Catalytic process for the preparation of bridged nitrogen-containing compounds

Abstract: A process for preparing bridged nitrogen-containing compounds which comprises contacting a cyclic nitrogen-containing compound reactant with a mixed metal oxide catalyst under conditions effective to produce the bridged nitrogen-containing compound.

Description: Brief Summary of the Invention Technical Field This invention relates to a process for preparing bridged nitrogen-containing compounds in particular triethylene amine or 2-methyl-triethyleneamine, which comprises contacting a cyclic nitrogen-containing compound reactant with a mixed metal oxide catalyst under conditions effective to produce the bridged nitrogen-containing compound. Background of the Invention Triethylenediamine, also referred to as 1,4-diazabicyclo[2.2.2]octane or DABCO, is an item of commerce which is used as a catalyst for -OH + OCN- reactions to form the urethane linkage in polyurethanes. Various processes for the production of triethylenediamine are known. For example, triethylenediamine may be produced by the method disclosed in WO 87/03592. As disclosed therein, triethylenediamine may be produced by bringing an amine compound having a specific amino group into contact with a crystalline metal silicate catalyst wherein the molar ratio of silicon dioxide (SiO 2 ) to an oxide of a trivalent metal (M 2 O 3 :M being a trivalent metal) is 12 or more. EP-A-0158319 discloses a method for preparing 1,4-diazabicyclo[2.2.2]octanes by contacting acyclic or heterocyclic amines with a high-silica zeolite having a silica to alumina ratio of at least 20 to 1. EP-A-0263463 discloses a method for preparing 1,4-diazabicyclo[2.2.2]octane and C-substituted 1,4-diazabicyclo[2.2.2]octane by reacting a particular heterocyclic amine in the presence of L-zeolites, phosphates with zeolite structure and zirconium phosphates as catalysts. Romanian Socialist Republic Specification 85563 discloses a process for the preparation of triethylenediamine characterized by the fact that N,N-dihydroxyethylpiperazine is cyclized in the gaseous phase on a alumina catalyst alkalized with a base chosen from alkali or alkaline earth hydroxides in an amount of from 0.01-10 weight percent based on alumina at a reaction temperature between 200°C and 550°C,- preferably 300°C-450°C, and an operating pressure between 0.1 and 10 atmospheres. US-A-4,973,709 relates to processes for the production of amines, more specifically, to processes for preparing triethylenediamine and/or one or more cyclic or acyclic amines by contacting one or more amine starting materials with one or more molecular sieves. By proper choice of catalysts and/or reaction conditions, the processes can be varied to alter their selectivity to a number of differing and useful products, including triethylenediamine and substituted triethylenediamines. In DE-A-2 442 929, a catalyst for the preparation of triethyleneamine is described which catalyst is Al 2 O 3 . US-A-3 166 558 teaches the use of certain gels which are supports for catalysts. In US-A-4.725 681 processes are described for preparing triethylenediamine in the presence of titanium or circonium containing catalyst. US-A-3 120 526 discloses a method for the preparation of triethylenediamine in the presence of a NaOH treated silica-alumina catalyst. The present invention relates to a process for preparing triethylenediamine or 2-methyl-triethylenediamine which comprises contacting a cyclic nitrogen-containing compound selected from the group consisting of 1-(2-hydroxyethyl)piperazine, 1,4-bis (2-hydroxyethyl)piperazine, 1-(2-hydroxypropyl)piperazine, 1-(2-aminoethyl)piperazine and 1,4-bis(2-aminoethyl)piperazine, with a mixed metal oxide catalyst comprising: (a) a material having the formula M x 2+ Q y 3+ (OH) 2x+3y-nz A z n-. aH 2 O wherein M is magnesium; Q is aluminum; and A is at least one anion providing a valence (n - ), wherein n is 1 to 4 and wherein a is a positive number, M, Q and A are provided in a proportion such that z/y is a number equal to or greater than 1, z has a value greater than zero such that x/z is between n and 12n, and 2x+3y-nz is a positive number, or (b) a material prepared by calcining the material of formula (I) having the formula M x 2+ Q y 3+ (OH) (2x+3y-nz)/2 D z n- wherein M, Q, x, y, z and n have the same meanings defined above in connection with formula (I), and D is at least one nonvolatile anion; under conditions effective to produce triethylenedimaine or 2-methyl-triethylenediamine. In a preferred embodiment, the invention relates to a process for preparing triethylenediamine which comprises contacting 1,4-bis(hydroxyethyl)piperazine with a catalyst consisting essentially of a magnesium-aluminum mixed metal oxide under conditions effective to produce triethylenediamine. The bridged nitrogen-containing compounds produced in accordance with the process of this invention are useful for a wide variety of applications such as polyurethane catalysts, acid scavengers and the like. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 67th Ed., 1986-87, inside cover. Also, for purposes of this invention, Group IIIB metal oxides embraces the lanthanides and actinides. As used herein, the term "oxide" embraces oxides, hydroxides and/or mixtures thereof. Detailed Description As indicated above, this invention relates to a process for preparing certain bridged nitrogen-containing compounds which comprises contacting a particular cyclic nitrogen-containing compound with a mixed metal oxide catalyst under conditions effective to produce the bridged nitrogen-containing compound. Suitable cyclic nitrogen-containing compound starting materials which can be employed in the process of this invention include 1,4-bis(2-hydroxyethyl)piperazine, 1-(2-hydroxyethyl)piperazine, 1,4-bis(2-aminoethyl)piperazine, and 1-(2-aminoethyl)piperazine. Suitable catalysts which can be employed in the process of this invention are magnesium:aluminum mixed metal oxides which are more fully described below. Both homogeneous and heterogeneous catalysts can be employed in the process. The amount of catalyst used in the process is not narrowly critical and is dependent on whether the process is conducted batchwise or continuously. If batchwise, the catalyst employed can range from about 0.01 weight percent or less to about 10 weight percent or greater of the total weight of the starting materials. If continuously, generally a fixed bed is employed. Suitable mixed metal oxides embraced within the scope of this invention are disclosed by Tanabe et al., Bulletin of the Chemical Society of Japan, Vol. 47(5), pp. 1064-1066 (1974). The mixed metal oxides described herein which can be used as catalysts may contribute to product selectivity and/or catalytic activity of the reaction and/or stability of the catalyst. As discussed hereinafter, the catalyst employed in this invention may also contain support(s), binding agent(s) or other additives to stabilize or otherwise help in the manufacture of the catalyst. The catalysts which comprise two or more metal oxides may be prepared in a wide variety of ways. For example, the two or more metal oxides can be provided from metal salts which can either be heated or precipitated to form the mixed metal oxides. Also, two or more metal oxides may be provided as a partial condensate on a support, such as a silica or alpha, beta or gamma alumina, silicon carbide, and the like, and then condensed by heating to effect polymerization to the desired oxide form. The two or more metal oxides may be condensed from hydrolyzable monomers to the desired oxides, indeed, to form oxide powders which can thereafter be compressed in the presence of a condensation catalyst to form pellets and larger structures of the mixed metal oxide catalyst. A blend of the powders and condensation catalyst can be made into a shapeable paste which can be extruded and cut into pellets according to conventional procedures. The extrudate may thereafter be fired to cure the condensation catalyst and fix the structure. The cut extrudate may be blended with a support material such as those characterized above, and the blend fired to fuse the mixed metal oxide catalyst to the support. In an embodiment of this invention, a magnesium salt, e.g., magnesium nitrate, and an aluminum salt, e.g., aluminum nitrate, are precipitated using ammonium hydroxide. The material is then washed with deionized water and calcined at a temperature of from about 350°C to about 450°C to afford the desired magnesium:aluminum mixed metal oxide catalyst. In another embodiment, a magnesium oxide, e.g., magnesium carbonate hydroxide pentahydrate, and an aluminum oxide, e.g., aluminum hydroxide hydrate, are added to deionized water and thoroughly mixed to form a paste. The paste is then calcined at a temperature of from about 350°C to about 450°C to afford the desired magnesium:aluminum mixed metal oxide catalyst. A preferred catalyst structure comprises a Group IIA and IIIA mixed metal oxide having a surface area of at least about 100 m 2 /gm which may or may not be bonded to a support material. The catalysts on a support preferably have a surface area greater than about 20 m 2 /gm to as high as about 260 m 2 /gm, or greater depending upon which metal oxides are employed. In the case of magnesium:aluminum oxides, the surface area can be greater than about 50 m 2 /gm to as high as about 260 m 2 /gm, more preferably, greater than about 100 m 2 /gm to as high as about 260 m 2 /gm, determined according to the single point N 2 method. The term "support," as used herein and in the claims, means a solid structure which does not adversely affect the catalytic properties of the catalyst and is at least as stable as the catalyst to the reaction medium. The support can function as a catalyst independent of the mixed metal oxide catalyst used herein, although it may have lower catalytic activity to the reaction. The support may act in concert with the catalyst to moderate the reaction. Some supports may contribute to the selectivity of the reaction. The catalyst structure can comprise from about 2 to about 60 percent by weight or greater of the support, more preferably from about 10 to about 50 percent by weight of the support, the remainder being the weight of the mixed metal oxides. Included in the weight of the support is the weight of any binding agent such as phosphates, sulfates, silicates, fluorides, and the like, and any other additive provided to stabilize or otherwise help in the manufacture of the catalyst. The support may be particles as large or larger than the catalyst component and "glued" to the catalyst by virtue of a binding medium. The support may constitute a separate phase in the process of extruding the catalytic structure. In this embodiment, the support forming material, preferably as a paste is blended with a paste of the catalyst or a partial condensate thereof. The paste may comprise the oxide forms of the support and the catalyst, each blended with water, and/or binding agents. The extrudate of the blend is passed through a multiorificed die and chopped into pellets of the desired sizes. The particles may be doughnut shaped, spherical, and the like. Then the particles are calcined to dry them and complete any condensation reaction in the support and/or the mixed metal oxide catalyst. The mixed metal oxide catalysts for use in this invention are materials having the formula: M 2+ x Q 3+ y (OH) 2x+3y-nz A n- z · a H 2 O wherein M is magnesium; Q is aluminum; and A is at least one anion providing a valence (n - ), wherein n is at least 1, e.g., between 1 and 4 and most often between 1 and 3, and wherein a is a positive number, M, Q, and A are provided in a proportion such that x/y is a number equal to or greater than 1, z has a value greater than zero and 2x+3y-nz is a positive number. M, Q and A may be selected to provide a layered structure. Preferably, x/y is in the range of 1 to 12, more preferably x/y is in the range of 1 to 6 and most preferably is in the range of 1 to 4. Preferably, z has a value such that x/z is between n and 12n, more preferably between n and 6n and most preferably between n and 4n. The composition of formula (I) also can include a wide range of anions, A. Any anion or combination of anions which can balance the charge of the cations can be used. Suitable anions include inter alia , halides (such as chloride, fluoride, bromide, and iodide), nitrite, nitrate, sulfite, sulfate, sulfonate, carbonate, chromate, cyanate, phosphite, phosphate, molybdocyanate, bicarbonate, hydroxide, arsenate, chlorate, ferrocyanide, borate, cyanide, cyanaurate, cyanaurite, ferricyanide, selenate, tellurate, bisulfate, as well as organic anions such as oxalate, acetate, hexanoate, sebacate, formate, benzoate, malonate, lactate, oleate, salicylate, stearate, citrate, tartrate, maleate, and the like. The class of metalate anions described in U.S. Patent No. 4,667,045, including metavanadate, orthovanadate, molybdate, tungstate, hydrogen pyrovanadate and pyrovanadate, also are suitable as anion A. Anions suitable for use in combination with the metal cations previously identified as being particularly suitable are carbonate, halide, phosphate, chromate, sulfate, hydroxide, oxalate, acetate, nitrate, hexanoate, sebacate, vanadate, molybdate, tungstate and ferrocyanate. The foregoing lists of suitable anions are meant to be illustrative and not exclusive. Those skilled in the art will recognize that other anions can be used provided that the specific type of cations and their relative amounts (x/y ratio) and the specific type of anions and their relative amount result in a mixed metal oxide composition. Included in the materials identified above are those based on exchangeable anionic clay minerals. Compositions of formula (I) wherein M is magnesium and Q is aluminum are related to hydrotalcites. In fact, mixed metal oxides prepared using magnesium as the divalent cation and aluminum as the trivalent cation exhibit the typical X-ray diffraction pattern of a hydrotalcite. In another preferred aspect, the process of this invention can utilize mixed metal oxide catalyst compositions prepared by calcining at an elevated temperature compositions according to formula (I). Suitable calcined compositions have the general formula: M 2+ x Q 3+ y (O) (2x+3y-nz)/2 D n - z wherein M, Q, x, y, z and n have the same meanings defined above in connection with formula (I), and D is at least one nonvolatile anion. Nonvolatile anions may include, inter alia , halides, nitrates, phosphites, phosphate, vanadate, molybdate, tungstate, sulfite, sulfate, chromate, arsenate, borate, chlorate and the like. This list is illustrative and not exclusive. Heat treating the formula (I) compositions to prepare the calcined mixed metal oxide compositions of formula (II) can be done, for example, at a temperature in the range of 200°C to 800°C for a period of time of about 12 to 24 hours under an inert atmosphere such as nitrogen or in appropriate cases under an oxidizing atmosphere such as air. Calcination of the mixed metal oxide composition dehydrates the composition and converts at least partially the metal hydroxides to metal oxides. Any nonvolatile anions may be present in the calcined material. Provided the calcination temperature is not excessive, the mixed metal oxide can be rehydrated to the mixed metal hydroxide with water. Generally, the mixed metal oxide can be restored readily if the calcination temperature does not exceed about 600°C. Mixed metal oxides which are calcined under more severe conditions are not easily rehydrated and lower surface area materials are obtained. Certain compositions falling within formula (I), such as hydrotalcite, which comprises a magnesium-aluminum hydroxide carbonate, are naturally occurring compositions. However, such compounds, as well as their related compositions, also can be prepared synthetically from inexpensive starting materials using well-known coprecipitation techniques. Procedures for direct synthesis of such materials are described in Itaya et al., Inorg . Chem . (1987) 26 :624-626; Taylor, R.M., Clay Minerals (1984) 19 :591-603; Reichle, U.S. Patent No. 4,476,324; Bish, D.L., Bull. Mineral (1980), 103 :170-175 and Miyata et al., Clays and Clay Minerals (1977), 25 :14-18. Using direct synthesis one has the ability to vary within wide limits the M +2 /Q +3 atomic ratio as well as the anion. For example, a composition of formula (I) where M +2 is magnesium, Q +3 is aluminum and A n- is carbonate can be prepared by adding, as aqueous solutions, (a) a mixture of nitrates, sulfates or chlorides of magnesium and aluminum in a desired atomic ratio of magnesium to aluminum, to (b) an aqueous solution of a stoichiometric amount of sodium hydroxide and a water soluble salt of the desired anion, e.g., sodium carbonate. The two solutions are mixed at a temperature of about 25°C to 35°C with vigorous stirring over a several-hour period to produce a slurry. The slurry then is heated for about 18 hours at a temperature within the range of about 50°C to 200°C (preferably between about 60°C to 75°C) in order to control crystallization and the ultimate particle size of the resulting crystals. After filtering, and thorough washing and drying, the solids are recovered, typically as a powder. Generally, the rate of metal ion addition to the aqueous caustic/anion solution is not critical and can be varied widely. For example, a preferred preparation method is described in Schaper, H. et al., Applied Catalysis , 54, 1989, 79-90. The reaction temperature also is not critical, although the temperature during the reaction preferably is kept below about 100°C. An important feature of the procedure is the use of efficient agitation during the mixing procedure to avoid the formation of undesired by-products. Loading of an anion A or D into the mixed metal oxide compositions is influenced by a variety of factors including (i) the amount of anion used in the preparation relative to the metal cations, (ii) the atomic ratio of the metal cations (x/y) in the preparation procedure, (iii) the size of the cations and anions and (iv) the preparation procedure. As used herein, "loading" is defined as the amount of available valences provided by a desired anion A or D expressed as a percentage of the total available valences for anion A or D. For example, carbonate loading in a hydrotalcite-type catalyst can be maximized by (i) using an excess (e.g., a greater than 3:1 molar ratio) of sodium carbonate to aluminum chloride during catalyst preparation and (2) adjusting the atomic ratio of magnesium to aluminum cations to about 2:1. Mixed metal oxide compositions suitable as catalysts also can be prepared from the native or synthetic hydrotalcite-type compositions by ion exchange. For example, hydrotalcite can be treated at ambient conditions with 0.01N phosphoric acid for about 18 hours to replace the carbonate anion with phosphate anion. A halide analog of hydrotalcite prepared directly or by anion-exchange could be contacted with molybdic acid or a water soluble salt thereof, or with a water soluble salt of tungstic acid or vanadic acid in order to substitute the transition metal anion for the halide anion in the catalyst structure thereby to produce a mixed metal oxide composition of formula (I). Other ion exchanges will be apparent to those skilled in the art. Calcined mixed metal oxide compositions may exhibit a higher level of selectivity/activity than uncalcined compositions. If a calcined mixed metal oxide catalyst composition experiences any decline in selectivity, it can be regenerated by a heat treatment in the presence of air to restore at least a portion of its initial level of selectivity/activity enhancement and reused. Conditions discussed above for calcining the hydrated mixed metal oxide compositions are suitable for regenerating compositions which have experienced a decline in activity. Catalysts having the formulas (I) and (II) above wherein M is magnesium, Q is aluminum, A is at least one of carbonate, bicarbonate, phosphate, sulfate and nitrate, x/y is between 1 and 20, z has a value which satisfies the relationship: x/z is between n and 12n, and a is a positive number, are generally preferred for vapor phase decarboxylation due to their combination of activity (conversion of precursor) and selectivity. A preferred process involves a vapor phase process using mixed metal oxide catalyst wherein M 2+ is magnesium, Q 3+ is aluminum, A n- is carbonate, x/y is about 1, and z is about 1. A group of preferred mixed metal oxide catalyst compositions which can be employed in the process of this invention is disclosed in US-A-5,064,804. This document teaches the compositions having formula I or formula II for the catalytic hydrolysis of alkylene oxide to alkylene glycol. The process of this invention may be effected in the liquid or vapor or supercritical liquid states or mixtures thereof. In this context, the vapor phase reaction is intended to refer to the general vapor state of the starting materials. Though the process conditions may range from subatmospheric or atmospheric to superatmospheric conditions, it is desirable to run the process from 133 Pa (about 1 mm Hg) to 665 kPa (about 5,000 mm Hg), preferably from 13.3 kPa (about 100 mm Hg) to 333 kPa (about 2,500 mm Hg). The temperature of the process may be as low as about 150°C to about 500°C. Preferably, the reaction temperature ranges from about 175°C to about 375°C, and most preferably from about 225°C to about 350°C. The process can be conducted in the presence of an inert diluent which can be either a liquid or gas. When a liquid diluent is employed, it should preferably be a good solvent for the starting materials, inert under the reaction conditions, and of such a nature that separation from the bridged nitrogen-containing compound product will not be difficult. For instance, the boiling points of the diluent and the bridged nitrogen-containing compound product should differ by an adequate amount and there should be no tendency of the diluent to form an azeotrope with the desired bridged nitrogen-containing compound product. Examples of useful liquid diluents that meet the foregoing qualifications include water, benzene, toluene, xylene, ethylbenzene, anisole, heptane, octane, nonane, decane, dibutyl ether, and the like. Hydrocarbons are preferred. Illustrative gaseous diluents include for example, nitrogen, methane, hydrogen, carbon monoxide or carbon dioxide. The gaseous diluent should of course be chosen so that it does not prevent the preparation of the desired products. While the use of such diluents may be beneficial, the process of this invention can be operated using pure starting material(s) as a liquid or gaseous feed. The degree of dilution of the starting materials with various diluents may vary considerably depending upon any process constraints restricting the use of the diluent. For example, in commercial production, the use of very large quantities of some gaseous diluents may be disadvantageous due to the cost of pumping large volumes of the gaseous diluent and increased difficulty in isolating the product, which increase the energy costs of the process. With liquid diluents, the use of very large quantities may be disadvantageous due to the energy cost associated with large recovery and recycle. If the process of this invention is to be carried out using a gaseous diluent, in general it is recommended that the starting material(s) constitute from about 1 to about 95, and preferably about 5 to about 50, mole percent of the starting material/carrier feed. Increasing the dilution of the starting material with a gaseous diluent such as hydrogen may tend to increase the selectivity of the reaction to the particular products desired. The amount of liquid diluent can vary widely, for instance, from no diluent to about 90 weight percent or greater of the total weight of the starting materials. The process of this invention is useful for preparing substituted and unsubstituted bridged nitrogen-containing compounds such as triethylenediamine, substituted triethylenediamines and the like. Illustrative bridged nitrogen-containing compounds prepared by the processes of this invention include, for example, triethylenediamine, 2-methyl-triethylenediamine and the like. Illustrative of suitable bridged nitrogen-containing compounds which can be prepared by the process of this invention include those permissible bridged nitrogen-containing compounds, including any permissible derivatives of described bridged nitrogen-containing compounds, which are described in Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, 1984. The bridged nitrogen-containing compound products produced by the process of this invention can be separated by distillation. For example, a crude reaction product can be subjected to a distillation-separation at atmospheric or reduced pressure through a packed distillation column. Reactive distillation may be useful in conducting the process of this invention. The process of this invention may be carried out using, for example, a fixed bed reactor, a fluid bed reactor, or a slurry reactor. The optimum size and shape of the catalyst will depend on the type of reactor used. In general, for fluid bed reactors, a small, spherical catalyst particle is preferred for easy fluidization. With fixed bed reactors, larger catalyst particles are preferred so the back pressure within the reactor is kept reasonably low. The process of this invention can be conducted in a batch or continuous fashion, with recycle of unconsumed starting materials if required. The reaction can be conducted in a single reaction zone or in a plurality of reaction zones, in series or in parallel or it may be conducted batchwise or continuously in an elongated tubular zone or series of such zones. The materials of construction employed should be inert to the starting materials during the reaction and the fabrication of the equipment should be able to withstand the reaction temperatures and pressures. Means to introduce and/or adjust the quantity of starting materials or ingredients introduced batchwise or continuously into the reaction zone during the course of the reaction can be conveniently utilized in the processes especially to maintain the desired molar ratio of the starting materials. The reaction steps may be effected by the incremental addition of one of the starting materials to another. Also, the reaction steps can be combined by the joint addition of the starting material(s) to the catalyst. When complete conversion is not desired or not obtainable, the starting materials can be separated for the bridged nitrogen-containing compound product, for example by distillation, and the starting materials then recycled back into the reaction zone. The process is conducted for a period of time sufficient to produce the bridged nitrogen-containing compound products. The exact reaction time employed is dependent, in part, upon factors such as temperature, nature and proportion of starting material(s), and the like. The reaction time will normally be within the range of from about one-half to about 100 hours or more, and preferably from less than about one to about ten hours. The process may be conducted in either glass lined, stainless steel or similar type reaction equipment. The reaction zone may be fitted with one or more internal and/or external heat exchanger(s) in order to control undue temperature fluctuations, or to prevent any possible "runaway" reaction temperatures. Illustrative of suitable reactants in effecting the process of this invention include by way of example: PIP - piperazine HEP - 1-(2-hydroxyethyl)piperazine DHEP - 1,4-bis(2-hydroxyethyl)piperazine HPP - 1-(2-hydroxypropyl)piperazine The products prepared by the process of this invention are: TEDA - triethylenediamine MTEDA - 2-methyl-triethylenediamine Illustrative of permissible reactions encompassed within the scope of this invention include, for example, the following reactant/product combinations: REACTANTS PRODUCT(s) DHEP TEDA HEP TEDA HPP MTEDA As used herein, the phrase "residue of an organic compound" is contemplated to include all permissible residues of organic compounds. In a broad aspect, the permissible residues include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and nonaromatic residues of organic compounds. Illustrative organic compound residues include, for example, alkyl, aryl, cycloalkyl, heterocycloalkyl, alkyl(oxyalkylene), aryl(oxyalkylene), cycloalkyl(oxyalkylene), heterocycloalkyl(oxyalkylene), hydroxyalkyl, hydroxyalkyl(oxyalkylene), hydroxy(alkyleneoxy) and the like. The permissible residues can be substituted or unsubstituted and the same or different for appropriate organic compounds. This invention is not intended to be limited in any manner by the permissible residues of organic compounds. As used herein, the term "substituted" is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and nonaromatic substituents of organic compounds. Illustrative substituents include, for example, alkyl, alkyloxy, aryl, aryloxy, hydroxy, hydroxyalkyl, amino, aminoalkyl, halogen and the like in which the number of carbons can range from 1 to about 20 or more, preferably from 1 to about 12. The permissible substituents can be one or more and the same or different for appropriate organic compounds. This invention is not intended to be limited in any manner by the permissible substituents of organic compounds. Certain of the following examples are provided to further illustrate the process of this invention. The following apparatus was used for the preparation of bridged nitrogen-containing compounds in the examples. An Applied Test Systems, Inc. Model 3620 Split Test Oven equipped with a preheater (stainless steel 0.32 cm (1/8 inch) o.d. x 61 cm (2 feet)) and 1.27 cm (1/2 inch) (o.d.) stainless steel reactor tube 20.3 cm ((8 inch) length) was packed with catalyst and heated to the desired reaction temperature using a Honeywell Dial-A-Trol temperature controller. The temperatures at the top of the reactor and the bottom were monitored using a digital temperature readout. The liquid feed was added (downflow) to the reactor via a Fluid Metering Inc. RP-G20 drive pump equipped with an 0.32 cm (1/8 inch) pump head. The system was maintained under nitrogen, which was introduced after the liquid preheater. The product mixture was collected in a 100 milliliter round bottom flask, vented first to a dry ice/acetone trap and then a Firestone valve. Analysis was performed by capillary gas chromatography (FID) using a DB-1701 column. Example 1 Preparation of Decarboxylation Catalyst A total of 44.1 grams of magnesium nitrate hexahydrate and 66.0 grams of aluminum nitrate nonahydrate were dissolved in 200 milliliters of distilled water to give a first solution. A total of 4.8 grams of ammonium carbonate was dissolved in 200 milliliters of concentrated ammonium hydroxide (28-29 weight percent) to give a second solution. About 100 milliliters of distilled water was heated in a flask at a temperature of 40°C and the first and second solutions were combined simultaneously with good agitation using a mechanical stirrer. The rates of addition of the first and second solutions were adjusted to maintain a pH of 9-10. The total addition took 10 minutes and a final pH of 9.5 was obtained. The contents were stirred at a temperature of 40°C for a period of 40 minutes. The resulting precipitate was filtered and washed (ca. 300 milliliters three to four times) with water at a temperature of 60°C until the pH of the wash was neutral. The filter cake was dried at a temperature of 80°C overnight. The weight of the dried filter cake was about 16 grams. The filter cake was then calcined in air at a temperature of 400°C for a period of 3 hours to afford a magnesium:aluminum mixed metal oxide. Example 2 Preparation of Triethylenediamine Using the apparatus described hereinabove, a 50 weight percent solution of 1-(2-hydroxyethyl)piperazine in water was passed through a catalyst bed containing 6.0 grams of a magnesium:aluminum mixed metal oxide (0.32 cm (1/8 inch tablets, Mg/Al 3:1) at a temperature of 325°C and a liquid feed rate of 0.25 milliliters per minute. After a period of 40 minutes, the run was stopped and the reactor effluent analyzed. The results are given in Table I below. Product Composition, area %: Piperazine 17.4 Triethylenediamine 9.5 1-(2-hydroxyethyl)piperazine 57.6 1,4-bis(2-hydroxyethyl)piperazine 4.5 Others 11.1 Example 3 Preparation of Triethylenediamine Using the apparatus described hereinabove, a 30 weight percent solution of 1,4-bis(2-hydroxyethyl)piperazine in water was passed through a catalyst bed containing 6.0 grams of a magnesium:aluminum mixed metal oxide (0.32 cm (1/8 inch tablets, Mg/Al 3:1) at a temperature of 325°C and a liquid feed rate of 0.22 milliliters per minute. After a period of 30 minutes, the run was stopped and the reactor effluent analyzed. The results are given in Table II below. Product Composition, area %: Piperazine 9.8 Triethylenediamine 48.6 1-(2-hydroxyethyl)piperazine 15.7 1,4-bis(2-hydroxyethyl)piperazine 10.1 Others 15.8 Example 4 Using the apparatus described hereinabove, a 30 weight percent solution of 1,4-bis(2-hydroxyethyl)piperazine in water was passed through the reactor tube described above packed with glass pellets at a temperature of 325°C and a liquid feed rate of 0.25 milliliters per minute. After a period of 0.5 hours, the run was stopped and the reactor effluent analyzed. The results are given in Table III below. Product Composition, area %: 1-(2-hydroxyethyl)piperazine 4.1 1,4-bis(2-hydroxyethyl)piperazine 94.4 Others 1.2

Claims: A process for preparing triethylenediamine or 2-methyl-triethylenediamine which comprises contacting a cyclic nitrogen-containing compound selected from the group consisting of 1-(2-hydroxyethyl)piperazine, 1,4-bis(2-hydroxyethyl)piperazine, 1-(2-hydroxypropyl)piperazine, 1-(2-aminoethyl)piperazine and 1,4-bis(2-aminoethyl)piperazine, with a mixed metal oxide catalyst comprising: (a) a material having the formula M x 2+ Q y 3+ (OH) 2x+3y-nz A z n- · aH 2 O wherein M is magnesium; Q is aluminum; and A is at least one anion providing a valence (n - ), wherein n is 1 to 4 and wherein a is a positive number, M, Q and A are provided in a proportion such that z/y is a number equal to or greater than 1, z has a value greater than zero such that x/z is between n and 12n, and 2x+3y-nz is a positive number, or (b) a material prepared by calcining the material of formula (I) having the formula M x 2+ Q y 3+ (OH) (2x+3y-nz)/2 D z n- wherein M, Q, x, y, z and n have the same meanings defined above in connection with formula (I), and D is at least one nonvolatile anion; under conditions effective to produce triethylenedimaine or 2-methyl-triethylenediamine. The process of claim 1 wherein the mixed metal oxide catalyst is associated with a support material. The process of claim 2 wherein the support comprises an alumina material or an alumina-silica material. The process of claim 2 wherein the support comprises an alumina a silica material or a silica-alumina material. The process of claim 2 wherein the support comprises from 2 to 50 percent by weight of the mixed oxide catalyst. The process of claim 1 wherein x/y is a number between 1 and 12 and z has a value which satisfies the relationship: x/z is between n and 12n. The process of claim 1 wherein A is selected from the group consisting of carbonate, halide, phosphite, phosphate, chromate, sulfate, hydroxide, oxalate, acetate, nitrate, hexanoate, sebacate, vanadate, molybdate, tungstate and ferrocyanate. The process of claim 1 wherein D is selected from the group consisting of halides, phosphite, phosphate, vanadate, molybdate, tungstate, sulfite, sulfate, chromate, arsenate, borate and chlorate. The process of claim 1 wherein x/y is a number between 1 and 6 and z has a value which satisfies the relationship: x/z is between n and 6n. The process of claim 1 wherein said material prepared by calcining the material of formula (I) has been heat treated at a temperature in the range of 200°C to 800°C for 12 to 24 hours. The process of claim 1 wherein the temperature is from 150°C to 500°C. The process of claim 1 wherein the temperature is from 175°C to 375°C. The process of claim 1 wherein the reaction time is from 0.5 hours to 100 hours. A process for preparing triethylenediamine which comprises contacting 1,4-bis(hydroxyethyl)piperazine with a catalyst consisting essentially of a magnesium-aluminum mixed metal oxide under conditions effective to produce triethylenediamine.

Inventors: KING STEPHEN WAYNE, KING, STEPHEN WAYNE
Applicants: OSI SPECIALTIES INC, OSI SPECIALTIES, INC.
Application year: 1991
Main classification: C07D487
IPC codes: C07B61, C07D471, B01J23, B01J21, C07D487