Silicon- and polysilyl cyamelurates as well as -cyanurates, methods for the production thereof and their use

The present invention relates to a new compound class of oligomeric and polymeric s-triazine and s-heptazine derivatives and to their use as intermediates, for example, as precursor compounds (precursors) for the manufacture of Si/(M)/C/N/(O) ceramics, as mesoporous materials, such as, for example, catalyst carriers, for storing gas, or as a stationary phase for chromatography, as flame proofing agents, plastic additives or for other organic/inorganic functional materials.

In the Russian publication A. S. Gordetsov, Yu. I. Dergunov, N. K. Gavrilova, “Synthesis of organotin derivatives of melam, melem, and cyamelluric acid,” Khimiya Elementoorgan. Soedin. (Gor'kii), 8 (1980), 59-61 (CAN 97:39048), the synthesis of tris(trimethylsilyl)melem C 6 N 7 (NHSiMe 3 ) 3 from melem and di(n-butyl)-trimethylsilylamine is described. In Yu. I. Dergunov, A. S. Gordetsov, I. A. Vostokov, E. N. Boitsov, “Silylation and stannylation of cyameluric acid,” Zhurnal Obshchei Khimii, 46 (1976), 1653-4, the synthesis of the tris(trimethylsilyl)cyameluric acid ester C 6 N 7 (OSiMe 3 ) 3 is described.

In numerous patents, the use of heptazine derivatives as components for fire resistant or low-flammability synthetic formulations is claimed. s-Triazine derivatives have been examined substantially better than the mentioned s-heptazine derivatives. Examples of application fields are in the electronic, plastic, wood and textile industries. The s-triazine ring, moreover, is found in different pharmacologically active substances. From the literature, the following, three silicon-containing, compounds are known: molecular silyl esters of cyanuric acid (C 3 N 3 (OH) 3 ): (C 3 N 3 (OSiMe 2 (SiMe 3 )) 3 ), (C 3 N 3 (OSiMe 2 H) 3 ) and (C 3 N 3 (OSiMe 3 ) 3 ).

To date, there are no known one-, two- and three-dimensionally extended covalent oligomers or polymers and frameworks based on C 6 N 7 —O—Si or C 3 N 3 —O—Si structural units.

Thus, the problem of the present invention is to make such systems available for the first time.

This problem is solved by the embodiments characterized in the claims.

In particular, the present invention makes available oligomers or polymers that comprise at least one structural unit which is chosen from the group consisting of silicon cyanurates, [Si 3 (C 3 N 3 O 3 ) 4 ] n ; silicon cyamelurates, [Si 3 (C 6 N 7 O 3 ) 4 ] n ; silyl cyanurates, [Si(R a R b ) 1.5 (C 3 N 3 O 3 )] n ; silyl cyamelurates, [Si(R a R b ) 1.5 (C 6 N 7 O 3 )] n ; silsesquicyanurates, [Si(R a )(C 3 N 3 O 3 )] n ; and silsequicyamelurates, [Si(R a )(C 6 N 7 O 3 )] n ; where

n stands for a whole number between 1 and ∞, preferably 1 to 50,000, and

R a and R b are chosen, independently of each other, from the group α, which consists of hydrogen, halogen, hydroxy, straight-chained or branched-chained (C 1 -C 18 ) alkyl residue, (C 3 -C 7 ) cycloalkyl residue, a straight-chained or branched-chained (C 2 -C 18 ) alkenyl residue, a straight-chained or branched-chained (C 2 -C 18 ) alkinyl residue, a straight-chained or branched-chained (C 1 -C 6 ) alkoxy residue, furyl, furanyl, benzofuranyl, thienyl, thiazolyl, benzothiazolyl, thiadiazolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, pyrazinyl, pyrrolidinyl, pyrimidinyl, imidazolinyl, pyrazolidinyl, phenyl, phenoxy, benzyl, benzyloxy, naphthyl, naphthoxy or pyridyl, which can each be substituted with one to five substituents chosen independently of each other from the group β, which consists of a straight-chained or branched-chained (C 1 -C 6 ) alkyl residue, a (C 3 -C 7 ) cycloalkyl residue, a straight-chained or branched-chained (C 1 -C 6 ) alkoxy residue, halogen, hydroxy, amino, di(C 1 -C 6 ) alkylamino, nitro, cyano, benzyl, 4-methoxybenzyl, 4-nitrobenzyl, phenyl and 4-methoxyphenyl.

The structure forming units of the compound class according to the invention or of the frameworks derived therefrom are the s-heptazine fragment (or the cyamelurate group [C 6 N 7 O 3 ] 3− ), 1, and/or the analogous s-triazine fragment (or the cyanurate structural unit [C 3 N 3 O 3 ] 3− ), 2, which are connected by a bridge, or expanded, via silicon-containing groups, preferably SiO x R 4-x tetrahedral (with x=2, 3 or 4; R and R′, respectively, are defined as R a and R b above, chosen particularly from a straight-chained or branched-chained (C 1 -C 6 ) alkyl residue, a (C 3 -C 7 ) cycloalkyl residue, a straight-chained or branched-chained (C 2 -C 6 ) alkenyl residue, an unsubstituted or substituted C 6 -C 10 aryl residue) (see FIG. 1 ).

Examples of the compound class according to the invention are, with the assumption of an idealized polymer stoichiometry:

silicon cyamelurate and cyanurate: Si 3 (C 6 N 7 O 3 ) 3 I and Si 3 (C 3 N 3 O 3 ) 4 II, respectively, the silsesqui compounds: [RSi(C 6 N 7 O 3 )] n III and [RSi(C 3 N 3 O 3 )] n IV [(R a R b Si) 3 (C 6 N 7 O 3 ) 2 ] n V and [(R a R b Si) 3 (C 3 N 3 O 3 ) 2 ] VI, and any combinations of I to VI.

In an embodiment of the present invention, an oligomer or polymer is produced, which is a silicon-centered dendritic compound of the first generation or of a higher generation derived therefrom, corresponding to Si[ΔR a 2 ] 4 , R a —Si[ΔR b 2 ] 3 or R a R b Si[ΔR c 2 ] 2 , with Δ=(C 3 N 3 O 3 ) cyanurate or (C 6 N 7 O 3 ) cyanurate, where R a and R b are defined as above, and R c is defined as R a and R b , respectively.

In an additional embodiment of the present invention, an oligomer or polymer is produced, which is a cyanurate- or cyamelurate-centered dendritic compound of the first generation, or of a higher generation derived therefrom, corresponding to [Δ(SiR a R b R c ) 3 ], [R a (C 3 N 3 O 3 )(SiR b R c R d ) 2 ] or [R a (C 6 N 7 O 3 )(SiR b R c R d ) 2 ], with Δ=C 3 N 3 O 3 cyanurate or N 6 N 7 O 3 cyanurate, where R a , R b , R c and R d are defined, independently of each other, as R a and R b above.

In the context of the present invention, dendrimers denote high-order, oligomeric to polymeric compounds with defined branching. They possess an initiator core, which is either cyanurate- or cyamelurate-centered, or correspondingly silicon-centered—from which the branching units originate and extend in all the directions of space. Around the initiator core of the core functionality, the branching units form corresponding spheres, which are called generations.

In yet another embodiment of the present invention, an oligomer or polymer is produced, which is a derivatized silyl cyanurate, ([Si(R a R b )—R d —Si(R e R f )] 1.5 [C 3 N 3 O 3 ]) n , or a derivatized silyl cyamelurate, ([Si(R a R b )—R d —Si(R e R f )] 1.5 [C 6 N 7 O 3 ]) n , where n, R a and R b are defined as above, R e and R f are defined, independently of each other, as R a and R b above, and where R d stands for a SiR a R b group, a chalcogen atom, particularly an oxygen atom, a (C 1 -C 6 ) alkylene group, particularly methylene, a (C 6 -C 10 ) arylene group, particularly phenylene, or an R 9 X bridge (X=element of the third or fifth main group, and R 9 is chosen from hydrogen, halogen, hydroxy, a straight-chained or branched-chained (C 1 -C 18 ) alkyl residue, a (C 3 -C 7 ) cycloalkyl residue, a straight-chained or branched-chained (C 2 -C 18 ) alkenyl residue, a straight-chained or branched-chained (C 2 -C 18 ) alkinyl residue, or a straight-chained or branched-chained (C 1 -C 6 ) alkoxy residue.

The oligomers or polymers according to the invention can be particularly in the form of a colloidal suspension (sols, gels) in appropriate solvents, preferably, tetrahydrofuran, dioxane, dialkyl ethers, petroleum ethers, hexane fraction, benzene, toluene and mesitylene.

Another object of the present invention relates to a method for the manufacture of the oligomers or polymers according to the invention, which comprises the step of the reaction of cyanuric acid and/or cyameluric acid with tetraalkyl orthosilicate or with a corresponding alkoxysilane with one, two or three substitutions.

Alternatively, the oligomers or polymers according to the invention can be manufactured by a method which comprises the step of the reaction of a tris(trialkylsilyl) cyanurate and/or tris(trialkylsilyl)cyamelurate with silicon tetrachloride or with a corresponding chlorosilane with one, two or three substitutions.

The above processes can be followed optionally by a subsequent polymerization or crosslinking by hydrolysis or ammonolysis of the corresponding halogen or alkoxy terminal group-containing derivatives.

Another object of the present invention is the use of the oligomers or polymers according to the invention as a stationary phase for chromatography, as a microporous filter material, as a storage medium for liquids and gases, as a catalyst and/or catalyst carrier for heterogeneous catalysis, as a flame proofing agent, particularly for plastics, textiles, wood products, paper, paperboards, plasters, insulation materials and composite building materials, for the manufacture of polymer foams, or for the manufacture of materials and components whose optical, acoustic, magnetic or (opto)electronic properties are used.

Furthermore, the oligomers or polymers according to the invention can be used, in the context of sol-gel procedures for manufacturing coatings, molded bodies and powders, aerogel and xerogels, particularly if the oligomers or polymers according to the invention are in the form of a colloidal suspension (sols, gels), as described above.

FIG. 1 describes the construction of the oligomers or polymers according to the invention by combining the components A (SiO x R 4-x tetrahedra) and B (s-heptazine group or s-triazine group).

FIG. 2 illustrates the modification of the polymers according to the invention by the use of different functionalized chlorosilanes.

FIG. 3 describes the general (idealized) reaction, which is the basis of Examples 1-7, where Δ=C 3 N 3 , C 6 N 7 and R═CH 3 and x=0, 1, or 2.

FIG. 4 illustrates the reaction described in Example 9.

The principle of the constitution of the oligomers or polymers according to the invention is apparent from FIG. 1 . Using the method according to the invention, it is also possible to produce polymers from complicated chlorosilanes, for example, α,ω-dichlorosilanes, or bridged chlorosilanes of the type CIR a R b Si—R c —SiR d R e Cl, where R a and R b are defined as above, and R d and R e are defined as R a and R b , while R c is chosen from a straight-chained or branched-chained (C 2 -C 18 ) alkenyl residue, a straight-chained or branched-chained (C 2 -C 18 ) alkinyl residue, or an unsubstituted or substituted (C 6 -C 10 ) arylene residue, where one substituent, or several substitutents, is or are chosen from the group β (see FIG. 2 ).

Depending on the manufacturing method, the polymers can contain significant quantities of terminal groups (for example, chloro- and trimethylsiloxy groups), without significantly influencing the fundamental structure, or the properties of the polymers according to the invention. The chemical structure and the morphology of the polymers according to the invention depend on the synthesis conditions used. Under appropriately chosen conditions, gels form, which can be converted into xerogels or aerogels. The latter are characterized by a very high specific surface area, and by pores in the micro range (<2 nm) and/or meso range (2-50 nm).

Highly porous framework structures, in which the transition metal-oxygen polyhedra are linked by multitoothed, usually rigid, aromatic ligands via ionic interactions; so-called “metal organic frameworks” (MOFs) have been studied intensively in the past few years and are also the subject of intense commercial interest. MOFs can be used to store gas, as catalysts in synthetic chemistry, and as sensor materials. Today, industrial pilot installations are already functioning. In some of these applications, the frameworks according to the invention may be superior, due to their high thermal stability, to the MOFs, by withstanding, for example, higher temperatures during the synthesis reactions.

The polymers according to the invention are generally colorless (white) and opaque, and they can be modified by the targeted incorporation of colored components. The polymers tend to undergo hydrolysis, and are therefore suitable for the formation of biodegradable, inorganic-organic materials.

The polymers according to the invention can be synthesized in principle by different pathways. Suitable starting substances, corresponding to the silicon cyanurates or cyamelurates according to the invention, are, for example, the oxygen halides C 3 N 3 Cl 3 , C 3 N 3 F 3 or C 6 N 7 O 3 , which can be reacted with soluble metal silicates, alkoxysilanes or siloxysilanes. Moreover, the “ortho acids,” cyanuric acid C 3 N 3 O 3 H 3 and cyameluric acid C 6 N 7 O 3 H 3 , and their alkylammonium salts can be reacted with alkoxysilanes or chlorosilanes.

Reactions that are particularly advantageous are those in which the poly(s-heptazine siloxanes) or poly(s-triazine siloxanes) are synthesized by exchange reactions from tris(trialkylsilyl)cyameluric acid esters, for example, (C 6 N 7 (OSiMe 3 ) 3 ) or tris(trialkylsilyl)cyanuric acid esters, for example, (C 3 N 3 (OSiMe 3 ) 3 ). Typical results and the associated reaction equations can be found below in the examples.

The products are produced at high yields. Moreover, it is noteworthy that, under appropriate conditions (dilution not excessive, and no stirring) a sol-gel process takes place phenomenologically. In the process, the homogeneous solution solidifies relatively abruptly at the so-called gel point. An aging process then follows, which is usually characterized by continued condensation reactions and syneresis. Depending on the educts, the preparation size, and the pressure and temperature conditions, the reaction time varies considerably. According to the present invention, the oligomers or polymers according to the invention can also be produced in pure (including crystalline) form.

In the context of the present invention, the corresponding compounds can also be present as terminal group-containing oligomers or polymers. In addition, corresponding combinations of the oligomers or polymers according to the invention are included.

The present invention is now described in greater detail in the following, nonlimiting, examples.

All the reactions are carried out under a protective gas with the Schlenk and glove box technique. Commercially available (Aldrich) chlorosilanes were used. The trimethylsilyl esters of cyameluric acid and of cyanuric acid were synthesized according to Y. I. Drgunov, I. A. Vostokov, A. S. Gordetsov, V. A. Gal'perin, Silylation and stannylation of cyanuric acid, Zhumal Obshchei Khimii (1976), 46(7), 1573-6. b) Yu. I. Dergunov, A. S. Gordetsov, I. A. Vostokov, E. N. Boitsov, Silylation and stannylation of cyameluric acid, Zhumal Obshchei Khimimi, 46 (1976), 1653-4.