JP2000053630A - Production of chlorosulfonyl isocyanate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing chlorosulfonyl isocyanate from a sulfur trioxide and cyanogen chloride in good operability and in high yield. SOLUTION: This method comprises feeding cyanogen chloride to a mixture of a sulfur trioxide and chlorosulfonyl isocyanate at -10 to 17 deg.C to produce the aimed chlorosulfonyl isocyanate; wherein the sulfur trioxide to be used may be any one provided that it is liquid, preferably γ-modified one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing chlorosulfonyl isocyanate. More specifically, the present invention relates to a method for producing chlorosulfonyl isocyanate from sulfur trioxide and chlorocyanide with good operability and high yield. Chlorosulfonyl isocyanate is used as a raw material for various organic products such as medical and agricultural chemicals.

[0002]

2. Description of the Related Art It is known that chlorosulfonyl isocyanate can be obtained by a reaction between sulfur trioxide and chlorocyan, and a liquid phase reaction at a relatively low temperature and a gas phase reaction at a relatively high temperature are known. As an example of the liquid phase reaction, a method of supplying sulfur trioxide in chlorocyan at −15 ° C. to −5 ° C. [Organic Synthesis Collective (Org. Synth. Coll.) Vol.
26 to 2312], a method of continuously supplying sulfur trioxide and chlorocyanide into the reaction system at 10 ° C to 50 ° C (Japanese Patent Publication No. 5-79059), and a method of supplying sulfur trioxide at 20 ° C to 50 ° C. To supply chlorocyanide into the inside (Japanese Patent Publication 7-27)
No. 09 publication). Examples of gas phase reactions include:
European Patent Application Publication No. 0294613, Swiss Patent Invention Specification 680292, and the like.

[0003] Comparing the known techniques of the liquid phase reaction and the gas phase reaction, the liquid phase reaction is preferred in terms of operability and yield.
However, as described above in the liquid phase reaction,
In the method of supplying sulfur trioxide into chlorocyan at −5 ° C., it is difficult to control the temperature and 2,6-dichloro-1,4,3,5-oxathiadiazine-4,4- Since the dioxide is precipitated in a large amount, the operability is poor and it is difficult to employ it for industrial production. Further, in the method of continuously supplying sulfur trioxide and chlorocyanide at 10 ° C. to 50 ° C. into the reaction system, it is difficult to control the flow rates of the two and 2,6-dichloro- The operability is poor because 1,4,3,5-oxathiadiazine-4,4-dioxide is precipitated and the raw material supply section is blocked. In addition, 20 ℃ ~ 5
In the method of supplying chlorocyanide into sulfur trioxide at 0 ° C., the temperature range is considerably higher than the boiling point of chlorocyanide (14 ° C.). Divergence occurs, and the operability is poor, and it is difficult to adopt the method for industrial production.

[0004]

On the other hand, the method of supplying chlorocyan in sulfur trioxide at a temperature close to or below the boiling point of chlorocyan requires that the freezing point of sulfur trioxide be 17 ° C. (γ-form). It is usually hard to imagine. Under such circumstances, the present inventors have conducted intensive studies with the aim of finding a method for producing chlorosulfonyl isocyanate with high operability and high yield from sulfur trioxide and chlorocyan. When chlorosulfonyl isocyanate or a liquid containing the same is added, it is found that the freezing point of sulfur trioxide is lowered, and further, the temperature in the liquid is lower than the freezing point of sulfur trioxide, specifically -10 ° C to 17 ° C. When chlorocyanide is supplied in the temperature range above, compared with the case where sulfur trioxide and chlorocyan react in a temperature range higher than the freezing point of sulfur trioxide,
It has been found that chlorosulfonyl isocyanate is produced with high operability and high yield, and the present invention has been completed.

[0005]

That is, the present invention relates to a method for producing chlorosulfonyl isocyanate from sulfur trioxide and chlorocyanide, comprising a process for producing a mixture of sulfur trioxide and chlorosulfonyl isocyanate at a temperature in the range of -10 ° C to 17 ° C. A method for producing chlorosulfonyl isocyanate, characterized by supplying chlorocyan.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the sulfur trioxide used in the present invention, any liquid sulfur can be used, but a γ-isomer is particularly preferred. The production method and the type and content of impurities are not particularly limited, but usually sulfur trioxide having a purity of about 90% by weight or more, preferably 95% by weight or more is used. In use, the sulfur trioxide is organosilicon,
It may contain known polymerization inhibitors such as carbon tetrachloride, dimethyl sulfate, boron compounds, phosphorus compounds, and aromatic sulfonic acids. The content of the polymerization inhibitor is not particularly limited, but is usually in the range of about 0.0001 to about 3% by weight.

The chlorocyan used in the present invention may be either a gas or a liquid. The method and purity of the chlorocyanane are not particularly limited as long as they are manufactured industrially.
Usually, about 90% by weight or more, preferably 95% by weight or more is used. In the present invention, chlorocyan is supplied to a mixture of sulfur trioxide and chlorosulfonyl isocyanate. The supply amount (use amount) of chlorocyan is about 0.2 molar equivalent to about 2 molar equivalent to sulfur trioxide. Preferably, it is from about 0.3 molar equivalent to about 1.0 molar equivalent, more preferably from about 0.4 molar equivalent to about 0.7 molar equivalent. If it is more than the above range, 2,6-dichloro-1,4,3,5
The generation of by-products such as -oxathiadiazine-4,4-dioxide increases, the yield decreases, and the operability deteriorates due to precipitation. On the other hand, if the amount is less than the above range, sulfur trioxide will be consumed more than necessary, resulting in disadvantages in post-treatment and cost.

[0008] The purity of the chlorosulfonyl isocyanate mixed with sulfur trioxide used in the present invention is not particularly limited, and may be high-purity chlorosulfonyl isocyanate or a liquid containing chlorosulfonyl isocyanate. Is also good. As the liquid containing chlorosulfonyl isocyanate, for example, a reaction solution for producing chlorosulfonyl isocyanate, a concentrated solution, a distillate,
And the like, but are not limited thereto.
The amount of chlorosulfonyl isocyanate mixed with sulfur trioxide is not unique because it varies depending on the reaction temperature and the like to be carried out.
It is from 0.01 to about 3 molar equivalents, preferably from about 0.1 to about 1 molar equivalent.

In the practice of the present invention, the production method is not particularly limited, but usually, sulfur trioxide and chlorosulfonyl isocyanate or a liquid containing them are supplied in advance to a container. Conditions such that the mixed liquid and chlorocyan are sufficiently in contact with the mixed liquid composed of sulfur trioxide and chlorosulfonyl isocyanate or the mixed liquid composed of sulfur trioxide and chlorosulfonyl isocyanate using a gas introduction tube or the like for Russian. For example, it is blown into a fine foam or used in combination with mechanical stirring. When chlorocyan is a liquid,
The chlorocyan may be supplied to the mixture using a liquid introduction tube or the like, or chlorocyan may be dropped into the mixture and reacted while mechanically stirring the mixture.

One of the features of the present invention is that the freezing point (17 ° C., γ-form) of sulfur trioxide is reduced by mixing sulfur trioxide with chlorosulfonyl isocyanate or a solution containing the same. Therefore, the upper limit is 17 ° C. Although the lower limit is not particularly limited,
The temperature is about −10 ° C. in consideration of the freezing point of chlorocyan, the reaction rate, the necessary amount of chlorosulfonyl isocyanate mixed with sulfur trioxide or the content thereof. That is, it is usually about -10 ° C to about 17 ° C, preferably about 0 ° C to about 15 ° C.
° C. If the reaction temperature is higher than the above range, the yield will decrease, and the operability will decrease due to the emission of chlorocyan, the blockage of the chlorocyan supply port, and the like. When the reaction temperature is lower than the above range, the yield decreases and 2,6-
Dichloro-1,4,3,5-oxathiadiazine-4,
By-products, such as 4-dioxide, precipitate and the operability deteriorates. The addition time of chlorocyan in the reaction system is not particularly limited, but is usually in the range of about 0.5 to about 10 hours, preferably about 1 to 5 hours. After the addition, the amount is further increased to about 0.
The stirring may be maintained for 5 to about 10 hours, preferably for about 1 to about 5 hours.

The reaction conditions other than the reaction temperature in the present invention are not particularly limited as long as the reaction system maintains a liquid phase. The reaction pressure is generally about 1 atm to about 5 atm, preferably about 1 atm to about 2 atm. The atmosphere of the reaction system is not particularly limited, but it is preferable to carry out the reaction in an atmosphere of an inert gas such as nitrogen.

In the process of the present invention, chloropyrosulfonyl isocyanate is formed together with chlorosulfonyl isocyanate. Since chloropyrosulfonyl isocyanate can be converted into chlorosulfonyl isocyanate and sulfur trioxide by thermal decomposition or the like, it can be regarded as a precursor of chlorosulfonyl isocyanate. When performing pyrolysis, the operation may be performed together with, for example, a distillation operation, or may be performed as a single operation. For example, a reaction solution containing chlorosulfonyl isocyanate is usually subjected to simple distillation or rectification under normal pressure to thermally decompose chloropyrosulfonyl isocyanate to chlorosulfonyl isocyanate and sulfur trioxide, and to remove chlorosulfonyl isocyanate originally present in the reaction solution. Distillation may be carried out together with sulfonyl isocyanate and sulfur trioxide.

The reaction solution obtained by the method of the present invention is further purified if necessary. In general, the purification may be performed by distillation of the reaction solution under normal pressure or reduced pressure, and the pressure, temperature, number of stages, and the number of times of distillation are not particularly limited. The recovered raw material may be subjected to a treatment such as purification and addition of a stabilizer if necessary, and may be reused.

[0014]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 156 g (1.95 mol) of sulfur trioxide (γ-form) and 397 g (2.81 mol) of chlorosulfonyl isocyanate were mixed and stirred at 10 ° C. 120 g (1.95 mol) at 10 ° C.
The mixture was supplied over a period of time (the same method was employed in the following Examples and Comparative Examples), and then stirred at 10 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of the produced chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 70% from chlorocyan.

Example 2 293 g (3.66 mol) of sulfur trioxide (γ-isomer) and 118 g (0.83 mol) of chlorosulfonyl isocyanate were mixed and stirred at 10 ° C.
After supplying 0 g (2.44 mol) at 10 ° C. over 3 hours, the mixture was stirred at 10 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of the generated chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 79% from chlorocyan.

Example 3 298 g (3.73 mol) of sulfur trioxide (γ-form) and 221 g (1.56 mol) of chlorosulfonyl isocyanate were mixed and stirred at 10 ° C.
After supplying 5 g (1.87 mol) at 10 ° C. over 3 hours, the mixture was stirred at 10 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of the produced chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 90% from chlorocyan.

Example 4 315 g (3.93 mol) of sulfur trioxide (γ-isomer) and 221 g (1.56 mol) of chlorosulfonyl isocyanate were mixed and stirred at 0 ° C.
g (1.96 mol) was supplied at 0 ° C. over 3 hours, followed by stirring at 0 ° C. for 1 hour. As a result of analyzing the reaction solution,
The combined yield of the produced chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 85% from chlorocyan.

Example 5 290 g (3.62 mol) of sulfur trioxide (γ form) and 250 g of the reaction solution obtained by the method of Example 2 (1.37 mol of chlorosulfonyl isocyanate and chloropyrrosulfonyl isocyanate in total, (195 g as a sulfonyl isocyanate) was mixed and stirred at 10 ° C., and 121 g (1.96 mol) of chlorocyanane was supplied therein at 10 ° C. over 3 hours, followed by stirring at 10 ° C. for 1 hour. . As a result of analyzing the reaction solution, the combined yield of the produced chlorosulfonyl isocyanate and its precursor chloropyrosulfonyl isocyanate was 80% from chlorocyan.

Comparative Example 1 250 g (3.12 mol) of sulfur trioxide (gamma form) was added at 30 ° C.
, And 200 g of chlorocyanine (3.25
Was supplied over 3 hours at 30 ° C., followed by stirring at 30 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 60% from chlorocyan.

Comparative Example 2 150 g (1.87 mol) of sulfur trioxide (γ-form) and 265 g (1.87 mol) of chlorosulfonyl isocyanate were mixed and stirred at 30 ° C.
After supplying 0 g (1.95 mol) at 30 ° C. over 3 hours, the mixture was stirred at 30 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of the produced chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 58% from chlorocyan.

Comparative Example 3 164 g (2.05 mol) of sulfur trioxide (γ-form) and 397 g (2.81 mol) of chlorosulfonyl isocyanate were mixed and stirred at 60 ° C.
After supplying 6 g (2.05 mol) at 60 ° C. over 3 hours, the mixture was stirred at 60 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of the produced chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 35% from chlorocyan.

Comparative Example 4 293 g (3.66 mol) of sulfur trioxide (γ-form) and 207 g (1.46 mol) of chlorosulfonyl isocyanate were mixed and stirred at 30 ° C.
After supplying 0 g (2.60 mol) at 30 ° C. over 3 hours, the mixture was stirred at 30 ° C. for 1 hour. As a result of analyzing the reaction solution, the combined yield of the produced chlorosulfonyl isocyanate and its precursor, chloropyrosulfonyl isocyanate, was 49% from chlorocyan.

[0023]

According to the method of the present invention, chlorosulfonyl isocyanate can be produced from sulfur trioxide and chlorocyanide with good operability and high yield.

Claims (2)

[Claims] 1. A process for producing chlorosulfonyl isocyanate from sulfur trioxide and chlorocyanide, comprising:
A method for producing chlorosulfonyl isocyanate, comprising supplying chlorocyan to a mixture of sulfur trioxide and chlorosulfonyl isocyanate in a temperature range of from 17 ° C to 17 ° C. 2. The method according to claim 1, wherein the chlorosulfonyl isocyanate mixed with sulfur trioxide is a chlorosulfonyl isocyanate-containing liquid.