JP4004867B2 - Method for producing chlorosulfonyl isocyanate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a method for producing chlorosulfonyl isocyanate, and is an industrially important compound as an intermediate material for pharmaceuticals and agricultural chemicals.
[0002]
[Prior art]
It has been conventionally known that chlorosulfonyl isocyanate can be synthesized by a reaction between sulfuric anhydride and chloroisocyanate, and various production conditions have been reported.
For example, Japanese Patent Application Laid-Open No. 2000-53630 discloses a temperature of -10 to 17 ° C., Japanese Patent Application Laid-Open No. 1-222895 and Japanese Patent Application Laid-Open No. 4-164064, 10 to 50 ° C., Japanese Patent Application Laid-Open No. 63-77855. No. Patent Gazette describes a method of reacting at 20 to 50 ° C.
In addition, a method of reacting at a high temperature of 100 to 200 ° C. is described in West German Patent No. 928896 and European Patent No. 294613B1.
[0003]
These methods are not yet sufficient from the viewpoints of process control such as yield, production of by-products, and gasification of raw materials.
[0004]
[Problems to be solved by the invention]
Accordingly, the present invention provides a method for economically producing high-purity chlorosulfonyl isocyanate in a high yield by reacting sulfuric anhydride with chlorocyan.
[0005]
[Means for Solving the Problems]
The present invention
(1) In a method of producing chlorosulfonyl isocyanate by reacting sulfuric anhydride with chlorocyan, 50% or more of chlorosulfonyl isocyanate is present in the reaction system, and liquid anhydrous sulfuric acid and liquid chlorocyan are added to 1 mol of anhydrous sulfuric acid. A process for producing chlorosulfonyl isocyanate, which is continuously fed into the reaction system at a ratio of 0.8 to 1.3 mol of chlorocyanide and reacted at 50 to 110 ° C. (but not including 50 ° C.) ,
(2) The production method according to the above (1), wherein the reaction temperature is 90 to 105 ° C.
(3) The production method according to the above (1) or (2), wherein chlorocyan is continuously supplied at a ratio of 0.9 to 1.1 mol with respect to 1 mol of anhydrous sulfuric acid, and
(4) Liquid sulfuric anhydride and liquid chlorocyan are continuously fed into the reaction system so that the reaction liquid corresponding to the supply amount of sulfuric anhydride and chlorocyan for 30 minutes or more stays. It is a manufacturing method in any one of said (1) thru | or (3) which pulls out continuously.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Any sulfuric acid anhydride can be used as long as it is in the form of a liquid, but γ type is desirable, and stabilized sulfuric acid anhydride which is polymerization-prevented is preferable.
Chlorocyan is industrially produced from hydrocyanic acid and chlorine, and is preferably used in the liquid state in the method of the present invention and dehydrated by a dehydrating agent or distillation.
In the present invention, the reaction system is maintained at 50 to 110 ° C., and liquid sulfuric anhydride and liquid chlorocyan are continuously supplied and reacted.
The reaction is an exothermic reaction, and it is necessary to remove reaction heat in the reaction. The reaction tank in the reaction system is cooled, and a reaction tank with a stirrer equipped with a tower packed with a filler and a reflux condenser is further provided. It is advantageous to use and maintain the desired reaction temperature.
As for the exhaust gas from the top of the packed tower, it is desirable to return the whole amount of the liquid cooled and condensed in the condenser to the packed tower, and further cool the gas not condensed in the condenser with brine to collect chlorocyan and return it to the reaction tank.
[0007]
The amount of chlorocyan used is 0.8 to 1.3 mol, preferably 0.9 to 1.1 mol, per mol of sulfuric anhydride. That is, when it is less than 0.8 mol times or exceeds 1.3 mol times, the formation of by-products increases, and both the yield and quality decrease.
Purification of chlorosulfonyl isocyanate from the obtained reaction solution can be performed by distillation. For example, the reaction solution can be continuously withdrawn from the reaction system, or the whole amount can be taken out batchwise, and distilled while decomposing by-products under normal pressure. The resulting crude chlorosulfonyl isocyanate can be further purified and distilled as desired to obtain high-quality chlorosulfonyl isocyanate.
[0008]
In the method of the present invention, anhydrous sulfuric acid and chlorocyan are reacted in a liquid phase reaction system, and further, vaporized from the liquid phase reaction system is reacted in a gas phase part.
Anhydrous sulfuric acid and chlorocyan are preferably present in an equimolar amount in the reaction system to prevent the formation of impurities, and it is further desirable to react anhydrous sulfuric acid and chlorocyan as diluted as possible. Therefore, in the case where a chlorosulfonyl isocyanate having a production amount of 30 minutes or more is previously present as a solvent and continuous supply of anhydrous sulfuric acid and chlorocyan is started, or when the reaction is continuously performed, preferably 30 minutes or more, The reaction solution corresponding to the supply amount of sulfuric anhydride and chlorocyan for 1 hour or more, more preferably 1 hour 30 minutes or more is always retained in the reaction system, and sulfuric acid anhydride and chlorocyan are continuously supplied, corresponding to the supply amount continuously at the same time. It is convenient to discharge the reaction solution to be discharged from the reaction system.
[0009]
【Example】
Example 1
A 300 ml four-necked flask was equipped with a stirrer, a thermometer, a packed column filled with 20 cm of a 3.0 mmφ glass Raschig ring in a packed column of 1.5 cmφ, and a reflux condenser.
In this four-necked flask, 141.5 g of chlorosulfonyl isocyanate was placed and heated to about 90 ° C.
While maintaining the reaction system at 90 to 105 ° C., chlorocyan was added dropwise at a rate of 2.05 g / min and sulfuric anhydride at a rate of 2.67 g / min for 1 hour. The total supply amount of chlorocyan was 123 g, and the total supply amount of sulfuric anhydride was 160 g. After completion of the dropwise addition, the reaction was completed by stirring at 100 to 105 ° C. for 0.5 hour.
[0010]
After completion of the reaction, distillation was carried out at normal pressure using the packed tower attached to obtain 421 g of crude chlorosulfonyl isocyanate as a fraction having a boiling point of 105 to 107 ° C./760 mmHg.
In order to obtain further high purity chlorosulfonyl isocyanate, a 300 ml flask was equipped with a 1.5 cmφ packed tower and a packed tower filled with 3.0 mmφ glass Raschig ring 20 cm and a reflux distributor. A fraction of 106-107 ° C./760 mmHg gave 410 g (yield 95.0%) of purified chlorosulfonyl isocyanate. The purity was 99.0%.
[0011]
Example 2
A 300 ml four-necked flask was equipped with a stirrer, a thermometer, a packed column filled with 20 cm of a 3.0 mmφ glass Raschig ring in a packed column of 1.5 cmφ, and a reflux condenser.
In this four-necked flask, 141.5 g of chlorosulfonyl isocyanate was placed and heated to about 90 ° C.
While maintaining the reaction system at 90 to 105 ° C., 2.05 g / min of chlorocyan and 2.67 g / min of sulfuric anhydride with a metering pump (the supply rate of chlorocyan and sulfuric anhydride was 2 mol per hour) Equivalent)) and dropped for 1.5 hours. Thereafter, the reaction solution of the same amount as the supply amount was continuously withdrawn while continuing the dripping, and the reaction was continued for 8 hours.
[0012]
After completion of the reaction, the discharged reaction solution was distilled at normal pressure to obtain crude chlorosulfonyl isocyanate as a fraction having a boiling point of 105 to 107 ° C./760 mmHg.
Furthermore, in order to obtain highly pure chlorosulfonyl isocyanate, it distilled at normal pressure according to Example 1, and refine | purified chlorosulfonyl isocyanate was obtained with the fraction of boiling point 106-107 degreeC / 760mmHg. The purity was 99.0% and the yield from chlorocyan was 95.0%.
[0013]
【The invention's effect】
Since the raw material is supplied in liquid form, the flow rate control is accurate. Therefore, there are few reaction by-products, the purity of chlorosulfonyl isocyanate is high, the yield is high, and the gasification step of the raw material is not required. However, it can be manufactured by a very simple method.

Claims (4)

In a process for producing chlorosulfonyl isocyanate by reacting sulfuric anhydride with chlorocyan, 50% or more of chlorosulfonyl isocyanate is present in the reaction system, and liquid anhydrous sulfuric acid and liquid chlorocyanide are mixed with 1 mol of anhydrous sulfuric acid. A process for producing chlorosulfonyl isocyanate, characterized in that it is continuously fed into a reaction system at a rate of 0.8 to 1.3 moles of Russian and reacted at 50 to 110 ° C. (but not including 50 ° C.) . The process according to claim 1, wherein the reaction temperature is 90 to 105 ° C. The process according to claim 1 or 2, wherein chlorocyan is continuously supplied at a ratio of 0.9 to 1.1 mol per 1 mol of anhydrous sulfuric acid. Liquid sulfuric acid anhydride and liquid chlorocyan are continuously fed into the reaction system so that the reaction liquid corresponding to the supply amount of sulfuric anhydride and chlorocyan for 30 minutes or more stays, and the reaction liquid in the reaction system is continuously supplied. The manufacturing method according to claim 1, wherein the method is drawn out .