DE3701113A1 - Process for the preparation of bifunctional compounds - Google Patents

Abstract

The application relates to a process for the preparation of bifunctional compounds of the formula <IMAGE> in which R<1>, R<2> and R<3> can denote alkyl radicals having 1 to 6 carbon atoms, R<2> and R<3> can additionally also denote hydrogen, R<2> can additionally also denote alkoxy radicals and R<4> can denote hydrogen, alkyl radicals having 1 to 6 carbon atoms and alkoxy radicals and there can be a double bond between the carbon atoms 2 and 3, by reaction of tetraalkoxyalkanes or dialkoxyalkanoic acid esters of the formulae <IMAGE> in which R<1> to R<4> have the above meaning, in the presence of catalysts such as zeolites, in particular of the pentasil type and/or phosphates and/or phosphoric acid on support material.

Description

The invention relates to a process for catalytic production of bifunctional compounds from tetraalkoxy channels or Dialkoxialkansäureestern.

Bifunctional compounds are usually very valuable building blocks in of organic synthesis. Such connections are particularly interesting the simple protective groups or groups with different or have graded reactivity, so that with each function targeted Implementations are possible.

This important class of substances includes, for example, the C₃ compounds the monoacetals of malonaldehyde or 3-alkoxiacroleine (Synthesis (1985) pp. 592-595). To make these connections a technically feasible way, synthetic variants such as the Ozonolysis of 1,1-dialkoxi-3-alkenes (C.A. (1961), 55, 20 926) or the Addition of alcohols to propargylaldehyde (Skoldinov et al, Zh. Org. Chim. (1968), p. 183, and (1970), p. 422) because the precursors only are difficult to access.

1,1,3-trialkoxipropenes can be prepared on the basis of acrolein. The disadvantage here is that the synthesis of 1,1,3-trialkoxipropenes several stages must take place and that one over a partial hydrolysis of the Acetals - after an upstream halogenation - only that Halogenmalonaldehyd-monoacetale can produce (US Pat. No. 28 16 109, U.S. Patent 28 15 384, U.S. Patent 28 70 221, Price Moos, J. Am. chem. Soc., 67 (1945), p. 207, McElvain, Morris, J. Am. chem. Soc. 73 (1950), p. 206, Rothstein, Whiteley, Soc. (1953), p. 4015.

Another possibility for the construction of malonaldehyde derivatives is in the combination of common C₁ and C₂ compounds. In the US-PS 24 65 586 is the preparation of such compounds Condensation of formic acid derivatives with acetaldehyde acetals described, but the condensation in the presence of large Amounts of metallic sodium or sodium alcoholates with poor Yielding proceeds.

The partial hydrolysis of tetraalkoxy propanes to monoacetals of Malonaldehyde or 3-alkoxia acrolein (Breitmeier, Gassenmann, Chem. Ber. 104 (1971), pp. 665-667, Ruegg et al, Helv. Chim. Acta 42 (1959), S. 847-853) usually leads to mixtures that are difficult  have it cleaned, as the tetraalkoxypropane used as starting products and the 3-alkoxiacroleins formed as reaction products almost have identical boiling points, creating a separation by distillation becomes impossible (Eskenazi, Maitte, Bull. Soc. Chem. Fr. 1976, pp. 995-8). To get to the pure compound, one has to use the alkali salts of Enol compounds go as an intermediate and this then by alkylation or further derivatize acylation (Eskenazi, Maitte, Bull. Soc. Chim. Fr. 1976, pp. 995-8, Maddaluno, D'Angelo, Tetrahedron Letters, (1983), Pp. 895-898). Pure 3-alkoxiacroleine is obtained when tetraalkoxypropane with cyclic anhydrides, such as maleic anhydride, Succinic anhydride, glutaric anhydride or phthalic anhydride in Temperature range from 150 to 180 ° C, are heated. Disadvantage of this Process is the fact that the cyclic anhydrides in stoichiometric amount are required and that this process with a Obtaining the corresponding esters of maleic acid, succinic acid, etc. is coupled.

It has been found that the disadvantages of the known processes are avoided and bifunctional compounds of the formula (I)

in which R¹, R² and R³ are alkyl radicals having 1 to 6 carbon atoms, R² and R³ additionally also hydrogen, R² additionally also alkoxy residues and R⁴ Hydrogen, alkyl radicals with 1 to 6 carbon atoms and alkoxy radicals can mean and between the carbon atoms and a Double bond can be obtained when tetraalkoxialkanes of the formula II or dialkoxialkanoic acid esters of the formula III

in the R¹ to R⁴ have the above meaning, in the presence of zeolites and / or phosphates and / or phosphoric acid on carrier material as Converts catalysts.  

The production of the tetraalkoxyalkanes and Dialkoxialkansäureester is e.g. B. from US-PS 24 59 076 known.

Suitable catalysts in the sense of the invention are generally suitable Zeolites of the pentasil type such as aluminum silicate zeolites, borosilicate zeolites, Iron silicate zeolites, and faujasite type zeolites.

The zeolites can e.g. B. with alkali metals, transition metals and with rare earth metals.

However, phosphates of the elements B, Al, Zr, Fe, Use Sr or their mixtures. Also hydrothermally produced phosphates are z. B. suitable as catalysts z. B. manufactured hydrothermally Aluminum phosphates, silicon aluminum phosphates or Silicon iron aluminum phosphates. You can also use them as catalysts Use phosphoric acid on substrates.

As catalysts for the process according to the invention, the Zeolites useful in the acidic form. Zeolites are crystalline Aluminum silicates that have a highly ordered structure with a rigid own three-dimensional network of SiO₄ and AlO₄ tetrahedra that are connected by common oxygen atoms. The ratio of Si and Al atoms to oxygen is 1: 2. The electrovalence of aluminum containing tetrahedron is by inclusion of cations in the crystal, e.g. B. balanced an alkali or hydrogen ion. A cation exchange is possible. The spaces between the tetrahedra are in front of the Dehydration occupied by drying or calcining water molecules.

Instead of aluminum, other elements such as B, Ga, Fe, Cr, V, As, Sb, Bi or Be or their mixtures in the lattice can be installed, or the silicon can be by a tetravalent element like Ge, Ti, Zr, Hf are replaced.

According to their structure, zeolites are divided into different groups divided. So form chains with the mordenite group or with the Chabazite group layers of tetrahedra while the zeolite structure the tetrahedra are arranged in polyhedra in the faujasite group, e.g. B. in Shape of a cubo-octahedron made up of four rings or six rings is. Depending on the linkage of the cubo-octahedron, which means different sizes Voids and pores are formed, a distinction is made in type A, L zeolites, X or Y.  

Suitable catalysts for the process according to the invention are Zeolites from the mordenite group or narrow-pore zeolites from the erionite or Chabazite-type or faujasite-type zeolites, e.g. B. Y, X or L zeolites. This group of zeolites also includes the so-called "ultra stable" faujasite type zeolites, i. H. dealuminated zeolites. Methods for producing such zeolites have been described in many different ways.

Zeolites of the pentasil type are particularly advantageous. These have as Basic building block together a five-membered ring made of SiO₄ tetrahedra. They are characterized by a high SiO₂ / Al₂O₃ ratio and by Pore sizes between those of type A zeolites and those of type X or Y are.

These zeolites can have different chemical compositions exhibit. These are alumino, boro, iron, beryllium, Gallium, chromium, arsenic, antimony and bismuth silicate zeolites or their Mixtures as well as alumino, boro, gallium and iron germanate zeolites or their mixtures. The alumino, boro and Iron silicate zeolites of the pentasil type for the process according to the invention. The aluminum silicate zeolite is e.g. B. from an aluminum compound, preferably Al (OH) ₃ or Al₂ (SO₄) ₃ and a silicon component, preferably highly disperse silicon dioxide in an aqueous amine solution, especially in polyamines such as 1,6-hexanediamine or 1,3-propanediamine or Triethylenetetramine solution with or in particular without alkali or Alkaline earth additive produced at 100 to 220 ° C under autogenous pressure. This also includes the isotactic zeolites according to EP 34 727 and EP 46 504. The aluminosilicate zeolites obtained contain, depending on the choice of the amounts of feed a SiO₂ / Al₂O₃ ratio of 10 to 40,000. This Aluminosilicate zeolites can in ethereal medium such as diethylene glycol dimethyl ether, in an alcoholic medium such as methanol or 1,4-butanediol or be synthesized in water.

Borosilicate zeolites can e.g. B. at 90 to 200 ° C under autogenous pressure synthesize by using a boron compound, e.g. B. H₃BO₃, with a Silicon compound, preferably highly disperse silicon dioxide in aqueous Amine solution, especially in 1,6-hexanediamine or 1,3-propanediamine or Triethylenetetramine solution with and in particular without alkali or Alkaline earth additive causes reaction. This also includes the isotactic Zeolites according to EP 34 727 and EP 46 504. Such borosilicate zeolites can can also be prepared if the reaction instead of in aqueous Amine solution in ethereal solution, e.g. B. diethylene glycol dimethyl ether or in alcoholic solution, e.g. B. 1,6-hexanediol.  

The iron silicate zeolite is obtained e.g. B. from an iron compound, preferably Fe₂ (SO₄) ₃ and a silicon compound, preferably highly disperse silicon dioxide in aqueous amine solution, in particular 1,6-hexanediamine, with or without addition of alkali or alkaline earth at 100 to 200 ° C under autogenous pressure.

To the silicon-rich zeolite (SiO₂ / Al₂O₃.)  10) also include the various ZSM types, ferrierite, NU-1 and Silicalit®.

The alumino, borosilicate and iron silicate zeolites produced in this way can their insulation, drying at 100 to 160 ° C, preferably 110 ° C and Calcination at 450 to 550 ° C, preferably 500 ° C, with a binder in a ratio of 90: 10 to 40: 60 wt .-% to strands or tablets be deformed. Various aluminum oxides are suitable as binders, preferably boehmite, amorphous aluminosilicates with an SiO₂ / Al₂O₃ ratio from 25:75 to 90: 5, preferably 75:25, silicon dioxide, preferred highly disperse SiO₂, mixtures of highly disperse SiO₂ and highly disperse Al₂O₃, TiO₂, ZrO₂ and clay. After the deformation, the extrudates or Compacts dried at 110 ° C / 16 h and calcined at 500 ° C / 16 h.

Advantageous catalysts are also obtained if the isolated catalyst Alumino or borosilicate zeolite is deformed directly after drying and is only subjected to calcination after the deformation. The Alumino and borosilicate zeolites can be produced in pure form without Binder, used as strands or tablets, being as Extrusion or peptizing aids, e.g. B. ethyl cellulose, Stearic acid, potato starch, formic acid, oxalic acid, acetic acid, Nitric acid, ammonia, amines, silicon esters and graphite or their Mixtures can be used.

Because of the way it is manufactured, the zeolite is not in the catalytically active, acidic H form before, but z. B. in the Na form, then can this by ion exchange, for. B. with ammonium ions and subsequent Calcination or by treatment with acids completely or partially in the desired H shape can be converted.

If when using the zeolitic catalysts according to the invention there may be a deactivation due to coke separation, it is recommended to use the zeolites by burning off the coke deposit Air or with an air / N₂ mixture at 400 to 550 ° C, preferably 500 ° C, too regenerate. This gives the zeolites their initial activity.  

By partial coking (pre-coke) it is possible to limit the activity of the Catalyst for a selectivity optimum of the desired Adjust reaction product.

For the highest possible selectivity, high sales and long downtimes To achieve this, it is advantageous to modify the zeolites. A suitable modification of the catalysts is e.g. B. in that the undeformed or deformed zeolites with metal salts by a Ion exchange or doped by impregnation. As metals Alkali metals such as Li, Cs, K, alkaline earth metals such as Mg, Ca, Sr, metals of 3rd, 4th and 5th main group such as Al, Ga, Ge, Sn, Pb, Bi, transition metals 4th-8th Subgroup such as Ti, Zr, V, Nb, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Sr, Ni, Pd, Pt, transition metals of the 1st and 2nd subgroup such as Cu, Ag, Zn, rare earth metals such as La, Ce, Pr, Nd, Er, Yb and U are used.

The doping is expediently carried out in such a way that the deformed one Zeolites placed in a riser and an aqueous at 20 to 100 ° C. or ammoniacal solution of a halide or a nitrate metals previously described. Such an ion exchange can made on the hydrogen, ammonium and alkali form of the zeolite will. Another way of applying metal to the zeolite is given by the zeolitic material, e.g. B. with a Halide, a nitrate or an oxide of the above metals in impregnated with an aqueous, alcoholic or ammoniacal solution. Either ion exchange as well as impregnation follows at least one drying, optionally another calcination.

A possible embodiment is, for. B. in that one Cu (NO₃) ₂ × 3 H₂O or Ni (NO₃) ₂ × 6 H₂O or Ce (NO₃) ₃ × 6 H₂O or LaNO₃) ₂ × 6 H₂O or Cs₂CO₃ dissolves in water and with this solution deformed or undeformed zeolite for a certain time, e.g. B. 30 minutes, soaks. The solution that may protrude is removed on the rotary evaporator from Free water. Then the soaked zeolite at about 150 ° C. dried and calcined at about 550 ° C. This watering process can be made several times in succession to the desired one Adjust metal content.

It is also possible to use an aqueous Ni (NO₃) ₂ solution or ammoniacal To produce Pd (NO₃) ₂ solution and therein the pure powdered zeolite slurrying at 40 to 100 ° C with stirring for about 24 h. After filtering, This can be done at around 150 ° C and calcined at around 500 ° C obtained zeolitic material with or without binders to strands, Pellets or eddy material can be processed further.  

An ion exchange in the H form or ammonium form or alkali form Zeolites present can be made so that the zeolite presented in strands or pellets in a column and z. Legs aqueous Ni (NO₃) ₂ solution or ammoniacal Pd (NO₃) ₂ solution at light increased temperature between 30 and 80 ° C in the circuit for 15 to 20 h. Then it is washed out with water, dried at about 150 ° C and at calcined at about 550 ° C. With some metal-doped zeolites, e.g. B. Pd-, Cu, Ni-doped zeolites is an aftertreatment with hydrogen advantageous.

Another possibility of modification is that one zeolitic material - deformed or undeformed - with a treatment Acids such as hydrochloric acid, hydrofluoric acid and phosphoric acid and / or water vapor submits. This is advantageous, for. B. in such a way that zeolites in Powder form treated with 1N phosphoric acid at 80 ° C for 1 hour. After Treatment is washed with water, dried at 110 ° C / 16 hours and calcined at 500 ° C / 20 hours. Treated according to a different way of working one zeolites before or after their deformation with binder, for. B. 1 to 3 hours at temperatures of 60 to 80 ° C with a 3 to 25 wt .-%, in particular 12 to 20% by weight aqueous hydrochloric acid. Then will the zeolite thus treated was washed with water, dried and at 400 ° C. calcined up to 500 ° C.

A special embodiment for the acid treatment is that one increases the zeolitic material before it is deformed Temperature with hydrofluoric acid, generally as 0.001 n to 2 n, preferably 0.05 n to 0.5 n hydrofluoric acid is used, treated, for example by heating under reflux for a period of im generally 0.5 to 5, preferably 1 to 3 hours. After isolation, e.g. B. by filtering and washing out the zeolitic material, this becomes expedient, e.g. B. at temperatures of 100 to 160 ° C, dried and at Temperatures of generally 450 C to 600 ° C calcined. According to one another preferred embodiment for the acid treatment is zeolitic material after deformation with binder at elevated Temperature, suitably at temperatures from 50 to 90 ° C, preferably 60 to 80 ° C, over a period of 0.5 to 5, preferably 12 to 20 wt .-% hydrochloric acid treated. The zeolite becomes expedient The material is then washed out at temperatures of 100 to 160 ° C dried and calcined at temperatures from 450 to 600 ° C. One HF treatment can also be followed by HCl treatment.

Another way of working is to apply zeolites by applying Phosphorus compounds, such as trimethoxyphosphate, trimethoxiphosphine, Modify primary, secondary or tertiary sodium phosphate.  

Treatment with primary sodium phosphate has been particularly advantageous proven. Here, the zeolites are in strand, tablet or Eddy form soaked with aqueous NaH₂PO₄ solution, dried at 110 ° C. and calcined at 500 ° C.

Other catalysts for the production of bifunctional compounds of the formula (I) from tetraalkoxialkanes of the formula (II) or Dialkoxialkansäureester of formula (III) are phosphates, in particular Aluminum phosphates, silicon aluminum phosphates, silicon iron aluminum phosphates, Cerium phosphate, zirconium phosphate, boron phosphate, iron phosphate or their mixtures.

As aluminum phosphate catalysts for the invention Processes, especially under hydrothermal conditions, synthesized Aluminum phosphates used. Suitable aluminum phosphates are e.g. B. APO-5, APO-9, APO-11, APO-12, APO-14, APO-21, APO-25, APO-31 and APO-33.

For example, AlPO₄-5 (APO-5) is synthesized by Orthophosphoric acid with pseudoboehmite (Catapal SB®) homogeneous in water mixes; to this mixture there is tetrapropylammonium hydroxide and then at about 150 ° C for 20 to 60 h under autogenous pressure in an autoclave. The filtered AlPO₄ is dried at 100 to 160 ° C and calcined at 450 to 550 ° C.

AlPO₄-9 (APO-9) is also made from orthophosphoric acid and pseudoboehmite but in aqueous DABCO solution (1,4-diazabicyclo- (2,2,2) octane) at approx. 200 ° C synthesized under autogenous pressure for 200 to 400 h. Used instead of DABCO solution, ethylenediamine leads to APO-12).

The AlPO₄-21 (APO-21) is synthesized from othophosphoric acid and Pseudoboehmite in aqueous pyrrolidone solution at 150 to 200 ° C below autogenous pressure for 50 to 200 h.

Known ones can also be used for the method according to the invention Silicon aluminum phosphates such as SAPO-5, SAPO-11, SAPO-31 and SAPO-34 deploy. These compounds are made by crystallization aqueous mixture at 100 to 250 ° C and autogenous pressure for 2 h to 2 weeks, the reaction mixture consisting of a silicon, aluminum and Phosphorus component is implemented in aqueous amino-organic solutions.

SAPO-5, for example, is suspended in aqueous by mixing SiO₂ Tetrapropylammoniumhydroxid solution with an aqueous suspension Pseudoboehmite and orthophosphoric acid and subsequent reaction at 150 up to 200 ° C, for 20 to 200 h under autogenous pressure in one Obtain stirred autoclave. The filtered powder is dried at 110 to 160 ° C and calcination at 450 to 550 ° C.  

Boron phosphates can be used as catalysts for the process according to the invention for example by mixing and kneading concentrated boric acid and Phosphoric acid and by subsequent drying and calcination in Inert gas, air or steam atmosphere at 250 to 650 ° C, preferably 300 up to 500 ° C.

Phosphoric acid is supported on SiO₂, Al₂O₃ or pumice, for. B. by Soak or spray applied. A phosphoric acid Catalyst can, for example, by impregnating H₃PO₄ or NaH₂PO₄ or Na₂HPO₄ solution on SiO₂ and subsequent drying or Calcination can be obtained. However, phosphoric acid can also be used with silica gel are sprayed together in a spray tower, then one closes Drying and usually a calcination. Phosphoric acid can also be used in a Impregnation mill to be sprayed onto the carrier material.

The catalysts described here can optionally be 2- to 4 mm strands or as tablets with 3 to 5 mm diameter or as grit with particle sizes from 0.1 to 0.5 mm or as a swirl contact will.

The chosen for the conversion of the invention usually reaction conditions are the preferred gas phase 100 to 500 ° C, in particular 200, in particular from 0.5 h to 400 ° C, and a WHSV = 0.1 h ^-1 to 5 to 20 ^{- 1} (g feed mixture / g catalyst and hour).

It is also possible to carry out the reaction in the liquid phase, e.g. B. suspension, Trickle or swamp mode, at temperatures between 50 and 200 ° C carry out.

The process is generally carried out at normal pressure or depending Volatility of the starting compound under reduced or increased pressure carried out, the implementation being continuous and discontinuous can be done.

Non-volatile or solid starting materials are in dissolved form, e.g. B. in THF, toluene or petroleum ether solution used. Generally is one Dilution of the starting material with such solvents or with Inert gases such as N₂, Ar, H₂O vapor possible.

After the implementation, the resulting products are replaced by conventional ones Process, e.g. B. isolated by distillation from the reaction mixture; unreacted feed mixture is, if necessary, in the Implementation traced.  

It is particularly advantageous to immediately add the gaseous reaction products bring a separation and disassemble into the individual components. A such separation can e.g. B. carried out in a fractionating column will. Through the separation, a back reaction can be prevented and an high sales can be achieved.

Examples 1 to 17

The reactions in the gas phase are carried out under isothermal conditions a tubular reactor (spiral, 0.6 cm inside diameter, 90 cm length) in the Performed for at least 6 hours. The reaction products are separated and characterized by conventional methods. The quantitative determination of the reaction products and the starting products is carried out by gas chromatography. The GC analyzes are carried out after 6 hours.

The catalysts used in each case are:

Catalyst A

A borosilicate zeolite of the pentasil type is used in a hydrothermal Synthesis from 604 g of highly disperse SiO₂, 122 g of H₃BO₃, 8000 g of an aqueous 1,6-hexanediamine solution (mixture 50: 50 wt .-%) at 170 ° C under autogenous Pressure created in a stirred autoclave. After filtering and The crystalline reaction product is washed out and dried at 100 ° C. for 24 hours and calcined at 500 ° C / 24 h. This borosilicate zeolite settles together from 94.2 wt .-% SiO₂ and 2.3 wt .-% B₂O₃.

This material is made by shaping with a shaping aid 2 mm strands produced, which dried at 100 ° C / 16 h and at 500 ° C / 24 h calcined.

Catalyst B

An aluminum silicate zeolite of the pentasil type is hydrothermal Conditions at autogenous pressure and 150 ° C from 65 g of highly disperse SiO₂, 20.3 g Al₂ (SO₄) ₃ × 18 H₂O in 1 kg of an aqueous 1,6-hexanediamine solution (Mixture 50: 50 wt .-%) in a stirred autoclave. To The crystalline reaction product is filtered off and washed out Dried 110 ° C / 24 h and calcined at 500 ° C / 24 h. This Aluminosilicate zeolite contains 91.6 wt .-% SiO₂ and 4.6 wt .-% Al₂O₃. The The catalyst is shaped into 2 mm strands, dried at 110 ° C./16 h and calcined at 500 ° C / 24.  

Catalyst C

Catalyst C is obtained by using the strands of catalyst A with impregnated with an aqueous Cs₂CO₃ solution, then drying at 130 ° C / 2 h and calcined at 540 ° C / 2 h. The Cs content is 0.6% by weight.

Catalyst D

200 g of catalyst A with 1 l of an aqueous solution of 16.7 g FeCl₃ × 6 H₂O and 50 g NH₄Cl ion exchanged at room temperature for 24 h, then washed thoroughly with H₂O Cl-free, dried at 150 ° C / 1 h and at 500 ° C / 2 h calcined. This powder is with highly disperse SiO₂ in Weight ratio 70: 30 deformed. After drying, the strands become Calcined at 500 ° C / 16 h.

Catalyst E

Catalyst E is obtained by using strands of catalyst A with impregnated with an aqueous solution of cerium and palladium nitrate, then at Dries 130 ° C / 2 h and calcined at 540 ° C / 2 h. The Ce content is 2.3% by weight, the Pd content 0.5% by weight.

Catalyst F

Catalyst F is produced like catalyst C, but with Cs₂CO₃ is replaced by Fe (NO₃) ₃. The Fe content is 2.9% by weight.

Catalyst G

Catalyst G is produced like catalyst C, but with Cs₂CO₃ is replaced by Ni (NO₃) ₂. The Ni content is 3.3% by weight.

Catalyst H

Catalyst H is prepared like catalyst C, but with Cs₂CO₃ is replaced by Ce (NO₃) ₃. The Ce content is 1.65% by weight.

Catalyst I

Catalyst I is produced like catalyst C, but with C2₂CO₃ is replaced by Co (NO₃) ₂. The co content is 3.1% by weight.  

Catalyst J.

Catalyst J is prepared like catalyst C, but with Cs₂CO₃ is replaced by Cr (NO₃) ₃. The Cr content is 1.9% by weight.

Catalyst K

AlPO _4-12 (APO-₁₂) is synthesized by dissolving or suspending 200 g of 98% phosphoric acid and 136 g of boehmite in 400 g of water, adding an aqueous solution of 60 g of ethylenediamine and 320 g of H₂O and adding this mixture to a stirred autoclave at 200 ° C for 24 hours under autogenous pressure. After filtering off, the crystalline material is dried at 120 ° C. and calcined at 500 ° C. for 16 hours. The AlPO _4-12 thus synthesized contains 55.5% by weight P₂O₅, 39.7% by weight Al₂O₃. This material is shaped into 3 mm strands using extrusion aids, dried again at 120 ° C. and calcined at 500 ° C. for 6 hours.

Catalyst L

Silicon aluminum phosphate-5 (SAPO-5) is made from a mixture from 220 g 98% phosphoric acid, 136 g boehmite, 60 g silica sol (30%) 287 g tripropylamine and 587 g H₂O. This mixture is kept at 150 ° C Implemented 168 hours under autogenous pressure. After filtration, it will crystalline product dried at 120 ° C and calcined at 500 ° C. SAPO-5 contains 49.8 wt .-% P₂O₅, 33.0 wt .-% Al₂O₃, 6.2 wt .-% SiO₂. SAPO-5 will formed into 3 mm strands with an extrusion aid, at 120 ° C dried and calcined at 500 ° C.

Catalyst M

Commercially available zirconium phosphate Zr₃ (PO₄) ₄ deformed in pure substance.

Catalyst N

Commercially available L-zeolite (Baylith L®) is mixed with boehmite in Weight ratio 80:20 to 2 mm strands deformed. After drying at The finished catalyst N is 110 ° C / 16 h and calcination at 500 ° C / 16 h in front.

Catalyst O

CePO₄ is by precipitation from 52 g Ce (NO₃) ₃ × 6 H₂O and 56 g NaH₂PO₄ × 2 H₂O received. After filtration, the material becomes strands  deformed, dried at 120 ° C and calcined at 450 ° C. Catalyst O contains 47.1 wt% Ce and 12.7 wt% P.

Example 18

There are 200 ml / h of tetramethoxypropane in a nitrogen stream from 300 ml / h evaporated and at a temperature of 220 ° C over 1 l of one Boron zeolite catalyst A, which is electrically heated from the outside Reaction tube is housed, directed.

The gaseous reaction mixture is in the middle part of a Fractionation column passed, the methanol formed and others Low boilers distill off overhead, while 3-methoxiacrolein small amounts of unreacted starting product in the bottom of the column can be deducted.

The pure production is achieved in a simple manner by a conventional one Distillation.

The conversion of tetramethoxypropane is <95%, the distillation yield is 91%.

After a reaction time of 85 hours, catalyst A still shows none Deactivation symptoms.

Example 19

The procedure is as in Example 18, but using tetraethoxypropane Brought reaction.

The yield of ethoxipropenal is 82% with a conversion of 93%.

Example 20

The procedure is analogous to Example 18, but the reaction product is not in a column, but passed into a template that is based on at least Is adjusted to pH 10 adjusted methanol. Sales of the used Tetramethoxypropane is <95%, the yield of 3,3-dimethoxypropionaldehyde is 61% of theory Th.

Example 21

Example 21, like Example 20, relates to the preparation of 3,3-dimethoxypropionaldehyde.  

In a stirrer to 700 ml of methanol, with 10.3 g of 30% methanolic sodium methylate solution are adjusted to pH 12, a Solution of 295 g of 3-methoxiacrolein in 175 ml of tetrahydrofuran at 25 ° C slowly added dropwise and after the addition has ended at 25 ° C. for 3 hours stirred. The pH is then adjusted to 7 with dilute sulfuric acid posed and worked up. There are 256 g of 3,3-dimethoxypropionaldehyde (Kp = 59 ° C / 22 mbar). Yield: 63% of theory Th.

Example 22

The procedure is analogous to Example 18 and 2,2,4,4-tetramethoxipentane 4-Methoxi-but-3-en-2-one implemented, the conversion <95% and the yield Is 93%.

Example 23

The procedure is analogous to Example 18 and 3,3-dimethoxibutyric acid methyl ester converted to 3-methoxicrotonic acid ester, the conversion <95% and the yield is 96%.

Table 1

Table 2

Table 3

Claims (13)

1. Process for the preparation of bifunctional compounds of the formula (I) in which R¹, R² and R³ can be alkyl radicals with 1 to 6 carbon atoms, R² and R³ can also be hydrogen, R² can also be alkoxy radicals and R⁴ can be hydrogen, alkyl radicals with 1 to 6 carbon atoms and alkoxy radicals and there can be a double bond between carbon atoms 2 and 3 , characterized in that tetraalkoxyalkanes of the formula (II) or dialkoxialkanoic acid esters of the formula (III) in the R¹ to R⁴ have the above meaning, in the presence of zeolites and / or phosphates and / or phosphoric acid on a support material as catalysts. 2. The method according to claim 1, characterized in that as Starting material 1,1,3,3-tetramethoxypropane or 2,2,4,4-tetramethoxipentane. 3. The method according to claim 1, characterized in that as Starting material 3,3-Dimethoxipropionsäuremethylester or 3,3-Dimethoxibuttersäuredimethylester used. 4. The method according to claim 1, characterized in that as Zeolite catalysts of the pentasil type used. 5. The method according to claim 1 and 4, characterized in that as Catalysts used aluminum silicate zeolites.   6. The method according to claim 1 and 4, characterized in that as Catalysts borosilicate zeolites used. 7. The method according to claim 1 and 4, characterized in that as Catalysts iron silicate zeolites used. 8. The method according to claim 1, characterized in that as Catalysts zeolites of the faujasite type used. 9. The method according to claim 1, characterized in that with Alkali metals, transition metals, rare earth metals doped Zeolites used as catalysts. 10. The method according to claim 1, characterized in that as Catalysts phosphates of elements B, Al, Zr, Fe, Sr or their Mixtures used. 11. The method according to claim 1, characterized in that as Catalysts hydrothermally produced phosphates used. 12. The method according to claim 1, characterized in that as Catalysts hydrothermally produced aluminum phosphates or Silicon aluminum phosphate or silicon iron aluminum phosphate used. 13. The method according to claim 1, characterized in that as Catalysts used phosphoric acid on support materials.