DE1545789A1 - Process for producing lactams - Google Patents

Description

Process for producing lactams is the subject of the invention a process for the production of lactams by rearrangement of ketoximes in the presence of catalysts. Ketoxime is known to experience in the presence of concentrated Mineral acids or coordinatively unsaturated metal halides are known as Beckiann's Rearrangement. These rearrangements are carried out on a large scale in technology. For example, cyclohexanone oxime is converted into caprolactam in concentrated sulfuric acid rearranged, which serves as a raw material for synthetic fibers.

The large consumption of chemicals is a disadvantage of this process and the costly reconditioning of the relocation products. That is why it has been several times proposed to rearrange the ketoximes with solid catalysts. Good results previously showed weakly acidic catalysts, e.g. B.

Phosphates or mixtures thereof and boron compounds, in particular Bordure, which are applied to carrier materials. In general the activity and effectiveness of the catalysts proposed so far too low, so that they still found no technical application.

Furthermore, fuller's earth with an addition of 4% hydrofluoric acid is also used Proposed catalyst for the rearrangement of cyclohexanone oxime to caprolactam been. However, this catalyst is less suitable than the other known ones Catalysts.

It now became a simple process for making lactams found by rearrangement of cyclic ketoximes when one uses the cycloaliphatic Ketoxime in vapor state rearranged on zeolites at elevated temperatures. It is expedient to use reduced pressure during the rearrangement. the Rearrangement can be carried out both in the fixed bed and in the fluidized bed process with and without Foreign gases take place.

Both natural zeolites such. B. Chabazite, Analcim, Hormotom as well as synthetically produced zeolites, which are used as zeolitic molecular sieves have found their way into technology, e.g. B. Na zeolite A, Na zeolite X, Na zeolite Y, etc.

The crystalline synthetic zeolites according to the general Formula Me 2 0: A12 02: a Si 02: b Ii2 0 n where a and b for each type of zeolite lies in a very specific area. Me is a metal, e.g. B. Na, K, Ca, Sr, Ag etc. and n its valence. Modified zeolites can also be produced by z. B. in a basic type such as Na zeolite A with the composition 1, 0 0, 2 Na20 A12 03.3, 85 0, Si 02 = y Si 02 a part of the sodium by other metals like Calcium, magnesium, zinc, manganese and cadmium is replaced by ion exchange. In anionic lattices, aluminum can be replaced by gallium or silicon by germanium be replaced.

Activated zeolites are preferably used. The activity of the Zeolites can be increased in various ways: by exchanging the cations against ammonium or ions of alkaline earth, light and heavy metals and i-zrch Fluorination with hydrofluoric acid, NH.Fund other compounds containing Lu.r.

Fluorine-containing zeolites are particularly suitable for the process according to the invention suitable. Fluorine can be introduced into the zeolites in a simple manner by they are treated with fluorine compounds or mixtures of fluorine compounds. For example, the zeolites can be mixed with neutral or acidic salts of the Hydrofluoric acid, with complex fluorine-containing acids or their salts or mix with fluorine-containing gases, optionally in the presence of water, steam, soak or otherwise bring into contact. He can also get follow-up treatment for example by drying or calcining, if appropriate in vacuo. Good results are achieved, for example, if the zeolites with aqueous solutions impregnated with fluorine-containing compounds, separated after some time from the aqueous phase, be dried and tempered. The fluorine content of the catalysts according to the invention can vary within wide limits, expediently between 0.01 and 10% by weight. The treated catalysts are advantageously calcined at between 100.degree and 600 ° C.

Compared to the catalysts proposed up to now stand out the zeolites are characterized by a higher activity and effectiveness. You just let yourself regenerate.

According to the process according to the invention, the rearrangement takes place Oximes to lactams expediently at temperatures between 150 ° C. and about 600 ° C., preferably between 250 ° C and 450 ° C.

The rearrangement can either be reduced or if necessary take place at increased pressure. It is advisable to work with pressures between 0, 1 and 1000 torr.

According to the invention, vaporous oxime is optionally mixed with other gases such as nitrogen, carbon dioxide, water vapor, ammonia, and amines the like and optionally mixed with volatile fluorine compounds the specified conditions via the fixed catalysts or by passed a fluidized catalyst bed.

The oxime can also be in solid or liquid form in or on the Contact layer are brought. This has the main advantage that the heat of reaction through the melting or.

Heat of evaporation is partially compensated.

The inventive method is suitable for cycloalkanone oximes with Rearrange 5 or more ring members to the corresponding lactams. In addition to 6-caprolactams In this way, for example, the lactams of aminovaleric acid -aminocaproic acid, w-aminocaprylic acid, w-aminoundecanoic acid and der-aminolauric acid in good yields be won.

Example 1: 100 g of zeolite (molecular sieves 4 A-Na zeolite with a Pore size of about 4 #) were treated with a solution of 25 g of ammonium hydrogen fluoride soaked in 150 ml of water and then dried at 120 ° C in a water jet vacuum.

From the dried product, which was in the form of sticks (1/16 inch), 10 g were used as a catalyst.

The reaction was kept at a constant temperature of 360 ° C in a Glass tube with a diameter of 20 mm carried out. Within 5 hours were at 3 Torr 73 g of cyclohexanone oxime passed through the contact layer.

This resulted in a conversion of 24% and a yield of 87% caprolactam achieved.

Example 2: 100 g of zeolite of the 13 X type with a grain diameter between 0, 6 and 1 mm were in the same way as in Example # #.) In ammonium flupride solution soaked and then dried. 10 g cle. Product were in the reaction chamber filled; Because of this. was passed at 360 ° C under 3 Torr of cyclohexanone oxime vapor, 50 g in 5 hours. The conversion was 91%, based on a yield of 92% converted cyclohexanone oxime.

Example 3: By 10 g of the same catalyst used in Example 2) was described, one passed at 400 ° C and -3 Torr for half of 5.5 hours. 55 grams of cyclohexanone oxime. At a conversion of 98%, the yield of caprolactam was 92%.

Example 4: With 10 g of the catalyst described in Example 2 54 g of cyclohexanone oxime were passed at 300 ° C. and 3 torr within 5 hours. The conversion was 53% and the yield was 92%, based on the converted cyclohexanone oxime.

Example 5: 36-g molecular sieves 13X with a grain size of 0.6-1 mm were used extracted with 500 ml of a 9% NH4Cl solution, dried at 120 ° C. and then Annealed at 1 Torr and 500 ° C hours. By 10 g of the catalyst thus obtained 72 g of cyclohexanone oxime were geieitet in 5 hours at 3 Torr and 360 ° C. At a Conversion of 40%, the caprolactam yield was 87%.

Example 6: 100 g molecular sieves 4 A in rod form (1/16 inch) was extracted with 500 ml of a% Mg-C12 solution and then at 120 ° C dried. 20 g of the catalyst obtained in this way were used in 5 hours at 3 Torr and 360 ° C. 73 g of cyclohexanone oxime passed. With a turnover of 18% the yield 83%.

Claims (2)

Claims: 1. Process for the production of lactams by Rearrangement of cycloalkanone ketoximes in the presence of catalysts, characterized in that that the ketoximes in the vapor state, optionally in a mixture with-opposite the reactants inert gaseous substances at temperatures between 150 ° and 600 ° C with zeolites in contact. 2. The method according to claim 1), characterized-y that one fluorine-containing Zeolites used.