JP3104323B2 - How to remove thiophosgene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing phenyl chlorothioformates, which are useful as intermediates for the production of pharmaceuticals and agricultural chemicals, by the reaction of typhosgene and phenols. On how to do it.

[0002]

2. Description of the Related Art As a method for producing phenyl chlorothioformates, thiophosgene and phenols are dissolved in an organic solvent or a mixed solvent of an organic solvent and water as disclosed in JP-B-63-047704 and JP-A-1-301654. There is known a method of obtaining phenyl chlorothioformates by reacting in the presence of a dehydrohalogenating reagent.

Further, as a method for obtaining the target product phenyl chlorothioformate in high yield, Japanese Patent Publication No. 63-047
No. 705 publication, etc.
A method is known in which the reaction is carried out using 1.05 times or more moles.

[0004] In these conventional methods, thiophosgene remains in the reaction solution after completion of the reaction, but a method for decomposing and removing this thiophosgene is not known.

[0005]

The thiophosgene remaining in the reaction solution of phenyl chlorothioformates produced by the above-mentioned prior art is relatively dangerous, and is extremely dangerous during the post-treatment operation. When a purification operation such as distillation is performed, the boiling point of thiophosgene is 73 ° C.
It is concentrated as a low boiling point and distilled out, and some kind of detoxification treatment is required.

For this reason, it is desired that the remaining thiophosgene be decomposed and removed immediately after the reaction, and to further enhance the safety, it is desired that the remaining thiophosgene be decomposed and removed without being taken out of the reactor. .

[0007]

Means for Solving the Problems As a result of intensive studies on the method for removing thiophosgene, the present inventors have found that after the reaction of phenols with thiophosgene in the presence of a dehydrohalogenating reagent, the reaction mixture is further dehydrogenated. The inventors have found that the remaining thiophosgene can be easily decomposed and removed without decomposing the phenyl chlorothioformates produced by adding the reagents, and have completed the present invention.

That is, in the present invention, a phenol is reacted with thiophosgene in an organic solvent or a mixed solvent of an organic solvent and water in the presence of a dehydrohalogenation reagent to form phenylchlorothioformates, and then the reaction solution is transferred. The present invention provides a method for removing thiophosgene by further adding a dehydrohalogenating reagent and decomposing and removing remaining thiophosgene without performing the method.

[0009]

Hereinafter, the present invention will be described in detail.

The method of the present invention comprises a reaction solution containing phenylchlorothioformates obtained by reacting phenols with thiophosgene in an organic solvent or a mixed solvent of organic solvent and water in the presence of a dehydrohalogenating agent. Then, it can be applied to everything.

The organic solvent used in the reaction includes chlorinated hydrocarbons such as dichloromethane, chloroform and carbon tetrachloride; aromatic hydrocarbons such as benzene, toluene and xylene; and fats such as pentane, hexane and cyclohexane. Group hydrocarbons and the like.

The phenols include unsubstituted phenol, methyl phenol, ethyl phenol, tert-
Substituted phenols such as butylphenol and condensed phenols such as β-naphthol and 5,6,7,8-tetrahydro-2-naphthol can be mentioned.

Examples of the dehydrohalogenation reagent to be added to the reaction include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, and alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide. Stuff,
Examples thereof include alkali metal carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate; alkali metal bicarbonates such as lithium bicarbonate, sodium bicarbonate and potassium bicarbonate; and organic bases such as pyridine and triethylamine. Sodium hydroxide and potassium hydroxide are preferred.

In the reaction method, a solution of phenols dissolved in an aqueous solution of a dehydrohalogenation reagent may be supplied to an organic solvent solution of thiophosgene, or phenols and thiophosgene may be previously dissolved in an organic solvent. The reaction may be carried out by supplying a hydrogen halide reagent.

[0015] The reaction can usually be achieved under normal pressure at a temperature in the range of 5 to 50 ° C for 1 to 10 hours and aging for 1 to 5 hours.

As the dehydrohalogenation reagent to be added after the completion of the reaction in the present invention, any dehydrohalogenation reagent that can be used in the reaction can be applied, but preferably sodium hydroxide or potassium hydroxide is used. Used as an aqueous solution. The type of the dehydrohalogenating agent used for the reaction and the type of the dehydrohalogenating agent added after the reaction may be the same or different, and several types of the dehydrohalogenating agent added after the reaction may be mixed. There is no problem even if used.

The dehydrohalogenation reagent to be added after the completion of the reaction is usually added as an aqueous solution and has a concentration of 1 to 30.
Used as a concentration by weight or a saturated solution thereof.

The amount of the dehydrohalogenating reagent to be added after the completion of the reaction is theoretically applicable as long as it is at least twice the molar amount of the remaining thiophosgene, but it is sufficient for stable decomposition. More than 10 times the molar amount of thiophosgene is used. More preferably, the starting phenol can be removed by this operation from the target phenyl chlorothioformate.

After completion of the reaction, the dehydrohalogenating reagent may be added to the reactor without transferring the solution, or when the reaction is carried out in a mixed solvent of an organic solvent and water, the entire aqueous layer may be removed. There is no problem even if the dehydrohalogenation reagent is added after the partial removal.

After the completion of the reaction, the addition of the dehydrohalogenating reagent can be carried out at any temperature.
It is preferable to carry out the reaction at the same temperature as the reaction temperature obtained by preparing phenyl chlorothioformates from thiophosgene and phenols. The addition of the dehydrohalogenation reagent after the completion of the reaction may be carried out while stirring the inside of the reactor, or may be stirred after the addition. After the dehydrohalogenation reagent is added, stirring is usually performed for several minutes to sufficiently achieve the object.

[0021]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 Thiophosgene 36.2 was placed in a 1-liter three-necked round-bottom flask equipped with a stirrer and a 500-ml dropping funnel and equipped with a cock.
g of cyclohexane and 60 g of cyclohexane, and the temperature was adjusted to 15 ° C on a water bath. Then, m-tert-butylphenol 45.
A solution in which 0 g was dissolved in 126 g of a 10% aqueous sodium hydroxide solution was added dropwise over 3.0 hours, and the mixture was further stirred at the same temperature for 1.0 hour. After the stabilization, the organic layer was sampled from the reaction solution and analyzed by gas chromatography. The concentration of thiophosgene was 360 mg / kg, and the total amount was 4 mg / kg.
5.2 mg remained. Note that the target substance m-tert-
The yield of butylphenyl chlorothioformate is 65.
6 g, yield 95.7%.

Example 1 After completion of the reaction of Example 1, 10.0 g of a 10% aqueous sodium hydroxide solution was added at 15 ° C. for 1.0 minute while stirring the reaction solution, and further stirred at the same temperature for 1.0 minute. Was done. After the stabilization, the organic layer was sampled from the treated solution and analyzed by gas chromatography. The detection limit of thiophosgene was:
It was 0.5 mg / kg or less. Note that the object m-te
The amount of rt-butylphenyl chlorothioformate recovered was 65.3 g, and the recovery before and after the treatment was 99.8%, and no decomposition was observed by the treatment.

Reference Examples 2 to 6 Using the same apparatus as in Reference Example 1, the reaction was carried out under the conditions shown in Table 1. Table 1 shows the obtained results.

[0025]

[Table 1]

Examples 2 to 6 After completion of the reactions of Reference Examples 2 to 6 in the same manner as in Example 1, treatment was carried out under the conditions shown in Table 2. Table 2 shows the obtained results.

[0027]

[Table 2]

Comparative Example 1 Using the same reactor as in Reference Example 1, 36.2 thiophosgene was used.
g, a solution consisting of 60 g of cyclohexane was brought to 15 ° C.,
To this, 45.0 g of m-tert-butylphenol was added.
A solution dissolved in 126 g of a 0% aqueous sodium hydroxide solution was supplied over 3 hours, and further stirred at the same temperature for 1 hour. After completion of the reaction, liquid separation was performed to obtain an organic layer, which was analyzed by gas chromatography.
g.

Next, the organic layer was put into a 300 ml distillation apparatus, and heated under normal pressure to recover cyclohexane. The recovered cyclohexane contained 800 mg / kg of thiophosgene.
And thiophosgene was concentrated in cyclohexane.

[0030]

According to the present invention, phenylchlorothioformates can be safely produced from thiophosgene and phenols, and a more industrial production method has been established.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F07C 329/02 F07C 329/04

Claims (1)

(57) [Claims] 1. A reaction between a phenol and thiophosgene in an organic solvent or a mixed solvent of organic solvent and water in the presence of a dehydrohalogenation reagent to form phenylchlorothioformates, and then transferring the reaction solution. A method for removing thiophosgene, further comprising adding a dehydrohalogenating reagent to decompose remaining thiophosgene.