The present invention relates to a process for preparing a polycarbonate using electrophilic aromatic substitution, comprising a reaction of a diaryl carbonate with a structure of formula (I) and a primary alkyl halide with a structure of formula (Ila) or (lib) as described below. Furthermore, the invention relates to a polycarbonate comprising a repeating unit with a structure of formula (III) as described below.

Polycarbonates, in particular aromatic polycarbonates, are known to exhibit improved mechanical and optical properties, heat resistance and weatherability. Due to such a property profile, polycarbonates are employed in various indoor and outdoor applications. Typically, polycarbonates are prepared by the generally known interphase phosgenation process or via melt transesterification. Both processes employ bisphenols, e.g. bisphenol A ((2,2-bis(4- hydroxyphenol)propane), reacting either with phosgene or a diaryl carbonate (cf. for example US8,962,788B2) to result in a polymeric structure. This means that typically the polymeric backbone is defined by the structure of the diol and the carbonate group, being introduced into said backbone by the polymerization reaction itself. Employing aromatic diols such as bisphenol A, bisphenol B, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol P, bisphenol TMC, bisphenol Z and e. g. specific bisphenols as described in US2020/0115494 Al, backbones may be formed that comprise the carbonate group at the aromatic ring. Said carbonate group is located para to the at least one other substituent at the aromatic ring which, depending on the structure of the diol, connects the carbonate-aromatic ring -group to the next carbonate group in the polycarbonate backbone.

However, there is a constant need for improving the properties of classical aromatic (co)polycarbonates including the use of bio-based aromatic diols. Thus, developing alternative synthesis routes besides the classical interphase phosgenation or melt transesterification processes - enabling to connect aromatic moieties with carbonate groups, raises scientific and economic interests.

Therefore, it is an object of the present invention to provide an alternative process for preparing a polycarbonate. Preferably, it is an object of the present invention to provide a process for preparing a polycarbonate with a repeating unit comprising two aromatic moieties being linked with each other and - within the repeating unit - one of the aromatic moieties being substituted with a carbonate group. More preferably, it is an object of the present invention to provide a process for preparing a polycarbonate with a repeating unit comprising two aromatic moieties being linked with each other and - within the repeating unit - one of the aromatic moieties being substituted with a carbonate group, wherein the carbonate group is introduced to the repeating unit without the need of separately forming the carbonate group. Still preferably, it is an object of the present invention to provide a process for preparing a polycarbonate, including a reaction for the formation of the repeating unit, comprising linking of two aromatic moieties with each other. Such a reaction mandatorily requires that the aromatic moieties comprise carbonate substituents in order to obtain a polycarbonate comprising carbonate groups. Therefore, it is also preferably an object of the present invention to provide a process for preparing a polycarbonate with a repeating unit that comprises two aromatic moieties being linked with each other, and - within the repeating unit - one of the aromatic moieties being substituted with a carbonate group, wherein said carbonate group is not affected by the process as such. In this context the term “affected” preferably means that the carbonate is not degraded.

Besides the above, it is an object of the present invention to provide a polycarbonate, that may be prepared by the process according to the invention. Also, it is an object of the invention to provide a polycarbonate comprising novel chemical and physical properties when compared to polycarbonates known from the state of the art.

A well-known organic reaction is the so-called “Friedel-Crafts alkylation” which is used to attach substituents to an aromatic ring. Generally, the procedure of a “Friedel-Crafts alkylation” involves the alkylation of an aromatic ring with an alkyl halide using a strong Lewis acid, such as aluminum chloride or ferric chloride, the latter acting as catalysts. It is thus a further objective of the present invention to investigate whether the Friedel-Crafts alkylation as such or in an amended way can be used to obtain a polycarbonate.

To date, several scientific studies have shown that the primary alkyl halide 1,4- bis(chloromethyl)benzene (also known as a,a'-dichloro- -xylene) can be used as a coupling agent for a Friedel-Crafts alkylation of aromatic compounds. In particular, the alkylation of l,4-bis(chloromethyl)benzene has been reported in combination with benzene using different Lewis acids. For example, Darbeau and White have proved this for TiCL (Darbeau and White: A Study of A-Nitrosoamide-Mediated Friedel-Crafts Type Benzylation of Benzene-Toluene and Benzene-Anisole. J. Org. Chem. 2000, 65, 1121-1131.), Hayashi et al. for ZnCL (Hayashi et al:. Convenient Preparation of 1,4-Dibenzylbenzene using Zinc Chloride in the Presence of Polar Solvents. Synth. Commun. 1995, 25, 2029-2036.) and Kodomari for CtiCL on a AI2O3- support (Kodomari: Friedel-Crafts benzylation using alumina-supported copper(II) chloride catalyst. Nippon Kagaku Kaishi 1994, 12, 1137-1139.). JP 2002095971 A describes the reaction in combination with diphenylmethane. Furthermore, the discussed reaction has been reported by Kodomari and Tagushi in combination with biphenyls (Kodomari and Taguchi: Friedel Crafts Arylmethylation of Aromatics with Bis(chloromethyl) benzenes Catalyzed by Zinc Chloride Supported on Silica Gel. J. Chem. Res. Syn. 1996, 5, 240-241.) and by Reyes et al. in combination with phenols (Reyes et al . Synthesis of Tri -Aryl Methane Epoxy Resin Isomers and Their Cure with Aromatic Amines. Macromol. Mat. Engin. 2020, 305, 1900546). Finally, CN 107986946 A describes the reaction in combination with benzenes being substituted with alkoxy groups. However, the reaction has not yet been investigated for coupling two aromatic rings bearing a carbonate group.

I,4-Bis(chloromethyl)benzene has also been employed for the synthesis of similar products using cross-coupling chemistry. Transition metals are used in those cases to achieve a coupling with aryl boronic acids (Chahen et al Suzuki Cross-Coupling Reaction of Benzylic Halides with Arylboronic Acids in the Presence of a Tetraphosphine/Palladium Catalyst. Synlett 2003,

II, 1668-1672.). It can also be coupled with aromatic Grignard reactants (Y amato, T.; Sakaue, N.; Suehiro, K.; Tashiro, M., A Convenient Preparation of Diphenylmethanes from Bromobenzenes Using the Grignard Cross-Coupling Reaction. Org. Prep. Proced. Int. 1991, 23, 617-620.) or organolithium derivatives (Bender etal: Synthesis of oligomeric chains with 9,10-dihydroanthracene units by carbanion alkylation. Chem. Ber. 1988, 121, 1177-1186.) via nucleophilic substitution.

Based on this prior art, it was a further object of the present invention to provide a process for preparing a polycarbonate (other than the interphase phosgenation or the melt transesterification method) and to provide a polycarbonate as such, the process and the polycarbonate being based on existing, but also novel aromatic building blocks, especially biobased building blocks. Preferably, this process should be economically and ecologically beneficial. Moreover, this process preferably should result in a polycarbonate having improved properties, especially with respect to mechanical and/or optical properties, heat resistance and/or weatherability.

At least one of the above-mentioned objects, preferably all of these objects have been solved by the present invention.

Surprisingly, the inventors found a process for preparing a polycarbonate that provides an alternative to known processes such as interphase phosgenation or melt transesterification. More surprisingly, the inventors identified a process for preparing a polycarbonate with a repeating unit comprising two aromatic moieties being linked with each other and - within the repeating unit - one of the aromatic moieties being substituted with a carbonate group. Still surprisingly, the inventors found a process for preparing a polycarbonate with a repeating unit comprising two aromatic moieties being linked with each other and - within the repeating unit - one of the aromatic moieties being substituted with a carbonate group, wherein the carbonate group is introduced to the repeating unit without the need of separately forming the carbonate group. As mentioned, the inventors were able to find a process for preparing a polycarbonate, including a reaction for the formation of the repeating unit, comprising linking of two aromatic moieties with each other. Such a reaction mandatorily requires that the aromatic moieties comprise carbonate substituents in order to form a polymer backbone with repeating units, each repeating unit comprising a carbonate group substituting one of the aromatic moieties. Confronted with this objective, the inventors then identified a process for preparing a polycarbonate with a repeating unit that comprises two aromatic moieties being linked with each other, and - within the repeating unit - one of the aromatic moieties being substituted with a carbonate group, wherein said carbonate group is not affected by the process as such. In this context the term “affected” preferably means that the carbonate is not degraded.

Furthermore, the inventors identified a polycarbonate, obtainable by the process according to the invention. Also, the inventors identified a polycarbonate comprising novel chemical and physical properties when compared to polycarbonates known from the state of the art.

The inventors have identified a process and a polycarbonate, that employ/comprise existing, but also novel aromatic building blocks, especially bio-based building blocks. Also, the inventors identified a process for preparing a polycarbonate with economic and ecologic efforts. The process identified by the inventors results in a polycarbonate having improved properties, in particular with respect to mechanical and/or optical properties, heat resistance and/or weatherability. The same applies to the polycarbonate as such.

Surprisingly, it was identified that the Friedel-Crafts alkylation employing primary alkyl halides, preferably primary alkyl chlorides, with a structure of formula (Ila) or (lib) and diaryl carbonates with a structure of formula (I) can be used to couple two aromatic moieties bearing a carbonate group, preferably both bearing a carbonate group, with an optionally substituted hydrocarbon bridge comprising alkyl groups and aromatic rings. This reaction as such can be used according to the present invention to polymerize such aromatic moieties to yield a polycarbonate. This reaction can be used for existing building blocks (such as for example diphenyl carbonate), but also for novel, especially bio-based building blocks (such as guaiacol carbonate, also known as bis(2-methoxyphenyl) carbonate). Moreover, the resulting polycarbonate obtained from this process preferably comprises a good property profde, especially with respect to mechanical and/or optical properties, heat resistance and/or weatherability.

In a further embodiment of the present invention secondary or tertiary alkyl halides can be used to couple two aromatic moieties bearing a carbonate group, preferably both bearing a carbonate group, with an optionally substituted hydrocarbon bridge comprising alkyl groups and aromatic rings.

Accordingly, the present invention provides a process for preparing a polycarbonate using electrophilic aromatic substitution, comprising a reaction of a compound with a structure of formula (I)

© and a compound with a structure of formula (Ila) or (lib) in the presence of a Lewis acid catalyst added in a stoichiometric or substoichiometric amount, yielding a polycarbonate comprising a repeating unit with a structure of formula (III)

wherein the repeating unit with the structure of formula (III) comprises two aromatic rings, a carbonate group -OC(=O)O- and a linking group -CH2R ⁴ CH2-, wherein one of the two aromatic rings is substituted with the carbonate group, the two aromatic rings are linked via the linking group and R ⁴ comprises a structure given in {} in formula (IVa) or (IVb), respectively, and wherein

- each R ¹ and R ² independently represents an R ¹ substituent and an R ² substituent, respectively, being capable of activating the aromatic ring which it substitutes by a mesomeric effect and/or an inductive effect,

- each m independently is 0 to 4, preferably 0 - 3,

- each X independently represents a halogen atom,

- each R ³ independently represents an R ³ substituent, preferably independently representing an alkyl or alkoxy group having 1 to 6 carbon atoms, a halogen atom or an alkyl group having 1 to 6 carbon atoms and being interrupted by an ester group, more preferably independently representing an alkyl or alkoxy group having 1 to 6 carbon atoms,

- p is 0 to 4,

- q is 1 to 4,

- r is 1 to 3 and

- n is the number of repeating units, preferably 6 to 60. Polycarbonates in the context of the present invention are either homopolycarbonates or copolycarbonates; the polycarbonates may be linear or branched depending on the type of monomers used in the process of the present invention. For the purpose of the present invention, the expression “bio-based” is understood as meaning that the relevant chemical compound is at the fding date available and/or obtainable via a renewable and/or sustainable raw material and/or preferably is such a renewable and/or sustainable raw material. A renewable and/or sustainable raw material is preferably understood as meaning a raw material that is regenerated by natural processes at a rate that is comparable to its rate of depletion (see CEN/TS 16295:2012). The expression is used in particular to differentiate it from raw materials produced from fossil raw materials, also referred to in accordance with the invention as petroleum-based. Whether a raw material is bio-based or petroleum-based can be determined by the measurement of carbon isotopes in the raw material, since the relative amounts of the carbon isotope C ¹⁴ are lower in fossil raw materials. This can be done, for example, in accordance with ASTM D6866-18 (2018) or ISO 16620-1 to -5 (2015) or DIN SPEC 91236 2011-07. An exemplary bio-based carbonate in the sense of this invention is guaiacol carbonate.

According to the present invention reference is made to an electrophilic aromatic substitution. This process is known to the person skilled in the art and is described in various textbooks dealing with organic chemistry. The process according to the present invention is based on a Friedel-Crafts alkylation reaction, but includes amendments to the classical name reaction. Therefore, reference is rather made to the more general electrophilic aromatic substitution. However, the person skilled in the art knowing and understanding the concepts of the Friedel- Crafts alkylation reaction and once having perceived the present invention can transfer the principles of this general concept to the amendments of the process of the present invention.

Moreover, according to the present invention reference is made to a substituent (of an aromatic ring) being capable of activating the aromatic ring which it substitutes by a mesomeric effect and/or an inductive effect. In the context of an electrophilic aromatic substitution, this concept is known to the person skilled in the art, too.

Preferably, the term “mesomeric effect” or M effect refers to the known resonance effect. Still preferably, the term refers to the delocalization of electrons in a molecule by the interaction of two pi bonds or between a pi bond and a lone pair of electrons present on an adjacent atom. The term is preferably used to describe the electronic effect of a substituent on an aromatic moiety based on relevant resonance structures. It often is symbolized by the letter M. The mesomeric effect can be negative (-M) when the substituent withdraws electrons from the aromatic ring through pi bonds - called resonance electron withdrawal. The effect can also be positive (+M, called resonance electron donation) when the substituent donates electrons through the pi bonds to the aromatic ring.

Preferably, the term “inductive effect” or I effect refers to the displacement of electrons via sigma bonds towards a more electronegative atom. Due to the inductive effect one end of a bond obtains a partial positive charge and the other end a partial negative charge. Relative inductive effects of substituents bonded to an aromatic ring are described with reference to hydrogen. For example, a substituent with a +1 effect (electron-donating character) donates its sigma electrons to the aromatic ring more strongly than hydrogen will. In contrast, a substituent with a -I effect (electron-withdrawing character) will more strongly withdraw or accept the sigma electrons compared to hydrogen.

The M and I effect in the context of an electrophilic aromatic substitution are known to the person skilled in the art. It is known that existing substituent groups on an aromatic ring affect the overall reaction rate or have a directing effect on the positional isomer of the products that are formed. Here, an electron-donating group preferably is an atom or functional group that donates some of its electron density into a conjugated pi system via mesomeric or inductive effects. This makes the pi system more nucleophilic. In terms of regioselectivity, some existing substituent groups on the aromatic ring promote further substitution at the ortho- or para- position(s) with respect to themselves. Other groups favor further substitution at the meta- position. Those groups are known to the person skilled in the art. Substituents exhibiting a +1 or +M effect direct to the ortho- and/or para-position with respect to themselves. Substituents exhibiting a -I or -M effect direct to the meto-position. As known to the person skilled in the art, an M effect of a substituent is in principle more important than an I effect. This means that a +M effect can overrule a small -I effect.

According to the present invention, it was found that the compound of formula (I) does not necessarily need any other substituent than the carbonate group to conduct the process of the present invention. Thus, in formula (I) m can be 0 for both R ¹ and R ² , i.e. there is no R ¹ and no R ² substituent at the respective aromatic rings. Also, in formula (1) m can be 0 for one of the substituents R ¹ or R ² . However, it was found that an additional R ¹ and/or R ² substituent at the aromatic ring can be beneficial for the reaction, preferably with respect to selectivity and/or reactivity. Therefore, each m in formula (I) and (III), respectively, independently is 0 to 4, preferably 0 to 3, more preferably 0 or 1, more preferably 1 or 2, more preferably 2 or 3, most preferably 0, most preferably 1, most preferably 2, most preferably 3, most preferably 4. The person skilled in the art knows that steric effects need to be considered, too, because a bulky substituent at the aromatic ring might affect the reaction and thus the resulting product. Accordingly, by choosing the R ¹ and/or R ² substituent(s) of the aromatic rings, the person skilled in the art is able to tailor the structure of the resulting polycarbonate.

It was found that the process according to the present invention can be used to obtain a regular polymer backbone having a linking group (-ClTRtlT-) between two linked aromatic moieties which is either in ortho-, meta- or para-position with respect to the carbonate group. According to the present invention, ortho, meta or para always refer to the position at the aromatic ring with respect to the mandatory carbonate group at the same ring, if not stated otherwise. The existing carbonate group has a small +M effect, directing an electrophile to the para-position with respect to the carbonate group. Without any additional R ¹ and/or R ² substituent at the aromatic rings (m = 0 for R ¹ and R ² ), mainly a polymer having para-linkages is obtained. Nevertheless, also other linkages are observed. However, in a preferred embodiment of the invention it was found that by having at least one R ¹ and/or R ² substituent at the aromatic ring, the para-directing effect of the carbonate group can be overruled by the described at least one R ¹ and/or R ² substituent, leading to a selective reaction, wherein a regular polymer can be obtained which has an ortho- or mc/a-linkagc with respect to the carbonate group. Especially, if at least one R ¹ and/or R ² substituent is present which has a para-directing effect (i.e. the at least one R ¹ and/or R ² substituent is capable of directing an electrophile to a position at the aromatic ring which is in para-position with respect to the at least one R ¹ and/or R ² substituent, respectively) and this at least one R ¹ and/or R ² substituent is in ort/zo-position with respect to the carbonate group substituting the same aromatic ring, a mc/a-linkagc with respect to the carbonate group is obtained. Thus, a selective coupling takes place wherein a polycarbonate is obtained which comprises essentially mc/a-linkagcs. If, in turn, at least one para-directing R ¹ and/or R ² substituent is present which is in mc/a-position with respect to the carbonate group substituting the same aromatic ring, an 0/7/70-linkagc and para-linkage with respect to the carbonate group is obtained. It is to be noted that a "para- directing” R ¹ and/or R ² substituent is generally to be understood as ortho- and para- directing substituent (in contrast to substituent that solely directs to a mc/a-position). The skilled person knows that a substituent may either be ortho-/para- directing or me/ -di reeling. Transferred to the present case, the “para-directing” R ¹ and/or R ² substituent principally directs in para- and o/7/70-position. In case that such a “para-directing” R ¹ and/or R ² substituent (which is generally ortho- and para-directing) is present in o/7/70-position with respect to the carbonate group (substituting the same aromatic ring), sterical hindrance leads to a fully para-selective substitution (leading to meta-X inkages with respect to the carbonate moiety). In this case no o/7/70-substitution is observed. However, in case that the “para-directing” R ¹ and/or R ² substituent (which is generally para- and 0/7/70-dirccting) is present in mc/a-position with respect to the carbonate group (substituting the same aromatic ring), less sterical hindrance occurs and both ortho- and para-substitution can be observed (leading to ortho- and para- linkages with respect to the carbonate moiety). Examples for such “para-directing” substituents are alkoxy groups.

The at least one R ¹ and/or R ² substituent can also be positioned in para-position with respect to the carbonate group at the same aromatic ring. The person skilled in the art knows how the directing effect of the additional R ¹ and/or R ² substituent(s) and their position at the aromatic ring with respect to the carbonate group substituting the same aromatic ring can affect the resulting linkages in the polycarbonate. The effect of a selective reaction is even more pronounced if two or three R ¹ and/or R ² substituents are present in addition to the carbonate group which are capable due to their chemical nature to direct the electrophile to the very same carbon atom. The person skilled in the art knows how more substituents affect the resulting polycarbonate.

Additionally, the compound of formula (Ila) or (lib) determines the structure of the linking group -CH2R ⁴ CH2- in formula (III). Accordingly, R ⁴ can have a structure of formula (IVa) or (IVb), respectively, depending on the structure of the compound of formula (Ila) or (lib) used in the reaction. The compound of formula (Ila) can be substituted by p = 0 to 4 R ³ substituents, preferably each independently representing an alkyl or alkoxy group having 1 to 6 carbon atoms. In a further embodiment, each R ³ substituent may be independently represented by a halogen atom (such as F, Cl, Br, I), a carbonyl group (e. g. with ketone or ester functionality), a trifluoromethyl group (-CF3) or any other suitable functional group. According to the present invention, it was found that the compound of formula (Ila) does not need any substituent to conduct the process of the present invention. Thus, in formula (Ila) p can be 0, i.e. there is no R ³ substituent. However, an R ³ substituent at the aromatic ring can be beneficial for the process. Therefore, p in formula (Ila) and thus, in formula (IVa) is 0 to 4, preferably 0 to 3, more preferably 0 to 2, more preferably 0 or 1, more preferably 1 to 4, more preferably 1 to 3, more preferably 1 or 2, still more preferably 3, still more preferably 4, most preferably 0, most preferably 1, most preferably 2. The person skilled in the art knows that steric effects need to be considered, too, because a bulky substituent at the aromatic ring might influence the resulting product. Accordingly, by choosing the R ³ substituent(s) of the compound of formula (Ila), the person skilled in the art is able to influence the structure of the resulting linking group in the repeating unit with the structure of formula (III) and therefore, the structure of the polycarbonate as a whole.

The reaction is even more complex, because the compound of formula (Ila) can have q = 1 to 4 benzenes and thus, be a benzene (when q = 1), a biphenyl (when q = 2), a terphenyl (when q = 3) or a quaterphenyl (when q = 4). If a compound of formula (lib) is used instead of a compound of formula (Ila), the reaction is similarly complex because the compound of formula (lib) comprises condensed benzenes and r can be 1 to 3. Consequently, the compound of formula (lib) can be a naphthalene (when r = 1), an anthracene (when r = 2), or a tetracene (when r = 3). Accordingly, by choosing a proper compound of formula (Ila) or (lib), the person skilled in the art is able to tailor the structure of the resulting linking group in the repeating unit with the structure of formula (II) and therefore, the structure of the polycarbonate as a whole.

“Alkyl” in the context of the invention, for example and if not mentioned differently, refers to a linear or branched hydrocarbon which is saturated and therefore, it comprises only single bonds between adjacent carbon atoms. Preferably, for steric reasons alkyl groups according to the present invention have 1 to 6 carbon atoms and thus, comprise methyl, ethyl, w-propyl. isopropyl, w-butyl. scc-butyl. / -but l. w-pcntyl. 1 -methylbutyl, 2-methylbutyl, 3- methylbutyl, neopentyl, 1 -ethylpropyl, cyclohexyl, cyclopentyl, w-hcx l. 1,1 -dimethylpropyl,

1.2-dimethylpropyl, 1,2-dimethylpropyl, 1 -methylpentyl, 2-methylpentyl, 3 -methylpentyl, 4- methylpentyl, 1,1 -dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl,

2.3-dimethylbutyl, 3, 3 -dimethylbutyl, I -ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2- trimethylpropyl, 1 -ethyl- 1 -methylpropyl, 1 -ethyl -2 -methylpropyl or 1 -ethyl -2 -methylpropyl. These structures can be limited in choice, in case the invention defines the carbon atoms of an alkyl group in a different manner.

“Alkoxy” in the context of the invention, for example and if not mentioned differently, refers to a linear or branched alkyl group singularly bonded to oxygen (-OR). Preferably, alkoxy groups according to the present invention have 1 to 6 carbon atoms and thus, comprise methoxy, ethoxy, w-propoxy. isopropoxy, w-butoxy. scc-butoxy. /ert-butoxy, w-pcntoxy. 1- methylbutoxy, 2-methylbutoxy, 3 -methylbutoxy, neopentoxy, 1 -ethylpropoxy, cyclohexoxy, cyclopentoxy, w-hcxoxy. 1,1 -dimethylpropoxy, 1,2-dimethylpropoxy, 1,2-dimethylpropoxy, 1 -methylpentoxy, 2-methylpentoxy, 3 -methylpentoxy, 4-methylpentoxy, 1,1 -dimethylbutoxy, 1,2-dimethylbutoxy, 1,3 -dimethylbutoxy, 2,2-dimethylbutoxy, 2,3 -dimethylbutoxy, 3,3- dimethylbutoxy, 1 -ethylbutoxy, 2-ethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2- trimethylpropoxy, 1 -ethyl- 1 -methylpropoxy, 1 -ethyl -2 -methylpropoxy or 1 -ethyl -2- methylpropoxy. These structures can be limited in choice, in case the invention defines the carbon atoms of an alkoxy group in a different manner.

The above enumerations should be understood by way of example and not as a limitation.

A “halogen atom” in the context of the invention, if not mentioned differently, refers to fluorine (F), chlorine (Cl), bromine (Br), iodine (I). Preferably, a halogen atom is F, Cl, Br or I, more preferably it is Cl or Br, most preferably it is Cl.

Moreover, formula (III) recites “n” as number of repeating units. Preferably, n is 6 to 60, more preferably it is 10 to 55, even more preferably it is 20 to 50, still more preferably it is 25 to 45 and most preferably it is 30 to 40. Depending on the length of the yielded polycarbonate (so depending on the number n of repeating units), physical, chemical and mechanical properties of the polycarbonate may vary. Depending on the number of repeating units, microscopic and/or macroscopic structures of the polycarbonate may change as well. By the preferred number n of repeating units, an optimum balance between processability and mechanical properties of the yielded polycarbonate can be established. Consequently, the skilled person may choose the number of n to tailor dedicated properties of the polycarbonate.

According to the present invention, it was found that a Lewis acid is required for the reaction. The Lewis acid acts as a catalyst. The term “Lewis acid” is known to the person skilled in the art. For the reaction to work, the Lewis acid catalyst can be added in a stoichiometric or substoichiometric amount. Whether the Lewis acid catalyst can be used in a stoichiometric or substoichiometric amount depends on the Lewis acid used. For example, the use of 1 molar equivalent of the Lewis acid TiCL experimentally worked well in a model Friedel-Crafts alkylation between diphenyl carbonate and l,4-bis(chloromethyl)benzene. It is well known that carbonates are acid sensitive. Consequently, carrying out the process according to the invention with a stoichiometric amount of Lewis acid is not a straightforward approach, much more the inventors showed that despite the strong acid sensitivity of carbonates it was possible to carry out the process in presence of a Lewis acid in a stoichiometric amount. For the Lewis acid FcBn. in contrast, an amount of 0.1 molar equivalent, and thus a substoichiometric amount, was sufficient in this model reaction. The person skilled in the art will be able to find out the optimal amount for other Lewis acid catalysts. Although the reaction described can be carried out without any R ¹ and R ² substituent (m = 0), in a preferred embodiment of the invention at least one R ¹ substituent and/or at least one R ² substituent is present, preferably with a +1 and/or +M effect, being capable of directing an electrophile to a position at the aromatic ring which is in ortho- or para-position, preferably para-position, with respect to the at least one R ¹ and/or R ² substituent, respectively. Thus, in formula (I) m preferably is at least 1 for R ¹ and/or R ² . The at least one R ¹ and/or R ² substituent typically increases the reactivity of the aromatic ring. This preferably means that the reactivity towards the electrophilic aromatic substitution is increased in comparison to a substrate that only comprises a carbonate group (and each m is 0). It has been found that the at least one R ¹ and/or R ² substituent typically overrules the para-directing effect of the carbonate group which exhibits a small +M effect only. As a result, a regular polymer can be found which has an ortho- or mc/a-linkagc. depending on the position of the at least one R ¹ and/or R ² substituent at the aromatic ring. An example for R ¹ and/or R ² substituents which exhibit a +M effect and are able to direct an electrophile to a position at the aromatic ring which is in ortho- or para- position, preferably para-position, with respect to themselves are alkoxy groups. Since alkoxy groups exhibit a bigger +M effect than a carbonate group, they are able to overrule the para- directing effect of the carbonate group. Again, referring to the embodiment of m = 0, the compound with the structure of formula (1) is diphenyl carbonate.

Furthermore, it is preferred that at least one R ¹ substituent and/or at least one R ² substituent independently is in ortho-, meta- or para-position with respect to the carbonate group substituting the same aromatic ring. Preferably, at least one R ¹ and at least one R ² substituent are in ort/zo-position. The R ¹ and/or R ² substituent of this preferred embodiment can but do not have be identical with the at least one R ¹ and/or at least one R ² substituent being capable of directing an electrophile to a position at the aromatic ring which is in ortho- or para- position, preferably para-position, with respect to the at least one R ¹ and/or R ² substituent, respectively.

Moreover, preferably a process is provided, wherein each R ¹ substituent and each R ² substituent independently represents an alkyl group or an alkoxy group, more preferably an alkyl or alkoxy group having 1 to 6 carbon atoms. Alkyl groups exhibit a +1 effect, alkoxy groups exhibit a +M effect. A substituent which has 1 to 6 carbon atoms is preferred for steric reasons. Thus, preferably each R ¹ substituent and each R ² substituent independently represents methyl, ethyl, w-propyl. isopropyl, w-butyl. scc-butyl. tert-butyl, w-pcntyl. 1 -methylbutyl, 2- methylbutyl, 3 -methylbutyl, neopentyl, 1 -ethylpropyl, cyclohexyl, cyclopentyl, w-hcxyl. 1,1- dimethylpropyl, 1,2-dimethylpropyl, 1,2-dimethylpropyl, 1 -methylpentyl, 2-methylpentyl, 3- methylpentyl, 4-methylpentyl, 1,1 -dimethylbutyl, 1,2-dimethylbutyl, 1,3 -dimethylbutyl, 2,2- dimethylbutyl, 2,3-dimethylbutyl, 3, 3 -dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2- trimethylpropyl, 1,2,2-trimethylpropyl, 1 -ethyl- 1 -methylpropyl, 1 -ethyl -2 -methylpropyl, 1- ethyl-2 -methylpropyl, methoxy, ethoxy, w-propoxy. isopropoxy, w-butoxy. scc-butoxy. tertbutoxy, M-pentoxy, 1 -methylbutoxy, 2-methylbutoxy, 3 -methylbutoxy, neopentoxy, 1- ethylpropoxy, cyclohexoxy, cyclopentoxy, w-hcxoxy. 1,1 -dimethylpropoxy, 1,2- dimethylpropoxy, 1,2-dimethylpropoxy, 1 -methylpentoxy, 2-methylpentoxy, 3- methylpentoxy, 4-methylpentoxy, 1,1 -dimethylbutoxy, 1,2-dimethylbutoxy, 1,3- dimethylbutoxy, 2,2-dimethylbutoxy, 2,3 -dimethylbutoxy, 3, 3 -dimethylbutoxy, 1- ethylbutoxy, 2-ethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1 -ethyl- 1- methylpropoxy, 1 -ethyl -2 -methylpropoxy or 1 -ethyl -2 -methylpropoxy.

Overall, the person skilled in the art knows how the choice of any compound of formula (I) affects the resulting polycarbonate comprising a repeating unit with a structure of formula (III). Thus, the skilled person is able to predict the influences of the structure of the compound of formula (I). Preferably, the compound of formula (I) is selected from diphenyl carbonate (m = 0), guaiacol carbonate, bis(3 -methoxyphenyl) carbonate or bis(2-(tert-butyl)-4- methoxyphenyl) carbonate. For guaiacol carbonate, m is 1 for R ¹ as well as for R ² and both the R ¹ and R ² substituent are a methoxy group, each located in ort/zo-position with respect to the carbonate group substituting the same aromatic ring. For bis(3 -methoxyphenyl) carbonate, m is 1 for R ¹ as well as for R ² and both the R ¹ and R ² substituent are a methoxy group, each located in meto-position with respect to the carbonate group substituting the same aromatic ring. For bis(2-(tert-butyl)-4-methoxyphenyl) carbonate, m is 2 for R ¹ as well as for R ² , wherein one R ¹ and one R ² substituent are a methoxy group, each located in para-position with respect to the carbonate group substituting the same aromatic ring and one R ¹ and one R ² substituent are a tert-butyl group, each located in ort/zo-position with respect to the carbonate group substituting the same aromatic ring. All of these exemplary diaryl carbonates which are substituted with different R ¹ and R ² substituents exhibiting a +M effect (here: methoxy) or a +1 effect (here: tert-butyl) were successfully coupled with a primary alkyl halide, in particular l,4-bis(chloromethyl)benzene, in model reactions.

The yielded polycarbonate comprises a repeating unit with a structure of formula (III), wherein R ⁴ preferably comprises a structure of formula (IVa). More preferably, the yielded polycarbonate comprises a repeating unit with a structure of formula (III), wherein R ⁴ comprises a structure of formula (IVb). The person skilled in the art knows how the choice of any compound of formula (Ila) or (lib) affects the resulting polycarbonate comprising a repeating unit with a structure of formula (III), wherein R ⁴ comprises a structure of formula (IVa) or (IVb), respectively. Thus, he or she is able to predict the influences of the structure of the compound of formula (Ila) or (lib) .

Therefore, in a preferred embodiment of the present invention a process is provided, wherein the compound of formula (Ila) is a bis(chloromethyl)benzene, bis(chloromethyl)-biphenyl, bis(chloromethyl)-terphenyl or bis(chloromethyl)-quaterphenyl. Thus, both X in formula (Ila) preferably represent Cl due to easy availability of the compounds. More preferably, the compound of formula (Ila) is l,3-bis(chloromethyl)benzene (also known as a.a'-dichloro-m- xylene), I,4-bis(chloromethyl)benzene or 4, 4 ’-bis(chloromethyl)- 1,1’ -biphenyl, still more preferably I,3-bis(chloromethyl)benzene or I,4-bis(chloromethyl)benzene. The named compounds, especially the more preferred, could successfully serve as a coupling partner for diaryl carbonates in model reactions. In these model reactions, reaction products with an alkene end group were observed as side products in addition to the desired reaction products. Very likely, these side products resulted from HC1 elimination of the chloromethylated intermediate. However, most preferably the compound of formula (Ila) is 1,3- bis(chloromethyl)benzene, as using this compound could prevent the described side reaction and consequently, longer reaction products can be obtained.

In another preferred embodiment of the present invention, a process is provided, wherein the compound of formula (lib) is a bis(chloromethyl)naphthalene, bis(chloromethyl)anthracene or bis(chloromethyl)tetracene. Thus, both X in formula (Ila) preferably represent Cl due to easy availability of the compounds. More preferably, the compound of formula (lib) is 1,8- bis(chloromethyl)naphthalene. Also, this compound could successfully serve as a coupling partner for diaryl carbonates in model reactions.

Preferably, either a halogenated solvent or no solvent at all is used for the described reaction. This means that the reaction can be performed neat or in the presence of a halogenated solvent. In case a solvent is used for the reaction, it is preferably selected from dichloromethane or dichloroethane, more preferably, dichloromethane.

According to a preferred embodiment of present invention, the Lewis acid catalyst used for the reaction is selected from a group consisting of Al CL. TiCL or FcBn. All of the named Lewis acids were capable in promoting coupling between the compound of formula (I) and the compound of formula (Ila) or (lib). Among these, FcBn is preferred based on price and practical reasons. Furthermore, in a preferred embodiment of the present invention the Lewis acid catalyst used for the reaction is added in a substoichiometric amount with respect to the compound of formula (Ila) or (lib), respectively. The use of a substoichiometric amount of the Lewis acid catalyst is preferred over the use of a stoichiometric amount as acids like the Lewis acid catalyst are able to degrade the carbonate group. Preferably, the Lewis acid catalyst used for the reaction is added in an amount of 0.05 to 0.50 molar equivalents, more preferably 0.10 to 0.20 molar equivalents, with respect to the compound of formula (Ila) or (lib), respectively. The described amounts of Lewis acid catalyst were sufficient for a good yield of the desired polycarbonate, specifically in the case of FcBn. Therefore, the use of FcBn in a substoichiometric amount is most preferred.

According to the present invention, the process comprises a reaction, wherein a compound of formula (I) is reacted with a compound of formula (Ila) or (lib) . The compound of formula (I) is a diaryl carbonate, the compound of formula (Ila) or (lib) is a primary alkyl halide, preferably a primary alkyl chloride. Moreover, the compound of formula (I) is preferably added in an amount of 1.0 to 4.0 molar equivalents, preferably 1.0 molar equivalent, with respect to the compound of formula (Ila) or (lib), respectively. It was found that having 1.0 to 4.0 equivalents, preferably 1.0 equivalent, of the compound of formula (I) with respect to the compound of formula (Ila) or (lib), respectively, is beneficial for obtaining a good yield.

Preferably, the reaction is performed at temperatures below room temperature, more preferably below 10 °C and most preferably below 5 °C. This is preferably followed by temperatures above room temperature. The person skilled in the art is able to adapt the reaction temperature and the reaction time in order to optimize yields.

Additionally, it is preferred that the reaction is carried out under an inert atmosphere so that no oxygen or water can hamper the desired reaction and the yield of the desired polycarbonate. Water may even destroy the activity of the employed Lewis acid.

In another aspect of the present invention, polycarbonates obtainable by the process of the present invention are provided. Those polycarbonates exhibit improved properties, in particular with respect to mechanical and/or optical properties, heat resistance and/or weatherability.

The definitions/explanations given above in context of the described process can directly be transferred to the polycarbonate described before and after this passage. All mandatory or preferred/advantageous features described in relation to the process according to the invention may form mandatory or preferred/advantageous features of the polycarbonate according to the invention as well.

As mentioned before, the objects of the present invention are (at least partially) solved by a polycarbonate. In particular, the invention relates to a polycarbonate comprising a repeating unit with a structure of formula (III) wherein the repeating unit with the structure of formula (III) comprises two aromatic rings, a carbonate group -OC(=O)O- and a linking group -CH2R ⁴ CH2-, wherein one of the two aromatic rings is substituted with the carbonate group, the two aromatic rings are linked via the linking group and R ⁴ comprises a structure given in {} in formula (IVa) or (IVb), respectively, and wherein each R ¹ and R ² independently represents an R ¹ substituent and an R ² substituent, respectively, being capable of activating the aromatic ring which it substitutes by a mesomeric effect and/or an inductive effect, each m independently is 0 to 4, preferably 0 to 3, each R ³ independently represents an R ³ substituent, preferably independently representing an alkyl or alkoxy group having 1 to 6 carbon atoms, p is 0 to 4, q is 1 to 4, r is 1 to 3 and n is the number of repeating units, preferably 6 to 60.

With respect to the polycarbonate, preferably, the linking group in each repeating unit independently is either in meta- or para-position with respect to the carbonate group.

With respect to the polycarbonate, preferably, at least one R ¹ substituent and/or at least one R ² substituent independently is in ortho-, meta- or para-position with respect to the carbonate group substituting the same aromatic ring.

With respect to the polycarbonate, preferably, each R ¹ substituent and each R ² substituent independently represents an alkyl group or an alkoxy group, preferably an alkyl or alkoxy group having 1 to 6 carbon atoms, more preferably methyl, ethyl, w-propyl. isopropyl, w-butyl. scc-butyl. /ert-butyl, w-pcntyl. 1 -methylbutyl, 2-methylbutyl, 3 -methylbutyl, neopentyl, 1- ethylpropyl, cyclohexyl, cyclopentyl, w-hcx l. 1,1 -dimethylpropyl, 1,2-dimethylpropyl, 1,2- dimethylpropyl, 1 -methylpentyl, 2-methylpentyl, 3 -methylpentyl, 4-methylpentyl, 1,1- dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3 -dimethylbutyl, 3, 3 -dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1- ethyl-1 -methylpropyl, 1 -ethyl -2 -methylpropyl, 1 -ethyl -2 -methylpropyl, methoxy, ethoxy, n- propoxy, isopropoxy, w-butoxy. scc-butoxy. /ert-butoxy, w-pcntoxy. 1 -methylbutoxy, 2- methylbutoxy, 3 -methylbutoxy, neopentoxy, 1 -ethylpropoxy, cyclohexoxy, cyclopentoxy, n- hexoxy, 1,1 -dimethylpropoxy, 1,2-dimethylpropoxy, 1,2-dimethylpropoxy, 1 -methylpentoxy, 2-methylpentoxy, 3 -methylpentoxy, 4-methylpentoxy, 1,1 -dimethylbutoxy, 1,2- dimethylbutoxy, 1,3 -dimethylbutoxy, 2,2-dimethylbutoxy, 2,3 -dimethylbutoxy, 3,3- dimethylbutoxy, 1 -ethylbutoxy, 2-ethylbutoxy, 1,1,2-trimethylpropoxy, 1,2,2- trimethylpropoxy, 1 -ethyl- 1 -methylpropoxy, 1 -ethyl -2 -methylpropoxy or 1 -ethyl -2- methylpropoxy.

A polycarbonate comprising the above features exhibits improved properties, in particular with respect to mechanical and/or optical properties, heat resistance and/or weatherability.

Brief description of the figures Figure 1. Nano-electrospray mass spectrum in DMSO of inventive example 6.

Figure 2. Nano-electrospray mass spectrum in DMSO of inventive example 8.

Figure 3. Nano-electrospray mass spectrum in DMSO of inventive example 9.

Examples

The following examples are used to describe the invention. It is to be noted that sometimes reactions are studied that do not represent polymerizations, but rather study the coupling (linking) of one aromatic moiety with another aromatic moiety (via a linking group), wherein at least one of those moieties comprises a carbonate group. However, based on those examples, the person skilled in the art can easily conclude that and how a polymerization reaction as such can be performed. Also, certain examples (experiments) did not lead to successful reactions. These examples are indicated as “comparative example”.

Materials used in the examples All solvents and commercially available reagents were used as received.

A) Commercially available chemicals

B) Non-commercial chemicals

General procedure 1:

A round-botomed flask equipped with a stir bar was charged with the substituted phenol (1.0 equiv), triethylamine (1.2 equiv) and dichloromethane (25 mL). The mixture was cooled to 0 °C in an ice-water bath. Subsequently, methyl chloroformate (1.2 equiv) was added dropwise over a period of 10 minutes. The mixture was stirred at room temperature for the indicated time. The precipitate was filtered off over a paper filter. The filtrate was extracted with HC1 (1 M, 1 x 30 mL), NaOH (0.5 M, 30 mL) and with saturated aqueous NaCl solution (1 x 30 mL). The organic layer was dried over anhydrous MgSO4, filtered and concentrated in vacuo. The product was purified as indicated.

General procedure 2:

An oven-dried round-botomed flask equipped with a stir bar was charged with the substituted phenol, triethylamine and dichloromethane (20 mL) under argon atmosphere. The mixture was cooled to 0 °C in an ice-water bath and stirred for 10 minutes. Subsequently, triphosgene dissolved in DCM (4 mL) was added dropwise over a period of 10 minutes. The mixture was stirred at room temperature for the indicated time. The filtrate was extracted with HC1 (1 M, 1 x 30 mL), NaOH (0.5 M, 30 mL) and with saturated aqueous NaCl solution (1 x 30 mL). The water layer was extracted with DCM (2 x 30 mL). The combined organic layers were dried over anhydrous MgSO ₄ , filtered and concentrated in vacuo. The product was purified as indicated.

2-Methoxyphenyl methyl carbonate

General procedure 1 was applied using 2-methoxyphenol (1.241 g, 10.0 mmol), NEt ₃ (1.7 mL, 12.0 mmol) and methyl chloroformate (980 pL, 9.6 mmol) for 2 h. The product was obtained in 80% (1.455 g) yield.

White solid, m.p.: 31-32 °C, 'H NMR (400 MHz, CDC1 ₃ ): 5 7.28-7.24 (m, 1H), 7.19 (dd, J = 7.9, 1.6 Hz, 1H), 7.15 (dd, J = 8.3, 1.3 Hz, 1H), 6.97 (td, J= 7.7, 1.5 Hz, 1H), 3.81 (s, 3H), 3.79 (s, 3H) ppm. ¹³ C NMR (101 MHz, CDC1 ₃ ): 5 153.3 (C), 150.9 (C), 139.5 (C), 127.3 (CH), 122.4 (CH), 120.6 (CH), 113.0 (CH), 55.8 (CH ₃ ), 55.5 (CH ₃ ) ppm. HRMS for C ₉ HnO ₄ [M+H] ⁺ calcd. 183.0652, found 183.0653.

3-Methoxyphenyl methyl carbonate

General procedure 1 was applied using 3 -methoxyphenol (880 pL, 8.0 mmol), NEt ₃ (1.4 mL, 9.6 mmol), 4-dimethylaminopyridine (49 mg, 5 mol%) and methyl chloroformate (930 pL, 9.6 mmol). The mixture was stirred for 3 h. The product was obtained in 67% (970 mg) yield.

Yellow oil, ’H NMR (400 MHz, CDC1 ₃ ): 5 7.28 (t, J= 8.2 Hz, 1H), 6.81-6.77 (m, 2H), 6.74 (t, J= 2.3 Hz, 1H), 3.90 (s, 3H), 3.80 (s, 3H) ppm. ¹³ C NMR (101 MHz, CDC1 ₃ ): 5 160.7 (C), 154.3 (C), 152.2 (C), 130.0 (CH), 113.3 (CH), 112.1 (CH), 107.1 (CH), 55.6 (CH ₃ ), 55.5 (CH ₃ ) ppm. HRMS (ESI) for C ₉ HnO ₄ [M+H] ⁺ calcd. 183.0652, found 183.0653.

2-(/er/-Butyl)-4-methoxyphenyl methyl carbonate

General procedure 1 was applied using 4-hydroxy-3-tert-butylanisole (1.802 g, 10.0 mmol), NEt ₃ (1.7 mL, 12.0 mmol) and methyl chloroformate (1.2 mL, 12.0 mmol). The mixture was stirred overnight. The product was purified by an automated flash chromatography system using a heptane/EtOAc gradient (from 100% heptane to 5% EtOAc in 40 min, 25 mL/min). The product was obtained in 47% (1.115 g) yield.

Colorless oil, ’H NMR (400 MHz, CDC1 ₃ ): 5 7.01 (d, J = 8.8 Hz, 1H), 6.92 (d, J = 3.0 Hz, 1H), 6.74 (dd, J = 8.8, 3.0 Hz, 1H), 3.91 (s, 3H), 3.80 (s, 3H), 1.35 (s, 9H) ppm. ¹³ C NMR (101 MHz, CDC1 ₃ ): 5 157.3 (C), 155.0 (C), 143.7 (C), 142.6 (C), 124.2 (CH), 113.9 (CH), 110.9 (CH), 55.7 (CH ₃ ), 55.5 (CH ₃ ), 34.8 (C), 30.2 (CH ₃ ) ppm. HRMS (ESI) for CI ₃ HI ₈ O ₄ K [M+K] ⁺ calcd. 277.0837, found 277.0828.

Bis(3-methoxyphenyl) carbonate

General procedure 2 was applied using 3 -methoxyphenol (1.3 mL, 12.0 mmol), NEt ₃ (2.1 mL, 15.0 mmol) and triphosgene (593 mg, 2.0 mmol). The mixture was stirred for 5 h. The product was obtained in 83% (1.360 g) yield without further purification.

Yellow oil, ’H NMR (400 MHz, CDC1 ₃ ): 8 7.32-7.28 (m, 2H), 6.89-6.81 (m, 6H), 3.81 (s, 6H) ppm. ¹³ C NMR (101 MHZ, CDC1 ₃ ): 8 160.7 (C), 152.1 (C), 152.0 (C), 130.1 (CH), 113.2 (CH), 112.4 (CH), 107.1 (CH), 55.7 (CH ₃ ) ppm. HRMS (ESI) for C15H14O5K [M+K] ⁺ calcd. 313.0473, found 313.0473.

Bis(2-(ter/-butyl)-4-methoxyphenyl) carbonate

General procedure 2 was applied using 4-hydroxy-3-tert-butylanisole (1.802 g, 10.0 mmol), NEt ₃ (1.6 mL, 11.7 mmol) and triphosgene (593 mg, 2.0 mmol). The mixture was stirred overnight. The product was purified by an automated flash chromatography system using a heptane/EtOAc gradient (from 100% heptane to 30% EtOAc in 35 min, 25 mL/min) and obtained in 57% (1.097 g) yield.

White solid, m.p.: 123-125 °C, ’H NMR (400 MHz, CDC1 ₃ ): 8 7.10 (d, J= 8.8 Hz, 2H), 6.96 (d, J= 2.9 Hz, 2H), 6.76 (d, J= 8.8, 2.9 Hz, 2H), 3.81 (s, 6H), 1.45 (s, 18H) ppm. ¹³ C NMR (101 MHz, CDC1 ₃ ): 8 157.3 (C), 153.2 (C), 143.7 (C), 142.5 (C), 124.1 (CH), 113.9 (CH), 110.9 (CH), 55.6 (CH ₃ ), 34.9 (C), 30.3 (CH ₃ ) ppm. HRMS (ESI) for C ₂₃ H ₃₀ O ₅ K [M+K] ⁺ calcd. 425.1725, found 425.1721.

General considerations and methods

Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker Avance III 400 (101 MHz for ¹³ C) Fourier Transform NMR spectrometer at 300 K (unless stated otherwise) using the non- or partly deuterated solvent as internal standard (’H: 8 = 7.26 ppm, ¹³ C: 8 = 77.16 ppm for CDC1 ₃ ). Chemical shifts (8) are given in ppm and coupling constants (J) are reported in Hertz (Hz). Multiplicities are described as s (singlet), d (doublet), t (triplet), q (quartet), br s (broad singlet) and m (multiplet) or combinations thereof. High resolution mass spectrometry (HRMS) samples were prepared by dissolving 0.1-5 mg of the compound in CH3CN/H2O and further dilution to a concentration of 10' ⁵ - 10' ⁶ M. Formic acid (0.1%) was added prior to injection. 10 pL of each sample was injected using the CapLC system (Waters, Manchester, UK) and electrosprayed using a standard electrospray source. Samples were injected with an interval of three minutes. Positive ion mode accurate mass spectra were acquired using a Q-TOF II instrument (Waters, Manchester, UK). The MS was calibrated prior to use with a 0.1% H3PO4 solution. The spectra were lock mass corrected using the known mass of the nearest H3PO4 cluster or a known background ion. Analytes were detected as protonated, sodium or as potassium adduct. All measured masses are within a difference of 5 ppm compared to the calculated mass unless specified otherwise.

Nano-electrospray mass analysis samples were prepared by dissolving 4 mg of the obtained solid in 1 mU of DMSO. This mixture was diluted by taking 10 pL and dissolving it in 990 pU DMSO and taking 100 pU from this solution and adding 900 pU of DMSO. The measurement was done by placing 3 pU of the obtained sample in a in a gold-coated borosilicate needle (inhouse made). The sample was then sprayed from this needle using a nano-electrospray source (Waters). Positive ion mode accurate mass spectra were acquired using a Q-TOF II instrument (Waters, Manchester, UK).

Flash chromatography was performed either manually on SiO2 (particle size 40-63 pm, pore diameter 60 A) using the indicated eluent and visualized by UV detection (254 nm) or on an automated chromatography system (Biotage® One Isolera Automatic Flash) with on-line UV detection using Grace® Silica flash Cartridges.

Thin layer chromatography (TUC) was performed using TUC plates from Merck (SiO2, Kieselgel 60 F254 neutral, on aluminium with fluorescence indicator) and compounds were visualized by UV detection (254 nm) unless mentioned otherwise.

Melting points were recorded on a Btichi M-565 melting point apparatus and are uncorrected.

Size exclusion chromatography was performed using a PSS SECcurity System; polycarbonate calibration (according to 2301-0257502-09D method of company Currenta GmbH & Co. OHG, Eeverkusen), dichloromethane as eluent, column 1 (PE-PC5) with a concentration of 2 g/E, a flow rate of 1.0 mL/min, at a temperature of 30 °C using UV and/or RI detection. Reaction optimization

Screening of Lewis acids

Synthetic procedure:

An oven-dried pressure vial of 10 mL equipped with a stir bar was charged with a Lewis acid as indicated in Table 1 under inert atmosphere. Subsequently, diphenyl carbonate (1.0 mmol, 1.0 equiv) dissolved in dichloromethane (1 mL, dry) was added. The vial was cooled to 0 °C, before a,a’-dichloro- -xylene dissolved in dichloromethane (1 mL, dry) was added dropwise over 15 minutes at this temperature. The resulting mixture was stirred for 2 h at 0 °C, and subsequently for 2 h at 30 °C, before it was quenched by the addition of methanol (10 mL). The formed precipitate was fdtered off over a paper fdter and dried in vacuo. In case no precipitate was formed (example 5), MeOH was evaporated and the crude product was partitioned between H2O (20 mL) and EtOAc (20 mL). The layers were separated and the organic layer was dried over anhydrous MgSCL, fdtered and concentrated in vacuo. A known amount of ethylene carbonate was added as internal standard and everything dissolved in CDCI3 in order to determine the amount of recovered diphenyl carbonate (DPC).

Table 1.

^[a] Sample does not dissolve completely in DCM, filtering of the solution was required. N.d. = not possible to determine via GPC as the sample did not dissolve.

Conclusion: The reaction of diphenyl carbonate with a,a’-dichloro- -xylene was studied as a model oligomerization and FcBn. AICI3 and TiCL were evaluated as a Lewis acid in stoichiometric amount (examples 1, 3 and 4). Pleasingly, no activation of the aromatic moiety of the carbonate was required and a range of oligocarbonates was obtained. With FcBn and AICI3 a precipitate was already formed during the reaction, which is probably due to a very high molecular weight of the formed oligomer. In both cases no diphenyl carbonate was recovered, but unfortunately we were unable to analyze these samples with GPC due to solubility issues. To our surprise, a catalytic amount of FcBn was sufficient to promote the Friedel-Crafts alkylation between diphenyl carbonate and a,a’-dichloro- -xylene delivering a range of oligomers with a number average molecular weight of M _n = 1917 g/mol and a weight average molecular weight of M _w = 306100 g/mol (example 2). The Lewis acid is crucial for the transformation as a comparative control reaction in the absence of a Lewis acid revealed full recovery of diphenyl carbonate (example 5).

Evaluation of the carbonate scope

A) Unsymmetrical methyl carbonates

General procedure 3:

An oven-dried pressure vial of 10 mL equipped with a stir bar was charged with FcBn under inert atmosphere. Subsequently, the carbonate dissolved in dichloromethane (1 mL, dry) was added. The vial was cooled to 0 °C, before the dihalo derivative dissolved in dichloromethane (1 mL, dry) was added dropwise at this temperature. The resulting mixture was then stirred for 2 h at 0 °C and subsequently for the indicated time at 30 °C, before it was quenched by the addition of MeOH (10 mL). The precipitation was fdtered off over a paper fdter and dried in vacuo.

REFERENCE EXAMPLE 6 - Oligomerization of a,a’-dichloro-p-xylene with 2- methoxy-phenyl methyl carbonate

The general procedure 3 was applied using 2-methoxyphenyl methyl carbonate (182 mg, 1.0 mmol), a.a'-dichloro-p-xylcnc (88 mg, 0.5 mmol) and FcBn (30 mg, 0.1 mmol). The mixture was stirred for 17 h at 30 °C. A solid was obtained, where besides the desired biscarbonate also longer oligomers were observed via nano-mass electrospray analysis as a result of ortho- and para-coupling of 2-methoxyphenyl methyl carbonate (see Figure 1). The repeating unit (n) had a m/z value of 284.1, with analytes detected as sodium adduct from 489.1 (n = 1, biscarbonate) until 2194.6 (n = 7). REFERENCE EXAMPLE 7 - Oligomerization of a,a’-dichloro-p-xylene with methyl phenyl carbonate

The general procedure 3 was applied using methyl phenyl carbonate (304 mg, 2.0 mmol), a,a’- dichloro-p-xylene (175 mg, 1.0 mmol) and FcBn (59 mg, 0.2 mmol). The mixture was stirred for 17 h at 30 °C. A solid was obtained, where besides the desired biscarbonate also longer oligomers were observed via nano-mass electrospray analysis as a result of ortho- and para- coupling of methyl phenyl carbonate. The repeating unit (n) had a m/z value of 254.1, with analytes detected as sodium adduct from 429.1 (n = 1, biscarbonate) until 1445.4 (n = 5).

Conclusion: Two unsymmetrical methyl carbonates (2 -methoxyphenyl methyl carbonate and methyl phenyl carbonate) were examined as coupling partner for a,a’-dichloro-p-xylene according to the present invention. To our surprise, besides the desired biscarbonate also longer oligomers were observed as a result of both ortho- and para-coupling in both cases. Pleasingly, the existing carbonate group is already sufficient to direct the electrophile at the ortho- and para-position due to its inherent small +M effect.

B) Symmetrical carbonates

INVENTIVE EXAMPLE 8 - Oligomerization of a,a’-dichloro-p-xylene with diphenyl carbonate

The general procedure 3 was applied using diphenyl carbonate (214 mg, 1.0 mmol), a,a’- dichloro-p-xylene (175 mg, 1.0 mmol) and FcBn (30 mg, 0.1 mmol). The mixture was stirred for 2 h at 30 °C. A white solid was obtained, where the formation of oligomers was proven via nano-mass electrospray analysis (see Figure 2). The repeating unit (n) had a m/z value of 316.1, with the desired analytes detected as sodium adduct from 553.2 (n = 1, biscarbonate) until 2449.8 (n = 7). In addition, sodium adducts of analytes with an alkene end group (as a result of HC1 elimination) were also visible in the mass spectrum from 1287.5 (n = 3) until 2868.0 (n = 9). GPC analysis confirmed the formation of oligomers with a number average molecular weight of M _n = 1917 g/mol and a weight average molecular weight of M _w = 60458 g/mol.

INVENTIVE EXAMPLE 9 - Oligomerization of a,a’-dichloro-m-xylene with diphenyl carbonate

The general procedure 3 was applied using diphenyl carbonate (214 mg, 1.0 mmol), a,a’- dichloro-m-xylcnc (175 mg, 1.0 mmol) and FcBn (30 mg, 0.1 mmol). The mixture was stirred for 2 h at 30 °C. A white solid was obtained, where the formation of oligomers was proven via nano-mass electrospray analysis (see Figure 3). The repeating unit (n) had a m/z value of 316.1, with the desired analytes detected as sodium adduct from 553.2 (n = 1, biscarbonate) until 2133.7 (n = 6). In addition, small peaks of the sodium adducts from the ring-closed oligomers were also visible in the mass spectrum from 971.3 (n = 3) until 2235.8 (n = 7). Interestingly, no sodium adducts of the analytes with an alkene end group (as a result of HC1 elimination) were observed. GPC analysis confirmed the formation of oligomers with a number average molecular weight of M _n = 5787 g/mol and a weight average molecular weight of M _w = 306100 g/mol.

INVENTIVE EXAMPLE 10 - Oligomerization of a,a’-dichloro-p-xylene with guaiacol carbonate

The general procedure 3 was applied using guaiacol carbonate (137 mg, 0.5 mmol), a,a’- dichloro- -xylene (96 mg, 0.5 mmol) and FcBn (15 mg, 0.05 mmol). The mixture was stirred for 2 h at 0 °C, followed by 2 h at 30 °C. A solid was obtained, where the formation of oligomers was proven via nano-mass electrospray analysis. The repeating unit (n) had a m/z value of 376.1, with analytes detected as sodium adduct from 673.2 (n = 1, biscarbonate) until

2178.6 (n = 5). In addition, sodium adducts of the analytes with an alkene end group (as a result of HC1 elimination) were also visible in the mass spectrum from 775.3 (n = 1) until

2280.7 (n = 5). GPC analysis confirmed the formation of oligomers with a number average molecular weight of M _n = 465 g/mol and a weight average molecular weight of M _w = 844 g/mol.

INVENTIVE EXAMPLE 11 - Oligomerization of a,a’-dichloro-p-xylene with bis(3- methoxyphenyl) carbonate

The general procedure 3 was applied using bis(3 -methoxyphenyl) carbonate (137 mg, 0.5 mmol), a,a’-dichloro- -xylene (88 mg, 0.5 mmol) and FcBn (15 mg, 0.05 mmol). The mixture was stirred for 2 h at 0 °C, followed by 2 h at 30 °C. A white solid was obtained, where the formation of oligomers was proven via nano-mass electrospray analysis. The repeating unit (n) had a m/z value of 376.1, with analytes detected as sodium adduct from 674.2 (n = 1, biscarbonate) until 2930.0 (n = 7). In addition, sodium adducts of the analytes with an alkene end group (as a result of HC1 elimination) were also visible in the mass spectrum from 1151.4 (n = 3) until 3032.1 (n = 8). GPC analysis confirmed the formation of oligomers with a number average molecular weight of M _n = 1481 g/mol and a weight average molecular weight of M _w = 2834 g/mol.

INVENTIVE EXAMPLE 12 - Oligomerization of a,a’-dichloro-p-xylene with bis(2-(Ze/7- butyl)-4-methoxyphenyl) carbonate

The general procedure 3 was applied using bis(2-(/ert-butyl)-4-methoxy phenyl) carbonate (193 mg, 0.5 mmol), a,a’-dichloro- -xylene (88 mg, 0.5 mmol) and FcBn (15 mg, 0.05 mmol). The mixture was stirred for 2 h at 0 °C, followed by 2 h at 30 °C. A white solid was obtained, where the formation of oligomers was proven via nano-mass electrospray analysis. The repeating unit (n) had a m/z value of 488.2, with analytes detected as sodium adduct from 897.2 (n = 1, biscarbonate) until 2362.2 (n = 4). In addition, sodium adducts of the analytes with an alkene end group (as a result of HC1 elimination) were also visible in the mass spectrum from 1101.6 (n = 2) until 2464.3 (n = 5). GPC analysis confirmed the formation of oligomers with a number average molecular weight of M _n = 1542 g/mol and a weight average molecular weight of M _w = 2384 g/mol.

Conclusion: According to the present invention several symmetrical aryl carbonates were successfully coupled with a,a’-dichloro- -xylene, delivering a range of oligomers. Pleasingly, the existing carbonate group in diphenyl carbonate is sufficient to achieve the coupling with the provided electrophile, due to its inherent small +M effect (example 8). Additional substituents (with an inherent +M and/or +1 effect) were also allowed at different positions of the aromatic ring as illustrated in inventive examples 10-12. Besides the desired oligomers, also oligomers with an alkene end group were observed as side compounds, with a,a’- dichloro-p-xylene as electrophile, as a result of HC1 elimination of the chloromethylated intermediate. By altering the electrophile to a.a'-dichloro-m-xylcnc. this side reaction could be prevented. Consequently, longer oligomers were observed by GPC analysis (example 9).