DE1112735B - Process for the preparation of aryl thioethers - Google Patents

Description

Process for the preparation of aryl thioethers The invention relates to on a new process for the preparation of aryl thioethers of the general Formula R-SCH2X In the general formula, R is a phenyl radical, which is optionally by halogen atom, a nitro or CH3, OCH3, CH3, CH3CONH or - CO OH group can be substituted. X means a chlorine or bromine atom.

Such compounds have hitherto been produced by the following processes been: Reaction of aryl mercaptomethanesulfonic acid salts with phosphorus or sulfur halides or oxyhalides, halogenation of thioanisole or substituted thioanisoles, Chlorination of diaryl monosulfides at low temperatures and conversion of Thiophenols, formaldehyde and anhydrous H Cl at low temperatures. the Compounds can also be made from alkali salts of thiophenols and a large excess produced by bromochloromethane.

The above methods all have certain disadvantages, such as a low yield, the generation of undesirable by-products and the necessity the application of several stages including intermediate cleaning to achieve the necessary Obtain starting materials.

According to the invention it has now been found that the halogenated Thioethers in high yield at ambient or room temperatures or above can be made by going to one made at room temperature Mixture of formaldehyde or a substance that supplies formaldehyde and concentrated aqueous hydrogen halide, an optionally substituted thiophenol in the presence of a solvent is slowly added dropwise, the molar ratio of hydrogen halide to formaldehyde to thiophenol is at least 7: 1, and the reaction product from isolated from the organic layer by evaporation of the solvent. The raw materials are relatively cheap as it is not necessary to use anhydrous hydrogen halides to use, and there are easily high yields of 90 to 96 ° / 0 of process product of relatively high purity, d. H. from 93 to 97 ° / O, achieved. As a result of the high yields and the high purity of the products produced by the process according to the invention a distillation of the process products for ordinary technical purposes is not necessary.

The reaction temperature can be pretty much about vary over a wide range, z. B. from 20 to 80 "C. The lower temperatures require longer reaction times necessary, while at the higher temperatures the hydrochloric acid loss is the process makes it uneconomical. The preferred temperature range is 40 to 60 "C.

The molar ratio of C H2O to aryl thiol should not be less than 1.1: 1 be. A higher ratio of CM2 0 can be used, e.g. B. such of 1.5: 1, but higher ratios are lossy and seem to decrease the yield and not to increase the purity of the product. The molar ratio of hydrogen halide to the aryl thiol should not be lower than 7: 1. Higher ratios can be used but they are wasted.

Except for the paraformaldehyde used in the examples below or formalin can also be gaseous formaldehyde and trioxane or other formaldehyde emitting substances are used.

In addition to benzene, toluene, xylene, halogenated solvents can also be used as solvents Benzenes and paraffinic hydrocarbons can be used.

The compounds of the invention are good pesticides and are particularly effective against rust, powdery mildew, aphids and the common housefly effective.

The method according to the invention is particularly advantageous Way to the desired products in high yield and excellent purity, as shown by infrared analysis. This is from the following comparative experiment evident: While in the method according to the invention initially a mixture of formaldehyde and acid is formed and only then is the thiophenol added is left, on the other hand, according to a known method on the thiophenol Act on formaldehyde in the presence of hydrogen halide.

According to this known procedure, p-chlorophenylchloromethyl sulfide was obtained prepared as follows: In a flask equipped with a stirrer and gas supply tube was, 18.7 cc of 40% formalin, 28.9 g (0.2 mol) of p-chlorothiophenol and 60.0 cc of concentrated hydrochloric acid was added. Stirring was started and hydrogen chloride gas introduced into the mixture from a cylinder for 2 hours. The temperature during the addition of hydrogen chloride was made possible by occasional cooling during the first Reaction hour and mild heating maintained at 35 to 38 "C during the second hour.

After cooling to room temperature, the reaction mixture was with 100 cc of benzene shaken to extract the product. After weaning it was the lower acid layer removed and the upper benzene layer with water, diluted aqueous sodium hydroxide and washed again with water.

The crude product was dried over anhydrous potassium carbonate, filtered and the benzene was evaporated on the steam bath. There were 34.4 g of p-chlorophenylchloromethyl sulfide (corresponding to 89.10 /, the theory). 30 = 1.6102. The purity of the end product was 87%; 10% of by-products had been formed. The product required further purification before it could be used for further reactions.

In contrast, in Example 1 below, according to the procedure product manufactured according to the invention, namely p-chlorophenylchloromethyl sulfide, an excellent purity of 97% according to infrared analysis and became obtained with a high yield of 96.4%. These products can also be used without that further purification is required can be used for further reactions.

The invention is explained in more detail in the following examples: Example 1 p-Chlorophenylchloromethyl sulfide In a 500 ml round bottom bottle, which was equipped with a stirrer, a thermometer and a dropping funnel, 7.5 g (0.25 mol) of paraformaldehyde and 50 cc of benzene were brought. The mixture was stirred at room temperature (26 "C), and there were 100 cc of concentrated hydrochloric acid added over a period of 5 minutes. The temperature dropped during the acid addition to 210 C.

The mixture was stirred for 10 minutes, then warmed to 30 ° C. and then added a solution of 28.9 g (0.2 mol) of p-chlorothiophenol dissolved in 50 cc of benzene, dropwise added over a period of 25 minutes.

The temperature was regulated by means of a warm water bath so that the addition of the p-chlorothiophenol solution took place at about 40 ° C. After all of the p-Chlorothiophenol solution was added, the temperature of the reaction mixture became increased to 50 ° C. and the mixture was stirred for 2 hours at 48 to 52 ° C. After cooling the lower acid layer and the upper benzene layer were stripped off at room temperature twice with 150 ml each washed in cold water. The benzene solution of the product was dried over anhydrous magnesium sulfate and filtered, and the filtrate was removed concentrated on the steam bath. The remaining benzene was removed the steam bath with a jet of air. The product, an almost colorless liquid, weighed 37.2 g (corresponding to 96.40% of theory). n30 ° 1.6014. An infrared analysis showed that 970/0 of the product was obtained from p-chlorophenylchloromethyl sulfide, ClC6HoSCH2CI, duration.

Example 2 p-Bromophenylchloride methyl sulfide Essentially in the in the same manner as in Example 1, p-bromophenylchloromethyl sulfide was used of 4.5 g (0.15 mol) of paraformaldehyde, 50 cc of concentrated hydrochloric acid and 18.9 g (0.1 mole) p-bromothiophenol. The yield of almost colorless liquid was 21.6 g (corresponding to 91.1% of theory). n25 = 1.6228.

Example 3 o-Methylphenylchloromethylsulfide In a similar manner the o-methylphenylchloromethyl sulfide from 4.5 g (0.15 mol) paraformaldehyde, 50 cc concentrated hydrochloric acid and 12.4 g (0.1 mol) of o-toluene thiol. The yield was 15.9 g (corresponding to 91.9% of theory). and 5 = 1.5853.

Example 4 p-Methoxyphenylchloromethylsulfide 9 g (0.3 mol) paraformaldehyde were mixed with 50 cc of benzene. Without cooling, 100 cc of concentrated hydrochloric acid became admitted fairly quickly. The temperature of the reaction mixture dropped somewhat. The mixture was stirred, warmed to 30 "C and then a solution of 24 g (0.17 mol) of p-methoxythiophenol in 50 cc of benzene added dropwise over a period of 30 minutes. the The temperature was kept at 36 to 50 ° C. during the addition of the p-methoxythiophenol. The mixture was then warmed to 45 "C and stirred at 45 to 47" C for 1 hour. To Cooling and transferring to a separatory funnel, the lower acid layer was stripped off and the top benzene layer was washed twice with 100 ccm of cold water each time and over dried anhydrous Mg 504. The anhydrous benzene solution was filtered off and the benzene removed on the steam room. The product, a yellow liquid, weighed 29.5 G. n3o0 = 1.5829.

Example 5 3-chloro-4-methylphenylchloromethyl sulfide From 24.0 g (0.15 Mol) 3-chloro-4-methylthiophenol, 7.5 g (0.25 mol) paraformaldehyde and 100 cc more concentrated Hydrochloric acid gave 28.8 g of 3-chloro-4-methylphenylchloromethyl sulfide according to the above procedure obtained in the form of a light yellow liquid. n3o0 = 1.5949.

Example 6 p-chlorophenylchloromethyl sulfide In a 500 cc bottle with a round bottom that comes with a thermometer, a stirrer and a dropping funnel was provided, 19 ccm of 400'0 des formalin, equivalent to 7.5 g (0.25 mol) of HCHO, and Brought 50 cc of benzene. While stirring and water cooling were 125 cc of concentrated hydrochloric acid added over a period of 5 minutes, whereby the temperature by regulating the additional speed between 20 and 25 ° C was held.

After increasing the temperature to 39 "C, a solution of 28.9 g (0.2 Moles) p-chlorothiophenol, dissolved in 50 cc benzene, dropwise over a period of time added of half an hour, the temperature during the thiol addition between 38 and 40 "C. The temperature was then increased to 50" C and the mixture was stirred for 1.5 hours at 48 to 52 "C. After cooling to 25" C., the lower acid layer removed and the upper benzene layer twice with 150 ccm each washed with cold water and then dried over anhydrous MgSO4. The filtered Benzene solution was concentrated on the steam bath to give 36.3 g of almost colorless p-chlorophenylchloromethyl sulfide. 300 = 1.6031.

Example 7 p-Chlorophenyl bromomethyl sulfide 4.5 g (0.15 mole) paraformaldehyde were mixed with 50 cc of benzene. Then 100 g of 480% hydrobromic acid were added with stirring (0.59 mole HBr) was added rapidly, the temperature dropping from 25 to 20 ° C. the The temperature was raised to 35 "C, then a solution of 14.5 g (0.1 Moles) p-chlorothiophenol dissolved in 25 cc of benzene, dropwise over a period of time added by 25 minutes. The temperature was increased to 40 to 45 "C during the addition held. After heating to 50 "C, the mixture was 1 hour and 15 minutes at 48 to 52 "C. After cooling, the lower acid layer was stripped off and the The upper benzene layer was washed twice with 100 ccm of cold water each time.

After drying over anhydrous MgSO4 and filtering, the benzene became evaporated on the steam bath. 21.2 g of p-chlorophenyl bromomethyl sulfide were in the form obtained a light yellow colored liquid. nD = 1.6278.

Example 8 2,5-dichlorophenylchloromethyl sulfide 4.5 g (0.15 mole) paraformaldehyde was mixed with 25 cc of benzene. The mixture quickly became 50cc with stirring concentrated hydrochloric acid added. The mixture was then heated to 45 "C and For this a solution of 17.9 g (0.1 mol) of 2,5-dichlorothiophenol in 50 cc of hot benzene dissolved, added dropwise over a period of 30 minutes. The addition took place in the temperature range from 45 to 50 "C. The reaction was carried out by stirring at 50 to 53 "C for a further 2 hours. Mixing was as at the previous examples worked up. This gave 21.8 g of 2,5-dichlorophenylchloromethyl sulfide obtained in the form of a colorless liquid. n300 = 1.6108. Yield 95 ° / 0.

Claims (4)

PATENT CLAIMS: 1. Process for the preparation of aryl thioethers of the general formula R-SCH2X in which R is an optionally substituted phenyl radical represents and X represents a chlorine or bromine atom, by reaction of thiophenol with formaldehyde and hydrogen halide, characterized in that one becomes one Mixture of formaldehyde or a formaldehyde produced at room temperature delivering substance and concentrated aqueous hydrogen halide, if necessary substituted thiophenol is slowly added dropwise in the presence of a solvent, wherein the molar ratio of hydrogen halide to formaldehyde to thiophenol at least 7: 1, 1: 1, and the reaction product from the organic layer by evaporation of the solvent isolated. 2. The method according to claim 1, characterized in that the implementation is carried out with the thiophenol at a temperature of 40 to 60 ° C. 3. The method according to claim 1 or 2, characterized in that Paraformaldehyde or formalin is used as the formaldehyde-supplying substance. 4. The method according to claim 1 to 3, characterized in that p-chlorothiophenol, 2,5-dichlorothiophenol, 3-chloro -4-methylthiophenol, o-toluene thiol or p-methoxythiophenol is used as the starting compound. Documents considered: German Patent No. 845 511