WO2022028850A9

WO2022028850A9 - Zinc-containing catalyst comprising at least one aromatic substituent

Info

Publication number: WO2022028850A9
Application number: PCT/EP2021/069838
Authority: WO
Inventors: Peter Hoffmann; Fabian DIELMANN; Emre LEVENT
Original assignee: Basf Se
Priority date: 2020-08-03
Filing date: 2021-07-15
Publication date: 2022-03-24
Also published as: WO2022028850A1

Abstract

The invention relates to a zinc-containing catalyst per se, which is defined by general formula (I) cited in the following text. The zinc-containing catalyst contains at least one group R1 which contains a carboxyl fragment as per general formula (II), wherein bonded to the carbon atom of the carboxyl group is a first carbon atom (α carbon) which in turn, according to the invention, is directly substituted by at least one aromatic compound. The present invention further relates to a process for producing such a zinc-containing catalyst, and to the use of such a zinc-containing catalyst to produce compounds that contain a urethane group.

Description

Zinc containing catalyst comprising at least one aromatic substituent

description

The invention relates to a zinc-containing catalyst as such, which is defined by the general formula (I) given below. The zinc-containing catalyst contains at least one radical R ¹ which, according to the general formula (II), contains a carboxyl fragment, a first carbon atom (a-carbon) being bonded to the carbon atom of the carboxyl group, which in turn is bonded according to the invention with at least one aromatic is directly substituted. The present invention further relates to a process for preparing such a zinc-containing catalyst and the use of such a zinc-containing catalyst for preparing compounds containing a urethane group.

WO 2018/069018 relates to a coating material system which comprises components (A) to (C) and optionally further components. Component (A) is at least one compound containing polyhydroxy groups and component (B) is at least one compound containing polyisocyanates. On the other hand, component (C) is a catalyst comprising at least two salts of an aliphatic monocarboxylic acid having at least four carbon atoms. The metal component of the first salt is bismuth (Bi), while the second salt has magnesium (Mg), sodium (Na), potassium (K), or calcium (Ca) as the metal component. According to a first option, the coating agent systems according to WO 2018/069018 can be designed in such a way that all components are present separately from one another, i.e. the individual components are not mixed with one another, while according to a second option of the corresponding coating agent system, the respective components are also completely or at least partially mixed with one another may exist.

US-A 4,895,827 discloses a catalyst in the form of a metal salt, the catalyst being part of a thermally sensitive color-forming composition which, in addition to the catalyst, comprises a chromogenic material, an acidic developer and a suitable binder. The metal salt can contain different metals as the central metal atom/metal ion, which include, for example, zinc, tin, aluminum or nickel. The corresponding metal salt contains organic compounds as ligands which, in addition to a carboxyl group, also include aromatic fragments and vinyl groups.

JP-A 58 87 087 discloses the use of a polyvalent metal salt of diphenylacetic acid, particularly diphenylzinc acetate, as a colorant whereby a water-resistant colored image can be produced. European patent application 19 155 916.0 discloses a bismuth-containing catalyst which is defined by the formula ((R ¹ )-) _x ((R ² )-) _y ((X)-) _z (Bi) ³⁺ . The bismuth-containing catalyst contains at least one radical R ¹ which contains a carboxyl fragment, a first carbon atom (a-carbon) being bonded to the carbon atom of the carboxyl group, which in turn is directly substituted with at least one aromatic.

The preparation of compounds containing a urethane group (urethane linkage) has also been known for a long time. A compound having a urethane group is usually obtained when a compound having an isocyanate group is reacted with a compound having a hydroxyl group. The reaction usually takes place in the presence of a catalyst. Although tin-containing catalysts show a very high activity in such reactions, the use of such tin-containing catalysts, in particular alkyl tin compounds, should be avoided because of their (very high) toxicity.

The object of the present invention was therefore to provide a new catalyst which can be used to prepare compounds containing a urethane group.

The object is achieved by a zinc-containing catalyst of the general formula (I)

((R ¹ )-)x ((R ² )')y(Zn) ²⁺ (I) in which the variables are defined as follows:

R ¹ is independently a radical of the general formula (II)

and x is 1 or 2;

R ² is independently hydroxy, halogen, carbonate, bicarbonate, R ⁷ or a radical of the general formula (III)

and y is 0 or 1 ; where the sum of x and y equals 2;

R ³ is unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or C ₇ -C ₃₀ aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF ₃ , -NH ₂ , C Cß -Alkoxy, CC ₃₀ alkyl or C ₆ -C ₁₄ aryl and the alkyl and aryl fragments of these substituents can in turn be at least monosubstituted with hydroxy, halogen, -CF ₃ , -NH ₂ or C Cß alkoxy, and the on the carbon atom of the carboxyl group of the general formula (III) directly attached carbon atom of the radical R ³ has no unsubstituted or at least monosubstituted C ₆ -C ₁₄ -aryl as a substituent.

R ⁴ , R ⁵ and R ⁶ are independently unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or C ₇ -C ₃₀ aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, - CF C ₃ , -NH ₂ , C Cß alkoxy, CC ₃₀ alkyl or C ₆ -C ₁₄ aryl and the alkyl and aryl fragments of these substituents in turn with hydroxy, halogen, -CF ₃ , -NH ₂ or C Cß alkoxy at least may be monosubstituted, and where at least one of the radicals R ⁴ , R ⁵ or R ⁶ is unsubstituted or at least monosubstituted C ₆ -C ₁₄ -aryl,

R ⁷ is unsubstituted or at least monosubstituted Ci-C ₃₀ -alkyl, C ₆ -Ci ₄ -aryl or C ₇ -C ₃₀ -aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF ₃ , -NH ₂ , Ci-C ₆ -alkoxy, Ci-C ₃₀ -alkyl or C ₆ -Ci ₄ -aryl and the alkyl and aryl fragments of these substituents in turn with hydroxy, halogen, -CF ₃ , -NH ₂ or Ci-C ₆ -alkoxy at least can be monosubstituted. The zinc-containing catalysts according to the invention are distinguished, inter alia, in that the use of toxic tin-containing catalysts in the production of compounds containing a urethane group can be avoided.

Furthermore, the catalyst activity of the zinc-containing catalysts according to the invention with regard to the formation of urethane groups from hydroxyl-containing compounds and isocyanates is better than the corresponding catalyst activity of already known zinc-containing catalysts such as zinc neodecanoate.

Advantageous properties are obtained with the catalysts according to the invention if at least one aromatic, in particular a phenyl group, is present in at least one of the substituents/ligands of the central zinc atom on the first carbon atom which is bonded to the carbon atom of the carboxyl group of the corresponding ligand , is directly substituted. This first carbon atom is referred to according to the invention (or sometimes also in chemical nomenclature) as the α-carbon. Well-known examples of this from chemical nomenclature are a-amino acids, where the a-C atom is the carbon atom to which the amino group and the carboxyl group are attached. Concrete examples of this numbering from the area of amino acids are ß-alanine and gamma-aminobutyric acid. In the chemical nomenclature, however, the carbonyl carbon is sometimes also counted and given the position 1. Accordingly, said first carbon atom in the immediate vicinity of the carbon atom of the carboxyl group is sometimes also referred to as the 2-position in chemical nomenclature. Accordingly, according to the invention there is at least one aromatic substituent, in particular at least one phenyl substituent, on the α-carbon (atom) or in the 2-position, in the latter case based on the respective total carboxyl-containing ligand to be considered.

Said carboxyl group of this substituent is (in terms of space) in the vicinity of the central zinc atom of the zinc-containing catalyst. According to the invention, the zinc-containing catalysts are represented as salts, the central zinc atom of the zinc-containing catalyst according to the invention being represented as a (double positively charged) cation of the corresponding salt (see, for example, the general formula (I)). The corresponding substituents/ligands of the zinc-containing catalyst, which are represented by the substituents/radicals R ¹ and R ² in the general formula (I) given above, form the corresponding anion component of the zinc-containing catalyst in this salt representation. Each of these so-called substituents/ligands is simply negatively charged. As detailed below, the two substituents R ¹ and R ² each have a carboxyl group. As a rule, the negative charge is in the corresponding substituents/ligands are located on said carboxyl group and/or the corresponding carboxyl group is in close proximity to the (positively charged) central zinc atom.

From a scientific point of view, however, it is also justifiable to choose a notation/representation instead of the salt notation used in the present application for the zinc-containing catalysts according to the invention, in which a chemical bond between the central zinc atom and the two ligands R ¹ and R ² according to general formula (I) is formed in each case completely or at least partially. In other words, this means that the zinc central atom is not present as a positively charged cation and the corresponding ligands are not present as negatively charged anions either, but instead the corresponding charge forms a chemical bond between the corresponding ligands on the one hand and the central zinc atom on the other. In the context of the present invention, such a definition, which is not based on a salt, also describes the disclosed zinc-containing catalysts according to the invention.

The catalytic activity and/or the hydrolytic stability/storage stability of the zinc-containing catalysts according to the invention is further improved if at least two aromatic substituents, in particular phenyl substituents, are present directly on at least one ligand on the first carbon atom (α-carbon atom/2-position), which in turn is attached to the carbon atom of the carboxyl group. If three aromatic substituents, in particular phenyl substituents, are bonded directly to said α-carbon atom, catalytically very active catalysts are also obtained, but their stability (primarily from a thermal point of view) generally decreases somewhat compared to the zinc-containing catalysts according to the invention. in which exactly two aromatics, in particular two phenyl groups, are present on said α-carbon atom (2-position) on at least one ligand. The catalytic activity of the zinc-containing catalysts according to the invention is all the higher, the higher the number of said radicals R ¹ in the zinc-containing catalyst according to the general formula (I) according to the invention. In this context, the best results are achieved when the zinc-containing catalyst according to the invention has two (identical or different) radicals R ¹ according to the above definition, ie when the variable x=2. Such particularly preferred catalysts are also represented below by the general formula (Ia).

In the context of the present invention, definitions such as "Ci-Cso-alkyl", as defined for example above for the radical R ⁴ in formula (II), mean that this substituent (rest) is an alkyl radical having a number of carbon atoms from 1 to 30, where appropriate present substituents in the number of carbon atoms do not are taken into account. The alkyl radical can be either linear or branched and, if appropriate, cyclic. Alkyl radicals that have both a cyclic and a linear component also fall under this definition. The same also applies to other alkyl radicals, such as a CC ₆ alkyl radical or a CC ^ alkyl radical. Examples of alkyl radicals are methyl, ethyl, n-propyl, sec-propyl, n-butyl, sec-butyl, isobutyl, 2-ethylhexyl, tert-butyl (tert-Bu/t-Bu), pentyl, hexyl, heptyl , cyclohexyl, octyl, nonyl or decyl.

In the context of the present invention, the term “aryl” or the term “Cß-Cu-aryl”, as defined above for the radical R ⁴ in formula (II), for example, means that the substituent ( radical ) is an aromatic. The corresponding aromatic has a carbon atom number of 6 to 14, any substituents present not being taken into account in the carbon atom number. The aromatic can be a monocyclic, bicyclic or optionally polycyclic aromatic. In the case of bi- or polycyclic aromatics, individual cycles may be fully or partially saturated. Preferably all cycles of the corresponding aromatic are fully unsaturated. Preferred examples of aryl are phenyl, naphthyl or anthracyl, especially phenyl.

In the context of the present invention, the definition “CyCso-aralkyl”, as defined for example above for the radical R ⁴ in formula (II), means that the substituent ( radical ) contains an alkyl radical (such as for example CC ₆ -alkyl according to the above definitions). , where this alkyl radical in turn is substituted with an aryl radical (according to the above definitions). The corresponding aralkyl substituent has a carbon number of from 7 to 30, the number of carbon atoms ignoring any substituents present. The alkyl radical contained therein itself can be either linear or branched and, if appropriate, cyclic.

In the context of the present invention, the term "Ci-C ₆ -alkoxy", as defined above, for example, as an (additional) substituent of the radical R ⁴ in formula (II), means that this is a substituent (rest) which is from is derived from an alcohol. The corresponding substituent thus contains an oxygen fragment (-O-), which in turn is linked to an alkyl radical such as Ci-C ₆ -alkyl (according to the above definitions). The alkyl radical itself can be either linear or branched and, if appropriate, cyclic.

In the context of the present invention, the term “halogen” means, for example as defined above for the radical R ² in formula (I), that the substituent ( radical ) is fluorine, chlorine, bromine or iodine, preferably R ² is fluorine or chlorine, particularly preferably chlorine. In the context of the present invention, the term "unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or CyCso aralkyl", as defined for example above for the radical R ⁴ in formula (II), that each of the total three listed substituents (residues) according to their definitions already mentioned above can either be present in unsubstituted form or have at least one further substituent (monosubstituted). If one or more substituents (for example bissubstituted, trisubstituted or even more highly substituted) are present, the corresponding substituents are selected independently from the substituent groups specified in each case.

In the case of, for example, a bisubstituted C ₆ -C ₁₄ -aryl, the corresponding aryl building block, such as phenyl, can be substituted, for example, with a hydroxy and a C 1 -C 4 alkyl substituent, such as methyl or ethyl. Alkyl or aryl fragments, in turn, may themselves contain at least one additional substituent according to the definitions given. The substitution can take place at any point of the corresponding fragment.

If a corresponding radical, such as R ⁴ , can occur two or more times due to the definition of, for example, formula (I) in connection with formula (II), the individual radicals R ⁴ can be selected completely independently of one another according to the respective definitions. If, for example, the variable x=2 in the general formula (I), the radical R ¹ occurs twice in the general formula (I). The radical R ¹ , which in turn includes the radical R ⁴ , can thus be present twice independently of one another in this situation. The individual radicals R ¹ can therefore be designed differently according to their basic definition. It is thus conceivable that a first radical R ¹ has a different definition than the corresponding second radical R ¹ with regard to the component of the radical R ⁴ that must be present in it. Unless stated otherwise in the following text, this also applies to all other radicals, such as R ² , R ³ , R ⁵ and/or R ⁶ .

Unless otherwise stated in the following description, preference is given to the unsubstituted definitions of the respective definitions of the radicals R ¹ to R ⁷ .

The present invention is further specified below.

A first object of the present invention is a zinc-containing catalyst of the general formula (I) ((R ¹ )')x ((R ² )-) _y (Zn) ²⁺ (I) in which the variables are defined as follows:

R ¹ is independently a radical of the general formula (II)

and x is 1 or 2;

and y is 0 or 1 ; where the sum of x and y equals 2;

R ³ is unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or C ₇ -C3o aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF ₃ , -NH ₂ , C Cß- Alkoxy, CC ₃₀ alkyl or C ₆ -C ₁₄ aryl and the alkyl and aryl fragments of these substituents can in turn be at least monosubstituted with hydroxy, halogen, -CF ₃ , -NH ₂ or C Cß alkoxy, and where the to the Carbon atom of the carboxyl group of the general formula (III) directly attached carbon atom of the radical R ³ has no unsubstituted or at least monosubstituted C ₆ -C ₁₄ -aryl as a substituent. R ⁴ , R ⁵ and R ⁶ are independently unsubstituted or at least mono-substituted CrCso-alkyl, C ₆ -C ₁₄ aryl or C ₇ -C ₃₀ aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, - CF ₃ , -NH ₂ , C Cß alkoxy, CC ₃₀ alkyl or C ₆ -C ₁₄ aryl and the alkyl and aryl fragments of these substituents in turn with hydroxy, halogen, -CF ₃ , -NH ₂ or C Cß alkoxy can be at least monosubstituted, and where at least one of the radicals R ⁴ , R ⁵ or R ⁶ is unsubstituted or at least monosubstituted C ₆ -C ₁₄ -aryl,

R ⁷ is unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or C ₇ -C ₃₀ aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF ₃ , -NH ₂ , C Cß -Alkoxy, CC ₃₀ alkyl or C ₆ -C ₁₄ aryl and the alkyl and aryl fragments of these substituents can in turn be at least monosubstituted with hydroxy, halogen, -CF ₃ , -NH ₂ or C Cß alkoxy.

In connection with the radicals (substituents/ligands) contained in the general formula (I), in particular the mandatory radical R ¹ and the optional radical R ² , it should be noted that the further/exact chemical definition of these radicals R ¹ or R ² from the general formula (II) with regard to the radical R ¹ via the radicals R ⁴ to R ⁶ or from the general formula (III) with regard to the radical R ² via the radical R ³ . According to the invention, the radical R ² is always chemically defined differently from the radical R ¹ . In other words, this means that a specific radical R ² or R ³ according to general formula (III) cannot fall under the corresponding definition of a radical R ¹ or the radicals R ⁴ to R ⁶ according to general formula (II). This results in particular from the fact that in the chemical definition of the radical R ² according to general formula (III) there is a radical R ³ which is defined in such a way that the radical R ³ is attached to the carbon atom which is directly attached to the carbon atom of the corresponding carboxyl group of the general formula (III) is bonded, no unsubstituted or at least monosubstituted C ₆ -Ci ₄ -aryl, in particular no phenyl, can be present as a direct substituent. In contrast, such a substituent is mandatory for at least one of the radicals R ⁴ , R ⁵ or R ⁶ in connection with the radical R ¹ according to the general formula (II). Accordingly, it is impossible for a substituent falling under the definition of the radical R ² according to general formula (III) to also fall under the corresponding definition of the radical R ¹ according to general formula (II).

The radical R ¹ according to general formula (II) is preferably defined according to the invention so that R ⁴ , R ⁵ and R ⁶ are independently unsubstituted or at least monosubstituted CrC^-alkyl or C ₆ -C ₁₄ -aryl, wherein the substituents are selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, and wherein at least one of the radicals R ⁴ , R ⁵ or R ⁶ is unsubstituted or at least monosubstituted C ₆ -C ₁₄ aryl. Preferably C ₆ -C ₁₄ aryl is phenyl, especially unsubstituted phenyl.

Furthermore, it is preferred according to the invention that in the general formula (II) the radicals R ⁴ to R ⁶ are defined as follows: i) R ⁴ is unsubstituted or at least monosubstituted phenyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, ii) R ⁵ is unsubstituted or at least monosubstituted phenyl or CrC ^ -alkyl, wherein the substituents are selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, and iii) R ⁶ is unsubstituted or at least monosubstituted phenyl or CrC ^ alkyl, wherein the substituents are selected from hydroxy, chlorine, -CF ₃ and Ci-Cß- alkyl.

With regard to the radical R ² according to general formula (III), it is preferred that the radical R ³ contained therein is unsubstituted or at least monosubstituted CrC ^ -alkyl, the substituents being selected from hydroxy, chlorine or -CF ₃ .

With regard to the radicals hydroxy, halogen, carbonate, bicarbonate and R ⁷ , it is preferred according to the invention that these are hydroxy, chlorine or R ⁷ and R ⁷ is unsubstituted or at least monosubstituted C ^ C ^ alkyl or C ₆ -C ₁₄ aryl, wherein the substituents are selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl.

In the zinc-containing catalyst of the general formula (I) according to the invention, the radicals R ¹ and R ² present in each case can each be present in any combination. However, the prerequisite here is that x is at least 1, ie at least one radical R ¹ is present in the zinc-containing catalyst according to general formula (I) according to the invention. Furthermore, the sum of x and y is equal to 2, the total number of ligands or negative charges is 2, so that overall there is charge neutrality with regard to the doubly positively charged zinc central atom. If individual ligands/residues such as R ¹ occur more than once, they can have the same or different definitions according to the respective basic definition. In connection with the general formula (I), the following case constellations are preferred according to the invention, where i) x is 1 and y is 1, or ii) x is 2 and y is 0, with x preferably being 2 and y is equal to 0.

In a preferred embodiment of the present invention, the zinc-containing catalyst according to the general formula (I) and (II) is defined as follows: i) R ⁴ is unsubstituted or at least monosubstituted phenyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, ii) R ⁵ is unsubstituted or at least monosubstituted phenyl or CrC^-alkyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and Ci-Cß-alkyl, iii) R ⁶ unsubstituted or at least monosubstituted C ^C^alkyl wherein the substituents are selected from hydroxy, chloro and -CF ₃ , and iv) x is 2 and y is 0.

In another preferred embodiment of the present invention, the zinc-containing catalyst is defined as follows: i) R ⁴ and R ⁵ are each phenyl, ii) R ⁶ is CrC 1-4 alkyl, preferably C ₆ -C ₁₀ alkyl, especially C ₈ alkyl and iii) x is 2 and y is 0.

In a particularly preferred embodiment of the present invention, the zinc-containing catalyst is defined by the general formula (Ia):

da) where the radicals R ⁴ to R ⁶ independently correspond to the definitions described above. As can be seen from formula (Ia) for comparison of the general formula (I), the catalyst according to the invention has in this Embodiment a total of two radicals R ¹ according to general formula (I). Each of these two radicals R ¹ contains a radical R ⁴ , a radical R ⁵ and a radical R ⁶ . In each of these two radicals R ¹ , the corresponding definitions of the radicals R ⁴ to R ⁶ can be the same or different from one another. According to the invention, however, it is preferred that each of the total of two radicals R ⁴ is the same, each of the total of two radicals R ⁵ is the same and each of the total of two radicals R ⁶ is the same.

Furthermore, it is preferred in connection with the general formula (Ia) that i) R ⁴ is unsubstituted or at least monosubstituted phenyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, ii) R ⁵ unsubstituted or at least monosubstituted phenyl or CrC^-alkyl with the substituents selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, and iii) R ⁶ is unsubstituted or at least monosubstituted CrC^-alkyl with the substituents selected from hydroxy , chlorine and -CF ₃ .

Even more preferred in connection with general formula (Ia) is that i) R ⁴ and R ⁵ are each phenyl, and ii) R ⁶ is CrC 1-4 alkyl, preferably C ₆ -C ₁₀ alkyl, especially C ₈ alkyl is.

A further subject of the present invention is therefore also a process for preparing a zinc-containing catalyst of the general formula (I) or the general formula (Ia) according to the above definitions. The process according to the invention for preparing such zinc-containing catalysts can be carried out, for example, in which i) at least one compound of the general formula (Ha)

or a corresponding salt thereof, where the radicals R ⁴ to R ⁶ are defined according to the above statements/definitions, ii) optionally at least one compound of the general formula (IIIa)

or a corresponding salt thereof, where the radical R ³ is defined according to the above statements/definitions, iii) with at least one zinc-containing compound selected from ZnO, zinc carbonate, zinc hydrogen carbonate, zinc halide, Zn(C ₆ -C ₁₄ -aryl) ₂ , Zn (CC ₁₂ alkyl) ₂ or metallic zinc is implemented.

The starting materials listed above, ie the acids of the general formulas (IIa) or (IIIa) or the corresponding corresponding salts as such, are known to the person skilled in the art. Sodium, potassium or calcium salts, for example, can be used as the corresponding salts. If appropriate, instead of the abovementioned acids of the general formulas (IIa) or (IIIa) or their corresponding salts, corresponding carboxylic acid esters, for example a methyl or ethyl ester, can also be used as starting material. Such carboxylic acid esters can be prepared by reacting the abovementioned acids or a corresponding salt thereof with a suitable alcohol, for example methanol or ethanol, if appropriate in the presence of a catalyst. The corresponding preparation processes for such carboxylic acid esters are known to those skilled in the art.

In principle, any zinc-containing compound which is suitable for forming the central zinc atom in the zinc-containing catalyst according to the general formula (I) by reaction with the corresponding compounds of the general formula (IIa) or optionally (IIIa) can be used in the process according to the invention . Zinc-containing compounds as such are known to those skilled in the art. If a zinc halide is used as the zinc-containing compound according to the invention, it is preferably a chlorine-containing compound, in particular ZnCl ₂ . Any special substituents / substitution patterns, such as on the radicals R ⁴ to R ⁶ , according to the invention can already in corresponding starting material must be present. If appropriate, such substituents/substitution patterns can also only be applied or completed after the above-described production process for a zinc-containing catalyst of the general formula (I).

The zinc-containing compound is preferably selected from ZnO, ZnCl ₂ , Zn(C ₆ H ₅ ) ₂ or metallic zinc.

The zinc-containing catalysts of the general formula (I) according to the invention are preferably prepared by reacting at least one compound of the general formula (IIa) and optionally at least one compound of the general formula (IIIa) with at least one zinc-containing compound, i) carrying out the reaction under a protective atmosphere and/or in the presence of at least one solvent, in particular toluene or tetrahydrofuran, and/or ii) the reaction is carried out for at least 10 hours and/or at a temperature of at least 100°C, and/or iii) subsequently volatile components are removed from the reaction, the zinc-containing catalyst is dried in vacuo and/or recrystallization is carried out.

Furthermore, it is preferred according to the invention that the at least one compound of the general formula (IIa) used as starting material in the process according to the invention is prepared from a corresponding compound of the general formula (IIb), the compounds of the general formula (IIa) differing from only differ from the corresponding compounds of the general formula (IIb) in that one or a maximum of two radicals selected from R ⁴ , R ⁵ and R ⁶ is defined as H (hydrogen) instead of the definitions given for the compounds of the general formula (IIa). This is preferably done by reacting a corresponding compound (IIb) in which R ⁵ and/or R ⁶ is H, however, with a lithium-containing compound, in particular with n-butyllithium, and then using the resulting intermediate with a haloalkane to introduce the radicals R ⁵ and R ⁶ is reacted to obtain a compound according to the general formula (IIa). Examples of haloalkanes that can be used are 1-bromooctane or 1-bromopropane. This process variant is used in particular when an inventive catalyst of the general formula (I) is to be prepared in which at least one of the radicals R ⁴ to R ⁶ , preferably precisely one of these radicals, is a C 1 -C 4 alkyl. Alternatively, it is also conceivable that instead of a haloalkane, a corresponding halo-aryl or Halogen-aralkyl compound is used if a complete or partial aromatic substituent is to be introduced into the corresponding compound (IIb) in the course of this process step. According to the invention, preference is given to using 2-arylacetic acid, 2,2-diarylacetic acid, in particular 2-phenylacetic acid or 2,2-diphenylacetic acid, particularly preferably 2,2-diphenylacetic acid, as the compound of the general formula (IIb).

Another object of the present invention is the use of at least one zinc-containing catalyst according to the above definitions for the preparation of compounds containing a urethane group.

The invention is illustrated below using examples.

I) Preparation of catalysts according to the invention la) Precursor of Example 1: 2,2-diphenyldecanoic acid (dpdH)

In a 200 mL Schlenk flask, 2,2-diphenylacetic acid (10.6 g; 48 mmol) is dissolved in 75 mL dry tetrahydrofuran (THF) under a protective gas atmosphere (argon or nitrogen) and cooled to -15 °C. A 1.6 M solution of n-butyllithium in hexane (60 mL; 96 mmol) is then added with stirring over a period of 30 minutes. The reaction solution is stirred at -15 °C for one hour and cooled to -78 °C for the addition of 1-bromooctane (8.3 mL; 48 mmol). The reaction solution is then slowly warmed to room temperature and stirred for a further 24 hours.

To work up and purify the 2,2-diphenyldecanoic acid, a saturated ammonium chloride solution (60 mL) is added to the reaction solution and the mixture is stirred for 30 minutes. The aqueous phase is separated using a separating funnel and extracted in each case with 3×25 mL diethyl ether. The collected organic phases are dried over magnesium sulfate (MgSO ₄ ). Finally, all volatile solvents are removed in vacuo (1-10' ³ mbar) and the solid obtained is dried at 140° C. in vacuo (1×10 ^-3 mbar) for 24 hours.

Characterization by means of ¹ H-NMR, ¹³ C-NMR, HRMS (high-resolution mass spectrometry), infrared spectroscopy. lb) Catalyst according to Example 1: Zn(2,2-diphenyldecanoate) ₂ (Zn(dpd)?)

Diethylzinc (Sigma-Aldrich or Merck; 0.94 g; 7.5 mmol) is added dropwise to a solution of 2,2-diphenyldecanoic acid (5, 86 g; 15 mmol) in 20 mL dry THF was added dropwise. A white suspension of Zn(dpd) ₂ forms after a short time. After a reaction time of 24 hours, the solvent is drawn off and a white crystalline substance is obtained

II) Determination of the catalyst activity for Examples 1 to 3

Table 1 below shows the respective catalyst activity of the individual working examples and comparative examples. The catalyst activity is checked by a reaction that produces a compound containing a urethane group. For this purpose, 11 mmol of 2-ethylhexyl-(6-isocyanatohexyl)carbamates (commercially available as Desmodur LD (3.3 mL)) are reacted with 11 mmol of n-butanol (1 mL) as starting material. The reaction was carried out in the presence of a solvent (2 mL xylene) and the catalysts listed in Table 1 (containing 0.1 mol % catalyst based on the amount of zinc) at a temperature of 60°C.

The decrease in isocyanate and thus the formation of a urethane group are examined using horizontal ATR-IR spectroscopy. For this purpose, 0.05 mL of the reaction solution is removed at defined time intervals and directly spectroscopy. The conversion is determined on the basis of the relative decrease in intensity of the asymmetric isocyanate stretching vibration at 2250-2285 cm- ¹ . The initial free isocyanate content was determined at room temperature of the reaction solution in the absence of a catalyst. All IR spectra were normalized to the symmetric and asymmetric CH ₂ stretching bands (3000 - 2870 cm- ¹ ).

The catalysts used in Table 1 are:

Zn(dpd) ₂ where dpd is 2,2'-diphenyl decanoate

Zn(neo) ₂ , where neo stands for neodecanoate (commercially available catalyst under the name Nacure® XC 251 from King Industries with a metal content of 7.2%)

without catalyst Table 1

As can be seen from Table 1, the catalyst according to the invention from example 1 shows a significantly increased catalytic activity compared to zinc-containing catalysts from the prior art (comparative example 2) or when the experiment was carried out without any catalyst at all (comparative example 3).

Claims

Expectations

1. Zinc-containing catalyst of the general formula (I)

((R ¹ )')x ((R ² )')y(Zn) ²⁺ (I) in which the variables are defined as follows:

R ¹ is independently a radical of the general formula (II)

and x is 1 or 2;

(Hi), and y is 0 or 1 , where the sum of x and y is equal to 2,

R ³ is unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or C ₇ -C ₃₀ aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF ₃ , -NH ₂ , CC ₆ -Alkoxy, CC ₃₀ -alkyl or C ₆ -C ₁₄ -aryl and the alkyl and aryl fragments of these substituents can in turn be at least monosubstituted with hydroxy, halogen, -CF ₃ , -NH ₂ or CC ₆ -alkoxy, and where the an the carbon atom of the carboxyl group of the general formula (III) directly attached carbon atom of radical R ³ has no unsubstituted or at least monosubstituted C ₆ - C ₁₄ -aryl as a substituent,

R ⁴ , R ⁵ and R ⁶ are independently unsubstituted or at least monosubstituted C Cso alkyl, C ₆ -C ₁₄ aryl or C ₇ -C ₃₀ aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF C ₃ , -NH ₂ , CC ₆ alkoxy, CC ₃₀ alkyl or C ₆ -C ₁₄ aryl and the alkyl and aryl fragments of these substituents in turn with hydroxy, halogen, -CF ₃ , -NH ₂ or CC ₆ alkoxy at least may be monosubstituted, and where at least one of the radicals R ⁴ , R ⁵ or R ⁶ is unsubstituted or at least monosubstituted C ₆ -Ci ₄ -aryl,

R ⁷ is unsubstituted or at least monosubstituted Ci-C ₃₀ -alkyl, C ₆ -Ci ₄ -aryl or C ₇ -C ₃₀ -aralkyl, where the substituents are selected from hydroxy, halogen, carboxyl, -CF ₃ , -NH ₂ , Ci-C ₆ -alkoxy, Ci-C ₃₀ -alkyl or C ₆ -Ci ₄ -aryl and the alkyl and aryl fragments of these substituents in turn with hydroxy, halogen, -CF ₃ , -NH ₂ or Ci-C ₆ -alkoxy at least can be monosubstituted.

2. Zinc-containing catalyst according to claim 1, characterized in that i) R ⁴ , R ⁵ and R ⁶ are independently unsubstituted or at least monosubstituted CrC ^ -alkyl or C ₆ -C ₁₄ -aryl, where the substituents are selected from hydroxy, Chlorine, -CF ₃ and CrCe-alkyl, and wherein at least one of the radicals R ⁴ , R ⁵ or R ⁶ is unsubstituted or at least monosubstituted C ₆ -C ₁₄ aryl, and/or ii) R ³ is unsubstituted or at least monosubstituted CrC^ -alkyl wherein the substituents are selected from hydroxy, chlorine or -CF ₃ , or

R ² is hydroxy, chlorine or R ⁷ and R ⁷ is unsubstituted or at least monosubstituted CrC ^ alkyl or C ₆ -C ₁₄ aryl, wherein the Substituents are selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl. Zinc-containing catalyst according to claim 1 or 2, characterized in that i) x is 1 and y is 1, or ii) x is 2 and y is 0, preferably x is 2 and y is 0. Zinc-containing catalyst according to any one of claims 1 to 3, characterized in that i) R ⁴ is unsubstituted or at least monosubstituted phenyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and Ci-C ₆ - alkyl, ii) R ⁵ is unsubstituted or at least monosubstituted phenyl or C Ci2 -alkyl, where the substituents are selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, and iii) R ⁶ is unsubstituted or at least monosubstituted phenyl or CC ₁₂ -alkyl, where the substituents are selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl. Zinc-containing catalyst according to any one of claims 1 to 4, characterized in that i) R ⁴ is unsubstituted or at least monosubstituted phenyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, ii) R ⁵ unsubstituted or at least monosubstituted phenyl or CC ₁₂ alkyl wherein the substituents are selected from hydroxy, chloro, -CF ₃ and CrCe alkyl, iii) R ⁶ is unsubstituted or at least monosubstituted CrC ^ alkyl wherein the substituents are selected from hydroxy, chloro and -CF ₃ , and iv) x is 2 and y is 0. 21 Zinc-containing catalyst according to any one of claims 1 to 5, characterized in that i) R ⁴ and R ⁵ are each phenyl, ii) R ⁶ is CrC ^ -alkyl, preferably C ₆ -C ₁₀ -alkyl, in particular C ₈ -alkyl , and iii) x is 2 and y is 0. Zinc-containing catalyst according to one of Claims 1 to 6, characterized in that the zinc-containing catalyst is defined according to general formula (Ia).

la) where the radicals R ⁴ to R ⁶ are independently defined according to any one of claims 1 to 6. A zinc-containing catalyst according to claim 7, characterized in that each of the total of two R ⁴ groups is the same, each of the total of two R ⁵ groups is the same and each of the total of two R ⁶ groups is the same. Zinc-containing catalyst according to claim 7 or 8, characterized in that i) R ⁴ is unsubstituted or at least monosubstituted phenyl, the substituents being selected from hydroxy, chlorine, -CF ₃ and Ci-C ₆ -alkyl, ii) R ⁵ unsubstituted or at least monosubstituted phenyl or CrC^-alkyl with the substituents selected from hydroxy, chlorine, -CF ₃ and CrCe-alkyl, and iii) R ⁶ is unsubstituted or at least monosubstituted CrC^-alkyl with the substituents selected from hydroxy , chlorine and -CF ₃ . A zinc-containing catalyst according to any one of claims 7 to 9, characterized in that i) R ⁴ and R ⁵ are each phenyl, and 22 ii) R ⁶ is CrC 1-6 alkyl, preferably C ₆ -C ₁₀ alkyl, especially C ₈ alkyl. Process for the preparation of a zinc-containing catalyst of the general formula (I) according to any one of Claims 1 to 10, characterized in that i) at least one compound of the general formula (I la)

or a corresponding salt thereof, where the radicals R ⁴ to R ⁶ are defined according to any one of claims 1 to 10, ii) optionally at least one compound of the general formula (Hla)

or a corresponding salt thereof, where the radical R ³ is defined according to any one of claims 1 to 10, iii) with at least one zinc-containing compound selected from ZnO, zinc carbonate, zinc hydrogen carbonate, zinc halide, Zn(C ₆ -C ₁₄ -aryl) ₂ , Zn(C ₁ -C ₁₂ -alkyl) ₂ or metallic zinc is reacted. Process according to Claim 10, characterized in that the zinc-containing compound is selected from ZnO, ZnCl ₂ , Zn(C ₆ H ₅ ) ₂ or metallic zinc. Method according to claim 11 or 12, characterized in that 23 i) the reaction is carried out under a protective atmosphere and/or in the presence of at least one solvent, in particular toluene or tetrahydrofuran, and/or ii) the reaction is carried out for at least 10 hours and/or at a temperature of at least 100° C., and/or iii) after the reaction, volatile components are removed, the zinc-containing catalyst is dried in vacuo and/or recrystallization is carried out.

14. The method according to any one of claims 11 to 13, characterized in that a compound of general formula (Ha) is prepared by reacting a corresponding compound (Hb) in which R ⁵ and / or R ⁶ is H, however, with a Lithium-containing compound, in particular with n-butyllithium, and the resulting intermediate is then reacted with a haloalkane to introduce the radicals R ⁵ and/or R ⁶ to obtain a compound of the general formula (Ha).

15. Use of at least one zinc-containing catalyst according to any one of claims 1 to 10 for the preparation of compounds containing a urethane group.