The method of obtaining cyclic lactams

 

(57) Abstract:

The method of obtaining cyclic lactams, in particular of E-caprolactam, by reacting the nitrile aminocarbonyl acid with water in the liquid phase in the presence of heterogeneous catalysts based on titanium dioxide, zirconium oxide, cerium oxide or aluminum oxide. Use nitrile aminocarbonyl acid formula

< / BR>
where m = 3 to 6, in the amount of 1 to 50% by weight solution of the nitrile in water or mixtures of water with organic solvent. The use of new catalysts improves the economic performance of the process. 4 C.p. f-crystals, 4 PL.

The invention relates to a new process for the preparation of cyclic lactams by reacting NITRILES aminocarbonyl acid with water in the presence of catalysts.

From U.S. patent N 4628085 known gas-phase interaction of nitrile 6-aminocaproic acid with water on acidic silica gel at a temperature of 300oC. the quality of the product quantitatively running reactions get caprolactam with an initial selectivity of 95%. However, there is a rapid decrease in productivity and selectivity. This method is described in U.S. patent N 4625023, according to which vysokorazvetvlennyi passed over a layer of silica gel and a layer of catalyst, containing oxides of titanium, copper, chromium and barium. At 85% conversion get caprolactam with a selectivity of 91%. And in this case there is a rapid deactivation of the catalyst.

The object of U.S. patent N 2301946 is not catalyzed reaction of nitrile 6-aminocaproic acid to caprolactam in the aqueous solution at a temperature of 285oC. the yield is less than 80%.

In the French patent N 2029540 described method of nitrile cyclization of 6-aminocaproic acid to caprolactam in the aqueous solution to a homogeneous catalyst based on zinc and copper. When caprolactam is obtained in yields up to 83%. However, complete separation of the catalyst from the target product is problematic because it forms complexes used as catalyst metals.

Therefore the task of the invention is to provide a method of producing cyclic lactams by reacting NITRILES aminocarbonyl acid with water, eliminating the aforementioned disadvantages.

The problem is solved according to the invention due to the fact that the reaction is carried out in the liquid phase in the presence of a heterogeneous catalyst based on titanium dioxide, zirconium oxide, cerium oxide and nitric oxide in the invention.

As starting substances used in the proposed method, NITRILES aminocarbonyl acid, preferably NITRILES aminocarbonyl acid of General formula (I)

< / BR>
where

n and m denote the number of 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9, and the sum n+m is at least 3, preferably at least 4.

R1and R2can represent any kind of deputies, and it is necessary only to draw attention to the fact that the reaction of cyclization deputies have no effect. Preferably R1and R2independent from each other and denote alkyl with 1-6 carbon atoms, cycloalkyl with 5-7 carbon atoms, or aryl with 6-12 carbon atoms.

Especially preferred parent compounds are NITRILES aminocarbonyl acid of General formula

< / BR>
where

m means the number 3, 4, 5 or 6, in particular 5. In the case of m = 5 source compound is a nitrile 6-aminocaproic acid.

According to the proposed method the above NITRILES aminocarbonyl acid is subjected to liquid-phase interaction of water on the heterogeneous catalyst to the cyclic lactam. When using NITRILES aminocarbonyl acid of the formula (I) receive a match is Especially preferred are the lactams, in which n is 0 and m is 4, 5 or 6, in particular 5 (in the latter case, get caprolactam).

The reaction is carried out in the liquid phase at temperatures of 140 to 320oC, preferably 160 - 280oC; the pressure is typically from 1 to 250 bar, preferably from 5 to 150 bar, and you should pay attention to the fact that under the reaction conditions, the reaction mixture is largely liquid. The reaction time is usually 1 to 120, preferably 1 to 90, in particular from 1 to 60 minutes In some cases completely was sufficient reaction time is 1 to 10 minutes

Per mole of nitrile aminocarbonyl acid is usually used at least 0.01 mol, preferably 0.1 to 20 mol, and in particular 1 to 5 mol of water.

It is advisable to use nitrile aminocarbonyl acid in the form of 1 to 50% by weight, preferably 5 to 50%, particularly preferably 5 to 30% by weight solution in water (the solvent is simultaneously reagent) or in a mixture of water and solvent. As a solvent, it should for example be mentioned alcohols, such as methanol, ethanol, n - and IHO-propanol, n-, ISO - and tert-butanol, polyols such as, for example, diethylene glycol and tetraethylene glycol, hydrocarbons, such as, the acts or the alkyl substituted lactams, such as, for example, N-organic N-methylcaprolactam or N-ethylcaproic, as well as esters of carboxylic acids, preferably carboxylic acids with 1 to 8 carbon atoms. Furthermore, the reaction can also be carried out in the presence of ammonia. Of course, you can also use a mixture of organic solvents. In some instances, particularly has proven itself a mixture of water and alkanols in the weight ratio of (1-75) : (25-99), preferably (1-50) : (50-99).

As catalysts, providing in the above reaction conditions, a very high conversion, yield and selectivity at high service life, should be called heterogeneous catalysts based on oxides of titanium, zirconium, cerium and aluminum. They can be used in the form of a powder, coarse grains, granules, wire harnesses or tablets. Typically, the oxide depends on the requirements of conducting the reaction, and in suspension use powder or large grains. In response to the fixed layer typically use tablets or bundles with a diameter of 1 to 10 mm

Aluminum oxide is suitable on all variants, which can be obtained by heating the precursor, aluminum hydroxide (gibbsite, boehmite, pseudo-boehmite, bayerite MESI.

The oxides can be used in pure form (the content of the corresponding oxide > 80 wt.%), as a mixture of the above-mentioned oxides, the amount of the above-mentioned oxides should be > 80 wt.%, or as a catalyst on the carrier, and the above-mentioned oxides can be applied to mechanically and chemically stable media, which in most cases has a high surface.

Pure oxides can be obtained by precipitation from aqueous solutions, for example, titanium dioxide by the so-called sulfate method or other methods, such as, for example, pyrogenic getting melkoporistoj aluminum oxide, titanium dioxide or zirconium dioxide, which are available for sale.

To obtain mixtures of different oxides are some of the methods. Oxides or their precursors, which by the calcination can be converted to oxides, can be obtained, for example, by co-deposition from a solution. Usually get a very good distribution of both oxides used. A mixture of oxides or their precursors can be obtained by deposition of a single oxide or a precursor in the presence of existing in the form of a suspension of finely distributed particles of the second Oka is whether predecessors, moreover, this mixture can be used directly to obtain the wiring harness or tablets.

To obtain the catalyst on the carrier there are a variety of methods. For example, the oxides in the form of Zola can be applied to the carrier by a simple impregnation. By drying and calcination is usually removed from the catalyst volatile components Zola. Such sols are commercially available for titanium dioxide, aluminium oxide and zirconium dioxide.

A further possibility of applying layers of active oxides consists in the hydrolysis or pyrolysis of organic or inorganic compounds. So, for example, ceramic media, you can apply a thin layer of titanium dioxide by hydrolysis of isopropylate titanium and other titanium alkoxides. Further suitable compounds are, for example, titanium tetrachloride, chloride Zirconia, aluminum nitrate and cerium nitrate. Suitable carriers are powder, the wiring or the tablets mentioned oxides or other stable oxides, such as silicon dioxide. To improve the transport of substances used carriers can be made of macroporous.

According to the proposed method are cyclic lactams, in particular caprolactam, high is e is illustrated by the following examples.

Examples 1-6. In a heated tubular reactor with a capacity of 25 ml (diameter 6 mm and length 800 mm), filled with titanium oxide (in the form of anatase) in the form of bundles with a length of 1.5 mm, is served at a pressure of 100 bar a solution of nitrile 6-aminocaproic acid (NAC) in water and ethanol shown in table weights. Coming out of the reactor product is subjected to analysis by gas chromatography and liquid chromatography under pressure. The results are also summarized in the following table. 1.

Comparative example. Analogously to example 1 in an empty tubular reactor, i.e., not containing heterogeneous catalyst, the reaction is subjected to a solution consisting of 10% nitrile aminocaproic acid, 6.4% of water and 83.6% of ethanol at a temperature of 250oC for 30 minutes When this conversion is 28%, and the selectivity of obtaining caprolactam - 74%.

Example 7-16. These experiments carried out in the same tubular reactor as examples 1-6. At the same time as the catalyst is used 13,3 titanium dioxide. The mode of experience and its results are summarized in table. 2.

Examples 17-22. These experiments carried out in the same tubular reactor as examples 1-6. The catalyst used 20 g of titanium dioxide. The mode of experience and it is about and examples 23 - 24. Using different catalysts. The mode of experience and its results are summarized in table. 4.

1. The method of obtaining cyclic lactams by reacting NITRILES aminocarbonyl acid with water in the presence of catalysts, characterized in that the reaction is carried out in the liquid phase in the presence of heterogeneous catalysts based on titanium dioxide, zirconium oxide, cerium oxide and aluminum oxide.

2. The method according to p. 1, characterized in that the reaction is carried out at 140 - 320oC.

3. The method according to one of paragraphs. 1, 2, characterized in that the use of NITRILES aminocarbonyl acid formula

H2N-(CH2)m-CN,

where m is 3, 4, 5 or 6.

4. The method according to p. 3, characterized in that as nitrile aminocarbonyl acid use nitrile 6-aminocaproic acid.

5. The method according to one of paragraphs. 1 to 4, characterized in that use 1 to 50% by weight solution of nitrile aminocarbonyl acid in water or a mixture of water and an organic solvent.

 

Same patents:

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to technology for preparing caprolactam by the cyclization reaction of derivatives of aminocaproic acid. Method is carried out by cyclizing hydrolysis of compound chosen from the group comprising aminocaproic acid esters or amides, or their mixtures. The process is carried out in the presence of water, in vapor phase at temperature 200-450°C in the presence of a solid catalyst comprising of aluminum oxide that comprises at least one macroporosity with pores volume corresponding to pores with diameter above 500 Å taken in the concentration 5 ml/100 g of above. Preferably, the specific square of catalyst particles is above 10 m2/g and the total volume of pores is 10 ml/100 g or above wherein pores volume corresponds to pores with diameter above 500 Å is 10 ml/100 g or above. Invention provides improving the process indices due to the improved properties of the solid catalyst.

EFFECT: improved preparing method.

5 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for synthesis of caprolactam from alkylcyanovalerate which involves bringing alkylcyanovalerate into contact with hydrogen in gaseous state in the presence of a hydrogenation catalyst and a ring formation catalyst, and treatment after condensation of a gaseous stream containing the formed lactam in order to separate ammonium which may be present, the formed alcohol and/or the caprolactam solvent and extraction of caprolactam, where the hydrogenation catalyst includes a metal element or a mixture of metal elements selected from a group containing an active metal element in form of iron, ruthenium, rhodium, iridium, palladium, cobalt, nickel, chromium, osmium and platinum or several metals from this list, and the ring formation catalyst is porous aluminium oxide.

EFFECT: obtaining caprolactam without intermediate separation of alkylaminocaproate.

10 cl, 5 ex, 1 tbl

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