Novel carboxyl ligand and application thereof in catalyst

Abstract

The invention relates to a novel carboxyl ligand and application thereof in a catalyst. The invention relates to a carboxyl ligand which is defined as shown in the following general formula (I). Furthermore, the invention relates to a bismuth-containing catalyst conforming to general formula (II) wherein the bismuth-containing catalyst comprises three carboxy ligands of general formula (I). Furthermore, the present invention relates to a process for preparing such carboxyl ligands and to a process for preparing such bismuth-containing catalysts. When the carboxyl ligand is prepared according to the invention, a ligand precursor conforming to the general formula (III) can also be obtained according to the invention. In addition, the invention also relates to the use of such bismuth-containing catalysts for the preparation of compounds containing urethane groups.

Description

[0001] The present invention relates to a carboxyl ligand, which is defined as the general formula (I) given below. In addition, the present invention relates to a bismuth-containing catalyst that conforms to the general formula (II), wherein the bismuth-containing catalyst comprises three carboxyl ligands of the general formula (I). In addition, the present invention relates to a process for preparing such a carboxyl ligand and a process for preparing such a bismuth-containing catalyst. When preparing the carboxyl ligand according to the present invention, a ligand precursor that conforms to the general formula (III) can also be obtained according to the present invention. In addition, the present invention also relates to the use of such a bismuth-containing catalyst for preparing a compound containing a urethane group.

[0002] WO 2020 / 160939 relates to a bismuth-containing catalyst, which is defined herein by the general formula (I). The bismuth-containing catalyst according to WO 2020 / 160939 contains at least one residue R 1 , the group contains a carboxyl fragment conforming to the general formula (II), wherein the first carbon atom (α-carbon) is bonded to the carbon atom of the carboxyl group, and the first carbon atom is directly substituted by at least one aromatic compound. WO 2020 / 160939 also relates to a process for preparing such a bismuth-containing catalyst, and the use of such a bismuth-containing catalyst for preparing a compound containing an ethyl carbamate group.

[0003] WO 2018 / 069018 relates to a coating system consisting of components (A) to (C) and, if necessary, other components. Component (A) refers to at least one polyhydroxy compound, and component (B) refers to at least one polyisocyanate compound. Component (C) is a catalyst having at least two salts of aliphatic monocarboxylic acids having 4 carbon atoms. The metal component of the first salt is bismuth (Bi), and the metal component of the second salt is magnesium (Mg), sodium (Na), potassium (K) or calcium (Ca). According to a first embodiment, the coating system according to WO 2018 / 069018 can be designed so that all components are separated from each other, that is, the individual components are not mixed with each other; and according to a second embodiment of the corresponding coating system, the individual components can also be completely or at least partially mixed with each other.

[0004] The preparation of compounds containing urethane groups (urethane bonds) is also known. If compounds containing isocyanate groups react with compounds containing hydroxyl groups, compounds with urethane groups are usually obtained. This reaction is usually carried out under the action of catalysts. Although tin-containing catalysts show extremely high activity in such reactions, the use of such tin-containing catalysts, in particular alkyltin compounds, should be avoided due to their (extremely high) toxicity.

[0005] It is therefore an object of the present invention to provide a novel ligand and / or a catalyst having such a novel ligand, wherein the catalyst can be used for preparing compounds containing urethane groups.

[0006] This object is achieved by ligands according to the general formula (I),

[0007]

[0008] The variables are defined as follows:

[0009] A is N or (NH) + (X) - ,

[0010] B is CH2, CH, CR 5 or CR 5 H,

[0011] D is CH2, CH, CR 6 or CR 6 H,

[0012] E is H or a base,

[0013] R 1 H or C1-C 10 alkyl,

[0014] R 2 H or C1-C 10 alkyl,

[0015] R 3 H or C1-C 10 alkyl,

[0016] R 4 H or C1-C 10 alkyl,

[0017] R 5 C1-C 10 alkyl,

[0018] R 6 C1-C 10 Alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms,

[0019] Among them, B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution,

[0020] R 7 C1-C 10 alkyl,

[0021] X is BF4, OH or halogen,

[0022] in

[0023] A is (NH) + (X) - ,

[0024] B is CH2, CH, CR 5 or CR 5 H,

[0025] D is CH2, CH, CR 6 or CR 6 H,

[0026] E is H,

[0027] R 1 is a C2 to C4 alkyl group,

[0028] R 2 is a C2 to C4 alkyl group,

[0029] R 3 is H or methyl,

[0030] R 4 H or methyl

[0031] As long as B and D are not CH2 or CH, R 5 and R 6 Together they form a bridge with four carbon atoms, where B, D, R 5 and R 6 Preferably together form an unsubstituted benzene fragment,

[0032] X is BF4.

[0033] Furthermore, the object is achieved by a bismuth-containing catalyst which corresponds to the general formula (II),

[0034]

[0035] The variables are defined as follows:

[0036] A is N or (NH) + (X) - ,

[0037] B is CH2, CH, CR 5 or CR 5 H,

[0038] D is CH2, CH, CR 6 or CR 6 H,

[0039] R1 H or C1-C 10 alkyl,

[0040] R 2 H or C1-C 10 alkyl,

[0041] R 3 H or C1-C 10 alkyl,

[0042] R 4 H or C1-C 10 alkyl,

[0043] R 5 C1-C 10 alkyl,

[0044] R 6 C1-C 10 Alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms,

[0045] Among them, B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution,

[0046] R 7 C1-C 10 alkyl,

[0047] X is BF4, OH or halogen,

[0048] Therein, in each of the three ligands of the bismuth-containing catalyst, the corresponding variables can be defined independently of the other two ligands or in the same way for all three ligands.

[0049] The bismuth-containing catalyst according to the invention is characterized primarily in that the use of toxic tin-containing catalysts can be avoided when producing compounds containing urethane groups. Compared to known representatives of effective, catalytically active, but toxic tin-containing catalysts, the bismuth-containing catalyst according to the invention has comparable catalytic activity.

[0050] Furthermore, it was surprisingly found that when using bismuth-containing catalysts according to the invention according to the general formula (II) in urethane reactions, the reaction process is inhibited during the first few minutes by using ligands according to the general formula (I) according to the invention. This is particularly important for applications where inhibition is required at room temperature. This blocking of the catalyst can extend the pot life in PU applications. According to the invention, the pot life refers to the length of time that the reactive material can be processed in the mixed state without any loss of quality in the corresponding application. The pot life depends on the gel time.

[0051] Furthermore, for the bismuth-containing catalyst according to the invention, it is not necessary for the catalyst to be present in the form of a salt in the corresponding acid. Therefore, the bismuth-containing catalyst according to the invention can also be used in the absence of the corresponding acid to form a urethane group-containing compound with high catalytic activity.

[0052] From a scientific point of view, it is reasonable to choose another symbol / representation instead of the salt representation used in the context of the present application for bismuth-containing catalysts according to the invention according to the general formula (II), in which chemical bonds are formed completely or at least partially between the bismuth central atom and the three ligands according to the general formula (II). In other words, this means that the bismuth central atom is not present as a positively charged cation and the corresponding ligands are not present as negatively charged anions, but rather the corresponding charges form chemical bonds between the corresponding ligands on the one hand and the bismuth central atom on the other hand. In the context of the present invention, this non-salt-based definition therefore also describes the disclosed bismuth-containing catalysts according to the invention.

[0053] In the context of the present invention, C1-C 10 Alkyl etc. are as defined above for the residue R in the general formula (I) 1 The following definition means that the substituent is an alkyl group having 1 to 10 carbon atoms, without taking into account any substituents that may be present. The alkyl residue may be straight-chain, branched or cyclic. Alkyl residues having both cyclic and linear components also fall within the scope of this definition. The same applies to other alkyl residues, such as C1-C6 alkyl residues or C1-C 12 Alkyl residues. Alkyl residues are, for example, methyl, ethyl, n-propyl, sec-propyl, n-butyl, sec-butyl, isobutyl, 2-ethylhexyl, tert-butyl, pentyl, hexyl, heptyl, cyclohexyl, octyl, nonyl or decyl.

[0054] In the context of the present invention, the term "halogen", as defined above for the residue X in the general formula (I), means that the substituent (residue) is fluorine, chlorine, bromine or iodine, X is preferably fluorine or chlorine, particularly preferably chlorine.

[0055] In the context of the present invention, the term "unsubstituted benzene or at least C1-C 10 "alkyl monosubstituted benzene", for example, in combination with the residue R in the general formula (I) 7 The definition given here is that benzene can exist in either an unsubstituted form or in a form with at least one C1-C 10 Alkyl substituents (monosubstitution). If one or more substituents are present (eg disubstituents, trisubstituents or higher substituents), the corresponding substituents can be selected independently of one another from the respectively specified substituent groups.

[0056] If, for example, according to the definition of formula (II) (in combination with formula (I)), the corresponding residue, for example R 1 , can appear two or more times, then the individual residues R can be selected completely independently of each other according to their respective definitions 1 Unless otherwise stated below, this also applies to all other groups, such as R 2 , R 3 , R 5 and / or R 6 .

[0057] Unless otherwise stated in the following description, the residue R 1 To R 7 Among the respective definitions of , the unsubstituted definition is preferred.

[0058] The present invention will be further described below.

[0059] The first object of the present invention is a ligand conforming to the general formula (I),

[0060]

[0061] The variables are defined as follows:

[0062] A is N or (NH) + (X) - ,

[0063] B is CH2, CH, CR 5 or CR 5 H,

[0064] D is CH2, CH, CR 6 or CR 6 H,

[0065] E is H or a base,

[0066] R 1 H or C1-C 10 alkyl,

[0067] R 2 H or C1-C10 alkyl,

[0068] R 3 H or C1-C 10 alkyl,

[0069] R 4 H or C1-C 10 alkyl,

[0070] R 5 C1-C 10 alkyl,

[0071] R 6 C1-C 10 Alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms,

[0072] Among them, B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution,

[0073] R 7 C1-C 10 alkyl,

[0074] X is BF4, OH or halogen.

[0075] Professionals can clearly understand that in R 5 and R 6 When B, D, R 5 and R 6 Together they form the benzene fragment, B and D are defined as follows:

[0076] B is CR 5 and

[0077] D is CR 6 ,

[0078] Among them, the residue R 5 and R 6 There are 4 carbon atoms and 4 hydrogen atoms, with 6 delocalized π electrons between the 6 carbon atoms. In other words, the residue R 1 , R 2 , R 4 , R 5 , B and D constitute a benzimidazole residue.

[0079] Furthermore, there may also be a double bond between B and D instead of a single bond. In this case it applies:

[0080] B is CH or CR5 ,and

[0081] D is CH or CR 6 .

[0082] According to the present invention, in the general formula (I), preferably

[0083] i) B and D and, if necessary, R 5 and R 6 Each has the same definition, among which B, D, R 5 and R 6 If necessary, preferably unsubstituted benzene fragments are formed together, and / or

[0084] ii) R 1 and R 2 each have the same definition, and / or

[0085] iii) R 3 and R 4 each have the same definition, and / or

[0086] iv) the base is sodium or potassium, preferably sodium, as long as E happens to be a base, and / or

[0087] v) Halogen is chlorine or bromine, provided X is exactly halogen.

[0088] However, it is also possible that R 1 and R 2 Different and / or R 3 and R 4 Different. Of course, B and D may also be different.

[0089] According to the present invention, in the general formula (I), more preferably

[0090] A is (NH) + (X) - ,

[0091] B is CH2, CH, CR 5 or CR 5 H,

[0092] D is CH2, CH, CR 6 or CR 6 H,

[0093] E is H,

[0094] R 1 is a C2 to C4 alkyl group,

[0095] R 2 is a C2 to C4 alkyl group,

[0096] R 3is H or methyl,

[0097] R 4 H or methyl

[0098] As long as B and D are not CH2 or CH, R 5 and R 6 Together they form a bridge with four carbon atoms,

[0099] Among them, B, D, R 5 and R 6 Preferably together form an unsubstituted benzene fragment,

[0100] X is BF4.

[0101] According to the present invention, particularly preferred ligands of the general formula (I) are 4-carboxy-N-(1,3-diisopropyl-1,3-dihydro-2H-benzo[d]imidazol-2-ylidene)-2,6-dimethylanilinium tetrafluoroborate or 4-carboxy-N-(1,3-di-tert-butylimidazolin-2-ylidene)anilinium tetrafluoroborate.

[0102] Another object of the present invention is a bismuth-containing catalyst conforming to the general formula (II),

[0103]

[0104] The variables are defined as follows:

[0105] A is N or (NH) + (X) - ,

[0106] B is CH2, CH, CR 5 or CR 5 H,

[0107] D is CH2, CH, CR 6 or CR 6 H,

[0108] R 1 H or C1-C 10 alkyl,

[0109] R 2 H or C1-C 10 alkyl,

[0110] R 3 H or C1-C 10 alkyl,

[0111] R 4 H or C1-C 10 alkyl,

[0112] R 5C1-C 10 alkyl,

[0113] R 6 C1-C 10 Alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms,

[0114] Among them, B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution,

[0115] R 7 C1-C 10 alkyl,

[0116] X is BF4, OH or halogen,

[0117] Therein, in each of the three ligands of the bismuth-containing catalyst, the corresponding variables can be defined independently of the other two ligands or in the same way for all three ligands.

[0118] However, it is preferred that all three ligands of the bismuth-containing catalyst are defined in the same way according to the general formula (II).

[0119] The above definitions and preferences for the ligands according to the general formula (I) also apply to the bismuth-containing catalysts according to the general formula (II).

[0120] According to the present invention, preferably

[0121] i) B and D and, if necessary, R 5 and R 6 Each has the same definition, among which B, D, R 5 and R 6 If necessary, preferably unsubstituted benzene fragments are formed together, and / or

[0122] ii) R 1 and R 2 each have the same definition, and / or

[0123] iii) R 3 and R 4 each have the same definition, and / or

[0124] iv) Halogen is chlorine or bromine, provided X is exactly halogen.

[0125] In this case, it is also possible that R 1 and R 2 Different and / or R 3 and R 4Different. Of course, B and D may also be different.

[0126] In the general formula (II), more preferably

[0127] A is (NH) + (X) - ,

[0128] B is CH2, CH, CR 5 or CR 5 H,

[0129] D is CH2, CH, CR 6 or CR 6 H,

[0130] R 1 is a C2 to C4 alkyl group,

[0131] R 2 is a C2 to C4 alkyl group,

[0132] R 3 is H or methyl,

[0133] R 4 H or methyl

[0134] As long as B and D are not CH2 or CH, R 5 and R 6 Together they form a bridge with four carbon atoms,

[0135] Among them, B, D, R 5 and R 6 Preferably together form an unsubstituted benzene fragment,

[0136] X is BF4.

[0137] The bismuth-containing catalyst conforming to the general formula (II) is particularly preferably bismuth (III)-(4-((1,3-di-tert-butylimidazolidin-2-ylidene)amino)benzoic acid)tetrafluoroborate)3 ([Bi(O2C(PNsItBu)H)3][BF4]3).

[0138] In the catalyst according to the invention, however, other metal central atoms can also be used instead of the bismuth central atoms, for example zinc, titanium or zirconium central atoms.

[0139] Therefore, another object of the present invention is a metal-containing catalyst, which is prepared by reacting at least one compound of the general formula (I) with at least one metal-containing compound, wherein the metal-containing compound is preferably a bismuth-, zinc-, titanium- or zirconium-containing compound, preferably a bismuth-containing compound.

[0140] Another object of the present invention is a ligand precursor conforming to the general formula (III),

[0141]

[0142] The variables are defined as follows:

[0143] A is N or (NH) + (X) - ,

[0144] B is CH2, CH, CR 5 or CR 5 H,

[0145] D is CH2, CH, CR 6 or CR 6 H,

[0146] R 1 H or C1-C 10 alkyl,

[0147] R 2 H or C1-C 10 alkyl,

[0148] R 3 H or C1-C 10 alkyl,

[0149] R 4 H or C1-C 10 alkyl,

[0150] R 5 C1-C 10 alkyl,

[0151] R 6 C1-C 10 Alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms,

[0152] Among them, B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution,

[0153] R 7 C1-C 10 alkyl,

[0154] X is BF4, OH or halogen

[0155] Y is halogen, preferably bromine.

[0156] In the general formula (III), preferably

[0157] A is (NH) +(X) - ,

[0158] B is CH2, CH, CR 5 or CR 5 H,

[0159] D is CH2, CH, CR 6 or CR 6 H,

[0160] R 1 is a C2 to C4 alkyl group,

[0161] R 2 is a C2 to C4 alkyl group,

[0162] R 3 is H or methyl,

[0163] R 4 H or methyl

[0164] As long as B and D are not CH2 or CH, R 5 and R 6 Together they form a bridge with four carbon atoms,

[0165] Among them, B, D, R 5 and R 6 Preferably together form an unsubstituted benzene fragment,

[0166] X is BF4.

[0167] The above definitions and preferences for the ligands according to the general formula (I) and the bismuth-containing catalysts according to the general formula (II) also apply to the ligand precursors according to the general formula (III).

[0168] Particularly preferred are the precursors N-(4-bromo-2,6-dimethylphenyl)-1,3-diisopropylbenzimidazol-2-imide (Br(P″NBiPr)) or N-(4-bromophenyl)-1,3-di-tert-butylimidazolidine-2-imide (Br(PNsItBu)).

[0169] Another object of the present invention is a method for preparing a ligand according to the present invention according to the general formula (I), wherein the ligand according to the present invention according to the general formula (I) is obtained from the corresponding precursor of the ligand of the general formula (III) by carboxylation in the presence of a catalyst.

[0170] For example, n-butyl lithium is a suitable catalyst for carboxylation.

[0171] Another object of the present invention is a method for preparing a bismuth-containing catalyst according to the general formula (II), wherein

[0172] i) at least one compound of the general formula (I) and

[0173] ii) at least one selected from Bi2O3, bismuth carbonate, bismuth bicarbonate, bismuth halide, bismuth carboxylate,

[0174] Bi(C6-C 14 -aryl)3, Bi(C1-C 12 -alkyl)3)-containing bismuth compounds or metallic bismuth react.

[0175] In principle, in the process according to the invention for preparing a bismuth-containing catalyst of the general formula (II), any bismuth-containing compound which is suitable for reacting with a corresponding compound according to the general formula (I) to form a bismuth central atom in a bismuth-containing catalyst according to the general formula (II) according to the invention can be used. Such bismuth-containing compounds are already known to those skilled in the art. If a bismuth halide is used as a bismuth-containing compound according to the invention, it is preferably a chlorine-containing compound, in particular BiCl3.

[0176] Preferably, the bismuth-containing compound is selected from Bi2O3, BiCl3, Bi(C6H5)3 or metallic bismuth.

[0177] Preferably, the bismuth-containing catalyst according to the present invention that conforms to the general formula (II) is prepared by reacting at least one compound that conforms to the general formula (I) with at least one bismuth-containing compound, wherein

[0178] i) the reaction is carried out in a protective atmosphere and / or in the presence of at least one solvent (especially toluene, acetonitrile or tetrahydrofuran), and / or

[0179] 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 bismuth-containing catalyst is dried in vacuo and / or recrystallized.

[0180] A further object of the invention is the use of at least one bismuth-containing catalyst meeting the above definition for preparing compounds containing urethane groups.

[0181] Another embodiment of the present invention includes a ligand conforming to the general formula (I),

[0182]

[0183] The variables are defined as follows:

[0184] A is N or (NH) + (X) - ,

[0185] B is CH2, CH, CR 5 or CR 5 H,

[0186] D is CH2, CH, CR 6 or CR 6 H,

[0187] E is H or a base,

[0188] R 1 H or C1-C 10 alkyl,

[0189] R 2 H or C1-C 10 alkyl,

[0190] R 3 H or C1-C 10 alkyl,

[0191] R 4 H or C1-C 10 alkyl,

[0192] R 5 C1-C 10 alkyl,

[0193] R 6 C1-C 10 Alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms,

[0194] Among them, B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution,

[0195] R 7 C1-C 10 alkyl,

[0196] X is BF4, OH or halogen.

[0197] The present invention is explained below with the aid of examples.

[0198] I. Synthesis and Comparative Examples of Electron-Rich Carboxylates

[0199] N-(4-Bromo-2,6-dimethylphenyl)-1,3-diisopropylbenzimidazole-2-imide (Br(P”NBiPr))

[0200] The precursor 2-chloro-1,3-diisopropylbenzimidazole tetrafluoroborate was synthesized according to the following literature: LFB Wilm, T. Eder, C. Mück-Lichtenfeld, P. Mehlmann, M. Wünsche, F. Buβand F. Dielmann, Green Chem., 2019, 21, 640-648.

[0201] In a Schlenk flask, 2-chloro-1,3-diisopropyl-benzimidazole tetrafluoroborate (3.38 g, 10.4 mmol, 1.00 equiv) and 4-bromo-2,6-hexidine (2.08 g, 10.4 mmol, 1.00 equiv) were dissolved in 35 mL of MeCN. After adding Et3N (2.90 mL, 20.8 mmol, 2.00 equiv), the reaction mixture was heated at 100 °C for 3 days. The progress of the reaction was monitored using H NMR. The solvent was then removed in vacuo and the residue was extracted with hot n-hexane (50 mL). After the solution was stored at -20 °C overnight, the product Br(P"NBiPr) was obtained as a white crystalline solid. The product Br(P"NBiPr) was then dried in vacuo at 80 °C for 24 h. Yield: 89% (3.90 g, 9.74 mmol).

[0202] N-(4-bromophenyl)-1,3-di-tert-butylimidazolidine-2-imide (Br(PNsItBu); according to Comparative Example Vgl.2 catalyst)

[0203] The reaction mixture was heated at -20 °C for 4 days. The progress of the reaction was monitored using H NMR. The solvent was then removed in vacuo and the residue was extracted with hot n-hexane (150 mL). After the solution was stored at -20 °C overnight, the product Br(PNsItBu) was obtained as a yellow crystalline solid. The product Br(PNsItBu) was then dried in vacuo at 80 °C for 24 h. Yield: 87% (15.1 g, 42.9 mmol).

[0204] 4-Carboxy-N-(1,3-diisopropyl-1,3-dihydro-2H-benzo[d]imidazol-2-ylidene)-2,6-dimethylanilinium Tetrafluoroborate ([HO2C(P ” NBiPr)H][BF4])

[0205] In a Schlenk flask, Br(P"NBiPr) (2.18 g, 5.44 mmol, 1.00 equiv) was dissolved in 25 mL of THF and cooled to -78°C. Then, 1.6 M n-butyllithium solution was slowly added to n-hexane (3.40 mL, 5.44 mmol, 1.00 equiv) and stirred at this temperature for 1 h. Then, CO2 was passed through the reaction solution using a Teflon cannula for 15 minutes, followed by stirring at room temperature for 1 h. All volatile components were removed in vacuo, and the residue was mixed with 10 mL of water. Next, 5.5 M tetrafluoroboric acid solution was slowly added to water (2.00 mL, 10.9 mmol, 2.00 equiv) and stirred for 15 minutes. The product [HO2C(P"NBiPr)H][BF4] was precipitated as a white solid. After filtering, it was washed with water and then with Et2O (3×20 mL). Finally, [HO2C(P″NBiPr)H][BF4] was dried under vacuum at 120 °C for 24 h to afford a white solid with a yield of 84% (2.10 g, 4.6 mmol).

[0206] 4-((1,3-diisopropyl-1,3-dihydro-2H-benzo[d]imidazol-2-ylidene)amino)-3,5-dimethylbenzyl Acid (HO2C(P"NBiPr))

[0207] HO2C(P"NBiPr) and dried in vacuo at room temperature overnight. Yield: 93% (256 mg, 0.70 mmol).

[0208] 4-Carboxy-N-(1,3-di-tert-butylimidazolidin-2-ylidene)anilinium tetrafluoroborate ([HO2C(PNsItBu)H] [BF4])

[0209] In a Schlenk flask, Br(PNsItBu) (5.64 g, 16.0 mmol, 1.00 equiv) was dissolved in 50 mL of THF and cooled to -78 °C. Then, 1.6 M n-butyllithium solution was slowly added to n-hexane (10.0 mL, 16.0 mmol, 1.00 equiv) and stirred at this temperature for 1 h. Then, CO2 was passed through the reaction solution using a Teflon cannula for 15 minutes, followed by stirring at room temperature for 1 h. All volatile components were removed in vacuo, and the residue was mixed with 25 mL of water. Next, 5.5 M tetrafluoroboric acid solution was slowly added to water (5.90 mL, 32.0 mmol, 2.00 equiv) and stirred for 15 minutes. The product [HO2C(PNsItBu)H][BF4] precipitated as a white solid. After filtering, it was washed with water and then with Et2O (3×50 mL). Finally, [HO2C(PNsItBu)H][BF4] was dried under vacuum at 120 °C for 24 h to afford a white solid with a yield of 90% (5.90 g, 14.6 mmol).

[0210] 4-((1,3-di-tert-butylimidazolidin-2-ylidene)amino)benzoic acid(HO2C(PNsItBu))

[0211] (219 mg, 0.69 mmol).

[0212] Bismuth(III)-(4-((1,3-di-tert-butylimidazolin-2-ylidene)carbamate)tetrafluoroborate)3([Bi(O2C (PNsItBu)H)3][BF4]3 / Bi(O2C(PNsItBu))3; Catalyst according to Example Bsp.4)

[0213] Compound [Bi(O2C(PNsItBu)H)3][BF4]3 was prepared in 20 mL of acetonitrile at 80°C according to a modified literature protocol (PC Andrews, GB Deacon, PC Junk, I. Kumar and M. Silberstein, Dalton Trans., 2006, 4852-4858) using BiPh3 (88.0 mg, 0.20 mmol) and compound [HO2C(PNsItBu)H][BF4] (243 mg, 0.60 mmol). The solid was then washed with 3×5 mL of toluene and dried overnight in vacuo at 120°C. Yield: 95% (270 mg, 0.19 mmol).

[0214] In order to prepare the catalyst Bi(O2C(PNsItBu))3, [Bi(O2C(PNsItBu)H)3][BF4]3 was deprotonated with potassium tert-butoxide standard solution in tetrahydrofuran to prepare the required amount for catalysis and directly used in the ethyl formate reaction.

[0215] Bismuth p-butylbenzoate (Bi(bbz)3; catalyst according to Comparative Example Vgl.1)

[0216]

[0217] II. Determination of Catalyst Activity

[0218] Table 1 below lists the catalyst activity of the various examples and comparative examples. The catalyst activity was tested by a reaction in which a compound containing urethane groups was formed. For this purpose, 11 mmol of 2-ethylhexyl-(6-isocyanatohexyl)-urethane (commercially available Desmodur LD (3.3 mL)) and 11 mmol of n-butanol (1 mL) were reacted as reactants. The reaction was carried out at room temperature in the presence of a solvent (2 mL of xylene) and a catalyst listed in Table 1 (0.05 mol % of the catalyst relative to the amount of bismuth).

[0219] The reduction of isocyanate and the formation of urethane groups were analyzed by horizontal attenuated total reflection infrared spectroscopy. For this purpose, 0.05 mL of the reaction solution was extracted at regular intervals and directly analyzed by spectroscopy. -1The relative decrease in the intensity of the asymmetric stretching vibration of the isocyanate at 4000 nm determines the conversion. The initial content of free isocyanate is determined at room temperature without a catalyst. All infrared spectra are normalized to the symmetric and asymmetric stretching vibration bands of the CH2 group (3000-2870 cm -1 ).

[0220] Table 1 details the catalysts used:

[0221] Comparative Example 1 (Vgl.1): Bi(bbz)3

[0222] Comparative Example 2 (Vgl.2): Br(PNsItBu)

[0223] Comparative Example 3 (Vgl.3): Bi(bbz)3+3 equivalents of Br(PNsItBu)

[0224] Example 4 (Bsp. 4): Bi(O2C(PNsItBu))3

[0225] Comparative Example 5 (Vgl.5): No Catalyst

[0226] Table 1

[0227]

[0228] As can be seen from Table 1, the activity of the dicarboxylates (Vgl.1) and the halogenated imines Br(PNsItBu) (Vgl.2) with the ligand bbz in the urethane reaction did not increase compared to the uncatalyzed reaction. The mixture consisting of Bi(bbz)3 and 3 equivalents of Br(PNsItBu) (Vgl.3) also showed only a slight increase in the catalytic activity in the urethane reaction compared to the uncatalyzed reaction. Surprisingly, the compound Bi(O2C(PNsItBu))3 was as inactive as the mixture consisting of Bi(bbz)3 and 3 equivalents of Br(PNsItBu) (Vgl.3) during the first 10 minutes of catalysis. However, after this inhibition period, the catalytic activity increased significantly, reaching a conversion of 90% after 60 minutes.

Claims

1. A ligand according to the general formula (I), The variables are defined as follows: A is N or (NH) + (X) - , B is CH2, CH, CR 5 or CR 5 H, D is CH2, CH, CR 6 or CR 6 H, E is H or a base, R 1 H or C1-C 10 -alkyl, R 2 H or C1-C 10 -alkyl, R 3 H or C1-C 10 -alkyl, R 4 H or C1-C 10 -alkyl, R 5 C1-C 10 -alkyl, R 6 C1-C 10 -alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms, of which B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution, R 7 C1-C 10 -alkyl, X is BF4, OH or halogen, in A is (NH) + (X) - , B is CH2, CH, CR 5 or CR 5 H, D is CH2, CH, CR 6 or CR 6 H, E is H, R 1 is a C2 to C4 alkyl group, R 2 is a C2 to C4 alkyl group, R 3 is H or methyl, R 4 H or methyl As long as B and D are not CH2 or CH, R 5 and R 6 Together they form a bridge with four carbon atoms, where B, D, R 5 and R 6 Preferably together form an unsubstituted benzene fragment, X is BF4.

2. The ligand according to claim 1, characterized in that i) B and D and, if necessary, R 5 and R 6 Each has the same definition, among which B, D, R 5 and R 6 If necessary, preferably unsubstituted benzene fragments are formed together, and / or ii) R 1 and R 2 have the same definition, and / or iii) R 3 and R 4 have the same definition, and / or iv) the base is sodium or potassium, preferably sodium, as long as E happens to be a base, and / or v) Halogen is chlorine or bromine, provided X is exactly halogen.

3. The ligand according to claim 1 or 2, characterized in that The ligand is 4-carboxyl-N-(1,3-diisopropyl-1,3-dihydro-2H-benzo[d]imidazol-2-ylidene)-2,6-dimethylanilinium tetrafluoroborate or 4-carboxyl-N-(1,3-di-tert-butylimidazolin-2-ylidene)anilinium tetrafluoroborate.

4. A bismuth-containing catalyst according to general formula (II), The variables are defined as follows: A is N or (NH) + (X) - , B is CH2, CH, CR 5 or CR 5 H, D is CH2, CH, CR 6 or CR 6 H, R 1 H or C1-C 10 -alkyl, R 2 H or C1-C 10 -alkyl, R 3 H or C1-C 10 -alkyl, R 4 H or C1-C 10 -alkyl, R 5 C1-C 10 -alkyl, R 6 C1-C 10 -alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms, of which B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution, R 7 C1-C 10 -alkyl, X is BF4, OH or halogen, Therein, in each of the three ligands of the bismuth-containing catalyst, the corresponding variables can be defined independently of the other ligands, or all three ligands can be defined in the same way.

5. The bismuth-containing catalyst according to claim 4, characterized in that All three ligands of the bismuth-containing catalyst are defined in the same way.

6. The bismuth-containing catalyst according to claim 4 or 5, characterized in that i) B and D and, if necessary, R 5 and R 6 Each has the same definition, among which B, D, R 5 and R 6 If necessary, preferably unsubstituted benzene fragments are formed together, and / or ii) R 1 and R 2 have the same definition, and / or iii) R 3 and R 4 have the same definition, and / or iv) Halogen is chlorine or bromine, provided X is exactly halogen.

7. The bismuth-containing catalyst according to any one of claims 4 to 6, characterized in that A is (NH) + (X) - , B is CH2, CH, CR 5 or CR 5 H, D is CH2, CH, CR 6 or CR 6 H, R 1 is a C2 to C4 alkyl group, R 2 is a C2 to C4 alkyl group, R 3 is H or methyl, R 4 H or methyl As long as B and D are not CH2 or CH, R 5 and R 6 Together they form a bridge with four carbon atoms, where B, D, R 5 and R 6 Preferably together form an unsubstituted benzene fragment, X is BF4.

8. The bismuth-containing catalyst according to any one of claims 4 to 7, characterized in that The bismuth-containing catalyst is bismuth (III)-(4-((1,3-di-tert-butylimidazolidin-2-ylidene)amino)benzoic acid)tetrafluoroborate)3([Bi(O2C(PNsItBu)H)3][BF4]3).

9. A ligand precursor according to the general formula (III), The variables are defined as follows: A is N or (NH) + (X) - , B is CH2, CH, CR 5 or CR 5 H, D is CH2, CH, CR 6 or CR 6 H, R 1 H or C1-C 10 -alkyl, R 2 H or C1-C 10 -alkyl, R 3 H or C1-C 10 -alkyl, R 4 H or C1-C 10 -alkyl, R 5 C1-C 10 -alkyl, R 6 C1-C 10 -alkyl, or R 5 and R 6 Together they form a bridge containing four carbon atoms, of which B, D, R 5 and R 6 can together form a benzene fragment which can be optionally separated from at least one residue R 7 Single substitution, R 7 C1-C 10 -alkyl, X is BF4, OH or halogen Y is halogen, preferably bromine.

10. A method for preparing a ligand according to any one of claims 1 to 3, characterized in that The ligands according to the general formula (I) are obtained from the corresponding precursors of the ligands according to the general formula (III) according to claim 10 by carboxylation in the presence of a catalyst.

11. A method for preparing a bismuth-containing catalyst of general formula (II) according to any one of claims 4 to 8, characterized in that i) at least one compound of the general formula (I) according to any one of claims 1 to 4, and ii) at least one selected from Bi2O3, bismuth carbonate, bismuth bicarbonate, bismuth halide, bismuth carboxylate, Bi(C6-C 14 -aryl)3, Bi(C1-C 12 -alkyl)3)-containing bismuth compounds or metallic bismuth react.

12. The method according to claim 11, characterized in that The bismuth-containing compound is selected from Bi2O3, BiCl3, Bi(C6H5)3 or metallic bismuth.

13. The method according to claim 11 or 12, characterized in that: i) the reaction is carried out in a protective atmosphere and / or in the presence of at least one solvent (especially toluene, acetonitrile 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) removing volatile components after the reaction, drying the bismuth-containing catalyst in vacuo and / or carrying out recrystallization.

14. Use of at least one bismuth-containing catalyst according to any one of claims 4 to 8 for preparing compounds containing urethane groups.

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