0176] In a preferred embodiment of the present invention, the purified diethylaminohydroxybenzoyl hexyl benzoate (I) has a PSDHE (II) content of less than 120 ppm, preferably less than 60 ppm, more preferably less than 20 ppm, even more preferably less than 5 ppm and most preferably less than 1 ppm, based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0177] In a preferred embodiment of the present invention, the purified diethylaminohydroxybenzoyl hexyl benzoate (I) has a rhodamine (III) content of less than 8 ppm, preferably less than 5 ppm, most preferably less than 1 ppm, based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0178] In a preferred embodiment of the present invention, the purified diethylaminohydroxybenzoyl hexyl benzoate (I) has a rhodamine hexyl ester (IV) content of less than 8 ppm, preferably less than 5 ppm and most preferably less than 1 ppm based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0179] According to one embodiment of the present invention, the purified diethylaminohydroxybenzoyl hexyl benzoate (I) has a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 250 ppm based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0180] In a preferred embodiment of the present invention, the purified diethylaminohydroxybenzoyl hexyl benzoate (I) has a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 100 ppm, preferably less than 60 ppm, more preferably less than 15 ppm, even more preferably less than 5 ppm and most preferably less than 1 ppm, based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0181] Certain combinations of by-products in the purified diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the process of the present invention are particularly preferred. In particular, it is preferred that the purified diethylaminohydroxybenzoyl hexyl benzoate (I) of the present invention has a PSDHE (II) content of less than 120 ppm, a rhodamine (III) content of less than 10 ppm and a rhodamine hexyl ester (IV) content of less than 10 ppm; more preferably a PSDHE (II) content of less than 5 ppm, a rhodamine (III) content of less than 5 ppm and a rhodamine hexyl ester (IV) content of less than 5 ppm; even more preferably a PSDHE (II) content of less than 5 ppm, a rhodamine (III) content of less than 1 ppm and a rhodamine hexyl ester (IV) content of less than 1 ppm; and most preferably a PSDHE (II) content of less than 1 ppm, a rhodamine (III) content of less than 1 ppm and a rhodamine hexyl ester (IV) content of less than 1 ppm; each based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

[0182] Certain other combinations of by-products in the purified diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the process of the present invention are also particularly preferred. In particular, it is preferred that the purified diethylaminohydroxybenzoyl hexyl benzoate (I) of the present invention has a PSDHE (II) content of less than 120 ppm, a rhodamine (III) content of less than 10 ppm, a rhodamine hexyl ester (IV) content of less than 10 ppm, and a 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid (V) content of less than 100 ppm; more preferably a PSDHE (II) content of less than 5 ppm, a rhodamine (III) content of less than 5 ppm, a rhodamine hexyl ester (IV) content of less than 5 ppm, and a 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid (V) content of less than 60 ppm. content; even more preferably less than 5 ppm of PSDHE (II) content, less than 1 ppm of rhodamine (III) content, less than 1 ppm of rhodamine hexyl ester (IV) content and less than 10 ppm of 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid (V) content; and most preferably less than 1 ppm of PSDHE (II) content, less than 1 ppm of rhodamine (III) content, less than 1 ppm of rhodamine hexyl ester (IV) content and less than 1 ppm of 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid (V) content; each based on the weight of the crystalline diethylaminohydroxybenzoyl benzoic acid hexyl ester (I).

[0183] Another preferred embodiment of the purified diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the process of the present invention has a PSDHE (II) content of less than 120 ppm, a rhodamine (III) content of less than 1 ppm, a rhodamine hexyl ester (IV) content of less than 1 ppm and a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V) content of less than 15 ppm, each based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

[0184] Another aspect of the present invention relates to a cosmetic composition comprising the purified diethylaminohydroxybenzoyl hexyl benzoate (I) of the present invention. Preferably, the purified DHHB in the cosmetic composition is in the form of pourable / flowable granules, pastilles or flakes.

[0185] In a preferred embodiment, the cosmetic composition further comprises additives and adjuvants.

[0186] In preferred embodiments, the cosmetic composition may be in the form of a cream, a gel, a milk, an alcoholic solution and an aqueous / alcoholic solution, an emulsion, a wax / fat combination, a stick preparation, a powder or an ointment.

[0187] In a preferred embodiment, the cosmetic composition further comprises adjuvants and additives selected from the following: mild surfactants, super-fatting agents, pearlescent waxes, consistency regulators, thickeners, polymers, silicone compounds, fats, waxes, stabilizers, bioactive ingredients, deodorant active ingredients, anti-dandruff agents, film formers, expanders, antioxidants, hydrotropes, preservatives, insect repellents, self-tanning agents, solubilizers, essential oils, colorants, bacterial inhibitors, etc.

[0188] In preferred embodiments, the cosmetic composition according to the invention claimed herein may further comprise defoamers, structurants, solubilizers, sunscreens, complexing agents, propellants, couplers and developer components as oxidative dye precursors, reducing agents and oxidizing agents as adjuvants.

[0189] In a preferred embodiment, the cosmetic composition is contained in a variety of cosmetic preparations, in particular in the following preparations:

[0190] - skin care preparations, for example skin washing and cleansing preparations in tablet form or in the form of liquid soaps, synthetic detergents or washing creams,

[0191] - bath preparations, such as liquid (bubble baths, milks, shower preparations) or solid bath preparations, such as bath pills and bath salts;

[0192] - skin care preparations, such as skin lotions, multi-emulsions or skin care oils;

[0193] - cosmetic personal care preparations, for example facial makeup in the form of day creams or powder creams, face powders (loose or pressed), rouge or cream makeup, eye care preparations, for example eye shadow preparations, mascaras, eyeliners, eye creams or eye repair creams; lip care preparations, for example lipsticks, lip balms, lip liners, nail care preparations, such as nail varnishes, nail varnish removers, nail hardeners or cuticle removers;

[0194] - foot care preparations, such as foot baths, foot powders, foot creams or foot ointments, special deodorants and antiperspirants or callus removal preparations;

[0195] - photoprotective preparations, such as sunscreens, lotions, creams or oils, sunscreens or tropicals, pre-tanning preparations or after-sun preparations;

[0196] - Skin tanning preparations, such as self-tanning creams;

[0197] - depigmenting preparations, for example preparations for bleaching the skin or skin lightening preparations;

[0198] - insect repellents, such as insect repellent oils, emulsions, sprays or sticks;

[0199] - Deodorants such as deodorant sprays, pump sprays, deodorant gels, sticks or roll-ons;

[0200] -Antiperspirants, such as sticks, creams or roll-ons;

[0201] - preparations for cleaning and caring for soiled skin, such as synthetic detergents (solid or liquid), peeling or scrubbing preparations or peeling masks;

[0202] - depilatory preparations in chemical form (depilatory), for example depilatory powders, liquid depilatory preparations, depilatory preparations in the form of creams or ointments, depilatory preparations in the form of gels or aerosol foams;

[0203] - shaving preparations, such as shaving soaps, foaming shaving creams, non-foaming shaving creams, foams and gels, pre-shave preparations for dry shaving, aftershave lotions or aftershave emulsions;

[0204] - perfumery preparations, for example perfumes (eau de toilette, eau de toilette, eau de toilette, perfume), essential oils or perfume creams;

[0205] - cosmetic hair treatment preparations, for example shampoo preparations in the form of shampoos and conditioners, hair care preparations, for example pretreatment preparations, hair tonics, setting creams, setting gels, pomades, conditioners, repair packs, intensive hair repairs, hair structuring preparations, for example perming preparations for permanent hair waves (hot perm, mild perm, cold perm), hair straightening preparations, liquid hair setting preparations, hair foams, hair sprays, bleaching preparations, for example hydrogen peroxide solutions, lightening shampoos, bleaching creams, bleaching powders, bleaching pastes or oils, temporary, semi-permanent or permanent hair dyes, preparations containing self-oxidizing dyes, or natural hair dyes such as henna or chamomile.

[0206] All statements made herein with respect to the purified DHHB of the present invention also apply to the purified DHHB comprised in the cosmetic composition of the present invention.

[0207] The invention claimed herein provides one or more of the following advantages:

[0208] 1) The process of the invention claimed herein provides crystalline DHHB with high purity and low amounts of impurities (II), (III), (IV) and (V). The process of the invention claimed herein provides crystalline DHHB with less than 10 ppm (II). Low amounts of (II) are relevant in view of regulatory requirements.

[0209] 2) The method of the invention claimed herein is rapid.

[0210] 3) The process of the invention claimed herein is efficient as it provides high yield of DHHB; it ranges from 85% to 99% based on the total amount of DHHB in the feed.

[0211] 4) The crystalline DHHB obtained by the process of the invention claimed herein has a low amount of fine particles.

[0212] Examples

[0213] General

[0214] Hexyl 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoate (I) in hexanol was prepared according to Example 2 of US20050165099.

[0215] The product obtained by this process was subjected to crystallization as described in the experiments.

[0216] method

[0217] The HPLC methods used for the determination of 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester (I), phthalate esters (II) and rhodamine type compounds (III) and (IV) and 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid have been carried out by standard state of the art methods.

[0218] The GC method for determination of phthalates and solvent residues has been performed by standard prior art methods.

[0219] Analytical standards used for calibration have been performed by standard prior art methods.

[0220] Comparative Example according to WO 03097578

[0221] Comparative Example C1: Crystallization according to WO 03097578

[0222] 664.3 g of a feed comprising 49.0 wt% 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester in hexanol containing 0.74 wt% di-n-hexyl phthalate, 0.14 wt% rhodamine and 0.32 wt% rhodamine hexyl ester (corresponding to 14847 ppm di-n-hexyl phthalate, 2786 ppm rhodamine and 6397 ppm rhodamine hexyl ester calculated based on 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester (s. above)) was charged to a 1.6 L reactor.

[0223] The charge was heated at 40°C to obtain a solution. The solution was cooled to 20°C within 1.3 h to obtain a 5.4 C:C * ratio of a supersaturated solution.

[0224] After 4 h at 20° C., crystallization started. The suspension was stirred at 20° C. overnight (12 h), further cooled to 0° C. within 4 h and stirred at 0° C. The product was filtered off and washed with a portion of 183 g precooled (0° C.) 1-hexanol and then with another portion of 200 g precooled (0° C.) 1-hexanol to provide 371.5 g hexanol-wet 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester having a 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester content of 80.6 wt %.

[0225] By-product contents calculated based on (I): 110 ppm of rhodamine (III), 131 ppm of rhodamine hexyl ester (IV) and 271 ppm of di-n-hexyl phthalate (II).

[0226] Comparative Example C2: Crystallization according to WO 03097578

[0227] 605.6 g of feed was charged into a 1.6 1 reactor and the feed was heated at 40° C. to obtain a solution, which contained 45.0 wt % of 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester in hexanol, containing 0.71 wt % of di-n-hexyl phthalate, 0.06 wt % of rhodamine and 0.33 wt % of rhodamine hexyl ester (corresponding to 15546 ppm of di-n-hexyl phthalate, 1298 ppm of rhodamine and 7292 ppm of rhodamine hexyl ester calculated based on 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester).

[0228] The solution was cooled to 20°C within 1 h to obtain a * 5.0c:c * ratio of a supersaturated solution.

[0229] After 3.5 h at 20° C., crystallization began. The mixture was stirred at 20° C. for another hour, then cooled to 0° C. over 4 h and stirred at 0° C. The product was filtered off and washed with a first portion of 169 g of precooled (0° C.) 1-hexanol, followed by a second portion of 183 g of precooled (0° C.) 1-hexanol to provide 310.9 g of hexanol-wet 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester having a 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester content of 79.1 wt %.

[0230] By-product contents calculated based on (I): 73 ppm of rhodamine (III), 187 ppm of rhodamine hexyl ester (IV) and 344 ppm of di-n-hexyl phthalate (II).

[0231] Example 1: Crystallization

[0232] 659 g of feed was charged into a 1.6 L reactor and the feed was heated at 60° C. to obtain a solution comprising 45.9 wt % of 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester in hexanol containing 2.28 wt % of di-n-hexyl phthalate, 0.07 wt % of rhodamine, 0.26 wt % of rhodamine hexyl ester and 0.01 wt % of 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid (corresponding to 47385 ppm of di-n-hexyl phthalate, 1555 ppm of rhodamine, 5724 ppm of rhodamine hexyl ester and 218 ppm of 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid calculated based on 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester).

[0233] The solution was cooled to 25 °C within 1.0 h to obtain a solution with a c:c of 3.2.* ratio of a supersaturated solution.

[0234] The supersaturated solution was seeded with 5.2 g (1.5 wt% calculated based on I) 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (87.2 wt%), followed by stirring at 25° C. for 3.5 h. The suspension was further cooled to 0° C. within 5 h and stirred at 0° C. The product was filtered off and washed with a first portion of 187.4 g precooled 1-hexanol (0° C.), followed by a second portion of 202.5 g precooled 1-hexanol (0° C., 389.9 g in total) to provide 309.8 g hexanol-wet 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I) having a 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I) content of 85.3 wt%.

[0235] By-product contents calculated based on (I): 246 ppm di-n-hexyl phthalate (II), 35 ppm rhodamine (III), 68 ppm rhodamine hexyl ester (IV) and 5 ppm 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V).

[0236] Example 2: Recrystallization of the crystal (I) obtained in Example 1

[0237] 278.4 g of the hexanol wet cake obtained in Example 1 containing hexyl 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoate (85.3 wt %) and 235 g of hexanol were charged into a 1.6 L reactor, and the feed was heated to 60° C. to obtain a solution.

[0238] The solution was cooled to 25 °C within 1.0 h to obtain a 2.9 c:c * ratio of a supersaturated solution.

[0239] The supersaturated solution was seeded with 4.1 g (1.5 wt% calculated based on I) 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (87.2 wt%), followed by stirring at 25° C. for 3.5 h. The suspension was further cooled to 0° C. within 5 h and stirred at 0° C. The suspension was filtered, and the product was washed three times with 185.2 g of precooled 1-hexanol (0° C., 555.6 g in total) to provide 232.3 g of hexanol-wet 2-(4'-diethylamino-2'-hydroxy-benzoyl) benzoic acid hexyl ester having a 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester content of 82.9 wt%.

[0240] By-product contents calculated based on (I): 0.4 ppm di-n-hexyl phthalate (II), 3 ppm rhodamine (III), 2 ppm rhodamine hexyl ester (IV) and 1 ppm 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V).

[0241] Example 3: Crystallization

[0242] 687 g of feed was charged into a 1.6 L reactor and the feed was heated to 60° C. to obtain a solution comprising 44.0 wt % 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester in hexanol, containing 0.63 wt % di-n-hexyl phthalate, 0.10 wt % rhodamine, 0.29 wt % rhodamine hexyl ester and <0.01 wt % 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid (corresponding to 14187 ppm di-n-hexyl phthalate, 2294 ppm rhodamine, 6501 ppm rhodamine hexyl ester and 12 ppm 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid calculated based on 2-(4′-diethylamino-2′-hydroxybenzoyl)benzoic acid hexyl ester).

[0243] The solution was cooled to 25 °C within 1.0 h to obtain a solution with a c:c of 3.0. * ratio of a supersaturated solution.

[0244] The supersaturated solution was seeded with 5.2 g (1.5 wt% calculated based on I) 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (87.2 wt%), followed by stirring at 25° C. for 3.5 h. The suspension was further cooled to 0° C. within 5 h and stirred at 0° C. The product was filtered off and washed four times with 241.8 g of precooled 1-hexanol (0° C., 967.2 g of 1-hexanol in total) to provide 266.4 g of hexanol-wet 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I) having a 2-(4'-diethylamino-2'-hydroxybenzoyl) benzoic acid hexyl ester (I) content of 84.9 wt%.

[0245] By-product contents calculated based on (I): 36 ppm di-n-hexyl phthalate (II), 34 ppm rhodamine (III), 61 ppm rhodamine hexyl ester (IV) and 3 ppm 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V).

[0246] Example 4: Recrystallization of the crystal (I) obtained in Example 3

[0247] 237.4 g of the hexanol wet cake obtained in Example 3 containing hexyl 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoate (84.9 wt%) and 200 g of hexanol were charged into a 1.6 L reactor, and the feed was heated at 60°C to obtain a solution.

[0248] The solution was cooled to 25°C within 1.0 h to obtain a supersaturated solution with a c:c* ratio of 2.9.

[0249] The supersaturated solution was seeded with 3.4 g (1.5 wt% calculated based on I) 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester (87.2 wt%), followed by stirring at 25° C. for 3.5 h. The suspension was further cooled to 0° C. within 5 h and stirred at 0° C. The suspension was filtered, and the product was washed with a first portion of 125.0 g of precooled (0° C.) 1-hexanol and a second time with 135.1 g of precooled 1-hexanol (0° C., 260.1 g in total) to provide 209.5 g of hexanol-wet 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester having a 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid hexyl ester content of 84.3 wt%.

[0250] By-product contents calculated based on (I): <1 ppm di-n-hexyl phthalate (II), 3 ppm rhodamine (III), 2 ppm rhodamine hexyl ester (IV) and 1 ppm 2-(4'-diethylamino-2'-hydroxybenzoyl)benzoic acid (V).

[0251] in conclusion

[0252] As demonstrated by the examples, the process of the present invention allows the preparation of clean crystalline DHHB (I) with very low amounts of by-products compared to previous methods of crystallizing DHHB.

Claims

1. A method for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), the method comprising steps (a) to (d), (a) providing a feed comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution, Wherein the diethylaminohydroxybenzoyl hexyl benzoate (I) has i) a content of dihexyl phthalate (PSDHE) (II) of up to 100,000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I); and wherein the amount of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the feed is in the range of 15.0 wt % to 65.0 wt % based on the total weight of the feed; (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of diethylaminohydroxybenzoyl hexyl benzoate (I); (c) seeding the supersaturated solution obtained in step (b) with crystals of diethylaminohydroxybenzoyl hexyl benzoate (I); wherein the amount of the seed crystal is in the range of 0.01 wt % to 15.0 wt % based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the solution; and (d) cooling the solution obtained in step (c) to a temperature in the range of -20°C to 17°C to obtain a suspension containing crystalline diethylaminohydroxybenzoyl hexyl benzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), and washing the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent at least a first time and a second time; as well as (e) optionally recrystallizing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d), which involves mixing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d); wherein the amount of the washing solvent in each of the at least first and second washings in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 63 wt.%, based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b) Wherein the first crystallization solvent comprises at least one C4-C8 alcohol.

2. A method for obtaining crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), the method comprising steps (a) to (d), (a) providing a feed comprising diethylaminohydroxybenzoyl hexyl benzoate (I) and at least a first crystallization solvent, and heating the feed to obtain a solution, Wherein the diethylaminohydroxybenzoyl hexyl benzoate (I) has i) a content of dihexyl phthalate (PSDHE) (II) of up to 100,000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I); and wherein the amount of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the feed is in the range of 15.0 wt % to 65.0 wt % based on the total weight of the feed; (b) cooling the solution obtained in step (a) to obtain a supersaturated solution of diethylaminohydroxybenzoyl hexyl benzoate (I); (c) seeding the supersaturated solution obtained in step (b) with crystals of diethylaminohydroxybenzoyl hexyl benzoate (I); wherein the amount of the seed crystal is in the range of 0.01 wt % to 15.0 wt % based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I) in the solution; and (d) cooling the solution obtained in step (c) to a temperature in the range of -20°C to 17°C to obtain a suspension containing crystalline diethylaminohydroxybenzoyl hexyl benzoate (I); subsequently isolating the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I), and washing the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) with a washing solvent; as well as (e) optionally recrystallizing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d), which involves mixing the diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) with at least a second crystallization solvent to obtain a feed, heating the feed to obtain a solution, and using the process steps (b) to (d); wherein the amount of the washing solvent in at least one of the step (d) of the crystallization or the step (d) of the recrystallization (e) is at least 130 wt.% based on the weight of the diethylaminohydroxybenzoyl hexyl benzoate (I) in the corresponding solution in step (b) Wherein the first crystallization solvent comprises at least one C4-C8 alcohol.

3. The method according to claim 1, characterized in that The solution in step (b) is cooled to a certain temperature so that the concentration c of diethylaminohydroxybenzoyl hexyl benzoate (I) dissolved at this temperature is equal to the equilibrium solubility c of diethylaminohydroxybenzoyl hexyl benzoate (I). * The ratio c:c * in the range of 1.1:1.0 to 9.0:1.0, and / or characterized in that the diethylaminohydroxybenzoyl hexyl benzoate (I) in step (a) has a dihexyl phthalate (PSDHE) (II) content of 10 to 70000 ppm, in particular 500 to 50000 ppm or 5000 to 40000 ppm or 7000 to 30000 ppm, based on the weight of diethylaminohydroxybenzoyl hexyl benzoate (I), and / or characterized in that after seeding the supersaturated solution obtained in step (b) with seed crystals of diethylaminohydroxybenzoyl hexyl benzoate (I), the supersaturated solution containing the seeds is stirred for up to 8 hours, in particular 20 minutes to 7 hours, and then cooled in step (d).

4. The method according to any one of the preceding claims, characterized in that The first and / or second crystallization solvent comprises or consists of at least one selected from the group consisting of C4-C8 alcohols, and / or is characterized in that the first and / or second crystallization solvent comprises or consists of 1-hexanol.

5. The method according to any one of the preceding claims, characterized in that The washing solvent comprises an alcohol, in particular selected from the group consisting of C1-C8 alcohols, in particular methanol, ethanol, isopropanol, n-propanol, isobutanol, tert-butanol, n-butanol, n-pentanol, sec-pentanol, cyclopentanol, n-hexanol, sec-hexanol, cyclohexanol, n-heptanol, sec-heptanol, n-octanol, sec-octanol.

6. The method according to any one of the preceding claims, characterized in that The wash solvent is different from the first crystallization solvent and / or the second crystallization solvent, or is characterized in that the wash solvent and the first crystallization solvent and / or the second crystallization solvent are the same.

7. The method according to any one of the preceding claims, characterized in that The washing is carried out by displacement washing and / or by reslurry / suspension washing, and / or is characterized in that in step (a) the feed is heated to a temperature in the range of 25°C to 80°C, in particular to a temperature in the range of 35°C to 60°C, and / or in that in step (b) the solution is cooled to a temperature in the range of 20°C to 35°C, and / or in that in step (c) the seeding is carried out at a temperature in the range of 20°C to 35°C, and / or in that in step (d) the solution is cooled at a cooling rate of 1 to 15 K / h.

8. The method according to any one of the preceding claims, characterized in that The solution is cooled in a linear manner in step (d), or characterized in that the solution is cooled in step (d) with a piecewise linear cooling curve, or characterized in that the solution is cooled in step (d) with a parabolic cooling curve with increasing cooling rate, or characterized in that the solution is cooled in step (d) with a dynamic cooling curve to maintain a relatively constant supersaturation in the crystallizer, or characterized in that the solution is cooled in step (d) by a vacuum cooling method.

9. The method according to any one of the preceding claims, characterized in that In step (d), the separation of crystals is carried out by filtration while the temperature of the solution is maintained within ±5°C of the temperature to which the solution is cooled in step (d), and / or characterized in that the washing of the separated crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) is carried out with a washing solvent having a temperature within ±5°C of the temperature to which the solution is cooled in step (d), and / or characterized in that the crystallization is carried out in a crystallizer selected from a stirred vessel with baffles, a forced circulation crystallizer, a draft tube crystallizer, a draft tube baffle crystallizer and an Oslo-type crystallizer.

10. The method according to any one of the preceding claims, characterized in that The method further comprises the following steps: i. dissolving the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained in step (d) or step (e) in a purified solvent; ii. contacting the solution obtained in step (i) with an adsorbent; and iii. removing the solvent from the solution obtained in step (ii) to obtain purified diethylaminohydroxybenzoyl hexyl benzoate (I).

11. The method according to claim 10, characterized in that The purification solvent is selected from toluene, cyclohexane and combinations thereof, and / or the adsorbent is selected from silica, charcoal and combinations thereof.

12. A crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the method according to any one of claims 1 to 9, having i) less than 250 ppm of dihexyl phthalate (PSDHE)(II); ii) a rhodamine (III) content of less than 150 ppm; and iii) a rhodamine hexyl ester (IV) content of less than 150 ppm; Each is based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

13. The crystalline diethylaminohydroxybenzoyl hexyl benzoate (I) according to claim 12, characterized in that The dihexyl phthalate (PSDHE) (II) content is less than 1 ppm and / or the rhodamine (III) content is less than 10 ppm and / or the rhodamine hexyl ester (IV) content is less than 10 ppm, each based on the weight of the crystalline diethylaminohydroxybenzoyl hexyl benzoate (I).

14. A purified diethylaminohydroxybenzoyl hexyl benzoate (I) obtained by the method according to claim 10 or 11, having i) less than 250 ppm of dihexyl phthalate (PSDHE)(II); ii) a rhodamine (III) content of less than 10 ppm; and iii) a rhodamine hexyl ester (IV) content of less than 10 ppm; Each is based on the weight of the purified diethylaminohydroxybenzoyl hexyl benzoate (I).

15. A cosmetic composition comprising the purified diethylaminohydroxybenzoyl hexyl benzoate (I) according to claim 14.

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