CS276382B6 - Method of acetone continuous oximation - Google Patents

Abstract

The solution of a continuous slope oximation of acetone with hydroxylamine sulphate and the formation of acetone oxime. Oximation process it runs under defined conditions that consist of defining a suitable pH around 4 and oximation temperatures of about 45 ° C, molar excess acetone and total water in the mixture. This will be virtually complete hydroxylamine sulfate on acetone oxime with its subsequent comfortable separation. The utilization of solutions is of great importance with a minimum content of hydroxylamine sulfate significant by other inorganic ones components.

Description

The present invention addresses a process for the continuous oximation of acetone with hydroxylamine sulfate to form acetone oxime. The resulting oximation product has a special use. It is used mainly in the pharmaceutical industry in the synthesis of new drugs, in the chemical industry of synthetic dyes. Appropriately separated acetone oxime can be used to produce hydroxylamine salts in particularly pure quality.

The hydroxylamine sulfate used in the oximation is obtained from the Rashig process modified by prion, which is commonly used in the production of caprolactam. It is produced as an aqueous solution with an active ingredient concentration of about 15% by weight, heavily contaminated with sulphate, ammonium hydrogen sulphate (up to 30% by weight) and other accompanying cations (Fe, Pb).

Oximation of hydroxylamine sulfate and acetone proceeds according to the equation:

CH 2 - C - CH 2 + NH 4 OH.1 / 2 H, SO. --------> CH 2 -C - CH 2 + H, O + 1/2 H, SO.

J j í. i- 4 j ji. L 4

II II. N - OH while neutralizing the liberated sulfuric acid with ammonia.

Acetone oxime can be prepared in the laboratory by direct reaction of hydroxylamine base with acetone. The hydroxylamine base is prepared e.g. from pure hydroxylamine sulphate by precipitation with barium hydroxide followed by separation of the barium sulphate. A batch process for the production of technical acetone oxime from a hydroxylamine salt solution is known technologically. In this procedure, a solution of technical hydroxylamine sulfate is first neutralized with ammonia or another alkali hydroxide to pH 7. After cooling the solution, acetone or acetone solution is added to leave an excess of hydroxylamine base in the reaction mixture. The solution is again neutralized to pH 7 and cooled to 20 ° C, whereby the organic and inorganic phases are separated.

The conditions for the production of acetone oxime from a technical solution of hydroxylamine sulphate by a continuous process must be strictly indicated from a physicochemical point of view. Otherwise, it is not possible to subsequently separate the acetone oxime without significant losses and reduction in quality.

The invention is carried out by continuously feeding a solution of hydroxylamine sulphate and acetone in a molar ratio of 1: 1 to 1: 1.25, preferably 1: 1.15, while neutralizing the reaction mixture to pH 3.9 to 4.2 with ammonia in gaseous or in the form of an aqueous solution at a temperature of 20 to 56 ° C, preferably 45 ° C, into a turbulently mixed flow zone with a residence time of 10 to 120 minutes, preferably 30 to 60 minutes. The total input of the raw materials to the reaction preferably contains at least 48% by weight. water.

Another advantage of the inventive process is the preparation of acetone oxime by a continuous process, which makes it possible to substantially increase the reactor power. This can be used in the industrial production of acetone oxime using a suitable separation process. In this way, quantitatively acetone oxime is obtained even from solutions containing at least amounts of hydroxylamine sulphate, in addition substantially contaminated with inorganic compounds.

The preparation method is illustrated by the following examples.

Example 1

A solution of technical hydroxylamine sulphate in an amount of 230 ml / h with a concentration of 153 g / l, an aqueous solution of acetone in an amount of 65 ml / h with a concentration of 100 g / l are continuously added to a stirred reactor with a volume of 500 ml. Ammonia gas is added through a nozzle introduced to the bottom of the reactor to maintain the pH of the solution at 4.1-0.1. The reactor is maintained at 47 ° C. In 1 hour, 302 ml of a heterogeneous solution of sulfate, acetone and 31 g of acetone oxime are prepared in practically 100% yield.

, CS 276 382 B6 2

Example 2

6,000 ml / h of a hydroxylamine sulphate solution with a concentration of 168 g / l of active ingredient and 280 g / l of NH4-HSO2 are continuously injected into a 10 liter reactor stirred with a paddle stirrer, and pure acetone at a flow rate of 1,100 ml / ha water at a flow rate of 1,650 ml / h. The pH of the reactor is maintained at 4.0 by supplying ammonia gas through a nozzle to the bottom of the reactor, controlled by a Kent pH meter via a control valve. The reactor is heated to 45 ° C. 8,800 ml / h of a heterogeneous mixture containing 890 g of acetone oxime, ammonium sulfate solution and acetone are continuously withdrawn from the reactor. The oximation yield relative to hydroxylamine sulfate is 99%.

Claims (2)

PATENT CLAIMS Process for the continuous oximation of acetone, characterized in that a solution of hydroxylamine sulphate and acetone is fed continuously in a molar ratio of 1: 1 to 1.25, preferably 1: 1.15, while neutralizing the reaction mixture to pH 3.9 to 4.2 with ammonia in the gaseous state or in the form of an aqueous solution and a temperature of 20 to 56 ° C, preferably 45 ° C, into a turbulently stirred flow zone with a residence time of 10 to 120 minutes, preferably 30 to 60 minutes. 2. The process according to item 1, characterized in that the concentration of the hydroxylamine sulphate solution may be volatile, but the total input of the raw materials to the reaction contains at least 48% by weight of water. .