DE1036845B - Process for the preparation of oximes from aliphatic and cycloaliphatic nitro compounds - Google Patents

Description

GERMAN

of oximes from aliphatic

and cycloaliphatic nitro compounds

Applicant:
Stamicarbon NV, Heerlen (Netherlands)

Representative: Dr. F. Zumstein, patent attorney, Munich 2, Bräuhausstr. 4th

Claimed priority:
Netherlands 28 January 1954

Sjoerd Kaarsemaker, Sittard (Netherlands),
has been named as the inventor

The invention relates to the preparation of oximes from aliphatic and cycloaliphatic nitro compounds. It is known that aliphatic and cycloaliphatic nitro compounds can be reduced by reduction in the liquid phase to obtain the corresponding oximes by means of hydrogen.

This reduction can be carried out with hydrogen-free metals in the presence of reducing agents according to German patent specification 855 253 as well as catalytically with the aid of gaseous hydrogen elevated pressure according to U.S. Patent 2,423,180.

It has now been found that the corresponding oximes may be prepared from aliphatic and cycloaliphatic nitro compounds, when reacted with an alkaline solid salt brings the nitro compounds in vapor form at a temperature of 150 to 35O ⁰ C a weak acid into contact.

When the process according to the invention is carried out, water 20 is found in the reaction products

suggests the formation of oximes from the nitro compound »

by splitting off water. However, it would be

then the formation of unsaturated oximes is close. Remarkably weak acid in contact. Let as suitable salts The reaction products are worthy of being predominantly carbonates, aluminates, borates, and also other alkagents from the corresponding saturated oximes, 25 lisch reacting salts of alkali metals, alkaline earth while one usually does not use more than 20 to 30% non-metallic or similar salts of other metals, saturated oxime. ; for example salts such as sodium carbonate, potassium car · '

The vapor of the nitro compound is preferably carbonate, rubidium carbonate, calcium carbonate, barium mixed with an inert carrier gas, the carrier gas can be carbonate, zinc carbonate, magnesium carbonate, thallium man instead of choosing water vapor, carbon dioxide, hydrogen carbonate, cadmium carbonate, sodium aluminate, sodium or Use nitrogen. Non-inert gases such as acid borate, potassium borate, manganese carbonate, and others, Substance and carbon dioxide are not used.

It has been found that, measured by the result obtained with another - inert - gas, for example with nitrogen, the use of hydrogen as a carrier gas is not particularly increased Yield of saturated oxime in consequence, which suggests that with the mentioned use ' of hydrogen almost no hydrogenation takes place.

The amount of carrier gas to be used can be very high. A named group can be used as a carrier vary. It is usually so large that the gaseous salt, for example calcium carbonate, or a Mix not more than 5 to 10 percent by volume of steam of the other product should be used. Good success he-nitro compound contains. one aims when the carrier is a metal oxide, for example

The temperature at which the reaction is carried out is zinc oxide, manganese or cadmium oxide. You have yor, is 150 to 350 ° C. One avoids using a carrier at higher temperatures, so one chooses the amount of the so that there are no undesirable, the contact materials and the carrier mostly so that the finished contact material form effective by-products. Preferably does not contain more than 10 percent by weight salt, wisely one applies temperatures of 225 to 275 ° C, expediently one can use the steam of the Nitfoverbin-

where a quick reaction, for which contact times fertilize with the salt by bringing that Less than 5 seconds is sufficient, and you can get it through a layer of finished contact material

Salts of weak acids that do not decompose at the reaction temperature. Mixtures of these salts can also be used use.

Particularly suitable contact substances, with which the reaction proceeds smoothly, are primarily the carbonates of the alkali metals, for example potassium carbonate and rubidium carbonate.

Furthermore, the salts can be attached to a carrier.

only a small amount of by-products attaches to the contact mass.

Bring the nitro compounds according to the invention with an alkaline solid salt

passes through. As the diameter of the solid particles of the Contact material, you usually choose the size 3 to 5 mm, but also coarser particles of irregular shape can be used. You can too

809 59S / 557

the solid continues in "agitation" during the reaction keep. In this case, the solid can be in the form of finely divided particles, which, for example, have a diameter below 0.1 mm in the flow state brought into contact with the vapor of the nitro compound been. In this form of implementation of the method is considered to be an advantage that, by a local Overheating of the solid is avoided, the temperature can easily be kept constant and thus achieved that the reaction proceeds smoothly.

The process according to the invention can be carried out continuously. With this type of implementation you can use the solid to remove unwanted products that may have adhered to the solid regenerate.

The regeneration of the solid can be done in a simple manner by passing over an oxygen-containing gas, for example from air. In order to prevent a sharp rise in temperature, you can add an inert gas, for example nitrogen or steam, to the regeneration gas. Appropriately holds during the regeneration, the solid is permanently in the flowing state, for example with the aid of the regeneration gas.

The oxime can be separated from the gaseous reaction products by cooling; the oxime can can still be purified, for example, by distillation. The carrier gas can be used again.

It has also been found that the yield of saturated oxime can still be increased by hydrogenating the unsaturated oxime present in the reaction products. For this purpose, the oxime obtained as the reaction product is subjected to a hydrogenation treatment with hydrogen and a hydrogenation catalyst consisting, for example, of palladium. This hydrogenation is preferably carried out at atmospheric pressure and a temperature of 15 to 25 ° C. Higher temperatures, for example 50 to 100 ^° C., can also be used.

example 1

It was first freshly prepared for the purpose of applying potassium carbonate to a carrier made of zinc oxide, zinc carbonate; This zinc carbonate was obtained from an aqueous zinc nitrate solution by precipitation with an aqueous potassium carbonate solution. The precipitate was separated from the liquid by filtration and then washed with water. 1000 g of the still moist product were introduced into a solution of 60 g of potassium bicarbonate in 500 g of water. It was then filtered. The product obtained in this way was then dried and then compressed into tablets. These tablets were then crushed into granules with a diameter of mm 3 to 5, which then for 4 hours were heated at 400 ⁰ C under Hinüber passing air long. The catalyst obtained in this way contained 8 percent by weight of potassium carbonate and 92 percent by weight of zinc oxide.

Of this catalyst in 38 g of a reaction tube were introduced (tube diameter 20 mm) and heated up to the reaction temperature of 25O ⁰ C.
Further, a gas mixture was continuously prepared by per hour 7.25 g of water at a temperature of 8O ⁰ C in nitrogen 141 (measured at ⁰ C and 1 atm.) And also 7.25 g nitrocyclohexane at a temperature of HO ⁰ C allowed to evaporate. After prior heating, this gas mixture was passed through the reaction tube, and the gases escaping from the tube were cooled, 3.2 g of oxime separating out per hour. In this way, 90% of the nitrocyclohexane was converted, while the yield of oxime, based on converted nitrocyclohexane, was 56% by weight.

Example 2

In a manner similar to that described in Example 1, a series of experiments were carried out with various catalysts. The catalyst mixtures were prepared in an analogous manner by impregnating the freshly prepared support (cf. Example 1).
The table below shows the results of the experiments. In this table, the amount of nitrocyclohexane which was passed through the catalyst mass by means of the carrier gas is given in g per kg of catalyst per hour.

catalyst salt carrier (KBO ₂ ) j ZnO (Rb ₂ CO ₃ ) ZnO salt Gas mixture Nitro Tempe Around- the end Rubidium carbonate sodium % cyclo-
hexane rature Wall- prey Potassium carbonate Zinc oxide (ZnO) (Na ₂ CO ₃ ) ZnO 2.3 cat / h ⁰ C lung
Degree at
Oxime (K ₂ CO ₃ ) Calcium carbonate carrier
gas 117 250 % ° / o Potassium metaborate ZnO (CaCO ₃ ) Cadmium oxide 3.5 98 60 Potassium carbonate (CdO) nitrogen 258 250 (K ₂ CO ₃ ) Manganese oxide 4.4 86 53 K ₂ CO ₃ (MnO) nitrogen 168 250 Activated carbon 17.0 87 62 K ₂ CO ₃ Aluminum silicate nitrogen 168 250 K ₂ CO ₃ 10.1 73 65 hydrogen 155 250 5.9 47 59 hydrogen 580 300 4.0 83 67 hydrogen 296 250 10.0 99 61 4.0 nitrogen 720 250 515 229 21 74 hydrogen 45 37 nitrogen

The table shows the degree of conversion as percent by weight of the amount of nitrocyclohexane fed in, the Yield of oxime mentioned as percent by weight of oxime formed. That is also in percent by weight Expressed as the amount of salt that the catalyst contains.

Claims (6)

Patent claims: 1. Process for the preparation of oximes from aliphatic and cycloaliphatic nitro compounds, characterized in that the nitro compound in Steam forms at a temperature of ISO up to 350 ° C with an alkaline solid salt weak acid is brought into contact. 2. The method according to claim 1, characterized in that a mixture of the nitro compound and contacting the salt with an inert carrier gas. 3. The method according to claims 1 and 2, characterized in that a temperature of 225 to 275 ° C is maintained. 4. Process according to Claims 1 to 3, characterized in that the salt is a carbonate of an alkali metal is applied. 5. Process according to Claims 1 to 4, characterized in that the salt is on a carrier provided metal oxide is attached. 6. Process according to Claims 1 to 5, characterized in that the resulting reaction product Oxime is subjected to a hydrogenation treatment. Considered publications:
German Patent Nos. 855253, 855254, 927506; U.S. Patent No. 2,423,180. 809 598/557 page 5 &