WO2020016120A1 - Method for producing oligomeric compounds by fractional extractive reaction - Google Patents

Abstract

The invention relates to a method for producing oligomeric compounds from the reaction of a monomer with one or more monomers and/or with an oligomer comprising units based on said monomer. The monomer and/or the oligomer are selected such that in the reaction products are formed that have a greater number of polar functional groups than the individual monomer. The method comprises introducing at least one monomer into an extraction container, which is designed for fractional liquid-liquid extraction with a pair of solvent systems forming two phases, comprising a first solvent system and a second solvent system. Preferably, polyisocyanates are converted into the trimeric isocyanurates.

Description

 Process for the preparation of oligomeric compounds by fractional extractive reaction

The present invention relates to a process for the catalyzed oligomerization of di- or polyfunctional monomers (further text: monomers), the oligomer formed being separated from the monomer and catalyst still present during the reaction.

The catalyzed oligomerization of di- or higher-functional monomers in batch reactors or continuous reactors, such as, for example, graft flow reactors, leads to products with exponentially increasing viscosity with increasing sales. Apart from the use of monofunctional regulators, which, however, only allow the production of oligomers with non-oligomerization-active end groups, the degree of oligomerization can only be regulated via the conversion. The production of oligomers with reactive end groups is therefore usually carried out with a partial conversion. In other words, sales and degree of oligomerization cannot be controlled independently. Furthermore, the catalyst or an optionally deactivated catalyst usually remains in the product.

Particular attention should be paid to oligomerization reactions, in which the monomers are not only linked to linear macromolecules via addition, condensation or chain reactions of the reactive group (s), but are, for example, formed three-dimensionally (by) crosslinked oligomer structures with the formation of carbo- or heterocycles. An example of a reactive group that can react via addition and condensation reactions are isocyanates. Two isocyanate groups can react linearly with uretdione formation or with elimination of CO ₂ with carbodiimide formation, while three isocyanate groups can react three-dimensionally cross-linked to form isocyanurate and / or iminooxadiazinedione groups. The same applies to other monomers with reactive heterokumulenes as end groups such as cyanate groups, thioisocyanate groups, thiocyanate groups or carbodiimide groups and monomers with end groups containing triple bonds, such as acetylenes, nitriles or isonitriles.

Monomers which contain two or more such reactive groups give, even at low conversions in conventional apparatus, a three-dimensional network which then leads to the gel point being exceeded, which leads to products which are difficult to handle and which may require complex cleaning of the reactor from failed polymer. Particularly critical monomers of this type are those with two reactive groups of the same or approximately the same reactivity, the reactivity of which is not or only slightly changed by incorporation into the oligomer. Hexamethylene diisocyanate (1,6-HDI) may be mentioned here by way of example, in which the free isocyanate groups of the oligomeric uretdiones, carbodiimides, isocyanurates and / or bninooxadiazinediones show only a slightly changed reactivity towards the isocyanate groups of the monomer. The oligomerization leads further via the di- and trimers to oligomers with 3,4,5 etc. (uretdione and / or carbodiimide formation) or 5,7,9,11 etc. (isocyanurate and / or bninooxadiazinedione formation) 1,6 -HDI units in the molecule. A study on cyclooligomerization can be found, for example, in IT Horvath, FU Richter et al., Angew. Chem. Int. Ed. 2005, 45, pages 107-110. An overview of isocyanate oligomerizations can be found in J. Prakt. Chem./Chem. Ztg. 1994, 336, pages 185-200.

The oligomerization of such diisocyanates to low molecular weight oligomers is generally characterized by a classic consecutive reaction sequence in which a diisocyanate monomer molecule (A) with one (uretdione and / or carbodiimide formation, ideal structures A2) or two other monomer molecules (isocyanurate and / or iminooxadiazinedione formation , Ideal structures A ₃ ) reacts. These ideal structures continue to react with all the compounds of the system containing isocyanate groups (A, A2, A ₃ , higher oligomers with more than one uretdione, carbodiimide, isocyanurate and / or iminooxadiazinedione group in the oligomer molecule). The target product for technical use is an oligomer mixture with a high ideal structure content.

Low-monomer oligomers with the highest possible content of dimers or trimers with exactly 2 or 3 monomer units in the molecule and as little higher oligomers as possible are desired. Even small proportions of higher oligomers lead to increased viscosities and a lower (by mass) end group content in the product, which is disadvantageous, for example, for applications in the coating sector. So far, the content of higher oligomers could only be reduced by carrying out the reaction only up to a low conversion. The unreacted monomer was separated, for example by distillation, while the oligomer remained in the residue without a further purification step.

The oligomerization catalyst usually also remained in the residue. Only by deactivating the catalyst was it possible to provide oligomers with sufficient stability. In addition, processes are known in which the oligomerization catalyst is separated from the polyisocyanate by distillation together with the monomer to be removed (cf. EP 1533301 and the prior art cited therein).

No. 4,871,460 discloses how isocyanate prepolymers with free NCO groups are separated from reaction mixtures which contain unreacted excess di- or polyisocyanate monomer. This is done by extracting the reaction mixture with an inert gas, especially carbon dioxide, in either the liquid or supercritical state. The highly purified polyisocyanates are suitable for the production of foams, elastomers, adhesives, lacquers and paints.

No. 5,298,431 describes a multistage process for isolating a cyclotrimerized isocyanate from a mixture which contains this cyclotrimerized isocyanate and higher isocyanate oligomers. The method comprises the steps of: (a) contacting the mixture with a liquid solvent to obtain a solvent-containing mixture; (b) extracting the solvent-containing mixture by means of liquid-liquid extraction in order to separate the mixture into an extract and a residue, the extract being a cyclotrimerized isocyanate which is essentially free of oligomers and which further (after separation of the solvent) is one has reduced viscosity compared to the original polyisocyanate mixture; and (c) separating the uncyclotrimerized monomer from the extract to obtain a reduced viscosity trimer product which is substantially monomer free. The reduced viscosity product obtained by this process is also described.

Although this patent speaks of a liquid-liquid extraction, no solvent pairs are used here. Rather, the reaction mixture is extracted with a single solvent. The separation operation is a simple extraction with only one floor and not a method of multiplicative distribution that has a separating effect from more than one floor. Furthermore, no reaction takes place there during the separation operation.

DE 10 2004 06 0131 A1 relates to a process for the preparation of polyisocyanates from diisocyanates and their use. The process is a continuous process for the partial trimerization of (cyclo) aliphatic isocyanates in the presence of at least one catalyst and is distinguished in that the process is carried out at least partially in at least two backmixed reaction zones.

In Ind. Eng. Chem. Res. 2008, 47, pages 7154-7160 describes the oligomerization of phenol under oxidative conditions in a two-phase system. However, it is only a simple extraction and not a multiplicative distribution method.

The concept of an extractive reaction is described, for example, in S. Kulprathipanja (ed.), Reactive Extraction Processes, Separation (Technology), Taylor & Francis, New York, 2002, pages 51-92. When uranium and plutonium are separated (page 56), chemical reactions such as complexation and redox processes take place in the multiplicative distribution apparatus, but these serve to enable the separation and not the desired ones To provide products. A reactive extraction using the example of hydrolysis reactions is described in the abovementioned document on pages 58-59, but it is a simple two-phase reaction without multiplicative distribution. The combination of reactant and product separation with methods of multiplicative distribution and reactions which lead to desired products and not only serve the main purpose of the separation is not described. Furthermore, the control of the product distribution of consecutive, preferably irreversible, reactions, such as oligomerizations, by methods of multiplicative distribution is not known.

Barth describes a reactive extraction in Chemie Ingenieur Technik 2008, 80 (12), pages 137-143, but describes the esterification of acetic acid with ethanol to ethyl acetate. This is not a consecutive reaction, but an equilibrium reaction in which the equilibrium is shifted by removing reaction products.

The task was therefore to control the conversion and degree of oligomerization in consecutive reactions independently of one another in such a way that products with a narrower molecular weight distribution are formed with a high proportion of ideal structure in comparison with products of the prior art.

This object is achieved according to the invention by providing a process in which the oligomerization and separation of the oligomers take place simultaneously by extraction.

The process according to the invention for the production of oligomeric compounds from the reaction of a monomer with one or more monomers and / or with an oligomer which units are based on this monomer, the monomer and / or the oligomer being selected such that products are formed in the reaction which have at least as many, but preferably a larger number, of polar functional groups than the individual monomer comprises the following steps: a) introducing at least one monomer into an extraction container, which is used for fractional liquid-liquid extraction with a two-phase solvent system pair comprising a first solvent system and a second solvent system, b) reaction of the monomer in the extraction container to form a reaction mixture comprising oligomers; c) fractionated liquid-liquid extraction of the reaction mixture obtained in step b) in the extraction container using the first and second solvent systems, the first solvent system being a linear, branched or cyclic, optionally partially or perfluorinated alkane (preferably all isomeric pentanes, hexanes, Heptanes, octanes, deans, undecanes, dodecanes, tridecanes, tetradecanes, pentadecanes, hexadecanes, cyclohexane, tetralin and any mixtures with one another), chloroaromatics and / or bromoaromatics (such as p-dibromobenzene) and the second solvent system comprises a solvent that is selected from the group comprising nitriles (preferably acetonitrile, propionitrile, phthalonitrile, dimethylmalonitrile, malononitrile, 3-butenitrile, particularly preferably acetonitrile), cyclic carbonates (preferably propylene and ethylene carbonate), cyclic ethers (preferably trioxane), sulfones (preferably diethyl sulfone), sulfoxides , N itroaromatics (preferably 2-nitrofuran, 1,3,5-trinitrobenzene), lactones (preferably 3H-luran-2-one, angelicalactone, gamma-butyrolactone), esters (preferably dimethyl oxalate), inorganic esters (preferably dimethyl sulfate), aldehydes (preferably 2-furfural, 3-furfural), formamides (preferably N-formylmorpholine), halogenated (where halogen is not fluorine) alkanes and / or dialkyl ethers of oligoethylene oxides; and d) withdrawing a stream comprising the second solvent system and the oligomer formed in step b) from the extraction container.

It has now been found that, in the process according to the invention, oligomerization reactions and the separation of the oligomers desired as the product from monomers and, if appropriate, catalysts in apparatus which enable multiplicative distribution, are possible simultaneously, the degree of oligomerization being able to be controlled by the ratio of reaction rate and rate of separation.

A technical advantage of the fractional extractive reaction is the energy saving in comparison with the known methods and the lower temperature load of the oligomers and possibly unreacted monomers, since only solvents have to be converted into the gas phase and not the high-boiling monomers such as diisocyanates. The process also enables the catalyst to be recycled in a recycle stream.

A further energy saving results from the fact that the conversion of the monomer can be driven to higher conversions in comparison with the known methods without the gel point being exceeded. This is due to the separation of the oligomers, in particular the ideal structures, during the reaction and the resulting slowdown or at least partially preventing their further reaction. Turnovers, based on the amount of substance of the monomer used, are possible between 30% and 99.9% or between> 30% and <99%. As a result, the amount of recirculated monomer is significantly reduced compared to classic single-stage oligomerization in a homogeneous phase.

In a further embodiment of the process according to the invention, the reaction is carried out up to a conversion of> 10% by weight to 30% by weight, based on the mass of the monomer originally present. In this way, with the same turnover, an increased selectivity compared to conventional processes with regard to the low oligomers (increased content of ideal structures A2 and A3 in the oligomer mixture) can be achieved. In the process according to the invention, the monomer and / or the oligomer are preferably selected such that products with the same or a larger number of polar functional groups are formed in the reaction with further monomers. Polar functional groups are to be understood here as those groups in which there is an electronegativity difference between 0.5 and 1.7 between two atoms bonded to one another. The electronegativity of the atoms is determined according to Pauling and is described, for example, in G. Simons et al., J. Am. Chem. Soc. 1976, 98, page 7896 tabulated. According to this table, the following electrical negativeities result: C (2.35), H (2.1), N (3.16) and O (3.52).

Examples of polar functional groups are in particular isocyanate groups, epoxy groups, hydroxyl groups, amino groups, carboxyl groups, ester groups, ether groups, urethane groups, urea groups and amide groups.

For example, in the case of an otherwise unfunctionalized diisocyanate as a monomer, the number of polar groups due to the two NCO groups is 2. If the diisocyanate is trimerized to the isocyanurate or iminooxadiazinedione, three terminal NCO groups remain. In this reaction product, the number of polar functional groups contained in a molecule has increased compared to the monomer. A further reaction to the pentamer results in four terminal NCO groups. When a heptamer molecule is formed, there are five terminal NCO groups. When a nonamer molecule is formed, there are six terminal NCO groups.

Another example of this approach is the reaction of an epoxide (monomer) with an alcohol. The number of polar functional groups in the monomer is 1. In the reaction with the alcohol, an ether group and a new hydroxyl group are formed, as a result of which the number of polar functional groups is now 2. Any further reaction with an epoxy molecule increases the number of polar groups in a molecule by another polar group.

Another example is the cyclization of two molecules containing NCO groups and one molecule of CO2. For example, two molecules of hexamethylene diisocyanate (1,6-HDI) and one molecule of CO2 react to form 3,5-di (6-isocyanatohexyl) -l, 3,5-oxadiazinane-2,4,6-trione, with two terminal NCO groups and a 1,3,5-oxadiazinane-2,4,6-trione ring are formed. Each further reaction with an isocyanate and a CO2 molecule increases the number of polar groups in a molecule by another polar 1,3,5-oxadiazinane-2,4,6-trione ring.

Apparatus which are suitable for carrying out the fractional liquid-liquid extraction according to the invention with the aid of methods of multiplicative distribution are described, inter alia, in S. Kulprathipanja (ed.), Reactive Extraction Processes, Separation (Technology), Taylor & Francis, New York, 2002, pages 51-92 and in Perrys Chemical Engineering Handbook, McGraw-Hill, 2008, section 15 ("liquid-liquid extraction and other liquid-liquid operations and equipment").

For example, extraction columns with dynamic or static mixing elements can be used or stirred tank cascades with various integrated or separated mixing and phase separation devices. The polar and the non-polar solvent of the two immiscible solvents forming the two-phase system are conducted in countercurrent to one another, the ratio of the phases being chosen so that the reactants and preferably catalysts are transported to one side of the apparatus and the products to the other side ,

The monomers and, if appropriate, the catalyst or a mixture of different catalysts can be metered in separately or with no solvent at all points in the column or stirred tank cascade, but preferably in the middle range which corresponds to> 40% to <60% of the number of trays of the total apparatus. If solvents are used for metering the monomers and, if appropriate, the catalyst or a mixture of different catalysts, one or both of the solvents which form the two-phase system are preferably used.

The first, non-polar solvent system is metered at the end to which the more polar partner of the pair of monomer-oligomer, here the oligomer, is transported. The polar, second solvent system is metered at the end to which the less polar partner of the pair of monomer-oligomer, here the monomer, is transported. The solvent systems do not have to be metered directly at one end of the apparatus for multiplicative distribution, but can also take place up to a distance which corresponds to <25% of the number of trays of the total apparatus.

Suitable solvent combinations with miscibility gaps are described, for example, in J. Phys. Chem. Ref. Data 2007, 36 (3), pages 733-1131 or McLure et al, Fluid Phase Equilibria 1982, 8, pages 271-284.

By definition, the solvent system pair forms two phases if a phase boundary between the two liquid phases can be seen with the naked eye. The first and the second solvent system each contain a solvent such that the two pairs of solvent systems show a miscibility gap within a certain temperature range. Likewise, the first and second solvent systems can each be present as mixtures of solvents, so that the two pairs of solvent systems show a miscibility gap within a certain temperature range.

In this respect, even in the presence of the monomer to be oligomerized, the more polar, second solvent system has a miscibility gap with the nonpolar first solvent system.

Also included is the case where the first and second solvents originally present in pure form partially mix with one another, as a result of which a first solvent system with the first solvent as main component and the second solvent as secondary component and a second solvent system with the second solvent as main component and the first solvent is obtained. Here too there is a phase boundary between the first and second solvent systems.

The volume ratio of the first to the second solvent system in the apparatus, which is used to carry out the fractional liquid-liquid extraction according to the invention with the aid of methods of multiplicative distribution, can for example be> 1: 1 to <50: 1 and preferably> 5: 1 up to <10: 1.

The amount of monomer metered in should be such that the two-phase nature of the solvent system pair is not eliminated, since in certain cases the monomer can also act as a phase mediator. On the other hand, the concentration of the monomer should be chosen as high as possible in order to accelerate the reaction and to enable a high space-time yield.

The reaction temperature can be, for example, in a range from> 20 ° C to <180 ° C and preferably from> 40 ° C to <120 ° C. When choosing the reaction temperature is too take into account that the miscibility gap in the quaternary system consisting of the first solvent system, second solvent system, monomer and oligomer is generally reduced by higher temperatures and the reaction rate is reduced by the then lower possible maximum concentration of monomer. On the other hand, the reaction is accelerated by higher temperatures, the boiling point of the solvent mixture being limiting when working at normal pressure. The optimal reaction temperature is therefore a compromise and has to be determined experimentally for each reaction system consisting of monomer (s), non-polar first solvent system, more polar second solvent system and catalyst.

The oligomer can be separated from the solvent of the more polar second solvent system by distilling off the solvent, by demixing, which can be achieved, for example, by cooling the mixture, by a subsequent extraction process or by membrane processes. The same measures can be used to separate the catalyst and any unreacted monomer from the solvent of the less polar first solvent system.

In the case of separation of the solvents by distillation, the combinations of linear, branched or cyclic alkanes such as “-pentane,“ -hexane, “-heptane,“ -octane, “-nonane,“ - decane, 2,2,4-trimethylpentane, Cyclohexane and / or tetralin with acetonitrile are particularly advantageous since low-boiling azeotropes can be formed (Smallwood, IM, Handbook of Organic Solvent Properties, Elsevier, 1996). This can lead to additional energy savings when the non-polar solvent is distilled off from the oligomeric products or when the polar solvent is distilled off from the possibly unreacted monomer compared to a solvent system pair which does not form an azeotrope.

Embodiments of the method according to the invention are described below, the embodiments being able to be combined with one another as desired, unless the context clearly indicates the opposite.

In one embodiment of the method according to the invention, the monomer is a monomolecular, dimolecular or trimolecular di- or polyisocyanate. Thus, an oligomerization of the isocyanate groups takes place in step (b). This is preferably a trimerization (isocyanurate and / or hninooxadiazinedione group formation).

Suitable starting materials for the oligomerization are, for example, hexamethylene diisocyanate (1,6-HDI), 1,8-octane diisocyanate, 4-isocyanatomethyl-1, 8-octane diisocyanate, 1,10-decane diisocyanate, 1,11-undecane diisocyanate, 1,12-dodecane diisocyanate, 2-methyl-l, 5-diisocyanatopentane, 1,3- and 1,4-cyclohexane diisocyanate, norbornane diisocyanate, 1,3- and 1,4-bisisocyanatomethylcyclohexane,

1,3- and 1,4-bis (isocyanatoethyl) cyclohexane, 2,4- and 4,4-diisocyanatodicyclohexylmethane, 1-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane (IMCI), isophorone diisocyanate (IPDI), 1,3 - And 1,4-bis (isocyanatomethyl) benzene, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-TDI, 4,4-diphenylmethane diisocyanate (MDI), 4,2-MDI, 1,3- and

1,4-diisocyanatobenzene, 3,3-dimethyl-4,4-diisocyanatodiphenyl, 3,4- and 4,4-

Diisocyanatodiphenyl ether and / or 1,5-diisocyanatonaphthalene. In addition, monoisocyanates such as, for example, methyl, ethyl, 1- and / or 2-propyl, butyl (all isomers), pentyl (all isomers) and / or hexyl isocyanates (all isomers) and their higher can also be used in the educt mixture Homologues may be present individually or in any mixture with one another and with the di- and triisocyanates mentioned above.

It is further preferred that the monomeric isocyanate is 1,6-hexamethylene diisocyanate. Its trimers can be used for a wide range of applications, particularly in the production of polyurethane coatings. With the exception of technically unavoidable impurities, only 1,6-hexamethylene diisocyanate is preferably present in the isocyanate used.

In a further embodiment of the process according to the invention, the monomer is an alkylene oxide and reacts with an alcohol in step b). Suitable alkylene oxides are, in particular, ethylene oxide and propylene oxide. Long-chain primary alkanols (for example fatty alcohols) are preferably used as alcohols.

In a preferred embodiment of the method according to the invention, in the fractional liquid-liquid extraction in step c), the first and second solvent systems are conducted in countercurrent to one another.

In a preferred embodiment of the process according to the invention, the extraction container is designed as a packed column or pulsed or non-pulsed sieve plate column, in a further embodiment as a multistage mixer-separator system (mixer-settler apparatus).

In a preferred embodiment, after step d), the second solvent system is separated off, optionally cleaned of oligomer, catalyst and unreacted monomer, and reintroduced into the extraction container. In this way, a cycle process can be implemented for the second solvent system.

Likewise, in a preferred embodiment of the process according to the invention, the first solvent system is separated off after step c), if appropriate from catalyst, oligomer and unreacted monomer cleaned and reintroduced into the extraction container. In one embodiment of the method according to the invention, this comprises the steps: e) removing a stream comprising the first solvent system and the monomer not reacted in step b) from the extraction container; f) separation of the first solvent system from the unreacted monomer; g) introducing the first solvent system obtained in step f) into the extraction container; and h) introducing the unreacted monomer obtained in step f) into the extraction container.

In this way, a cycle is also realized for the first solvent system and for the monomer.

In a further embodiment of the method according to the invention, this further comprises the steps: i) removing a stream of material from the extraction container, the stream of material removed in this way containing the second solvent system and being free of products from the reaction in step b), followed by feeding this stream of material back directly a location of the extraction container different from its removal; and / or k) removing a stream of material from the extraction container, the stream of material removed in this case containing the first solvent system and being free of monomers, followed by separating off any catalyst which may be present and feeding this stream of material back to a location of the extraction container which is different from its removal.

In this way, internal recycling of the solvent systems can be achieved without further separation operations. This reduces the energy requirement of the overall process. In this context, "free of products" and "free of monomers" mean that technically unavoidable residues are included. For example, the solvent systems may contain up to 1% by weight of other components in addition to the solvents.

The direct feed back means in particular that the material flows are not subjected to distillation. Any catalysts present in the first solvent system can, for example, by means of a distillation device or via reversible adsorption be separated from an adsorbent and fed back to the reaction mixture for step b) of the process according to the invention.

In the event that the first and the second solvent system are guided in countercurrent to one another in the extraction container, a flow direction of the first solvent system and a discharge direction of the second solvent system are established. In this case, it is advantageous if the material stream containing the first solvent system is fed in directly at a point on the extraction container which, viewed in the direction of release of the first solvent system, lies within the extraction container upstream of the removal point of this material stream.

It is also advantageous if the material stream containing the second solvent system is fed in directly at a point on the extraction container which, viewed in the direction of release of the second solvent system, lies within the extraction container upstream of the removal point of this material stream.

In a further embodiment of the method according to the invention, the first solvent system comprises linear, branched and / or cyclic alkanes, such as, for example, “-hexane, n-heptane, ao-octane, cyclohexane and / or hexadecane, and the second solvent system comprises acetonitrile. With the exception of technically unavoidable traces, there are preferably no further solvents other than the solvents mentioned in the first and second solvent systems.

With this selection of solvent combinations, gaps in the mixture were verified experimentally. The combinations of acetonitrile with the alkanes mentioned are particularly favorable since low-boiling azeotropes are formed. This leads to energy savings when distilling off. hn Lall of 1,6-HDI as a monomer in the solvent system pair n-heptane / acetonitrile, the maximum concentration of the monomer depends on the chosen reaction temperature. At lower temperatures, higher concentrations of the monomer can be achieved without the two-phase nature of the overall system being impaired by the phase switching of the monomer. At 60 ° C the preferred content of 1,6-HDI in the area of the feed point in the reactive extraction apparatus lies between 5 and 20% by weight. At 30 ° C the preferred content of 1,6-HDI in the area of the feed point lies in the reactive extraction apparatus between 5 and 40% by weight. Furthermore, reaction temperatures between 20 ° C and 70 ° C, preferably 30 ° C and 60 ° C, have proven to be advantageous. The oligomerization reaction in step b) of the process according to the invention usually takes place in the presence of a catalyst, even if a purely thermally induced reaction is possible. In the case of oligomerization of isocyanate monomers, depending on the selected temperature, it generally leads to uretdione groups (lower reaction temperature) or carboxiimide / uretonimine group-containing polyisocyanates (very high reaction temperature). The latter is not preferred in the present process. The so-called isocyanate trimerization with the formation of isocyanurate and / or iminooxadiazinedione groups generally requires the use of special catalysts.

Examples of such catalysts for the isocyanate trimerization are onium salts of phosphorus, nitrogen, sulfur or of nitrogen heterocycles such as imidazole, triazole and tetrazole with counterions, which anions of acids with a pK _a value below 4.5, preferably below 3.5 are. Preferred counterions are aliphatic or aromatic carboxylates or alcoholates, such as acetate, propionate, 3,3,3-trifluoropropionate, butyrate, capronate, octanoate, laurate, palmitate, stearate, isobutyrate, ethylhexanoate, pivalate, neodecanoate, phenolate, cresylate. Small anions such as fluoride, hydrogen (di- and poly) fluoride, hydroxide are also suitable.

Also suitable for the isocyanate trimerization are, if appropriate, cyclic phosphines with substituents from the group consisting of linear or branched alkyl, cycloalkyl and alkenyl, linear or branched alkyl and cycloalkyl substituents being preferred. Also suitable are those polycyclic phosphorus-containing heterocycles which are formed when radicals are attached to cyclooctadiene by free radicals. The common name for such phosphines is Phobane. Suitable catalytically active groups are also nitrogen heterocycles such as imidazoles, triazoles and tetrazoles.

A preferred class of catalysts for isocyanate trimerization is based on polyhedral oligomeric silsesquioxanes, which will be explained in more detail below.

In a further embodiment of the process according to the invention, the reaction in step b) takes place in the presence of a catalyst and the catalyst is selected such that a greater proportion is present in the first solvent system than in the second solvent system. In the process according to the invention, the monomers are less polar than the oligomers and are therefore more strongly represented in the non-polar phase (first solvent system), at least relative to the oligomers. Catalyst-free oligomers can be obtained by the fractional reactive extraction method if the catalysts can be separated from the oligomers together with the monomers. To do this, they must at least be more strongly represented in the monomer-rich phase than the oligomers, preferably even more strongly than the monomer. For example, in a preferred solvent _system pair of n-heptane / acetonitrile at 60 ° C., the partition coefficient K = x _«-heptane / x _acetomet rii of 1.6-HDI 0.189 and that of the trimeric isocyanurate (ideal structure) is 0.038. The catalyst should therefore have a distribution coefficient greater than 0.038, preferably greater than 0.189.

The more the catalyst partitions into the non-polar first solvent system, i.e. the greater the partition coefficient of the catalyst, the more selectively the oligomerization can be stopped at the level of the ideal structure, since then there is more catalyst in the monomer-rich phase and less in the oligomer-rich phase, where it favors the undesired further reaction of the oligomers , On the other hand, the monomer can be represented in both phases, in the case of 1,6-HDI in the preferred solvent system pair n-heptane / acetonitrile, 1,6-HDI also partitions more strongly into the polar phase, only not as pronounced as that oligomer. It is therefore advantageous for the space-time yield if the catalyst is also in the polar phase.

A particularly favorable compromise is generally present when the partition coefficient of the catalyst between the first solvent system and the second solvent system is> 0.19 to <9 and the catalyst in the first solvent system is therefore compared in> 0.19 times to <9 times the amount with the second solvent system. The distribution coefficient is preferably> 0.50 to <4.

The catalyst is advantageously used in a proportion of 0.1% by weight to <35% by weight, based on the amount of monomer used. A proportion of 5% by weight to <30% by weight is particularly favorable. Because the catalyst can be separated off and recycled in the process according to the invention, high catalyst contents can be used expediently.

In a preferred embodiment of the process, no deactivation of the catalyst is carried out after step (b). Deactivation here means in particular the addition of a catalyst poison or a substance which reacts chemically with the catalyst.

Preferred catalysts for the isocyanate trimerization with high solubility in the non-polar solvent system are representatives of the proazaphosphatranes such as 2,8,9-trialkyl-2,5,8,9-tetraaza-l-phosphabicyclo [3.3.3] undecane, 2.8 , 9-tricycloalkyl-2,5,8,9-tetraaza-l-phosphabicyclo [3.3.3] undecane or 2,8,9-triaralkyl-2,5,8,9-tetraaza-l-phosphabicyclo [3.3. 3] undecane, the substituents in the 2-, 8- and 9-position being the same or different could be. C1-C10 radicals which can be linear or branched, preferably branched, come as alkyl substituents, C4-C12 radicals which can in turn be substituted by alkyl radicals and cycloalkyl radicals and benzyl radicals which in turn can be substituted by alkyl or alkoxy radicals Question. The catalyst preferably comprises 2,8,9-tri-o-methoxybenzyl-2,5,8,9-tetraaza-l-phosphabicyclo [3.3.3] undecane, 2,8,9-tricyclopentyl-2,5,8, 9-tetraaza-l-phosphabicyclo [3.3.3] undecane, 2,8,9-triisopropyl-2,5,8,9-tetraaza-l-phosphabicyclo [3.3.3] undecane and / or 2.8, 9-Tn-.yer-butyl-2,5,8,9-tetraa / .a- 1 -phosphabicyclo [3.3.3] undecane. The latter compound is shown as an example in the following formula:

For example, in the solvent system pair nI Icptaii / acctonitrile, it has a distribution coefficient K = x _«-HePtan / x _Acetomt rii of 3.9.

Preferred catalysts for the isocyanate trimerization with high solubility in the non-polar solvent system include polyhedral oligomeric silsesquioxanes of the general formula (I):

wherein RI, R2, R3, R4, R5, R6, R7 and R8 are independently selected from groups (Ia) and / or (Ib) with the proviso that at least one of the radicals RI, R2, R3, R4, R5 , R6, R7 and R8 is selected from group (Ib): (La): alkyl, cycloalkyl, aryl, heteroaryl, heterocyclyl, alkenyl, alkynyl, perfluoroaryl,

Perfluoroalkenyl, perfluoroalkynyl, alkoxy, perfluoroalkyl, perfluoroalkoxy, polyoxyalkylene,

(Lb): -A-R9, where:

A = (CR2) _n with n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, and R for identical or different substituents from group H and / or Ia; or

A = ortho-, meta- or para-C _ö R _t , where R has the meaning given above; or

A = (CR ₂ ) ₂ -Si (R ₂ ) - (CR ₂ ) _n , with n = 1, 2, 3, 4, where R has the meaning given above; and

 R9 = N (R10) (R11), P (R10) (R11), N (R10) (R11) (R12) X, P (R10) (R11) (R12) X,

 COOM, OM, or another substituent according to Lormel (I), wherein

 RIO, RI 1 and RI 2 are independently alkyl or aryl,

X is carboxylate, alcoholate, hydrogen carbonate, or carbene and M is ammonium, phosphonium, an alkali or alkaline earth metal cation.

Such catalysts are particularly suitable for the trimerization of monomeric polyisocyanates such as 1,6-HDI to isocyanurates.

This choice of the catalyst is based on the knowledge that its solubility or its distribution coefficient can be influenced in a two-phase system by a modular structure consisting of a non-polar partial structure and a catalytically active partial structure.

For example, the non-polar and the catalytically active partial structure can carry opposite ionic charges and be held together by means of electrostatic interactions. It is also possible for the two substructures to be connected to one another by a covalent bond. The non-polar partial structure of the catalyst is formed in the present invention by the substituted silsesquioxane structure. The catalytically active substructure is bound via one or more substituents as described above.

The catalytic partial structure comprises an ionic or non-ionic nucleophile that catalyzes the starting oligomerization. An example of an ionic catalytically active partial structure is a silsesquioxane in which one or more of the substituents RI to R8 are - (CH ₂ ) _n -P (alkyl) 3X and X = R-COO with R = CH3-, CH3CH ₂ - , «-Propyl, ao-propyl, ieri.-butyl, tert-amyl, CH ₃ (CH ₂ ) _n - with n = 4, 5, 6, 7, 8, CH3CH (OH), phenyl, 4-methoxyphenyl and / or 3,4,5- Trimethoxyphenyl or RO with R = phenyl or 2,6-bis (l, l-dimethylethyl) -4-methylphenyl. An example of a non-ionic catalytically active partial structure is given if one or more of the substituents RI to R8 are - (CH2) _n -P (alkyl) 2. The exocyclic Si-substituted substituents R2 to R8 which are not substituted by catalytically active substructures are preferably ao-butyl, cyclohexyl and / or ao-octyl groups, particularly preferably ao-butyl groups, both in the ionic and in the nonionic case ,

According to the invention it can be provided that the substituent R9 is a further substituent according to formula (I). This includes oligomeric catalysts with more than one silsesquioxane unit, for example dimers or trimers.

The fact that the distribution of the catalyst in a two-phase system can be influenced means that a process can be carried out which, instead of exclusively separating the starting material by distillation, permits extraction which takes place at the same time as the catalyzed reaction or is carried out downstream of the catalyzed reaction. In particular, a process can be implemented in which the catalyst and the starting material are preferably in the non-polar phase and the oligomeric polyisocyanate is preferably in the polar phase. To obtain the desired oligomer, only the polar solvent has to be distilled off after phase separation. Reactive extraction processes can also be implemented.

For the purposes of the present invention:

Alkyl: acyclic aliphatic hydrocarbon residues that do not contain any C-C multiple bonds. Alkyl is preferably selected from the group consisting of methyl, ethyl, propyl, 2-propyl, n-butyl, isobutyl, sec-butyl, isobutyl, n-pntyl, a-pentyl, Pentyl, nI Iexyl, nI Ieptyl, n-octyl, n-nonyl and / or n-decyl.

Cycloalkyl: cyclic aliphatic (cycloaliphatic) hydrocarbons with in particular 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms, where the hydrocarbons can be saturated or unsaturated (but not aromatic), unsubstituted or mono- or polysubstituted. The cycloalkyl radicals can furthermore be bridged once or several times, for example in the case of adamantyl, bicyclo [2.2.1] heptyl or bicyclo [2.2.2] octyl. Cycloalkyl is preferably selected from the group comprising cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, adamantyl, cyclopentenyl, cyclohexenyl, cycloheptenyl and / or cyclooctenyl. Alkenyl: acyclic aliphatic hydrocarbon radicals which have at least one CC double bond. Alkenyl is preferably selected from the group comprising ethenyl (vinyl), propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl and / or decenyl.

Alkynyl: acyclic aliphatic hydrocarbon radicals which have at least one C-C triple bond. Alkynyl is preferably selected from the group comprising ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl, octynyl, nonynyl and / or decynyl.

Aryl: aromatic hydrocarbons with up to 14 ring members, especially phenyls and naphthyls. Each aryl radical can be unsubstituted or mono- or polysubstituted, and the aryl substituents can be the same or different and can be in any and possible position of the aryl. Aryl is preferably selected from the group containing phenyl, 1-naphthyl and 2-naphthyl, which can each be unsubstituted or substituted one or more times. A particularly preferred aryl is phenyl, unsubstituted or mono- or polysubstituted.

Heteroaryl: a 5- or 6-membered cyclic aromatic radical which contains at least 1, optionally also 2, 3, 4 or 5 heteroatoms, where the heteroatoms are each independently selected from the group S, N and O and the heteroaryl Radical may be unsubstituted or mono- or polysubstituted; in the case of substitution on the heteroaryl, the substituents can be identical or different and can be in any desired position of the heteroaryl. It is preferred that the heteroaryl radical is selected from the group consisting of benzofuranyl, benzoimidazolyl, benzothienyl, benzothiadiazolyl, benzothiazolyl, benzotriazolyl, benzooxazolyl, benzooxadiazolyl, quinazolinyl, quinoxalinyl, carbazolyl, quinoluryl, furlylenzylyl, diblenzylanyl, diblenzylanyl, diblenzylanyl, diblenzylanyl, diblenzylanyl, dibenzylyl, furlylenzylyl, dibenzylyl, furl , Imidazolyl, imidazothiazolyl, indazolyl, indolizinyl, indolyl, isoquinolinyl, isoxazoyl, isothiazolyl, indolyl, naphthyridinyl, oxazolyl, oxadiazolyl, phenazinyl, phenothiazinyl, phthalazinyl, pyrazolyl, pyridyl, 3-pyridyl, 2-pyridyl, 2-pyridyl, 2-pyridyl, 2-pyridyl, 2-pyridyl, Pyridazinyl, pyrimidinyl, pyrazinyl, purinyl, phenazinyl, tetrazole, thienyl (thiophenyl), triazolyl, tetrazolyl, thiazolyl, thiadiazolyl and / or triazinyl.

Heterocyclyl: aliphatic saturated or unsaturated (but not aromatic) cycloalkyls with in particular three to ten, ie 3, 4, 5, 6, 7, 8, 9 or 10 ring members, in which at least one, optionally also two or three carbon atoms by a hetero atom or a heteroatom group each independently selected from the group consisting of O, S, S (= 0) ₂ , N, NH and N (Cl-8-alkyl), preferably N (CH3), are replaced, the ring members being unsubstituted or can be substituted one or more times. Heterocyclyl radicals from the group comprising azetidinyl, aziridinyl, azepanyl, azocanyl, diazepanyl, dithiolanyl, dihydroquinolinyl, dihydropyrrolyl, dioxanyl, dioxolanyl, dioxepanyl, dihydroindenyl are preferred Dihydropyridinyl, hydropyridinyl dihydrofuranyl, dihydroisoquinolinyl, Dihydroindolinyl, dihydroisoindolyl, imidazolidinyl, isoxazolidinyl, morpholinyl, oxiranyl, oxetanyl, pyrrolidinyl, piperazinyl, 4-methylpiperazinyl, piperidinyl, pyrazolidinyl, pyranyl, tetrahydropyrrolyl, tetrahydropyranyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, Tetrahydroindolinyl, tetrahydrofuranyl, tetra-, Tetrahydrothiophenyl, tetrahydro-pyridoindolyl, tetrahydronaphthyl, tetrahydro-carbolinyl, tetrahydroisoxazolo-pyridinyl, thiazolidinyl and / or thiomorpholinyl.

Perfluoroaryl: aryl radicals as defined above, where all aromatically bound hydrogen atoms have been replaced by fluorine atoms.

Perfluoroalkenyl: alkenyl radicals as defined above, where all hydrogen atoms have been replaced by fluorine atoms.

Perfluoroalkynyl: alkynyl radicals as defined above, where all hydrogen atoms have been replaced by fluorine atoms.

Alkoxy: alkyl group attached via an oxygen atom as defined above.

Perfluoroalkyl: alkyl radicals as defined above, where all hydrogen atoms have been replaced by fluorine atoms.

Perfluoroalkoxy: alkoxy radicals as defined above, where all hydrogen atoms have been replaced by fluorine atoms.

Polyoxyalkylene: polyether groups obtained from the polymerization of alkylene oxide units, in particular polymers, copolymers and block copolymers of ethylene oxide and propylene oxide.

Carboxylate: salts of carboxylic acids, especially of alkyl and aryl carboxylic acids.

Preferably:

R2, R3, R4, R5, R6, R7 and R8 ao-butyl,

RI is - (CFO _ni -PAlkyF or - (CFO _ni -PAlkyFX with nl = 2, 3, 4, 5, 6, 7 or 8 and

X is selected from the group comprising

R13-COO with R13 = CH3-, CH3CH2-, n-propyl, ao-propyl, ieri.-butyl, tert.-amyl, CH3 (CH2) _n - with n = 4, 5, 6, 7, 8, phenyl , 4-methoxyphenyl and / or 3,4,5-trimethoxyphenyl, R14-0 with R14 = phenyl or 2,6-bis (l, l-dimethylethyl) -4-methylphenyl.

For example, the partition coefficient K = x «- _HePtan / x _Acetomt rii, defined as the amount of a compound in the non-polar phase divided by the amount of the compound in the polar phase, of a catalyst of the general formula (I) with RI = - ( C 11:) ₃ - P (Be; - Buty I) ₃ ⁺ CH ₃ COO and R2 to R8 = Ao-butyl in the n-heptane / acetonitrile system determined to be 0.74.

The synthesis of the ionic silsesquioxane catalysts SQ ⁺ R-COO or SQ ⁺ RO (SQ + stands for [3- (3,5,7,9, ll, 13,15-heptaisobutylpentacyclo [9.5.1.1 ^3.9 .l ^{5 15.} L ^{7 13} ] - octasilox-l-yl) propyl] (triisobutyl) phosphonium substituents) can be achieved as follows:

A mixture of l- (3-iodopropyl) -3,5,7,9, ll, 13,15-heptaisobutylpentacyclo [9.5.1.1 ³ ' ⁹ .l ^{5 15} . l ^{7 '13} ] - octasiloxane and triisobutylphosphine in toluene was heated under reflux and stirred. The quaternary salt obtained is isolated by removing the solvent in a partial vacuum. The residue is then dissolved in dichloromethane and a suspension of the corresponding silver carboxylate Ag ⁺ R-COO or silver alcoholate Ag ⁺ RO in water is added. The mixture is stirred at room temperature. The mixture is then filtered, the organic phase is separated off and dried over sodium sulfate. The end product SQ ⁺ R-COO or SQ ⁺ RO is obtained after removing the solvent in a partial vacuum.

Examples of catalysts that can be obtained in this way are:

Catalyst 1 (SQ ⁺ CH ₃ -COO)

Catalyst 2 (SQ ⁺ tert-butyl-COO)

Catalyst 3 (SQ ⁺ CH ₃ (CH ₂ ) ₈ -COO)

Catalyst 4 (SQ ⁺ phenyl-COO)

Catalyst 5 (SQ ⁺ 4-methoxyphenyl-COO)

Catalyst 6 (SQ ⁺ 3,4,5-trimethoxyphenyl-COO)

Catalyst 7 (SQ ⁺ phenyl-O)

Catalyst 8 (SQ ⁺ 2,6-bis (l, l-dimethylethyl) -4-methylphenyl-0)

Catalyst 9 (SQ ⁺ CH ₃ -CH (OH) -COO)

Catalyst 10 (SQ ⁺ CF ₃ -COO) Examples

In the following examples, the following were used as reagents: 1,6-diisocyanatohexane (1,6-HDI), the corresponding isocyanurate of 1,6-HDI (1,3,5-tris (6-isocyanatohexyl) -1,3,5 -triazinane-

2.4.6-trion, "symmetrical trimer"). A mixture of the isocyanurate of 1,6-HDI ("symmetrical trimer") and the iminooxadiazinedione of 1,6-HDI ("asymmetrical trimer") in a ratio of> 95: 1 and traces of higher oligomers is referred to below as 1.6- Designated HDI trimer. A commercially available 1,6-HDI oligomer mixture was also included

1.6-HDI trimer and higher oligomers in a ratio of 63.05% by weight 1.6-HDI trimer ("A3"), 21.00% by weight 1.6-HDI pentamer ("A5"), 8, 76% by weight 1,6-HDI heptamer ("A7") and 7.19% by weight 1,6-HDI nonamer ("A9"). 1- (2-Methoxyphenyl) piperazine (MPP) was used as the internal standard for HPLC chromatography. 2,8,9-Tri-.vec-butyl-2,5,8,9-tetraaza-l-phosphabicyclo [3.3.3] undecane (TTPU) was also used.

The concentrations of 1,6-HDI, trimer and higher oligomers were determined by HPLC chromatography. For the measurement, 0.1 g of the sample to be measured was diluted to a volume of 5 ml with acetonitrile. From this solution, 0.5 ml was diluted to a volume of 5 ml with acetonitrile. 0.1 ml of this solution was mixed with 0.4 ml of a solution of 250 mg of MPP in 50 ml of acetonitrile and 0.5 ml of a solution of 4.07 g of dichlorobenzene in 391.53 g of acetonitrile. The solution was shaken for 30 seconds. Then 0.01 ml of the solution was injected into the sample loop of an HPIL device from Agilent (1200 Series), which was equipped with a Lichrospher 60RP Select B column (5 pm, 125 x 4 mm). The column was thermostatted to 35 ° C. A mixture of (A) 550 ml water, 360 ml acetonitrile and 90 ml phosphate buffer pH = 7 and (B) acetonitrile was used as eluent (1.5 ml / min). The gradient was 97% A (2 min) - 15 min - 37% A (2 min). The substances were detected with a UV detector at 254 nm (reference 360 nm). The HPLC method was calibrated with solutions of pure 1,6-HDI and the isocyanurate of 1,6-HDI. In the following, the symmetrical and the asymmetrical 1,6-HDI trimer were integrated together. The same response factor was assumed for the higher oligomers as for 1,6-HDI trimer.

In the context of the present invention, the description "SQ ⁺ " is used to describe the catalyst for the silsesquioxane cation, in which R2, R3, R4, R5, R6, R7 and R8 are ao-butyl and RI for - (C 11 p - P («- B u ty I) _3. An example of this name is the acetate SQ ⁺ CH ₃ COO-.

The synthesis of the ionic silsesquioxane catalyst SQ ⁺ CI LCOO was carried out according to the following procedure: a mixture of l- (3-iodopropyl) -3,5,7,9, ll, 13,15-heptaisobutyl-pentacyclo [9.5.1.1 ^{3 , 9} .l ^5.15 .l ^7.13 ] octasiloxane (9.86 g, 10 mmol) and triisobutylphosphine (2.02 g, 10 mmol) in 30 mL toluene was heated under reflux for 6 hours and stirred. The quaternary salt obtained was isolated by removing the solvent in a partial vacuum. The residue was then dissolved in 50 ml of dichloromethane and a suspension of the corresponding silver carboxylate Ag ⁺ CI LCOCT (1.67 g, 10 mmol) in 100 ml of water was added. The mixture was stirred at room temperature for 8 hours. The mixture was then filtered, the organic phase separated and dried over sodium sulfate. The final product SQ ⁺ CI LCCXV was obtained after removal of the solvent in a partial vacuum and characterized by means of high-resolution mass spectroscopy, infrared spectroscopy, X-ray fluorescence analysis (RLA) and multi-core NMR spectroscopy, whereby in the respective proton and carbon spectra those in the figure with letters identified groups were clearly assigned by comparison with literature data based on displacement and integral.

The mass spectra were measured by electrospray ionization on a Thermo Lisher Scientific Orbitrap XL. For this purpose, the samples were dissolved in CHCL, the solution was diluted with MeOH (containing 0.1% acetic acid) and injected into the ESI source system via the direct inlet using a syringe pump (electrospray voltage 4 kV, current 0.7 mA, volume flow Sheath Gas 5 arb, volume flow shock gas 5 arb, capillary temperature 300 ° C, capillary voltage 0.05 V, tube lens voltage 150 V). The detection was carried out with an Orbitrap ion trap.

The infrared spectra were measured on a Bruker alpha FT-fR spectrometer, the samples in each case being applied in bulk to the ATR crystal. The spectra were measured in the range from 4000 to 400 cm ¹ with a resolution of 4 cm ¹ by averaging 32 individual spectra against air as the background spectrum (averaging 100 individual spectra).

The ICP analysis was carried out on an ICP-MS-HR Element2 equipped with an ECM detector using argon as cooling, auxiliary, carrier and additional gas, generator power 1200 - 1600 watts, masses: ³¹ P, ²⁹ Si, quantification via external Calibration with rhodium as an internal standard.

The ³¹ P { ¹ H} NMR spectra were measured at 161.9 MHz in CDCI3 on a Bruker AV400 Ultrashield. The 11 NMR spectra were measured at 400 MHz in CDCI3 with a Bruker AV400. The chemical shifts were calibrated relative to the solvent signal (CDCI3, d = 7.26 ppm). ³ C { ¹ 11} NMR spectra were measured at 100.6 MHz in CDCI3 with a Bruker AV400 Ultrashield. The chemical shifts were calibrated relative to the solvent signal (CDCI3, d = 77.16 ppm). The assignment the signals were obtained by comparison with the ¹³ C APT NMR spectra of the products (APT = Attached Proton Test). Corresponding to the solvent signal of CDCb (positive polarity), signals with positive polarity were assigned to quaternary C atoms or CEb groups, signals with negative polarity to CH or CH3 groups. The type of splitting is specified as a singlet (s), two singlets (2xs), three singlets (3xs), doublet (d), triplet (t), multiplet (m) or broad signal (b).

Catalyst SQ ⁺ CI ECOCT

HR-MS (ESI): calculated 1059.47935 (C ₄₃ H ₉₆ 0i ₂ PSi ₈ ⁺ ), found 1059.4753. FT-fR 2913.0 (s), 1463.77 (s), 1365.93 (s), 1228.76 (m), 1084.29 (b), 837.48 (m), 743.57 (m ), 472.35 (m) cm ¹ .

The silicon and phosphorus content was determined by ICP analysis to be 17.0% by weight Si (theoretically: 20.1%) and 2.1% by weight P (theoretically: 2.8%).

³¹ R {Ή} NMR (CDCI3, 161.9 MHz): d = 30.24 (s) ppm. Table 1-la: Chemical shift and assignment of the characteristic signals for catalyst 1 (SQ ⁺ CHs-COO) in the Ή NMR spectra.

Table 1-lb: Chemical shift and assignment of the characteristic signals for catalyst 1 (SQ ⁺ CHs-COO) in the ³ C f ¹ 11} NMR spectra.

The present invention is explained in more detail with reference to the following examples and the figures, but without being restricted thereto. Show it:

FIG. 1 shows the arrangement of the glass vessels in Example 1

FIG. 2a the concentration profile of the non-polar phases from Example 1

FIG. 2b the concentration profile of the polar phases from example 1

FIG. 3a a simulation of a concentration profile in non-polar phases

FIG. 3b a simulation of a concentration profile in polar phases

FIG. 4a the concentration profile of the non-polar phases from example 3

FIG. 4b the concentration profile of the polar phases from example 3

FIG. 5 shows a reaction method with a fractional extractive reaction

FIG. 6a and 6b further reaction processes with fractional extractive reaction.

example 1

The fractionated extraction was demonstrated using the following procedure: First, 15 mF n-I Ieptane and 2.5 mF anhydrous acetonitrile were equilibrated at 60 ° C in 15 glass vessels. The glass vessels were numbered 1 to 15. A cyclic process was then repeated 40 times:

0.1 mF of a mixture of approx. 50% (mass fraction in each case) acetonitrile and 25% 1,6-HDI and 25% 1,6-HDI trimer were added to the central vessel (No. 8). - All glass jars were stirred for 3 minutes. After weaning (approx. 5

Seconds) 5 mF were removed from the upper, n-Icptan-rcichen phase. 0.5 mF (from tubes 1 to 8) and 0.4 mF (from tubes 9 to 15) of the lower, acetonitrile-rich phase were also removed.

From vials 1 to 14 (number j), the upper phase sample was added to the next vial (number _j +1). The upper phase sample from vessel 15 was made as raffinate collected and placed in tube # 1, 5 mL of monomer and trimer free equilibrated n-heptane.

The samples from the lower phases were distributed as described in the previous step, but distributed in the opposite direction to the vessels. The extract was removed from vessel No. 1 and monomer-free and trimer-free acetonitrile was added to vessel 15.

The procedure is shown schematically in FIG. 1 reproduced. At the end of the experiment, a sample of the upper and the lower phase was analyzed from each of the vessels by means of HPLC and a concentration profile was created therefrom.

To simulate the procedure, a discontinuous model based on batch contacts and a linear driving force approximation was used for the mass transfer between the phases.

The liquid-liquid equilibrium parameters in such a model (non-linear equilibrium isotherms) were trimer for the system acetonitrile / nI ieptane / l, 6- 1, 6-111) 1/1, 6- 1, 6- 111) experimentally determined at 60 ° C. For this purpose, the phase diagrams for the ternary systems n-heptane / acetonitrile / 1,6-HDI, n-heptane / acetonitrile / 1, 6-HDI trimer, and nI ieptane / 1, 6- 111) 1/1, 6- 1 IDI-Tri cr determined at a temperature of 60 ° C via turbidity titration. Ternary mixtures of acetonitrile, 1,6-HDI and 1,6-HDI trimer are miscible in the entire range and form only one phase.

A mixture of 1.42 g of n-heptane, 1.65 g of acetonitrile and different amounts of 1,6-HDI (0.11347, 0.18034, 0.28166, 0 , 35709, 0.4407 or 0.55099 g) equilibrated with stirring for 2 hours at 30 ° C or 60 ° C. The two phases were then separated from one another and a sample was taken from each of the two phases for HPLC chromatography. The observed distribution curves can be described with the following formula (I), where X _{A stands} for the mass fraction of 1,6-HDI in nI ieptane and T for the temperature. _Extrapolated from the slope of the curves to low concentrations, the partition _coefficient K = x _«-HePtan / x _Acetomt rii is calculated from 1,6-HDI to 0.127 at 30 ° C and 0.189 at 60 ° C. 1,6-HDI is therefore preferably soluble in the acetonitrile-rich phase. x _A = - (0.07067 x T + 18.90040) xx _A ² + (-0.08681 x T + 34.22076) xx _A (FI)

To determine the distribution coefficient of the 1,6-HDI trimer, a mixture of 1.42 g of n-heptane, 1.65 g of acetonitrile and various amounts of 1.6-HDI trimer (0.05798, 0.16823, 0 , 18819, 0.20261, 0.2964, 0.31701 or 0.42409 g) with stirring for 2 hours at 30 ° C or 60 ° C equilibrated. The two phases were then separated from one another and a sample was taken from each of the two phases for HPLC chromatography. The observed distribution curves can be described with the following formula (F-II), where X _A 3 stands for the mass fraction of 1,6-HDI trimer in nI ieptane and T for temperature. _Extrapolated from the slope of the curves to low concentrations, the partition _coefficient K = x _«-heptane / x _acetonit rii of 1.6-HDI trimer is calculated to be 0.0094 at 30 ° C and 0.038 at 60 ° C. 1,6-HDI trimer is therefore preferably soluble in the acetonitrile-rich phase. The partition coefficient for the higher oligomers was set equal to the partition coefficient of the 1,6-HDI trimer.

X _A3 = (-2.66103 x T + 912.88226) xx _A3 (FP)

The mass transition parameters for monomer, trimer, pentamer, heptamer and nonamer were estimated from the diffusion coefficients known from the literature to be 0.75, 0.39, 0.29, 0.23 and 0.20 min ¹ , respectively.

The experimentally determined concentration profiles after 40 runs and the mathematical modeling in the equilibrium state are shown in FIG. 2a (upper, nIcptan-rciche phase) and FIG. 2b (lower, acetonitrile-rich phase). With the counter j, the x-axes indicate the number of the respective vessel and the y-axes the mass fraction M of the respective component in the non-polar phase (M _u ) and polar phase (M _p ). Rectangles () for the measured values and the upper line for the result of the simulation with regard to vessel number 1 are assigned to the 1,6-HDI trimer ("A3"). Rectangular rectangles (¨) and the bottom line with regard to vessel number 1 are assigned according to the monomeric 1,6-HDI ("A").

From FIG. 2a and 2b it can be seen that it is possible to separate monomeric and trimeric 1,6-HDI from one another by means of fractional liquid-liquid extraction. Mathematical modeling correlates best with the experimental data on the trimer. From this it is concluded that its profile is already close to the state of equilibrium.

Example 2

In this example, the simulations from Example 1 were additionally carried out with 1% by weight (based on the amount of 1,6-HDI originally used) of a catalyst which is distributed predominantly in the n-heptane-rich phase. The distribution coefficient of the catalyst SQ ⁺ CI LCCX L was determined experimentally by dissolving 0.100 g of the catalyst obtained as described above in a mixture of nI ieptane (5 g) and acetonitrile (5 g). The mixture was heated to 60 ° C with stirring for 2 hours. The stirrer was then switched off and the two phases were separated. 1 g solution was obtained from each phase removed, the solvent removed and the remaining residue weighed. The partition coefficient K = x «- _HePtan / x _Acetomt rii is calculated as the ratio of the measured amount of the catalyst dissolved in the n-heptane phase and the measured amount of the catalyst dissolved in the acetonitrile phase 0.74.

The distribution coefficient of the catalyst TTPU was also determined experimentally by dissolving 0.103 ml of TTPU in a mixture of nI ieptane (5 g) and acetonitrile (5 g). The mixture was heated to 60 ° C with stirring for 2 hours. The stirrer was then switched off and the two phases were separated. 1 g of solution was removed from each phase, the solvent was drawn off and the remaining residue was weighed. The partition coefficient K = x «- _HePtan / x _acetonit rii of TTPU is calculated as the ratio of the measured amount of TTPU dissolved in the nI Ieptane phase to the measured amount of TTPU dissolved in the acetonitrile phase K = 3.9.

The results of the simulation analogous to FIG. 2a and 2b taking into account the partition coefficient of the catalyst SQ ⁺ CH ₃ COO of K = 0.74 are shown in FIG. 3a and 3b. The mass fraction of the catalyst is shown by the dashed line. The curves for the 1,6-HDI and the 1,6-HDI trimer correspond to those from FIG. 2a and 2b. It can be seen that the catalyst is distributed towards vessel number 15 and can thus be separated from the product, the 1,6-HDI trimer.

Example 3

In this example, the procedure was analogous to example 1. However, a reaction mixture was used, as was also obtained in an actual experiment. The composition of the mixture was 0.5% by weight of the catalyst SQ ⁺ CI LCOCL ("Cat."), 24.88% by weight of 1,6-HDI monomer ("A"), 15.68% by weight of 1 , 6-HDI trimer ("A3"), 5.22% by weight 1.6-HDI pentamer ("A5"), 2.18% by weight 1.6-HDI heptamer ("A7") and 1.79% by weight 1,6-HDI nonamer ("A9") in 49.75% by weight acetonitrile. Such a composition can be obtained in a simple manner from 50% by weight of acetonitrile, 25% by weight of 1,6-HDI and 25% by weight of a commercially available 1,6-HDI oligomer mixture and the corresponding addition of catalyst.

The experimentally determined mass fractions of A, A3, A5, A7 and A9 are shown in FIG. 4a and FIG. 4b reproduced as corresponding data points. FIG. 4a shows the mass fractions in the non-polar phase and FIG. 4b in the polar phase. FIG. 4a and 4b as solid or different dashed lines, results of simulations of the concentration profile of the individual components. It can be seen that the catalyst follows the nI icptan and is driven completely towards the raffinate (vessel number 15). In this way, the catalyst can be separated from the product. It can also be seen how unreacted monomer can be separated from the reaction mixture and is thus available for a continuous reaction process.

It should be generally noted that in the figures described above, the deviations of the simulated concentration profiles from the experimentally determined ones stem from the fact that a steady state was taken as a basis in the simulations. In the experiments, this has in some cases not yet been reached after 40 cycles.

Example 4

In this example the distribution of the catalyst SQ ⁺ CI ECOCT was investigated experimentally. The extract and the raffinate from Example 4 after the 40th cycle were analyzed for the presence of silicon and phosphorus using ICP analysis. 0.0084% by weight of Si and 0.0009% by weight of P were found in the raffinate. In contrast, the extract had 0.0380% by weight of Si and 0.0038% by weight of P. In the extract there is a 4.4 times higher catalyst concentration than in the raffinate. Evidence of the enrichment of the catalyst in the extract was thus provided.

FIG. 5 schematically shows a reaction method with a fractional extractive reaction. The trimerization of 1,6-HDI is explained using this figure as an example.

Stream 1 with 1,6-HDI monomer and a trimerization catalyst is introduced into the central region of the extraction column 2. The extraction column 2 is designed as a multi-stage mixer-separator system operated in countercurrent for a liquid-liquid extraction. Acetonitrile is passed through the column from top to bottom, following gravity. N-I Icptan is led from bottom to top. In column 2 there is now an enrichment of 1,6-HDI and the catalyst in the n-I ieptane-rich phase analogously to Example 3. The catalyst is selected such that it is partitioned more strongly than 1,6-HDI in the n-I ieptane-rich phase, but can also still be present in the acetonitrile-rich phase.

The extract containing 1,6-HDI thus obtained is removed as stream 3 from the upper region of column 2 and introduced into the solvent recovery unit 4. The nI ieptane-rich phase is distilled off in the solvent recovery unit 4. The recovered 1,6-HDI together with the catalyst is re-entered as stream 6 in the middle area of the extraction column 2. Furthermore, the distilled-off non-polar solvent is fed back to the lower end of the extraction column 2 as stream 5. Due to its higher polarity, the 1,6-HDI trimer is enriched in the acetonitrile-rich phase. This is withdrawn at the bottom of column 2 as stream 7 and introduced into the solvent recovery unit 8. The polar solvent is distilled off and fed as stream 9 to the upper end of column 2. The 1,6-HDI trimer obtained after the distillation is removed as product stream 10.

This procedure reduces the contact time between 1,6-HDI trimer and other monomers and the catalyst. As a result, the speed of the undesirable subsequent reactions decreases. A high turnover of 1,6-HDI is achieved with a high selectivity for the trimer. The trimer product is obtained in the raffinate free of catalyst and monomer. The separated solvent fractions are used again for the operation of the plant.

FIG. 6a and 6b schematically show one of the previously in connection with FIG. 5 discussed reaction processes analogous process with internal solvent recovery. The trimerization of 1,6-HDI is also explained here as an example.

Stream 1 with 1,6-HDI monomer and a trimerization catalyst is introduced into the central region of the extraction column 2. The extraction column 2 is designed as a multi-stage mixer-separator system operated in countercurrent for a liquid-liquid extraction. Acetonitrile is passed through the column from top to bottom, following gravity. N-I Ieptau is led from bottom to top. Analogous to example 3, in column 2 there is now an enrichment of 1,6-HDI and the catalyst in the n-I-ceptane phase. The catalyst is selected such that it is partitioned more strongly than 1,6-HDI in the n-Ictau-rciche phase, but can also still be present in the acetonitrile-rich phase.

The extract containing 1,6-HDI thus obtained is removed as stream 3 from the upper region of column 2 and introduced into the solvent recovery unit 4. In the solvent recovery unit 4, the n-Ictau-rciche phase is distilled off. The recovered 1,6-HDI together with the catalyst is re-entered as stream 6 in the middle area of the extraction column 2. Furthermore, the distilled-off non-polar solvent is fed back to the lower end of the extraction column 2 as stream 5.

Due to its higher polarity, the 1,6-HDI trimer is enriched in the acetonitrile-rich phase. This is drawn off in the lower region of column 2 as material stream 7 and introduced into the solvent recovery unit 8. The polar solvent is distilled off and fed as stream 9 to the upper end of column 2. The 1,6-HDI trimer obtained after the distillation is removed as product stream 10. In the in FIG. 6a, the fact that an acetonitrile phase is present at the lower end of column 2, which is essentially free of further constituents, is also used. Then, bypassing the solvent recovery unit 8 in an internal recycling process, the material stream 11 can be fed directly onto the upper end of the column 2.

In the in FIG. 6b, there is a heptane phase at the upper end of column 2 which is essentially free of other constituents, with the exception of the catalyst. Bypassing the solvent recovery unit 4, it is drawn off as material stream 12 in an internal recycling. In the solvent recovery unit 14, the catalyst is separated off and fed to stream 1 for further use in the oligomerization reaction. The solvent stream 14 obtained after the solvent recovery unit is fed to the lower end of the column.

Overall, the energy balance of the process is further improved since the amount of external material separation required can be reduced. Of course, this variant also has the one previously described in connection with the method from FIG. 5 described advantages.

Claims

claims

1. Process for the preparation of oligomeric compounds from the reaction of a monomer with one or more monomers and / or with an oligomer which comprises units based on this monomer, the monomer and / or the oligomer being selected such that products are present in the reaction are formed which have a larger number of polar functional groups than the individual monomer and the method comprises the following steps: a) introducing at least one monomer into an extraction container (2) which is used for fractional liquid-liquid extraction with a two-phase Solvent system pair, comprising a first solvent system and a second solvent system, is set up, b) reaction of the monomer in the extraction container (2) to form a reaction mixture comprising oligomers; c) Fractionated liquid-liquid extraction of the reaction mixture obtained in step b) in the extraction container (2) using the first and second solvent systems, the first solvent system comprising a linear, branched or cyclic alkane chloroaromatic and / or bromine aromatic and the second solvent system comprises a solvent which is selected from the group comprising nitriles, cyclic carbonates, cyclic ethers, sulfones, sulfoxides, nitroaromatics, lactones, esters, inorganic esters, aldehydes, formamides, halogenated (where halogen is not fluorine) alkanes and / or dialkyl ethers of oligoethylene oxides; and d) removing a stream (7) comprising the second solvent system and the oligomer formed in step b) from the extraction container (2).

2. The method according to claim 1, wherein the monomer is a monomolecular, dimolecular or trimolecular di- or polyisocyanate.

3. The method according to claim 1, wherein the monomer is an alkylene oxide and reacts with an alcohol in step b).

4. The method according to claim 1, wherein in the fractional liquid-liquid extraction in step c), the first and second solvent systems are guided in countercurrent to one another.

5. The method according to claim 1, wherein the extraction container (2) is designed as a packed column or pulsed or non-pulsed sieve plate column.

6. The method according to claim 1, wherein the extraction container (2) is designed as a multi-stage mixer-separator system.

7. The method according to claim 1, wherein after step d) the second solvent system is separated and reintroduced into the extraction container (2).

8. The method according to claim 1, further comprising the steps of: e) removing a stream (3) comprising the first solvent system and the monomer not reacted in step b) from the extraction container (2); f) separation of the first solvent system from the unreacted monomer; g) introducing the first solvent system obtained in step f) into the extraction container (2); and h) introducing the unreacted monomer obtained in step f) into the extraction container

(2).

9. The method according to claim 1, further comprising the steps of: i) removing a stream of material (11) from the extraction container (2), the stream of material (11) removed in this process containing the second solvent system and being free of products from the reaction in step b) , followed by feeding this material stream (11) directly back to a location of the extraction container (2) that is different from its removal; and / or k) withdrawing a stream (12) from the extraction container (2), the stream (12) removed in this process containing the first solvent system and being free of monomers, followed by separating off any catalyst present and feeding this stream (12, 14) at a different location from the extraction container (2).

10. The method of claim 1, wherein the first solvent system comprises linear, branched and / or cyclic alkanes and the second solvent system comprises acetonitrile.

11. The method according to claim 1, wherein the reaction in step b) takes place in the presence of a catalyst and the catalyst is selected such that it is present to a greater extent in the first solvent system than in the second solvent system.

12. The method according to claim 11, wherein the catalyst is used in a proportion of> 0.1% by weight to <35% by weight, based on the amount of monomer used.

13. The method according to claim 11, wherein after step (b) no deactivation of the catalyst is carried out.

14. The method according to claim 11, wherein the catalyst comprises polyhedral oligomeric silsesquioxanes of the general formula (I):

wherein RI, R2, R3, R4, R5, R6, R7 and R8 are independently selected from groups (Ia) and / or (Ib) with the proviso that at least one of the radicals RI, R2, R3, R4, R5 , R6, R7 and R8 is selected from group (Ib):

(La): alkyl, cycloalkyl, aryl, heteroaryl, heterocyclyl, alkenyl, alkynyl, perfluoroaryl, perfluoroalkenyl, perfluoroalkynyl, alkoxy, perfluoroalkyl, perfluoroalkoxy, polyoxyalkylene,

(Lb): -A-R9, where:

A = (CR2) _n with n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, and R for identical or different substituents from group H and / or Ia; or

A = ortho-, meta- or para-C R, where R has the meaning given above; or A = (CR ₂ ) ₂ -Si (R ₂ ) - (CR ₂ ) ", with n = 1, 2, 3, 4, where R has the meaning given above; and

 R9 = N (R10) (R11), P (R10) (R11), N (R10) (R11) (R12) X, P (R10) (R11) (R12) X,

 COOM, OM, or a further substituent according to formula (I), wherein

 RIO, RI 1 and RI 2 are independently alkyl or aryl,

X is carboxylate, alcoholate, hydrogen carbonate, or carbene and M is ammonium, phosphonium, an alkali or alkaline earth metal cation.

15. The method of claim 14, wherein:

R2, R3, R4, R5, R6, R7 and R8 are a-butyl, RI is - (CH ₂ ) _ni -PAlkyl ₂ or - (CH ₂ ) _ni -PAlkyl ₃ X with nl = 2, 3, 4, 5 , 6, 7 or 8 and

X is selected from the group comprising

R13-COO with R13 = CH3-, CH3CH ₂ -, n-propyl, ao-propyl, ieri.-butyl, tert.-amyl, CH ₃ (CH ₂ ) _n - with n = 4, 5, 6, 7, 8, phenyl, 4-methoxyphenyl and / or 3,4,5-trimethoxyphenyl, R14-0 with R14 = phenyl or 2,6-bis (l, l-dimethylethyl) -4-methylphenyl.