JP2001002625A - Production of trichloronitrosomethane and production of lactam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing trichloronitrosomethane by which the compound is produced while reducing the required amount of nitrosyl chloride, and the removal of the remaining nitrosyl chloride after stopping the reaction is facilitated by carrying out the stirring of a liquid during the irradiation of light by using a specific method when carrying out the photoreaction of the nitrosyl chloride with chloroform. SOLUTION: The stirring of a liquid during the irradiation of light is carried out by the stirring by the blowing or jetting of an inert gas when carrying out the photonitrosation of (A) nitrosyl chloride with (B) chloroform to provide the objective trichloronitrosomethane. The reaction is carried out by dissolving the component A in the component B having combined two roles of the reagent and the solvent, and irradiating the obtained solution with the light of 400-600 nm, preferably 500-600 nm at 0-30 deg.C preferably under a normal pressure. The amount of the component A dissolved in the component B is preferably 0.5-30 g/L, more preferably 5-15 g/L. The inert gas includes a gas inert to the reaction of the components A and B (e.g. hydrogen chloride gas) besides the inert gas such as nitrogen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a lactam. More specifically, the present invention relates to a process for producing trichloronitrosomethane, which is used as a nitrosating agent for producing cycloalkanone oxime (a reaction intermediate of lactam) or directly lactam by photonitrosation of cycloalkane.

[0002]

2. Description of the Related Art Lactam is widely used as a raw material for nylon, and its production method is described in many documents. Among them, cycloalkane oxime is obtained from cycloalkane through photonitrosation, and this is subjected to Beckmann rearrangement.A method for producing a lactam is described below. In addition to nitrosyl chloride as a nitrosating agent, trichloronitrosomethane is used to obtain the obtained oxime. A method of performing Beckmann rearrangement with sulfuric acid is known.

As a method for producing trichloronitrosomethane, a method has been proposed in which light irradiation is performed while introducing nitrosyl chloride into chloroform (Japanese Patent Application Laid-Open No. 10-25279).

[0004]

In the case of performing a photoreaction using a corrosive gas, a lamp required for light irradiation is inserted into a reaction tank, and a stirring blade is generally used due to corrosion. Is difficult to stir by the method described in JP-A-10-252.
The method 79 is excellent in that the liquid can be easily stirred even in the presence of a lamp by nitrosyl chloride gas blowing and stirring, but the raw material chloroform (also used as a solvent) is used.
Due to the high solubility of nitrosyl chloride in nitrosyl chloride, a large amount of nitrosyl chloride is required if the liquid is stirred by such gas blowing and stirring, and a large amount of nitrosyl chloride remains in the reaction solution after the reaction is stopped. Nitrosyl chloride is more reactive than trichloronitrosomethane, so if this reaction solution is used as a starting material for other reactions with nitrosyl chloride remaining, a side reaction occurs in which nitrosyl chloride reacts. Must be removed after the reaction is stopped, but if the residual amount is large, the removal requires a lot of time and labor.

An object of the present invention is to provide a means for reducing the amount of nitrosyl chloride required for the production of trichloronitrosomethane by a photoreaction and facilitating the removal of residual nitrosyl chloride after the termination of the reaction.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that when performing a photoreaction between chloroform and nitrosyl chloride, an appropriate amount of nitrosyl chloride is dissolved in chloroform beforehand, and the solution during light irradiation is dissolved. It has been found that by performing stirring by blowing and / or stirring with an inert gas, the amount of nitrosyl chloride used can be significantly reduced, and the time required for removing nitrosyl chloride after the reaction is stopped can be shortened and the operation can be simplified. The present invention has been reached.

That is, the present invention is characterized in that, when producing trichloronitrosomethane by photonitrosation of nitrosyl chloride and chloroform, liquid stirring during light irradiation is carried out by blowing inert gas and / or jetting. A cycloalkane oxime by photonitrosating a cycloalkane in the presence of sulfuric acid and the trichloronitrosomethane obtained by the above method to produce a cycloalkanone oxime, and subjecting the resulting cycloalkanone oxime to Beckmann rearrangement. Lactam production method.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

The nitrosyl chloride used in the method of the present invention can be obtained by a known method, for example, a reaction between nitrosyl sulfuric acid and hydrogen chloride. This nitrosyl chloride can be used after purifying the product obtained by the above-mentioned method or used without purification without any problem.

In the reaction performed in the present invention, chloroform as a raw material also serves as a solvent. There is no problem if chloroform contains an inert substance such as carbon tetrachloride or hydrogen chloride.

The reaction carried out in the present invention can be carried out by dissolving nitrosyl chloride in the solvent chloroform and then irradiating it with light under conventional photochemical reaction conditions. Generally, the reaction is carried out at a temperature of 0 to 30 ° C. and light of 400 to 600 nm, preferably 500 to 600 nm. The present invention can be carried out under increased pressure, reduced pressure, or normal pressure. The reaction is preferably performed under reduced pressure, normal pressure, and more preferably under normal pressure. The amount of nitrosyl chloride dissolved in the solvent chloroform varies depending on the photoreaction time and light amount, but is preferably 0.5 to 30 g / liter, and more preferably 5 to 15 g from the viewpoint of light efficiency and the reduction of the amount of nitrosyl chloride used. Per liter.

The inert gas blowing and stirring of the present invention refers to a method of stirring and mixing a reaction solution by blowing a gas containing an inert gas into a reaction tank. The gas inlet may be provided at any of the upper, middle and lower positions of the reaction tank.
Preferably, it is provided in the middle and lower parts of the reaction tank, more preferably in the lower part of the reaction tank. Any number of gas inlets may be used. Further, it is preferable to provide a porous filter in the gas blowing port from the viewpoint of dispersibility of bubbles. The amount of gas blown varies depending on the form of the reaction tank and the inert gas used, and may be any amount as long as the temperature range of the reaction solution is not generated. However, from the viewpoint of preventing nitrosyl chloride loss, 1 liter / liter of the reaction solution is used. It is preferred to be not more than min.

The inert gas of the present invention is an inert gas having low solubility in chloroform. In addition to a so-called inert gas such as nitrogen and argon, a gas inert to the reaction between nitrosyl chloride and chloroform, for example, hydrogen chloride Refers to gas, etc. The concentration of these inert gases in the blown gas may be any ratio. From the viewpoint of reducing the amount of nitrosyl chloride used, it is preferably at least 50 vol%, the remaining portion may contain nitrosyl chloride, or only inert gas,
If necessary, nitrosyl chloride can be injected in a form dissolved in the solvent chloroform.

The jet stirring of the present invention is not limited to a method using a high-speed jet from a jet nozzle. The reaction liquid is extracted from an outlet provided in the reaction tank, and the reaction tank is re-used by using a circulation pump. To return from the jet nozzle (return inlet). Centrifugal pumps for circulation
Any type such as a reciprocating type and a rotary type may be used. Examples of such a pump include a volute pump, a turbine pump, a piston pump, a plunger pump, a Milton Roy pump, a gear pump, a partition pump, a screw pump, a Wesco pump, and the like. The outlet and return port for the reaction solution may be provided at any part of the reaction tank, and a plurality of each may be provided. Preferably, an outlet at the bottom of the reactor, an inlet at the top,
Alternatively, a discharge port is provided at the upper part of the reaction tank, and a return port is provided at the lower part. The return entrance is preferably located near the lamp. The material of the pump and the line can be used without any particular problem as long as they are inert to nitrosyl chloride, chloroform, trichloronitrosomethane, and gas when stirring by air bubbles. The circulation speed of the liquid varies depending on the shape of the return port, but any speed may be used as long as the temperature does not cause a temperature gradient in the reaction solution. Generally, it is preferable to operate the reaction solution with a residence time of 6 to 10 minutes.

[0015] Nitrosyl chloride remaining in the trichloronitrosomethane-chloroform solution obtained by the method of the present invention may be removed by any method.
For example, the solution can be removed by blowing an inert gas such as nitrogen or argon, or can be removed by a method such as distillation to purify the solution.

The chloroform solution of trichloronitrosomethane obtained by the method of the present invention is mixed with cycloalkane and sulfuric acid, and is irradiated with light in a known method (Japanese Unexamined Patent Publication No.
No. 25279) can be used to produce an oxime. The oxime obtained here can be used to produce a lactam by the so-called Beckmann rearrangement. Any known method may be used for the Beckmann dislocation. For example, using concentrated sulfuric acid,
Examples include those using a solid catalyst, those using DMF, and the like. Preferably, rearrangement by concentrated sulfuric acid is performed.

[0017]

The present invention will be described in more detail with reference to the following examples. Example 1 Chloroform 1 was placed in a 1-liter inner volume photoreaction vessel equipped with an immersion-type central lamp support and a high-pressure sodium lamp.
A liter was added, and nitrosyl chloride was gradually introduced from the lower part of the reaction vessel to dissolve 8 g.

The photoreaction vessel was cooled, and cooling water was flowed between the lamp support and the lamp to adjust the temperature of the liquid to 15 ° C.
The lamp was turned on while flowing nitrogen at 1 liter / hr for stirring. The output was 250 W. At this time, the gas discharged from the reaction vessel contained almost no nitrosyl chloride. After irradiation for 7 hours, the light was turned off.

By continuing nitrogen bubbling (1 liter / min) (3.5 hours), unreacted nitrosyl chloride was removed, and the remaining amount was reduced to 0.1 g / liter. At this time, a blue solution was obtained. The concentration of trichloronitrosomethane in chloroform was 10 g / l.

The trichloronitrosomethane in chloroform was determined by measuring transmittance at 592 nm with a cell length of 10 mm using UV-2200 manufactured by Shimadzu Corporation. Comparative Example 1 Using the same reaction vessel as in Example 1, 1 liter of chloroform was added, and nitrosyl chloride was gradually introduced from the lower part of the reaction vessel to dissolve 8 g.

The photoreaction vessel was cooled, and cooling water was flowed between the lamp support and the lamp to adjust the temperature of the liquid to 15 ° C.
Lights while flowing 8 liters / hr to sufficiently stir nitrosyl chloride from the bottom of the reaction vessel (output 250W)
did. At this time, the gas discharged from the reactor contained about 20% of nitrosyl chloride. After irradiation for 7 hours, the light was turned off.

Nitrogen bubbling (1 liter / min, 3.5
Attempt to remove unreacted nitrosyl chloride by time), but the removal was not possible due to the high concentration of nitrosyl chloride, and the color of the solution was brown of nitrosyl chloride. The pressure was reduced (30 Torr) at room temperature using a rotary evaporator to remove the nitrosyl chloride until the color of the nitrosyl chloride disappeared. As a result, the concentration of trichloronitrosomethane in the resulting solution was 1 g / liter.

[0023]

According to the present invention, the amount of nitrosyl chloride used can be significantly reduced, and the time required for removing nitrosyl chloride after stopping the reaction and the operation can be simplified.

Claims (3)

[Claims] 1. A process for producing trichloronitrosomethane by photonitrosation of nitrosyl chloride and chloroform, wherein liquid stirring during light irradiation is performed by inert gas blowing stirring and / or jet stirring. Manufacturing method. 2. The method for producing trichloronitrosomethane according to claim 1, wherein the weight concentration of nitrosyl chloride before light irradiation is 0.5 to 30 g / l. 3. A cycloalkanone oxime is produced by photonitrosating a cycloalkane in the presence of sulfuric acid and trichloronitrosomethane obtained by the method according to claim 1 or 2, and the resulting cycloalkanone oxime is A method for producing a lactam, which comprises Beckmann rearrangement.