DIELMANN FABIAN (AT)
LEVENT EMRE (DE)
| WO2020160939A1 | 2020-08-13 | |||
| WO2018069018A1 | 2018-04-19 | |||
| WO2020160939A1 | 2020-08-13 | |||
| WO2020016093A1 | 2020-01-23 |
| US4895827A | 1990-01-23 | |||
| JP5887087B2 | 2016-03-16 |
J. BRESIEN ET AL., DALTON TRANS., vol. 48, 2019, pages 3786
| Claims 1. A bismuth-containing catalyst of the general formula (I) in which the variables are defined as follows: R1 is mutually independently a residue of the general formula (II) and x is 1 2 or 3; R2 is mutually independently a residue of the general formula (III) and y is 0, 1 or 2; X is mutually independently hydroxyl, halogen, carbonate, hydrogencarbonate or R12 and z is 0, 1 or 2; wherein the sum total of x, y and z is equal to 3; R3 is unsubstituted or at least monosubstituted C1-C30-alkyl, C6-C14-aryl or C7-C30-aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF3, -NH2, C1-C6-alkoxy, C1-C30- alkyl or C6-C14~aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF3, -NH2 or C1- C6-alkoxy, under the proviso that in case R3 is unsubstituted or at least monosubstituted C1-C30-alkyl or C7-C30-aralkyl, the carbon atom of the residue R3 bonded directly to carbon atom of the carboxyl group of the general formula (III) does not comprise any unsubstituted or at least monosubstituted C6-C14-aryl as substituent, R4 and R5 are mutually independently residues of the general formula (IV) (IV) R6, R7 and R8 are mutually independently hydrogen or unsubstituted or at least monosubstituted C1-C30-alkyl, C6- C14~aryl or C7-C30-aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF3, -NH2, C1-C6-alkoxy, C1-C30- alkyl or C6-C14~aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF3, -NH2 or C1- Cg-alkoxy, R9, R10 and R11 are mutually independently hydrogen or unsubstituted or at least monosubstituted C1-C30-alkyl, C6- C14~aryl or C7-C30-aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF3, -NH2, C1-C6-alkoxy, C1-C30- alkyl or C6-C14~aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF3, -NH2 or Ci- Cg-alkoxy, and wherein at least one of the residues R9, R10 or R11 is unsubstituted or at least monosubstituted C6-C14- aryl, R12 is unsubstituted or at least monosubstituted C1-C30- alkyl, C6-C14-aryl or C7-C30-aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF3, -NH2, C1-C6-alkoxy, C1-C30- alkyl or C6-C14~aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF3, -NH2 or C1- C6-alkoxy. The bismuth-containing catalyst as claimed in claim 1, wherein i) R9, R10 and R11 are mutually independently hydrogen or unsubstituted or at least monosubstituted C1-C12-alkyl or C6-C14-aryl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, and wherein at least one of the residues R9, R10 or R11 is unsubstituted or at least monosubstituted C6-C14- aryl, and/or ii) R6, R7 and R8 are mutually independently hydrogen or unsubstituted or at least monosubstituted C1-C12-alkyl or C6-C14-aryl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, and/or iii) R3 is unsubstituted or at least monosubstituted C1-C12- alkyl, wherein the substituents are selected from hydroxyl, chlorine or -CF3, and/or iv) X is hydroxyl, chlorine or R12 and R12 is unsubstituted or at least monosubstituted C1-C12-alkyl or C6-C14-aryl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl. The bismuth-containing catalyst as claimed in claim 1 or 2, wherein i) x is equal to 2 or 3, y is equal to 0 or 1 and z is equal to 0 or 1, or ii) x is equal to 3 and y and z are each equal to 0, or iii) x is equal to 2, y is equal to 0 and z is equal to 1, or iv) x is equal to 2, y is equal to 1 and z is equal to 0, wherein preferably x is equal to 3 and y and z are each equal to 0. The bismuth-containing catalyst as claimed in any of claims 1 to 3, wherein i) the residues R4 and R5 have the same definition, ii) R9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, iii) R10 is hydrogen or unsubstituted or at least monosubstituted phenyl or C1-C12~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, iv) R11 is hydrogen or unsubstituted or at least monosubstituted phenyl or C1-C12~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, v) R6 is hydrogen or unsubstituted or at least monosubstituted C1-C12~alkyl, wherein the substituents are selected from hydroxyl, chlorine and -CF3, vi) R7 is hydrogen or unsubstituted or at least monosubstituted C1-C12~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6- alkyl, and vii) R8 is hydrogen or unsubstituted or at least monosubstituted phenyl or C1-C12-alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl. The bismuth-containing catalyst as claimed in any of claims 1 to 4, wherein i) the residues R4 and R5 have the same definition, ii) R9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, iii) R10 is hydrogen or unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, iv) R11 is hydrogen or unsubstituted or at least monosubstituted C1-C12~alkyl, wherein the substituents are selected from hydroxyl, chlorine and -CF3, v) R6 and R7 are hydrogen, vi) R8 is hydrogen or unsubstituted or at least monosubstituted phenyl or C1-C12-alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, and vii) x is equal to 3 and y and z are each equal to 0. The bismuth-containing catalyst as claimed in any of claims 1 to 5, wherein i) the residues R4 and R5 have the same definition, ii) R9 and R10 are each phenyl, iii) R11 is hydrogen or C1-C12~alkyl, preferably hydrogen or C1-C5-alkyl, especially hydrogen, iv) R6 and R7 are hydrogen, v) R8 is hydrogen or C1-C12~alkyl, preferably hydrogen or C1-C5-alkyl, especially methyl, and vi) x is equal to 3 and y and z are each equal to 0. The bismuth-containing catalyst as claimed in any of claims 1 to 6, wherein the bismuth-containing catalyst is defined according to the general formula (la) wherein the residues R6 to R11 are mutually independently defined as claimed in any of claims 1 to 6. The bismuth-containing catalyst as claimed in claim 7, wherein each of the total of three residues R6 are the same, each of the total of three residues R7 are the same, each of the total of three residues R8 are the same, each of the total of three residues R9 is the same, each of the total of three residues R10 is the same and each of the total of three residues R11 is the same. The bismuth-containing catalyst as claimed in claim 7 or 8, wherein i) R9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, ii) R10 is hydrogen or unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl, iii) R11 is hydrogen or unsubstituted or at least monosubstituted C1-C12-alkyl, wherein the substituents are selected from hydroxyl, chlorine and -CF3, iv) R6 and R7 are hydrogen, and v) R8 is hydrogen or unsubstituted or at least monosubstituted phenyl or C1-C12~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF3 and C1-C6-alkyl. The bismuth-containing catalyst as claimed in any of claims 7 to 9, wherein i) R9 and R10 are each phenyl, ii) R11 is hydrogen or C1-C12~alkyl, preferably hydrogen or C1-C5-alkyl, especially hydrogen, iii) R6 and R7 are hydrogen, and iv) R8 is hydrogen or C1-C12~alkyl, preferably hydrogen or C1-C5-alkyl, especially methyl. A method for preparing a bismuth-containing catalyst of the general formula (I) as claimed in any of claims 1 to 10, wherein i) at least one compound of the general formula (Ila) or a corresponding salt thereof, wherein the residues R6 to R11 are defined as claimed in any of claims 1 to 10, ii) optionally at least one compound of the general formula (Illa) or a corresponding salt thereof wherein the residue R3 is defined as claimed in any of claims 1 to 10, iii) is reacted with at least one bismuth-containing compound selected from Bi2O3, bismuth carbonate, bismuth hydrogencarbonate, bismuth halide, Bi (C6-C14- aryl)3, Bi (C1-C12-alkyl)3 or metallic bismuth. The method as claimed in claim 10, wherein the bismuth- containing compound is selected from BI2O3, BiCI3, Bi(C6H5)3 or metallic bismuth. The method as claimed in claim 11 or 12, wherein i) the reaction is carried out under a protective atmosphere and/or in the presence of at least one solvent, especially toluene or tetrahydrofuran, and/or ii) the reaction is conducted for at least 10 hours and/or at a temperature of at least 100°C, and/or iii) following the reaction, volatile constituents are removed, the bismuth-containing catalyst is dried under reduced pressure and/or a recrystallization is carried out. The method as claimed in any of claims 11 to 13, wherein a compound of the general formula (Ila) is prepared by reacting a corresponding compound (lib), but in which at least one of the two fragments consisting of the carbon atom and the residues R9, R10 and R11 are replaced by H, with a lithium-containing compound, especially with n- butyllithium, and the intermediate obtained in this case is subsequently reacted with a haloalkane to introduce the corresponding fragment consisting of the carbon atom and the residues R9, R10 and R11 to obtain a compound according to the general formula (Ila). The use of at least one bismuth-containing catalyst as claimed in any of claims 1 to 10 for preparing compounds comprising a urethane group. |
Description
The invention relates to a bismuth-containing catalyst as such, which is defined by the general formula (I) detailed in the subsequent text. The bismuth-containing catalyst comprises at least one residue R 1 , which comprises a carboxyl fragment according to the general formula (II), wherein the first carbon atom (a-carbon), which is bonded directly to the carbon atom of the carboxyl group, is part of an aromatic fragment. The present invention further relates to a method for preparing a bismuth-containing catalyst of this kind and also to the use of such a bismuth-containing catalyst for preparing compounds comprising a urethane group.
WO 2018/069018 relates to a coating composition system comprising the components (A) to (C) and optionally further components. The component (A) is at least one polyhydroxyl group-containing compound and the component (B) is at least one polyisocyanate-containing compound. In contrast, the component (C) is a catalyst comprising at least two salts of an aliphatic monocarboxylic acid having at least 4 carbon atoms. In this case, the metal component of the first salt is bismuth (Bi), while the second salt comprises magnesium (Mg), sodium (Na), potassium (K) or calcium (Ca) as metal component. The coating composition system according to WO 2018/069018 may be configured according to a first option such that all components are present separately from one another, i.e. the individual components are not mixed with one another, whereas according to a second option of the corresponding coating composition system, the respective components can also be present completely or at least partially mixed with one another.
US-A 4,895,827 discloses a catalyst in the form of a metal salt, in which the catalyst is a constituent of a heat-sensitive color-forming composition, which, in addition to the catalyst, comprises a chromogenic material comprising an acidic developer and a suitable binder. The metal salt may comprise different metals as central metal atom/metal ion comprising, for example, zinc, tin, aluminum or nickel. The corresponding metal salt comprises organic compounds as ligands which, in addition to a carboxyl group, also comprise aromatic fragments and vinyl groups. However, bismuth-containing catalysts are not disclosed in US-A 4,895,827.
JP-A 58 87 087 discloses the use of a multivalent metal salt of diphenylacetic acid, especially diphenylzinc acetate, as colorants, wherein a water-proof colored picture can be produced. However, bismuth-containing metal salts or the use of metal salts for preparing a compound comprising a urethane bond are not disclosed in JP-A 58 87 087.
WO 2020/160939 relates to a bismuth-containing catalyst as such, which is defined by the general formula (I). The bismuth-containing catalyst comprises at least one residue R 1 , which comprises a carboxyl fragment according to the general formula (II), wherein a first carbon atom (a-carbon) is bonded to the carbon atom of the carboxyl group, which in turn is directly substituted with at least one aromatic system according to the invention. By consequence, the residue R 1 of the bismuth-containing catalyst of WO 2020/160939 does not comprise any aromatic fragments bonded directly to the carbon atom of the carboxyl group.
J. Bresien et al., Dalton Trans. 2019, 48, 3786, relates to the synthesis of sterically demanding primary phosphanes of the type R Bhp-PH2 (Bhp = 2,6- bis (benzylhydryl)-4-R-phenyl, R = Me, tBu) as well as the isolation and characterization of several halogenated precursors, a diazonium intermediate and a dihalostibane. Bresien et al. does not disclose any bismuth-containing catalysts. The preparation of compounds comprising a urethane group (urethane bond) has likewise been known for a long time.
A compound having a urethane group is generally obtained if a compound comprising an isocyanate group is reacted with a compound comprising an hydroxyl group. The reaction generally takes place in the presence of a catalyst. Although tin-containing catalysts exhibit very high activity in such reactions, the use of such tin- containing catalysts, especially alkyltin compounds, should be avoided owing to their (very high) toxicity.
The object of the present invention, therefore, was to provide a novel catalyst that can be used for preparing compounds comprising a urethane group.
The object is achieved by a bismuth-containing catalyst of the general formula (I) in which the variables are defined as follows:
R 1 is mutually independently a residue of the general formula (II)
and x is 1, 2 or 3;
R 2 is mutually independently a residue of the general formula (III) and y is 0, 1 or 2 ;
X is mutually independently hydroxyl, halogen, carbonate, hydrogencarbonate or R 12 and z is 0, 1 or
2; wherein the sum total of x, y and z is equal to 3;
R 3 is unsubstituted or at least monosubstituted C 1
C 30 -alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy, under the proviso that in case R 3 is unsubstituted or at least monosubstituted C 1 - C 30 -alkyl or C 7 -C 30 -aralkyl, the carbon atom of the residue R 3 bonded directly to carbon atom of the carboxyl group of the general formula (III) does not comprise any unsubstituted or at least monosubstituted C 6 -C 14 -aryl as substituent,
R 4 and R 5 are mutually independently residues of the general formula (IV)
R 6 , R 7 and R 8 are mutually independently hydrogen or unsubstituted or at least monosubstituted C 1 -C 30 - alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy,
R 9 , R 10 and R 11 are mutually independently hydrogen or unsubstituted or at least monosubstituted C 1 -C 30 - alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy, and wherein at least one of the residues R 9 , R 10 or R 11 is unsubstituted or at least monosubstituted C 6 -C 14 -aryl,
R 12 is unsubstituted or at least monosubstituted C 1 - C 30 -alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy.
The bismuth-containing catalysts according to the invention are characterized in that, inter alia, the use of toxic tin-containing catalysts in the production of compounds comprising a urethane group can be avoided. The bismuth-containing catalysts according to the invention have a comparable catalytic activity as known representatives of the effective, on the one hand catalytically active, but on the other hand toxic, tin- containing catalysts.
However, the catalytic activity of the bismuth-containing catalysts according to the invention is better than the corresponding catalytic activity of the bismuth- or zinc- containing catalysts already known. In particular, the catalytic activity of the bismuth-containing catalysts according to general formula (I) of the present invention is better than the respective catalytic activity of bismuth-containing catalysts as described in WO 2020/16093 having an aliphatic first carbon atom (cx- carbon) bonded to the carbon atom of the carboxyl group. Moreover, the bismuth-containing catalysts according to the invention exhibit improved hydrolytic stability compared to bismuth-containing catalysts already known. For example, low amounts of water can already be sufficient in order to significantly or fully reduce the catalytic activity of bismuth-containing catalysts based on pure alkyl ligands, such as laurate-containing bismuth catalysts. Whereas such catalysts known from the prior art start to precipitate on contact with water, the bismuth-containing catalysts according to the invention are much more stable. Owing to the increased stability to hydrolysis - and thus also storage stability - the bismuth-containing catalysts according to the invention exhibit their improved catalytic properties over a much longer time period.
Furthermore, in the case of the bismuth-containing catalysts according to the invention, it is also not required that the catalyst must be present as a salt of the corresponding acid. The bismuth-containing catalysts according to the invention can thus be used without the presence of the corresponding acid at high catalytic activity in order to form compounds having urethane groups. Advantageous properties are then already obtained in the catalysts according to the invention if in at least one of the substituents/ligands of the bismuth central atom, an aromatic fragment is directly bonded to the carbon atom of the carboxyl group of the corresponding ligands as shown in formula (II). The aromatic fragment (directly bonded to the carbon atom of the carboxyl group) in turn is again substituted in both p-positions (residues R 4 and R 5 ) with at least one further residue containing an aromatic fragment such as R 9 , R 10 and/or R 11 as shown in formulas (II) and (IV).
In accordance with the invention, this first carbon atom of the aromatic part of the residue according to formula (II), which is directly bonded to the carbon atom of the carboxyl group, is referred to as the a-carbon (atom). Within the context of the present invention, the two carbon atoms of the aromatic part of the residue according to formula (II), which are directly bonded to the a-carbon atom, are both referred to as p-carbons
(atoms).
The said carboxyl group of this substituent is located (spatially speaking) in proximity to the bismuth central atom of the bismuth-containing catalyst. The bismuth- containing catalysts according to the invention are represented as salts, wherein the bismuth central atom of the bismuth-containing catalyst according to the invention is represented as a (triple positively charged) cation of the corresponding salt (see for example the general formula (I))• The corresponding substituents/ligands of the bismuth-containing catalyst, which are represented by the substituents/radicals R 1 , R 2 and X in the general formula (I) detailed above, form the corresponding anion components of the bismuth-containing catalyst in this salt representation. Each of these so- called substituents/ligands is singly negatively charged. As detailed below, the two substituents R 1 and R 2 each comprise a carboxyl group. In general, the negative charge in the corresponding substituents/ligands of said carboxyl group is localized and/or the corresponding carboxyl group is located in spatial proximity to the (positively charged) bismuth central atom.
From a scientific standpoint however, it is also tenable, in place of the salt notation used in the context of the present application for the bismuth-containing catalysts according to the invention, to select a notation/representation in which a chemical bond between the bismuth central atom and the three ligands R 1 , R 2 and X according to general formula (I) is completely or at least partially formed in each case. Expressed in other words, this means that the bismuth central atom is not present as a positively charged cation and the corresponding ligands are also not present as negatively charged anions, but rather the corresponding charge form a chemical bond between the corresponding ligands on the one hand and the bismuth central atom on the other hand. In the context of the present invention, the bismuth- containing catalysts disclosed according to the invention therefore also describe such a definition that is not based on a salt.
In the context of the present invention, definitions such as C 1 -C 30 -alkyl, such as defined, for example, for the radical R 8 in formula (II) above, signifies that this substituent (radical) is an alkyl radical having a carbon atom number of 1 to 30, wherein substituents optionally present are not taken into consideration in the carbon atom number. The alkyl radical may be either linear or branched as well as optionally cyclic. Alkyl radicals having both a cyclic and a linear component also fall under this definition. The same applies to other alkyl radicals such as a C 1 -C 6 -alkyl radical or a C 1 -C 12 -alkyl radical for example. Examples of alkyl radicals are methyl, ethyl, n-propyl, sec-propyl, n-butyl, sec-butyl, isobutyl, 2-ethylhexyl, tertiary-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 "C 6 -C 14 ~aryl", as defined, for example, for the radical R 9 in formula (IV) above, signifies that the substituent (radical) is an aromatic system. The corresponding aromatic system has a carbon atom number of 6 to 14, wherein substituents optionally present are not taken into consideration in the carbon atom number. The aromatic system may be a monocyclic, bicyclic or optionally polycyclic aromatic system. In the case of bicyclic or polycyclic aromatic systems, individual rings may optionally be fully or partially saturated. Preferably, all rings of the corresponding aromatic systems are fully unsaturated. Preferred examples of aryl are phenyl, naphthyl or anthracyl, especially phenyl.
In the context of the present invention, the definition "C 7 -C 30 ~aralkyl ", as defined for example for the radical R 9 in formula (IV) above, signifies that the substituent (radical) comprises an alkyl radical (such as C 1 -C 6 -alkyl according to the definitions above), wherein this alkyl radical is in turn substituted by an aryl radical (according to the definitions above). The corresponding aralkyl substituent has a carbon atom number of 7 to 30, wherein substituents optionally present are not taken into consideration in the carbon atom number. The alkyl radical itself present therein may be either linear or branched as well as optionally cyclic. In the context of the present invention, the term "C 1 - C 6 -alkoxy", as defined for example as (additional) substituent of the radical R 9 in formula (IV) above, signifies that it is a substituent (radical) in this case which is derived from an alcohol. The corresponding substituent thus comprises an oxygen fragment (-O-), which is in turn linked to an alkyl radical, such as C 1 - C 6 -alkyl (according to the definitions above). The alkyl radical itself may be either linear or branched as well as optionally cyclic.
In the context of the present invention, the term "halogen", such as defined for example for the radical X in formula (I) above, signifies that the substituent (radical) is fluorine, chlorine, bromine or iodine, X preferably being fluorine or chlorine, particularly preferably chlorine.
In the context of the present invention, the term "unsubstituted or at least monosubstituted C 1 -C 30 -alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl ", such as defined for example for the radical R 9 in formula (IV) above, signifies that each of the in total three substituents (radicals) detailed corresponding to their definitions already specified above may be present either in unsubstituted form or have at least one further substituent (monosubstituted) . If one or more substituents are present (for example disubstituted, trisubstituted or even higher substituted), the appropriate substituents are selected independently of one another from the substituent groups specified in each case.
In the case of a disubstituted C 6 -C 14 -aryl for example, the corresponding aryl unit, such as phenyl for example, may be substituted for example by an hydroxyl and a C 1 - C 30 -alkyl substituent, such as methyl or ethyl. Alkyl or aryl fragments may themselves in turn comprise at least one additional substituent according to the definitions stated. The substitution may be at any desired position of the corresponding fragment.
Provided that an appropriate radical, such as R 8 for example, owing to the definition of, for example, formula (I), may occur two or more times in connection with formula (II), the individual radicals R 8 may be selected completely independently of one another according to the respective definitions. For example, if in the general formula (I) the variable x=3, the radical R 1 occurs in total three times in the general formula (I). The radical R 1 , which in turn comprises the radical R 8 , can therefore be present three times independently of one another in this scenario. The individual radicals R 1 can therefore be configured differently according to their basic definition. Thus, it is feasible that a first radical R 1 , with regard to the constituent of the radical R 8 necessarily present therein, has a definition other than the corresponding second and/or third radical R 1 . Unless otherwise stated in the following text, this logically applies also for all other radicals, such as R 2 to R 7 , R 9 , R 10 and/or R 11 .
Unless otherwise specified in the following description, the respective definitions of the radicals R 1 to R 12 are in each case the preferred unsubstituted definitions.
The present invention is further specified hereinbelow.
The present invention firstly relates to a bismuth- containing catalyst of the general formula (I) in which the variables are defined as follows:
R 1 is mutually independently a residue of the general formula (II)
and x is 1, 2 or 3;
R 2 is mutually independently a residue of the general formula (III) and y is 0, 1 or 2;
X is mutually independently hydroxyl, halogen, carbonate, hydrogencarbonate or R 12 and z is 0, 1 or 2; wherein the sum total of x, y and z is equal to 3;
R 3 is unsubstituted or at least monosubstituted C 1 -
C 30 -alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy, under the proviso that in case R 3 is unsubstituted or at least monosubstituted C 1 - C 30 -alkyl or C 7 -C 30 -aralkyl, the carbon atom of the residue R 3 bonded directly to carbon atom of the carboxyl group of the general formula (III) does not comprise any unsubstituted or at least monosubstituted C 6 -C 14 -aryl as substituent,
R 4 and R 5 are mutually independently residues of the general formula (IV)
R 6 , R 7 and R 8 are mutually independently hydrogen or unsubstituted or at least monosubstituted C 1 -C 30 - alkyl, C 6 -C 14 -aryl or C 7 -C 30 -aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy,
R 9 , R 10 and R 11 are mutually independently hydrogen or unsubstituted or at least monosubstituted C 1 -C 30 - alkyl, C 6 -C 14 -aryl or Cv-Cso-aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy, and wherein at least one of the residues R 9 , R 10 or R 11 is unsubstituted or at least monosubstituted C 6 -C 14 -aryl,
R 12 is unsubstituted or at least monosubstituted Ci- Cso-alkyl, C 6 -C 14 -aryl or Cv-Cso-aralkyl, wherein the substituents are selected from hydroxyl, halogen, carboxyl, -CF 3 , -NH 2 , C 1 -C 6 - alkoxy, C 1 -C 30 -alkyl or C 6 -C 14 -aryl and the alkyl and aryl fragments of these substituents may in turn be at least monosubstituted by hydroxyl, halogen, -CF 3 , -NH 2 or C 1 -C 6 -alkoxy.
In connection with the residues (radicals/substituents/ligands ) present in the general formula (I), particularly the necessary residue R 1 and the optional residue R 2 , it should be noted that the further/exact chemical definition of these radicals R 1 or R 2 is a result of the residues R 4 to R 11 of the general formulas (II) and (IV) with respect to the residue R 1 and is a result of the residue R 3 of the general formula (III) with respect to the residue R 2 . In accordance with the invention, the residue R 2 is chemically always defined differently than the residue R 1 . Expressed in other words, this signifies that a specific radical R 2 or R 3 in accordance with general formula (III) cannot fall under the corresponding definition of a radical R 1 or the radicals R 4 to R 11 according to general formulas (II) and (IV).
The radical R 1 in accordance with general formulas (II) and optionally (IV) is preferably defined that i) R 9 , R 10 and R 11 are mutually independently hydrogen or unsubstituted or at least monosubstituted C 1 -C 12 -alkyl or C 6 -C 14 -aryl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, and wherein at least one of the residues R 9 , R 10 or R 11 is unsubstituted or at least monosubstituted C 6 -C 14 -aryl, and/or ii) R 6 , R 7 and R 8 are mutually independently hydrogen or unsubstituted or at least monosubstituted C 1 -C 12 -alkyl or C 6 -C 14 -aryl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl.
The radical R 1 in accordance with general formula (II) is more preferably defined according to the invention such that R 4 and R 5 have the same definitions according to formula (IV) in connection with the residue R 9 to R 11 . It should be noted that the staggered line crossing the bond on the left side of formula (IV) indicates that this bond is the connection of the respective residue R 4 or R 5 to the aromatic fragment of formula (II). The radical R 1 in accordance with general formulas (II) and (IV) is more preferably defined in connection with the residue R 9 to R 11 as follows: i) R 9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, and/or ii) R 10 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 -alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, and/or iii) R 11 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl.
With respect to the radical R 2 according to general formula (III), it is preferable that the radical R 3 present therein is unsubstituted or at least monosubstituted C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine or -CF 3 .
With regard to the radical X, it is preferred in accordance with the invention that this is hydroxyl, chlorine or R 12 and R 12 is unsubstituted or at least monosubstituted C 1 -C 12 -alkyl or C 6 -C 14 -aryl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl.
In the bismuth-containing catalyst according to general formula (I) according to the invention, the radicals R 1 , R 2 and X present in each case can be present in each case in any combination. A precondition in this case however is that x is at least 1, i.e. at least one radical R 1 is present in the bismuth-containing catalyst according to the invention according to general formula (I). Furthermore, the sum total of x, y and z is 3, the total number of ligands or negative charges is 3, so that in total charge neutrality is present with respect to the 3-fold positively charged bismuth central atom. If individual ligands/radicals such as R 1 , R 2 or X occur repeatedly, these can have the same or different definitions according to the respective basic definition.
In the context of general formula (I), the following scenarios are preferred in accordance with the invention, wherein i) x is equal to 2 or 3, y is equal to 0 or 1 and z is equal to 0 or 1, or ii) x is equal to 3 and y and z are each equal to 0, or iii) x is equal to 2, y is equal to 0 and z is equal to 1, or iv) x is equal to 2, y is equal to 1 and z is equal to 0, wherein preferably x is equal to 3 and y and z are each equal to 0.
In a preferred embodiment of the present invention, the bismuth-containing catalyst according to the general formula (I), (II) and optionally (IV) is defined as follows: i) the residues R 4 and R 5 have the same definition, ii) R 9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, iii) R 10 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, iv) R 11 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 -alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, v) R 6 is hydrogen or unsubstituted or at least monosubstituted C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine and -CF 3 , vi) R 7 is hydrogen or unsubstituted or at least monosubstituted C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, and vii) R 8 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl.
In a more preferred embodiment of the present invention, the bismuth-containing catalyst is defined as follows: i) the residues R 4 and R 5 have the same definition, ii) R 9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, iii) R 10 is hydrogen or unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, iv) R 11 is hydrogen or unsubstituted or at least monosubstituted C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine and -CF 3 , v) R 6 and R 7 are hydrogen, vi) R 8 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, and vii) x is equal to 3 and y and z are each equal to 0.
In an even more preferred embodiment of the present invention, the bismuth-containing catalyst is defined as follows: i) the residues R 4 and R 5 have the same definition, ii) R 9 and R 10 are each phenyl, iii) R 11 is hydrogen or C 1 -C 12 ~alkyl, preferably hydrogen or C 1 -C 5 -alkyl, especially hydrogen, iv) R 6 and R 7 are hydrogen, v) R 8 is hydrogen or C 1 -C 12 ~alkyl, preferably hydrogen or C 1 -C 5 -alkyl, especially methyl, and vi) x is equal to 3 and y and z are each equal to 0.
In a particularly preferred embodiment of the present invention, the bismuth-containing catalyst is defined by the general formula (la):
wherein the residues R 6 to R 11 mutually independently correspond to the definitions described above. As evident from formula (la) compared to the general formula (I), the catalyst according to the invention in this embodiment has in total three residues R 1 according to general formula (I). Each of these in total three residues R 1 in each case comprises one residue R 6 , one residue R 7 , one residue R 8 , one residue R 9 , one residue R 10 and one residue R 11 . In each of these three residues R 1 , the corresponding definitions of the residues R 4 to R 11 can be the same or different from one another. However, it is preferred in accordance with the invention that each of the total of three residues R 6 are the same, each of the total of three residues R 7 are the same, each of the total of three residues R 8 are the same, each of the total of three residues R 9 are the same, each of the total of three residues R 10 are the same and each of the total of three residues R 11 are the same. Furthermore, in the context of the general formula (la), it is preferable that i) R 9 is unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, ii) R 10 is hydrogen or unsubstituted or at least monosubstituted phenyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl, iii) R 11 is hydrogen or unsubstituted or at least monosubstituted C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine and -CF 3 , iv) R 6 and R 7 are hydrogen, and v) R 8 is hydrogen or unsubstituted or at least monosubstituted phenyl or C 1 -C 12 ~alkyl, wherein the substituents are selected from hydroxyl, chlorine, -CF 3 and C 1 -C 6 -alkyl.
In the context of the general formula (la), it is even more preferable that i) R 9 and R 10 are each phenyl, ii) R 11 is hydrogen or C 1 -C 12 ~alkyl, preferably hydrogen or C 1 -C 5 -alkyl, especially hydrogen, iii) R 6 and R 7 are hydrogen, and iv) R 8 is hydrogen or C 1 -C 12 ~alkyl, preferably hydrogen or C 1 -C 5 -alkyl, especially methyl.
The present invention therefore further relates also to a method for preparing a bismuth-containing catalyst of the general formula (I) or of the general formula (la) according to the definitions above. The method according to the invention for preparing such bismuth-containing catalysts can be carried out for example, in which i) at least one compound of the general formula (Ila)
or a corresponding salt thereof, wherein the radicals R 6 to R 11 are defined according to the embodiments/definitions above ii) optionally at least one compound of the general formula (Illa) or a corresponding salt thereof, wherein the radical R 3 is defined according to the embodiments/definitions above, iii) is reacted with at least one bismuth-containing compound selected from Bi 2 O 3 , bismuth carbonate, bismuth hydrogencarbonate, bismuth halide, Bi (C 6 -C 14 -aryl)3, Bi (C 1 -C 12 -alkyl) 3 or metallic bismuth.
The reactants listed above, i.e. the acids according to the general formulae (Ila) or (Illa) or the appropriate corresponding salts as such, are known to those skilled in the art. The corresponding salts used can be, for example, sodium, potassium or calcium salts. Optionally, instead of the aforementioned acids according to the general formulae (Ila) or (Illa) or corresponding salts thereof as reactants, it is also possible to use corresponding carboxylic esters, for example a methyl or ethyl ester. Such carboxylic esters can be prepared by reacting the aforementioned acids or a corresponding salt thereof with a suitable alcohol, for example methanol or ethanol, optionally in the presence of a catalyst. The appropriate preparation methods of such carboxylic esters are known to a person skilled in the art.
In principle, any bismuth-containing compound can be used in the method according to the invention, which is suitable for the purpose of forming the bismuth central atom in the bismuth-containing catalyst of the general formula (I) according to the invention, by reaction with the appropriate compound according to the general formula (Ila) or optionally (Illa). Bismuth-containing compounds as such are known to those skilled in the art. If, in accordance with the invention, a bismuth halide is used as bismuth-containing compound, it is preferably a chlorine-containing compound, especially BiCI 3 . Any specific substituents/substitution patterns, such as the radicals R 6 to R 11 for example, may already be present in the corresponding reactant. Optionally, such substituents/substitution patterns can also be attached or completed even after the preparation process of a bismuth-containing catalyst according to the general formula (I) described above.
Preferably, the bismuth-containing compound is selected from Bi2O3, BiCis, Bi(C6Hs)3 or metallic bismuth.
The bismuth-containing catalysts according to the general formula (I) according to the invention are preferably prepared by reacting at least one compound of the general formula (Ila) and optionally at least one compound of the general formula (Illa) with at least one bismuth- containing compound, wherein i) the reaction is carried out under a protective atmosphere and/or in the presence of at least one solvent, especially toluene or tetrahydrofuran, and/or ii) the reaction is conducted for at least 10 hours and/or at a temperature of at least 100°C, and/or iii) following the reaction, volatile constituents are removed, the bismuth-containing catalyst is dried under reduced pressure and/or a recrystallization is carried out.
Furthermore, it is preferred in accordance with the invention that the at least one compound of the general formula (Ila) used as reactant in the method according to the invention is prepared from a corresponding compound according to the general formula (lib), wherein the compounds according to the general formula (Ila) only differ from the corresponding compounds of the general formula (lib) in that one or at most two radicals selected from R 9 , R 10 and R 11 is defined as H (hydrogen) in place of the definitions listed for the compounds according to general formula (Ila). This is preferably effected by reacting a corresponding compound (lib), but in which R 9 , R 10 and/or R 11 is H, with a lithium-containing compound, especially with n-butyllithium, and the intermediate obtained in this case is subsequently reacted with a haloalkane to introduce the radicals R 9 , R 10 and R 11 to obtain a compound according to the general formula (Ila). Haloalkanes used can be, for example, 1-bromooctane or 1-bromopropane . This method variant is thus used in particular if a catalyst according to the invention in accordance with general formula (I) is intended to be prepared in which at least one of the radicals R 9 to R 11 , preferably precisely one of these radicals, is a C 1 -C 30 - alkyl. Alternatively, it is also conceivable that, instead of a haloalkane, an appropriate haloaryl or haloaralkyl compound is used if, in the context of this method step, a fully or partially aromatic substituent is intended to be introduced into the corresponding compound (lIb). Preferably, the compound according to the general formula (lib) used is 2-arylacetic acid, 2,2- diarylacetic acid, particularly 2-phenylacetic acid or 2,2-diphenylacetic acid, particularly preferably 2,2- diphenylacetic acid.
The present invention further relates to the use of at least one bismuth-containing catalyst according to the definitions above for preparing compounds comprising a urethane group.
The invention is illustrated hereinafter by examples.
I) Preparation of catalysts according to the invention 1.1 Synthesis of 2,6-Bis(benzhydryl)-4-methylaniline
(precursor)
Diphenylmethanol (114.79 g, 623.1 mmol), 4-methylaniline (33.25 g, 310.3 mmol) and zinc chloride (21.66 g, 158.9 mmol) are placed together in a 1 L round-bottom flask with a large stir bar. After adding concentrated hydrochloric acid (37.0 %, 35 mL), the flask is equipped with a condenser and the mixture is heated to 150 °C for 2 hours in an oil bath. After cooling to ambient temperature, the product is extracted with dichloromethane (600 mL). Residual acid is neutralized via slow addition of an aqueous potassium carbonate solution (55 g in 400 mL). Layers are separated and the organic layer is washed twice with water. After drying over sodium sulfate, the solution is decanted and volatiles are removed at the rotary evaporator. The crude product is crushed into a fine powder and washed with cold ethyl acetate, leaving a white solid. 1.2 Synthesis of 2,6-bis(benzhydryl)-4-methyl-jodide
(precursor)
In a 2 L two-neck round-bottom flask, equipped with a big stir bar, a dropping funnel and a condenser, 2,6- bis (benzhydryl)-4-methyl-aniline (66.50 g, 151.3 mmol) is dissolved in dichloromethane (500 mL). After cooling to 0 °C, concentrated hydrochloric acid (37.0 %, 90 mL) and glacial acetic acid (99.5 %, 90 mL) are added. Afterwards, an aqueous solution (40 mL) of sodium nitrite (12.00 g, 173.9 mmol) is added dropwise, resulting in a bright red mixture, which is stirred for 30 min. An aqueous solution (400 mL) of potassium iodide (253.00 g,
1524.1 mmol) is subsequently added dropwise, resulting in visible gas formation. The mixture is then warmed to ambient temperature and stirred for another 30 min. Remaining iodine/triiodide is reduced by adding an aqueous solution (500 mL) of sodium sulfite (120.00 g,
952.1 mmol), resulting in a colorless aqueous and orange organic layer. Phases are separated, the aqueous layer is washed twice with dichloromethane and the organic layer is washed with water to pH neutrality. Organic phases are combined, dried over magnesiumsulfate and decanted. Volatiles are removed at the rotary evaporator and the product is crystallized from a mixture of toluene and n-pentane (3:2).
1.3 Synthesis of Lithium-2,6-dibenzhydryl-4-methyl- benzoate (precursor)
2,6-bis (benzhydryl)-4-methyl-phenyliodide (1.76 g, 3.20 mmol, 1.00 eq.) was dissolved in 50 mL Tetrahydrofurane in a Schlenk tube and cooled to -78 °C. Then a 1.6 M solution of n-butyllithium in hexane (2 mL, 3.20 mmol, 1.0 eq.) was slowly added and the resulting red solution was stirred for 1 h at this temperature. Subsequently, carbon dioxide was passed through the reaction solution with a Teflon tube for 15 min and then stirred for 1 h at room temperature. The product was precipitated with 100 mL n-pentane, then filtered and washed with n- pentane. The resulting material was air dried and obtained as a white solid.
1.4 Synthesis of 2,6-Bis (benzhydryl)-4-methyl- benzoate ("dbhmb"/precursor)
To a suspension of Lithium-2,6-dibenzhydryl-4- methylbenzoate (0.76 g, 1.60 mmol, 1.00 eq.) in 60 mL Et2O, a 1 M aqueous solution of hydrochloric acid (1.60 mL, 1.60 mmol, 1.00 eq.) was added at room temperature and stirred for 30 min. The reaction solution was transferred to a separating funnel and washed with water (3 x 10 mL). The organic phase was then separated, then dried and filtered with MgSO4. The solvent was removed under vacuum and the product 2b was obtained as white solid.
1.5 Synthesis of the respective Bi-Salt
(Bi(dbhmb)3/working example 1)
In a Schlenk tube 0.75 mmol, 3.00 eq.of the precursor (of step 1.4) and BiPhs (110 mg, 0.25 mmol, 1.00 eq.) was heated in 5 ml acetonitrile to 110 °C for 16 h. In each case a crystalline solid was obtained after slowly cooling the solution. The crystalline compound was washed with diethyl ether (3x5 mL) and dried in vacuum at 80°C to give bismuth salts as white solid. II) Preparation of comparative examples
Ila) Precursor of comparative example 3:
2,2-Diphenyldecanoic acid (dpdH)
2,2-Diphenylacetic acid (10.6 g; 48 mmol) are dissolved in 75 ml of dry tetrahydrofuran (THF) under a protective gas atmosphere (argon or nitrogen) in a 200 ml Schlenk flask and cooled to -15°C. A 1.6M solution of n- butyllithium in hexane (60 ml; 96 mmol) is then added with stirring and 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). Subsequently, the reaction solution is slowly warmed to room temperature and stirred for a further 24 hours.
For the work-up and purification of the 2,2- diphenyldecanoic acid, a saturated ammonium chloride solution (60 mL) is added to the reaction solution and stirred for 30 minutes. The aqueous phase is separated by means of a separating funnel and extracted with 3 x 25 mL of diethyl ether. The combined organic phases were dried over magnesium sulfate (MgSO 4 )• All volatile solvents are then removed under reduced pressure (1 • 10" 3 mbar) and the resulting solid dried at 140°C under reduced pressure (1 • 10 3 mbar) for 24 hours.
Characterization by ^-H-NMR, 13 C-NMR, HRMS (high- resolution mass spectrometry), infra-red spectroscopy. lib) Catalyst according to comparative example 3: Bi(2,2- diphenyldecanoate)3 (Bi(dpd)3)
Triphenylbismuth (1.1 g; 2.5 mmol) and 2,2- diphenyldecanoic acid (2.43 g; 7.5 mmol) are initially charged under a protective gas atmosphere in a 25 mL three-necked flask equipped with stirrer bar, reflux condenser, thermometer and protective gas atmosphere inlet (argon or nitrogen). 12.5 mL of dry tetrahydrofuran or dry toluene (5 mL of solvent per 1 mmol of triphenylbismuth) are added to the reactants and the mixture is heated at 110°C under a protective gas atmosphere for at least 16 hours. The reaction course is monitored by ^-H-NMR (nuclear magnetic resonance spectroscopy) . After complete conversion of triphenylbismuth with formation of benzene, the reaction is terminated and cooled. All volatile solvents are then removed under reduced pressure (1 • 10 3 mbar) and the resulting solid dried at 60°C under reduced pressure (1 10 3 mbar) for 24 hours. As required, the resulting compound is purified from toluene and hexane at -40 °C or by recrystallization from hot toluene.
Characterization by ^-H-NMR, 13 C-NMR, C/H/N elemental analysis, infra-red spectroscopy. lie) Catalyst according to comparative example 4: Bi(2,2- diphenylpropionate)3 (Bi(dpp)3)
The catalyst Bi (dpp)3 according to comparative example 4 is prepared analogously to the comparative catalyst Bi(dpd)s described above, in which no synthesis of the precursor is required since the corresponding propionic acid derivative is commercially available (from Sigma- Aldrich), which is reacted with triphenylbismuth to give the comparative catalyst Bi (dpp)3.
III) Determination of the catalytic activity of examples 1 to 5
The respective catalytic activity of the individual working and comparative examples can be found in Table 1 below. The catalytic activity is tested by means of a reaction in which a compound is formed comprising a urethane group. For this purpose, 11 mmol of 2-ethylhexyl (6-isocyanatohexyl)carbamate (commercially available as Desmodur LD (3.3 mL)) are reacted with 11 mmol of n- butanol (1 mL) as reactants. The reaction was carried out in the presence of a solvent (2 mL of xylene) and the catalysts listed in Table 1 (with a content of 0.05 mol% catalyst based on the amount of bismuth) at a temperature of 21°C.
The isocyanate decrease and thus the formation of a urethane group are investigated by horizontal ATR-IR spectroscopy. For this purpose, 0.05 mL of the reaction solution are withdrawn at defined time intervals and investigated directly by spectroscopy. The conversion is determined by the relative decrease in intensity of the asymmetrical isocyanate stretching vibration at 2250 - 2285 cm 1 . The starting content of free isocyanate of the reaction solution at room temperature in the absence of catalyst was determined. All IR spectra were normalized to the bands of the symmetrical and asymmetrical stretching vibrations of the CH2 groups (3000 - 2870 cm 1 ).
The catalysts used are detailed in Table 1. Example 1: Bi(dbhmb)3, wherein dbhmb is 2,6-
Bis(benzhydryl)-4-methyl-benzoate
Comparative example 2: DBTL (Dibutyltin dilaurate), commercially available catalyst
Comparative example 3: Bi(dpd)3, wherein dpd is 2,2'- diphenyl decanoate Comparative example 4: Bi(dpp)s, wherein dpp is 2,2'- diphenyl propionate
Comparative example 5: without catalyst
H PJ cr
CD
■u
U1
As can be deduced from Table 1, the catalyst according to the invention (working example 1) shows a better catalytic activity to the known tin-containing catalysts according to comparative example 2. Tin-containing catalysts should be avoided however, owing to their considerable toxicity. The catalytic activity of working example 1 is however distinctly improved in comparison to bismuth-containing catalysts according to the prior art (comparative examples 3 and 4) or conducting the experiment wholly without catalyst (comparative example 5).