DE1021358B - Process for the preparation of oximes - Google Patents

Description

GERMAN

It is known that oximes are obtained when one reacts to primary amines whose amino group is attached to a primary or secondary carbon atom is bonded, in the presence of a salt of an acid of tungsten, Molybdenum or uranium hydrogen peroxide can act (cf. Swiss Patent 288 168). Disadvantageous in this process is that considerable losses of hydrogen peroxide occur and the reaction, especially when using lower aliphatic amines, larger amounts of by-products leads.

It has now been found that oximes are obtained when using primary amines in the presence of oxygen-transferring amines Catalysts under irradiation with light sources emitting short-wave light and allows molecular oxygen to act in the presence of water.

The exposure can take place with any short-wave light emitting light sources. Particularly High pressure mercury lamps are suitable. Since not only the extremely short-wave part of the spectrum for the intended implementation is effective, but also the fractions not absorbed by glass, so the exposure can also be carried out from outside the reaction vessel through glass walls or windows. But you can also use the usual quartz immersion lamps.

The water-soluble salts of acids are particularly suitable as oxygen-transferring catalysts of molybdenum, tungsten and uranium.

If air is used for the oxidation, it must be carefully freed from the added carbon dioxide, because this disturbs the oxidation, presumably as a result of carbonate formation with the amine.

The most favorable proportions of water and amine can easily be determined by preliminary tests. One oxidizes z. B. only a part of the amine and selects the ratio of water and Amine so that the reaction mixture separates into two layers after irradiation. The resulting Most of the oxime is then located in the amine layer and can be fractionated from it Distillation can be obtained pure. The recovered amine and the aqueous layer, if any still contains some oxime and amine and the catalyst dissolved are used again.

Blank tests without irradiation showed no detectable amounts of oxime. On the other hand, could when introducing oxygen into amine-free water, no hydrogen peroxide can be detected even under exposure. The present method is based on a specific reaction between amine, light activated Oxygen and water, from the well-known oxidation of amines with hydrogen peroxide Process for the preparation of oximes

Applicant:

Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen / Rhein

Dr. Herbert Friederich, Worms,

and Dr. Werner Luck, Ludwigshafen / Rhine,

have been named as inventors

is different. That it is possible to convert primary amines into oximes with photochemically activated oxygen, was unexpected and offers over the use of the previously used as an oxidizing agent Hydrogen peroxide has significant economic benefits.

example 1

By a solution of 125 g of cyclohexylamine and 1.25 g of sodium tungstate in 125 g of water, which is in an oarz jar, it is conducted at ordinary temperature under irradiation with a high-pressure mercury lamp a brisk stream of oxygen. After 50 hours, the layers formed are separated and subjects the upper to fractional distillation, 105 g of cyclohexylamine being recovered. The residue left behind was 16 g of crude cyclohexanone oxime, which was recrystallized once from acetone melts at 86 °.

If a common Ouarz immersion lamp is used as the light source, similar results are obtained. A flask can also be used as the reaction vessel use ordinary glass.

Example 2

It is brought into a solution prepared from 125 g of n-butylamine, 1.25 g of sodium tungstate and 125 g of water a water-cooled mercury vapor immersion lamp and conducts during the irradiation in a brisk stream of oxygen into the solution at ordinary temperature. After 30 hours of treatment the reaction mixture is fractionally distilled. In addition to 115 g of unreacted n-butyl

709 846/486

amine 5 g of pure butyraldoxime determined by the ultrared spectrum was identified.

Example 3

A solution of 125 g of cyclohexyl amine in 125 g of water to which 1 percent by weight of potassium molybdate (K ₂ MoO ₄ ) was added, in a Quar vessel, is used to pass a moderate stream of oxygen at normal temperature while irradiating with a water-cooled mercury vapor lamp. After 50 hours, the layers formed are separated and the upper, non-aqueous layer is subjected to fractional distillation. 105 g of unreacted cyclohexylamine are recovered. The distillation residue is recrystallized from acetone, 15 g of pure cyclohexanone oxime being obtained.

If the amount of 1 percent by weight of potassium molybdate added to the solution is replaced by the same amount of silver chromate (Ag ₂ CrO ₄ ), 111 g of pure cyclohexanone oxime are obtained under otherwise identical conditions using the same procedure as in paragraph. If 1 percent by weight of silver nitrate is added to the solution of 125 g of cyclohexylamine in g of water and the procedure is otherwise the same, the yield of cyclohexanone oxime is 21 g.

Claims (1)

Claim Process for the preparation of oximes by oxidation of primary amines, their amino group is bound to a primary or secondary carbon atom, characterized in that that on the amines in the presence of oxygen-transferring catalysts with irradiation with light sources emitting short-wave light and molecular oxygen in the presence of water can act. Considered publications:
German Patent Nos. 927 506, 923 913;
Swiss patent specification No. 288 168. © 709 8W4K 12.57