CS196390B2 - Method of preparing esters of thiocarbamic acid - Google Patents

Description

(54) A method for preparing thiocarbamic acid esters

The present invention relates to a process for preparing thiocarbamic acid esters by reacting carbonyl sulfide with amines.

Thiocarbamic acid esters are useful for a variety of purposes. Some are effective herbicides, others are effective as inhibitors of the growth of microorganisms such as bacteria, and still others are effective insecticides. These compounds are prepared, for example, by the following processes:

According to U.S. Patent No. 2,983,747, various thiocarbamic acid esters are prepared by direct reaction of carbamyl chlorides with mercaptans using zinc chloride as a catalyst. Although the reaction may be carried out without the use of a solvent, however, when a solvent is used, it must be a solvent inert to the catalyst, such as organic solvents.

U.S. Pat. No. 2,913,327 discloses a process according to which a mercaptan sodium salt is prepared and then reacted with carbamoyl chloride in the presence of a solvent. The use of mercaptan sodium causes problems with filtration and handling of solids. The use of solvent reduces the capacity of the reactor and can cause recovery problems. In addition, the hydrogen released during the preparation of the sodium salt causes problems with its removal.

U.S. Pat. No. 3,836,524 discloses a process wherein carbamyl chloride is treated with mercaptan in the presence of an aqueous alkali metal hydroxide solution. This process requires considerable agitation to ensure a large interfacial surface between the two liquid phases, in addition to achieving the desired conversion and purity of the product, the hydroxide concentration must be high.

U.S. Pat. No. 3,133,947 discloses a process wherein a secondary or primary amine is treated with a carbonyl sulfide in the presence of a base, which may be any amine, including a tertiary amine, and then reacting the intermediate with an organic sulfate such as dialkyl sulfate or dialkyl sulfate. In this process, the sulfate value is lost, thereby increasing the overall cost.

According to the procedure described in U.S. Pat. No. 3,176,571, carbonyl sulfide is reacted with a primary or secondary amine in an aqueous alkaline solution at a temperature of 20 ° C or less. The condensation of the amine salt of thiocarbamic acid is then carried out by reacting the salt with an organic halide. This procedure has two disadvantages. Organic halides with lower reactivity do not react at this temperature. Although such less reactive halide 19B390 nides readily react at temperatures of about 100 degrees Celsius, these temperatures cannot be used in the process because the aqueous medium does not absorb carbonyl sulfide at temperatures too high above 20 ° C. In addition, the amount of carbonyl sulphide used must be strictly controlled, since its excess causes the decomposition of the thiocarbamate. Thus, considerable amounts of by-products are obtained, the quantities of which can be reduced only at the cost of reducing the yield.

Also, the process described in U.S. Patent No. 3,151,119 requires low temperatures. This process has similar disadvantages to the previous process.

The latest carbonylsulfide process is that disclosed in U.S. Patent No. 3,954,729, wherein the secondary amine is treated with carbonyl sulfide in the presence of an aromatic solvent to form an amine salt of thiocarbamic acid, which is then reacted with an alkyl halide to form the ester. thiocarbamic acids. However, at a stoichiometric molar ratio of carbonyl sulfide to amine, the maximum achievable purity of the non-aging product is 92%. Aging and excess carbonyl sulphide further reduce the purity of the product. In order to increase the purity of the product, this patent proposes to use at least 4% molar carbonyl sulfide deficiency in the first reaction and an amount of alkyl halide in the second reaction that exactly matches the stoichiometric amount. In order to achieve both a maximum dose-related yield and a minimum amount of by-products, a high degree of accuracy must be maintained when measuring the relative amounts of reagents. This is undesirable since this increases the cost of monitoring the reaction and loses the flexibility of the process. By-product formation is further reduced by lowering the reaction temperature in the second reaction stage to a temperature in the range of 0 to 60 ° C. Although the alkyl halides mentioned in the examples of the patent react at an acceptable rate at a temperature in this range, the same is not true using less reactive alkyl halides. For example, lower alkyl chlorides will react extremely slowly or will not react at all within this temperature range.

In view of these problems, it is an object of the present invention to provide a process for the preparation of thiocarbamic acid esters which provides high yields and high conversions while achieving savings on starting materials.

It is also an object of the present invention to provide a process for the preparation of thiocarbamic acid esters which does not require precise monitoring of the reaction, as in U.S. Patent No. 3,954,729, and which allows the use of alkyl chlorides which are unreactive in the process.

The class of compounds with which the invention is concerned is referred to as thiocarbainates or thiocarbamic acid esters. Sometimes the synonymous thiolcarbamates are also used to refer to the same compounds. At these positions, the term thiocarbamic acid esters is used.

It has now been found in the context of the present invention that a new process can be efficiently and economically obtained to obtain thiocarbamic acid esters in high yield and purity. The present invention provides a process for the preparation of thiocarbamic acid esters of formula (I)

R ¹ O

R ² —N — C — S — R ³ (I), wherein each of the symbols

R ¹ and R ² , independently of each other, represent a C 1 -C 12 alkyl group or a C 3 -C 7 cycloalkyl group or together

R ¹ and R ² , taken together with the nitrogen atom to which they are attached, represent a C 2 -C 6 polyalkyleneimine scrubber, and

R ³ represents a C -C alkyl group, characterized by preparing an anhydrous mixture of an amine of formula II

...... R ¹ ..... ........ .......

AND

R @ ² NH (II) wherein

R ¹ and R ² are as defined above and an organic halide of the formula III

R ³ X (III), where

R ³ is as defined above and

X is chlorine, bromine, or iodine, and carbonylsulfide gas is bubbled below the liquid mixture at a carbonylsulfide to amine molar ratio of from 0.502 to 0.750, 70 to 110 ° C and an overpressure of 68.7 to 1030.5 kPa. then isolating the desired ester of formula (I) from the resulting mixture comprising thiocarbamic acid ester of the general formula (I) and a salt of formula (I).

The term "C1-C12 alkyl" refers to a monovalent saturated straight or branched chain aliphatic hydrocarbon group having 1 to 12, preferably 2 to 6 and most preferably 2 to 4 carbon atoms, for example methyl, ethyl, propyl, iso196390 propyl, , tert-butyl-, 2-methyloctyl and the like.

The term "C 3 -C 7 cycloalkyl" refers to a monovalent cyclic saturated hydrocarbon group containing 3 to 7 carbon atoms, for example cyclobutyl, cyclohexyl and the like.

Under the term "C 2 -C 6 polyalkyleneimine". is a monovalent saturated heterocyclic ring containing one nitrogen atom and 2 to 6 carbon atoms, for example dimothylene ¹ 'mino-, trimethylenimino-, tetramethylenimino-, pentamethylenimino-. and hexamethyleneimino.

All ranges of carbon atom numbers given herein are intended to include upper and lower limit values.

According to the invention, one mole of carbonyl sulfide is treated with about two moles of a primary or secondary amine, preferably a secondary amine, and the resulting product is then treated with an organic halide to produce the desired product.

The reaction must be carried out under anhydrous conditions to prevent the reaction of carbonyl sulfide with water to form hydrogen sulfide and other impurities. In order to achieve maximum conversion of the amine, an excess of carbonyl sulfide corresponding to a carbonyl sulfide / amine molar ratio of 0.502 to 0.750 and preferably 0.515 to 0.550 is used. Although the pressure and temperature at which the reaction is carried out are not essential to the invention, it is expedient to operate at a temperature of from 70 to 110 ° C, under positive pressure

68.7 to 1030.5 kPa.

The reactions may be carried out in the absence of a solvent or in the presence of any anhydrous aprotic solvent. The term "aprotic solvent" means an organic solvent that neither provides nor receives protons. Examples of such solvents include benzene, toluene, alkanes and their halogenated derivatives. Unsuitable solvents over a wide temperature range are solvents that hydrolyze the reaction product, for example water, alcohols, aldehydes or ketones. Preferably, the reaction is carried out either without a solvent or using either an organic halide or a product, i.e. a thiocarbamic acid ester, as the solvent. Most preferably, the reaction is carried out either without a solvent or using the prepared thiocarbamic acid ester as solvent. .

Anhydrous conditions are also particularly important because, at temperatures above about 60 ° C, the amine salt decomposes and releases carbonyl sulfide gas, which in the presence of water converts to hydrogen sulfide and carbon dioxide. The hydrogen sulfide is combined with the unreacted salt and the ester product to produce by-products that reduce the purity of the desired reaction product.

A further advantage of working in an anhydrous environment is that a wider range of organic halides can be used, including less reactive organic halides, including less reactive organic halides, which readily react only at temperatures above about 60 degrees Celsius. Examples of such less reactive halides are C 1 -C 4 alkyl chlorides. If at such a temperature is not functioning in an anhydrous environment, there would be a large amount of ^by: product, since carbonyl sulfide release rate increases with increasing temperature. In an anhydrous environment, the temperature has substantially no effect on the formation of by-products, since carbonyl sulfide in the absence of water does not form hydrogen sulfide to combine with a salt or ester.

In order to improve the conjugation of the amine salt to the thiocarbamic salt ester, an excess of organic halide may be used, such as a molar ratio of halide to salt of from about 1.0 to about 1.5, preferably from about 1.03 to about 1.1. Examples 1 to 8

In Examples 1 to 7, the appropriate amine is placed in a pressure vessel and the appropriate organic halide is added to the amine. The vessel was then sealed and carbonyl sulfide was placed below the liquid and bubbled through the reaction mixture. The contents of the vessel were stirred with a magnetic stirrer and the vessel was placed in a heated bath. The reaction is complete in 1 hour or less. The amine hydrochloride is dissolved in water and separated from the product. The resulting product was washed with water and dilute aqueous hydrochloric acid. The aqueous fractions were then extracted with hexane and the volatiles removed from the product in vacuo.

In Example 8, the amine is first saturated with carbonyl sulfide at atmospheric pressure. Saturation is then carried out when an organic halide is added.

Table 1 lists the reagents used in the experiments and the thiocarbamic acid esters obtained. Table II lists the reagent ratios and reaction conditions in each experiment, together with the results obtained in terms of yield and purity.

199390

Reaction Amin

Table I

Reaction

Organic halide Product di-n-propylamine diisobutylamine hexamethylenimine ethyl chloride ethyl chloride ethyl chloride di-n-propylamine n-propyl chloride ethylcyclohexylamine ethyl chloride ethyl-n-butylamine n-propyl chloride diethylamine p-chlorobenzyl chloride

S-ethyldipropylthiocarbamate

S-ethyldiisobutylthlokarbamate

S-ethylhexahydro-1H-azepine-1-carbothioate

S-propyldipropylthiocarbamate

S-ethylcyclohexylethylthiocarbamate

S-propylbutylethylthiocarbamate

S-p-chlorobenzyldiethylthiocarbamate

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136390

Efficacy data of compounds

As already mentioned, thiocarbamic acid esters prepared by the process of the invention are useful as pre-emergence and post-emergence herbicides, growth inhibitors and insecticides. The herbicidal activity of some of the compounds prepared in the above examples was determined as follows.

Test of pre-emergence herbicidal action

Weigh 20 mg of the test compound onto a piece of glass-binding paper on an analytical balance. The paper and compound are placed in a 30 mL wide-necked flask and 3 mL of acetone containing 1% emulsifier defined as polyoxyethylene sorbitan monolaurate (Tween 20 ^R ) is added to dissolve the compound. If the substance is not soluble in acetone, another solvent such as water, alcohol or dimethylformamide (DMF) is used instead of acetone. When DMF is used, only 0.5 ml or less of this solvent is added to dissolve the compound and then the volume is made up to 3 ml with another solvent. Spray 3 ml of the solution evenly on the soil contained in a small bowl of fibrous material 1 day after sowing the weed seeds in the bowl.

Spraying is carried out with a spray gun [DeVilbiss No. 152] operating with compressed air at a pressure of 35 kPa. The spraying rate is 9 kg / 10,000 m ² and the spraying volume is 1344 1 / 10,000 m ² .

The day before the above treatment, a fiber dish of 18 cm long, 13 cm wide and 7 cm deep was filled to a depth of 5 cm with loamy sand. Seeds of seven different weed plants are sown in individual rows arranged across the dish, with seeds of only one species being sown in each row. The seeds are covered with soil so that they are sown in depth

1,25 cm. The seeds of the bloodweed (Digitaria sanguinalisj), the gray scar (Setaria glauca), the amaranth (Amaranthus rectroflexusj), the mustard (Brasslca juncea), the sorrel (Rumex crispus), the hedgehog (Echinochloa crsa sativa) and ova are used. Seeds are sown in each row to yield about 20 to 50 seedlings in each row, depending on the size of the plant.

After treatment, the dishes are placed in a greenhouse where they are placed. maintains a temperature of 20 to 29 ° C and water is supplied by sprinkling. Two weeks after treatment, the degree of damage or suppression is determined by comparison with untreated test plants of the same age. For each species, the percentage of damage (0 to 100 percent) is determined, with 0% indicating no damage and 100% complete killing.

Postemergence herbicidal effect

Seeds of six plant species, namely bloody dew, hedgehogs corn, oat, sareptic mustard, sorrel and bean (Phaseolus vulgaris) are sown in pans of fibrous material described in the pre-emergence test. The dishes were placed in a greenhouse at 20-29 ° C. The water is supplied once a day using a sprinkler. About 10 to 14 days after sowing, when the primary leaves of the bean plants are almost fully developed and the first three-lobed leaves are being formed, spraying is applied to the plants. Prepare the spray by weighing 20 mg of the test compound, dissolve the compound in 5 ml of acetone containing 1% Tween 20 ^R and add 5 ml of water. The solution is sprayed onto the leaves using a spray gun [DeVilbiss # 152] operating at a pressure of 35 kPa. The spray concentration is 0.2 and the spraying rate is 9 kg / 10,000 m ² , at a volume of 4488 liters. The degree of damage is determined 14 days after application. The rating system is the same as in the preemergence test.

The results are summarized in Table III.

10

Table III

Herbicidal effect

Product Preemergence effect:% suppression with application of 9 kg of active ingredient / 10,000 m ²

number RK BS JK OS LO MS with 2 0 95 80 100 ALIGN! 0 0 0 3 20 May 90 95 100 ALIGN! '0 10 .40 4 90 80 97 100 ALIGN! 30 20 May 0 5 98 98 90 100 ALIGN! 10 10 10 6 20 May 80 70 100 ALIGN! 10 10 10 Product Preemergence effect: % suppression when applied- from the example kaci 9 kg active substance / 10 000 m ² • number RK JK OS HS WITH AFTER 2 0 0 0 0 0 0 3 0 0 0 0 0 10 4 0 80 80 0 0 0 5 30. 0 0 0 98 0 6 0 0 0 0 0 0

Symbols used:

RK rosička krevavá BS bér sivý JK hedgehog corns the leg OS oats LO Kindweed bent HS sarept mustard WITH sorrel FO bean

Claims (2)

SUBJECT YOU A process for the preparation of thiocarbamic acid esters of the general formula I R ¹ O R ² —N — C — S — R ³ '(I), wherein each of the symbols R ¹ and R ² , independently of each other, represent a C 1 -C 12 alkyl group or a C 3 -C 7 cycloalkyl group or together R ¹ and R ² , taken together with the nitrogen atom to which they are attached, represent a C 2 -C 6 polyalkyleneimine group and R ³ is C 1 -C 6 alkyl, characterized in that an anhydrous amine mixture of formula II is prepared Ri R ² —NH (Π) where R ¹ and R ² are as defined above and the organic halides of formula III R ³ X (III), FIND WHERE R ³ is as defined above and X is chlorine, bromine or iodine, and carbonylsulfide gas is bubbled beneath the surface of the liquid mixture at a carbonylsulfide to amine molar ratio of from 0.502 to 0.75, 70 to 110 ° C and positive pressure. 68.7-1030.5 kPa, followed by a mixture comprising a thiocarbamic acid ester of formula I and a salt of formula Xx10 * isolates the desired ester of formula AND. 2. A process according to claim 1, wherein di-n-propylamine is used as the compound of formula II and ethyl chloride is used as the compound of formula III. 3. A process according to claim 1, wherein the compound of formula (II) is 189390 11 12 is diisobutylamine and, as the compound of formula III, ethyl chloride. 4. The process of claim 1 wherein hexamethylenimine is used as the compound of formula (II) and ethyl chloride is used as the compound of formula (III). 5. A process according to claim 1, wherein the compound of formula II is dipropylamine and the compound of formula III is n-propyl chloride. 6. A process according to claim 1, wherein the compound of formula II is ethylbutylamine and the compound of formula III is n-propyl chloride. 7. The process of claim 1 wherein ethylcyclohexylamine is used as the compound of formula (II) and ethyl chloride is used as the compound of formula (III). SsvstognJit, n. P., Xtvod 7, Most