JPS6323122B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a granular sodium amide dispersion, and more particularly to a method for producing a granular sodium amide dispersion by pouring molten sodium amide into an organic solvent.

An object of the present invention is to provide a method for producing a granular sodium amide dispersion that has excellent storage stability and is easy to use from sodium amide in a molten state.

Sodium amide has high reactivity and can be used in the synthesis of indigonoids, the introduction of amino groups into pyridine rings and quinoline rings, the synthesis of the corresponding amidine sodium salts from aldehydes and nitrites, medicines, agricultural chemicals, dyes, etc. It is an important substance as a raw material for the synthesis of intermediates.

However, sodium amide is a dangerous substance that reacts explosively when it comes into contact with water, and is susceptible to the effects of trace amounts of oxygen (air) and moisture, so it cannot be used even if it is subdivided and sealed in a nitrogen gas atmosphere. During long-term storage, it often turns yellow or brown as purity decreases. It is said that the highly colored material is due to the formation of sodium azide, but it is known that it can violently explode with a simple impact. Therefore, it is common knowledge that long-term storage is dangerous, and sodium amide has traditionally had many problems in handling and storage, especially if it has been opened and must be used up immediately.

Conventionally, sodium amide produced in a molten state is kept in a molten state in the same reactor, and unless it is used for the next reaction, it is solidified while cooling inside the reaction vessel, excluding air and moisture. It has been used by crushing or pulverizing it, or by transferring it to another container, cooling it, solidifying it, and then crushing it. However, because minute particles and dust of sodium amide are generated during crushing, special consideration has been required to maintain a good working environment when filling small containers. In addition, powdered sodium amide has a large surface area, so it is particularly unstable and easily deteriorates, so unless it is crushed in a reaction vessel and used as is for the next reaction in the same vessel, it is extremely unstable. It was difficult to handle. In other words, if finely powdered sodium amide adheres to a coarsely crushed lump, it is likely to cause deterioration of the entire lump, so especially when it is transported to a remote location or used after being stored, It is preferable to remove the sodium amide, and in such a case, the powdered sodium amide has to be disposed of as waste, which is also a factor in reducing the yield. In addition, if it is necessary to pre-disperse the reaction raw material or solvent before use, it may be necessary to carefully crush it as described above and then add and disperse it, or to add the properly crushed material and crush it in a wet process. I have performed the operation. When using flammable organic solvents, it was necessary to take into account that materials stored for long periods may be exposed to the risk of unexpected explosion or ignition due to the impact of pulverization.

A known method for obtaining a dispersion of particulate sodium amide is a method in which solid metallic sodium is reacted and precipitated in a sufficient amount of liquid ammonia using iron nitrate or the like as a catalyst. In this method, sodium amide in the form of sand particles is obtained, and if necessary, by evaporating excess liquid ammonia and replacing it with an arbitrary solvent, sodium amide in a solvent-dispersed state can be obtained. This method is an excellent method for small quantities in the laboratory, but for industrial purposes it is necessary to maintain large amounts of liquid ammonia at low temperatures, requiring a powerful refrigerator, recovering a large amount of excess ammonia, and requiring long periods of time. There are various drawbacks such as low efficiency due to time reaction, and it is not necessarily a safe method.

Sodium amide is an important raw material with extremely wide range of uses, and it has been desired to improve its storage stability and ease of handling, and to make it easier to transport to remote locations.

As a result of various studies to improve the above situation, the present inventors discovered that while stirring an inert organic solvent that does not essentially react with sodium amide under an inert gas atmosphere, sodium amide molten in this solvent was and disperse the organic solvent at a temperature of 150°C or less, preferably 120°C or less.
They discovered that it is possible to granulate and mold the particles to an appropriate particle size by maintaining the temperature below ℃, and that sodium amide thus dispersed in an organic solvent has extremely good storage stability, and completed the present invention. It came to this.

The present invention provides a sodium amide inlet, a stirring device,
A container equipped with a reflux condenser, replacement gas inlet, etc. is used as a dispersion device, and an inert organic solvent such as xylene is charged in the dispersion device. After connecting the container holding molten sodium amide and the sodium amide inlet, the system is This can be safely carried out by replacing the inside with an inert gas such as nitrogen gas, and pouring molten sodium amide into the inert organic solvent while stirring the inert organic solvent. The sodium amide that has reached the liquid surface of the inert organic solvent is dispersed by stirring and at the same time is rapidly cooled and precipitates as a white granular solid with a relatively uniform particle size.

Therefore, the granular sodium amide dispersion obtained by the method of the present invention has extremely good storage stability, and when stored under the surface of an inert organic solvent in a tightly capped container, it can be stored for a long period of at least one year without coloring. It has the characteristic of maintaining purity, and is easy to store for long periods and transport to remote locations. In addition, the particles are rounded and do not have sharp fracture surfaces, so they exhibit good fluidity and are easy to handle, such as when filling and discharging them into transportation containers. Since no dust is generated, the working environment is improved, and there is an advantage that loss and harm caused by dust can be completely eliminated. In addition, the reactivity when used in organic synthesis reactions is equal to or higher than that of sodium amide crushed according to conventional methods or sand-like sodium amide synthesized in liquid ammonia.
For example, sodium amide dispersed in xylene can be advantageously used in the monoamination reaction of nuclei such as pyridine and picoline, and a yield of 80% or more can be obtained in the monoamination reaction. Moreover, it can be utilized for the synthesis of useful intermediates such as the synthesis of corresponding amidine-sodium salts from aldehydes and nitriles, and the synthesis of corresponding sodium salts from primary or secondary amines.

The inert organic solvent used in the present invention does not need to essentially react with sodium amide, and it is most rational to select the inert organic solvent to be used as a reaction solvent depending on the intended use of sodium amide. . For example, water-free benzene, toluene, xylene, mesitylene, tetralin, decalin, liquid paraffin, tripropylamine, tributylamine, dimethylaniline, etc. can be used individually or in combination in any proportion. The amount of the inert organic solvent to be used is preferably at least 3 times the weight of the sodium amide, but 10 times or less is sufficient.

The temperature of the inert organic solvent during the addition of molten sodium amide depends on the stirring state, the injection rate of the molten sodium amide, and the temperature of the sodium amide being added, but at temperatures exceeding 150°C, the dispersed sodium amide may It is easy to re-fuse and form coarse lumps, and to prevent this, the pouring speed must be significantly slowed down, which is undesirable. Accordingly
It is preferable to maintain the temperature at 120°C or lower, more preferably between room temperature and 100°C. However, it is not always necessary to maintain a constant temperature, and there is no problem even if the temperature rises due to the sensible heat and latent heat of sodium amide. Therefore, no special cooling is required if sufficient amounts of solvent are used.

The molten sodium amide to be added is most preferably produced by a high-temperature reaction between sodium and gaseous ammonia and then used in its molten state in an ammonia gas atmosphere or an inert gas atmosphere such as nitrogen gas. . Although it is possible to remelt sodium amide that has been crushed and stored in subdivided containers, this can be very dangerous depending on the storage conditions and should be avoided. The temperature of the molten sodium amide is preferably selected within the range of 240°C to 380°C, more preferably 250°C to 350°C. The injection of molten sodium amide is preferably carried out through a nozzle with an inner diameter of 10 mm or less. Note acceleration is
The injection rate per nozzle can be selected in the range of 0.05 to 1 kg/min, preferably in the range of 0.05 to 0.5 kg/min.

It is important to stir the molten sodium amide in a manner that quickly stirs the liquid surface on which it falls.
Although it is preferable to increase the rotational speed for a given required power, various selections can be made in relation to the injection speed depending on the desired particle size.

Sodium amide, which is originally a dangerous chemical, is treated with 300 ml of sodium amide, which can easily ignite in the air.
There has been no attempt to directly pour and disperse it into a highly flammable, low-boiling organic solvent in a high-temperature molten state around 0.degree. C., nor have there been any reports suggesting such a method.

Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 A stainless steel container with an internal volume of 20 mm equipped with a reflux condenser, a stirrer, a sodium amide inlet (8 mmφ), and a nitrogen inlet was used as a dispersion device. After charging 9 kg of xylene, the interior of the container and piping was replaced with nitrogen gas. Next, after heating the sodium amide piping and reaching 240°C, xylene was stirred at a rotation speed of 100 to 120 revolutions per minute, and about 1.8 kg of sodium amide was kept at 310°C while continuing to supply a small amount of nitrogen gas. was added over 12 minutes. During this time, the temperature of the xylene increased from 23°C to 92°C. The particle sizes of the white granular sodium amide dispersion obtained were almost all below 5 mm and were mainly distributed between 2 and 5 mm. Also, as a result of analysis, its purity is
It was 98.8%.

120 g of this granular sodium amide dispersion (approximately 20 g of sodium amide) was placed in a wide-mouth sample bottle, the upper space was replaced with nitrogen gas, and the sealed sample was used as a preserved sample to examine changes over time. It was confirmed that no coloring of the sodium amide particles was observed even after this, and the purity was 98.4%, which showed almost no decrease.

Example 2 Using the same dispersion device as in Example 1, tetralin
About 1.4 kg of sodium amide kept at 270°C was added and dispersed. It took 4 minutes to add and disperse. During this time, the temperature of the tetralin increased from 22°C to 84°C. The purity of the obtained white granular sodium amide dispersion was 99.1%, and the particle size was mostly distributed in the range of 2 to 5 mm.

125 g of this granular sodium amide dispersion (approximately 15 g of sodium amide) was placed in a wide-mouthed sample bottle, the upper space was replaced with nitrogen gas, and the sealed sample was used as a preserved sample to examine changes over time. It was confirmed that no coloration of the sodium amide particles was observed even after this, and the purity was 98.6%, which showed almost no decrease.

Example 3 A stainless steel reactor with an internal volume of 4 equipped with a sodium inlet, a nitrogen gas inlet, an ammonia gas blowing pipe, a gas outlet, a thermometer, and a liquid extraction outlet was replaced with nitrogen gas, and 815 g of sodium was charged. After that,
Ammonia gas was blown into the reactor at a reaction temperature of 340 to 360° C., and the reaction was carried out for 5 hours. Add this reaction solution to 320 ml
After cooling to ℃, using the same dispersion device as in Example 1, 5.5 kg of xylene was poured over 5 minutes. During this time, the temperature of the xylene increased from 23°C to 94°C. 6.86 kg of white granular sodium amide dispersion with a diameter of 5 mm or less was obtained, and the purity of sodium amide was 99.0.
It was %. From this, the yield of granular sodium amide was 97.4% based on the raw material sodium.

70 g of the above sodium amide dispersion (approximately 14 g of sodium amide) was placed in a wide-mouthed sample bottle, the upper space was replaced with nitrogen gas, and the sealed sample was used as a preserved sample to examine changes over time. It was confirmed that no coloring of the sodium amide particles was observed, and the purity was 98.5%, showing almost no decrease.

Reference example 1 Sodium amide dispersion obtained in Example 1
720 g (approximately 120 g of granular sodium amide) was transferred to a 2-meter tube equipped with a reflux condenser, a stirrer, a thermometer, and a dropping funnel.
Pour into a 4-necked flask and heat on an oil bath to 125 ml.
Pyridine 285 with stirring at a reaction temperature of ~135 °C
g was added dropwise over 6 hours to carry out the reaction. After the dropwise addition, reflux was continued for another 2 hours, the mixture was cooled, and 250 g of water was gradually added dropwise. After separating the reaction solution, the oil layer was concentrated to recover a distillate containing 590 g of xylene and 51 g of pyridine. Further, the concentrated solution was distilled under reduced pressure to obtain a fraction containing 225 g of 2-aminopyridine. The reaction rate of pyridine was approximately 82%, and the yield of 2-aminopyridine was approximately 81%.

Claims (1)

[Claims] 1. Stirred in an inert gas atmosphere and
A method for producing a sodium amide dispersion, which comprises adding molten sodium amide to an inert organic solvent maintained at 150°C or below, dispersing and solidifying it. 2. The production method according to claim 1, wherein the amount of the inert organic solvent used is at least three times the weight of the molten sodium amide to be added. 3 The holding temperature of molten sodium amide
The manufacturing method according to claim 1, which is carried out at a temperature in the range of 240 to 380°C. 4 Inject the molten sodium amide into an inner diameter of 10
2. The manufacturing method according to claim 1, wherein the injection is performed through a nozzle having a diameter of 1 mm or less, and the injection rate is in the range of 0.05 to 1 kg/min per nozzle. 5. Claim 1 in which the molten sodium amide is produced by reacting ammonia gas with molten metallic sodium at high temperature.
Manufacturing method described in section.