HU187632B - Process for producing herbicide esters of thiocarbamidic acid - Google Patents

Abstract

According to the present invention, thiourea acid esters of herbicidal activity are prepared in the formula (I): R, ethyl or n-propyl; R2 is n-propyl or cyclohexyl; R3 is ethyl or n-propyl. The essence of the process is to provide the secondary amines of formula (II): R 1; and R2 represents the above and is reacted countercurrently in a 2: 1 molar ratio of carbonyl sulfide and the resulting reaction mixture is maintained at 60-65 ° C. the resulting thiocarbanide acid amine salt is continuously removed, followed by dialkyl sulfal or an alkyl halide of formula III wherein R 1 is alkylated above. after alkylation, the resulting salt is removed from the lyocarbamide acid ester by washing with water and the ester is distilled by fractional distillation. -1-

Description

(54) PROCESS FOR THE PRODUCTION OF HERBICIDAL THIOCARBAMIC ACID ESTERS (57)

The present invention provides herbicidal thiocarbamic acid esters having the formula (I):

- R, ethyl or n-propyl;

- R _{2 is} n-propyl or cyclohexyl;

- R _{3 is} ethyl or n-propyl.

The process consists in providing secondary amines of formula II - R 1; and R ₂ is as defined above and is reacted upstream of carbonyl sulfide in a 2: 1 molar ratio and the resulting reaction mixture is maintained at 60-65 ° C, the thiocarbamic acid amine salt thus obtained is continuously drained, followed by dialkyl sulphide or alkyl halide is alkylated above. after alkylation, the resulting salts are removed from the lyocarbamic acid ester by washing with water and the ester is dried by fractional distillation.

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The present invention relates to a process for the preparation of herbicidal lyocarbamic acid esters of the formula (I).

In the formula (I), the substituents have the following meanings:

- R, ethyl or n-propyl;

R _{2 is} η-propyl or cyclohexyl;

R1 is ethyl or n-propyl.

Thiocarbamic acid esters of the formula I can be used as herbicides and various processes have been developed for their preparation. One of the main groups of processes used in the industry is synthesis based on the reaction of the secondary amine and carbonyl sulfide.

In U.S. Patent 3,133,947, the preparation of the above thiourea esters is accomplished by reacting the corresponding amine with a stoichiometric amount of carbonyl sulfide in the presence of another basic material at a temperature of -30 to +60 ° C, preferably 40 to 50 ° C, and the resulting intermediate is alkylated after appropriate purification.

50,86030. According to Japanese Patent Specification No. 6,105, the starting amine is reacted with carbonyl sulfide in a 2: 1 molar ratio in an organic solvent medium and alkylated in a solvent medium after the reaction. As the reaction medium, special solvents are used which are expensive to regenerate.

According to the method disclosed in German Patent No. 2,513,196, 1 mole of a secondary amine is reacted with 0.48-0.30 moles of carbonyl sulfide in an organic solvent medium at a temperature of 0-60 ° C, preferably 10-15 ° C. the amine salt of thiourea is alkylated with an alkyl halide.

According to U.S. Patent Nos. 2,743,513 and 2,844,305, ester formation with alkyl halide is carried out under pressure. The amine hydrochloride formed during the reaction forms a solid phase which can be removed from the reactor by aqueous solution. The process can only be performed in batch equipment, and the salt formed is highly corrosive. The installation of pressure equipment is costly.

According to German Patent No. 2,743,513, thiocarbamic acid esters are prepared in a solvent-free medium. The secondary amine is reacted with an excess of carbonyl sulfide and then the organic halide formed is added to the thiourea acid amide salt formed. The reaction requires pressure equipment and it is disadvantageous that the excess carbonyl sulfide used is decomposed with water to produce hydrocarbon and CO ₂ during the washing with hydrochloric acid. H ₂ S reacts with the amine salt in the aqueous medium to form a by-product which is difficult to remove.

No. 2,844,305. According to the German patent, carbonyl sulphide gas is introduced into the mixture of secondary amine and water and care is taken to leave a free amine at the end of the reaction. However, in the aqueous medium, the amino salt of the thiourea formed is decomposed and sulfur-containing organic compounds are formed. Another disadvantage is that the alkylation must be carried out below 50'C, at which temperature the alkyl chlorides do not react at a sufficient rate so that the thiourea acid amine salt is decomposed.

According to Belgian Patent 872 524, thiocarbamic acid esters are obtained by the reaction of CO and S in the secondary amine, followed by alkylation of the thiocarbamic acid amino salt with dialkyl sulfate. The disadvantage of this process is that it is necessary to produce pure CO, which is very costly, and also needs to be applied in sulfur dissolved state, which requires an auxiliary solvent. Continuous production of the sulfur solution is difficult because up to 2% sulfur in the solvent mixture can be achieved. Conversion of 85% and excess sulfur contaminates the finished product.

The molar ratio of carbonyl sulfide to the parent amine is considered to be very important because otherwise the decomposition of the amine salt of thiocarbamic acid occurs with the formation of mercaptans, hydrogen sulfide or sulfur. It is also important to keep the temperature values accurately in the reaction of the carbonyl sulfide with the amine as thermal decomposition occurs above 60 ° C.

Accurate adherence to molar ratios makes the synthesis extremely difficult to perform under industrial conditions. The removal of by-products formed is difficult as the environment is contaminated and the separation and neutralization of sulfur compounds must be solved in a closed system. A further disadvantage is that the strictly defined molar ratio of the corresponding amine and carbonyl sulfide is difficult to observe, even with batch or DC continuous equipment.

In batch DC systems, the reaction of the carbonyl sulfide with the amine is slow, and as the reaction progresses, the reaction rate decreases as the proportion of reaction partners in the mixture decreases. The amine salt of the thiourea formed is a highly viscous melt into which carbonyl sulfide can be introduced and dispensed by special procedures.

SUMMARY OF THE INVENTION It is an object of the present invention to provide continuous thiocarbamic acid esters of formula (I), wherein the substituents have the meanings given above, in which the problems of the known processes can be overcome.

It has been found that a good molar ratio of carbonyl sulfide to secondary amine reacting with it is a prerequisite for good yield and purity of the final product in the preparation of the thiourea acid intermediate salt. This molar ratio can be achieved at a sufficient reaction rate and without the risk of forming by-products by saturating the melt of the thiocarbamic acid amine salt with carbonyl sulfide at a temperature above the decomposition point of the thiocarbamic acid amine salt. At a selected temperature of 60-65 ° C, the secondary amine and carbonyl sulfide can be reacted in countercurrent without the risk of by-product formation. The concentration of the thiourea acid amine salt can be monitored by measuring the electrical conductivity, so that the molar ratio of the reaction components can be kept constant.

The process of the invention is a herbicidal owner-2,

For the continuous preparation of thiocarbamic acid esters of the formula 187 having the general formula (I)

- R, ethyl or n-propyl;

- R _{2 is} η-propyl or cyclohexyl;

- means R ₃ is ethyl or n-propyl, (II) a secondary amine of Formula and carbonyl reaction and the resulting thiocarbamic amine alkylation is characterized in that the secondary amine of formula (II), amines are - in which R, and R ₂ substituents and reacting carbonyl sulfide in a countercurrent ratio of 2: 1 by maintaining the temperature in the vicinity of the amine inlet at 30-50 ° C and in the vicinity of the urea sulfide inlet at 60-65 ° C to form the thiourea formed. the amine salt is continuously drained and then alkylated with an alkyl halide or dialkyl sulfate of the formula (III) wherein R ₃ is as defined above, the salt after alkylation is removed from the thiocarbamic acid ester by aqueous washing and the ester is fractionated by distillation. dried.

The ratio of the starting materials in the amine inlet environment is measured based on electrical conductivity and the proportion of materials added is controlled as the change occurs.

Preferably, the apparatus of Figure 1 may be used to carry out the process. The apparatus consists of a cascade reactor 1, 2 and 3, an alkylation reactor 4 and 5 coupled to the reactor 3, an associated washing-separation device 6, a finished product separator 7 and a vacuum distillation device 8. The lower part of the washer-separator 6 is connected to the vessel 9. Reactor I is equipped with a dosing line 11 for feeding amine and a device 13 for measuring electrical conductivity and 12 air ducts. In the upper part of reactors I, 2 and 3, an overflow line is provided to discharge the reaction product, and the reactors are provided with a gas inlet pipe reaching down to the bottom. At the introduction of reactor 3, carbonyl sulfide gas is introduced into the apparatus. In addition, the alkylation reactor 4 is fed with the alkylating agent at the inlet port 14. From the apparatus, amine 17 is discharged into the vessel 9, which is recovered in the vessel 9 and used as an acid binder, line 16 the wastewater and line 15 the finished product.

Note that more than one or two reactors may be used instead of reactors 1 and 2, if desired.

Reaction of the carbonyl sulfide with the secondary amine results in the formation of the amino salt of lyocarbamic acid, but it is also possible to form thiocarbamic acid below 60 ° C.

The decomposition point of lyocarbamic acid is lower than that of the thiourea acid. If the secondary amine is thereby reacted with carbonyl sulfide at a temperature above the decomposition point of the lyocarbamic acid but below the decomposition point of the amine salt of the lyocarbamic acid, then the carbonyl sulfide may optionally be present in the reaction mixture in excess. The formation of thiourea and its by-products at temperatures above the point of decomposition of thiourea is not possible because the amino salt of thiourea is further formed in the reaction mixture by the formation of carbonyl sulfide. The carbonyl sulfide only reacts in the system where at least 2 moles of secondary amine are present stoichiometrically and the amino salt of thiourea is formed.

During the countercurrent reaction line, the thiourea acid amine salt, which contains an excess of amine, is further reacted with the introduced carbonyl sulfide. The excess of locally formed carbonyl sulfide has increased the average reaction rate and the reaction can be completed.

The temperature of 60-65 ° C used in the introduction of carbonyl sulfide according to the invention ensures that the thiourea acid salt leaving the reactor is a uniform pure product which is free of starting materials. The equilibrium of the reaction is greatly facilitated by the accurate measurement of the concentration of the thiourea acid amine salt in the reaction mixture, including the degree of conversion. By adjusting and controlling the amount of starting materials required for the equilibrium reaction, the unit can be operated at optimum load and power.

Figure 2 shows, by way of example, that the electrical conductivity of a mixture of di (n-propyl) amine and thiourea acid salt at a certain stage of the reaction, with a degree of conversion of from 0.2 to 0.35, is highly dependent on thiourea acid. amine salt concentration. Accordingly, the reaction can be well controlled within the given conversion rate range. Figure 2 shows the concentration of the thiourea acid salt in moles on the horizontal axis and plots the electrical conductivity as a function of this (in cm2).

Figure 2 is drawn from the data in Table 1.

/. spreadsheet

Thiourea acid amine salt (morj 0.6 6.4 13.56 20.9 29.1 58.j 5 48.0 59.0 71.1

Ve / nbsp (pS cm) 0.06 0.15 1.2 5.5 17.5 55.8 54.0 62.0 54.0

Tivcarbanide salt (ni al · ',,) 84.7 100 \ vveióepC'SCg (pS cm) 37.5 31.8

Table 11 illustrates the thermal boiling of thiourea acid and di (npropyl) amine salt. The reaction temperature of the carbonyl sulfide gas phase in equilibrium at various temperatures was measured by the molar ratio of carbonyl sulfide to amine.

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Table 11

Temperature 'C COS / di (n-propyl) amine molar ratio 45 .533 50 0.517 55 0.508 60 .499 65 0.491 70 0,484 75 0.470 80 0.455 85 0,425 90 0.377 95 0,274 100 0.126

From the table it can be seen that a favorable molar ratio of 1: 2 COS / di (n-propyl) amine to the formation of the thiourea acid amine salt is formed at a temperature of 60-65 ° C.

The invention will be further illustrated by the following embodiments.

Example 1

The reaction is carried out in the apparatus of Figure 1. Reactors 1-5 consist of cooled and heated double-walled, well-stirred flasks with a useful volume of 500 cm ³ . The flasks have an overflow line at the top of the flasks to conduct the reaction mixture, and reactors 1-4 are connected via a bypass line to the inlet at the bottom of the next reactor. At reactor 5, the crude product is passed through a condenser. The reactors 1 to 3 have a gas inlet pipe down to the bottom, the gases leaving the reactor 3 are connected to the gas inlet of the reactor 2 and the gas pipe from the reactor 2 is connected to the gas inlet of the reactor 1. The gas from the reactor 1 is discharged outdoors. The reactor 1 is equipped with a pair of platinum electrodes connected to an electrical conductivity meter. Water is passed through the cooling jacket of reactors 1, 2 and 4, and reactors 3 and 5 are maintained at a constant temperature with a thermostat. The reactor is equipped with a feed line for the addition of the alkylating agent and the solvent. After cooling, the effluent from the reactor 5 is fed to a collecting vessel, and the resulting crude product is processed batchwise.

During the reaction, 404 g (4 mol / h) of di (n-propyl) amine are introduced into reactor 1 and carbonyl sulfide gas is introduced into reactor 3 at a rate such that the specific conductivity measured in reactor 1 is 10-15 pS / cm. . This conductivity interval corresponds to a conversion of about 25% in reactor 1. Excess di (n-propyl) amine in reactor 1 ensures complete absorption of the carbonyl sulfide gas passed from reactor 2. In Reactor 2, due to the excess carbonyl sulfide, the di-n-propylamine is fully reacted. The reaction heat of salt formation between reactor 1 and reactor 2 is essentially consistent with the degree of conversion: 75% of the reaction heat is released in reactor 2 and 25% in reactor 1. Reactors 1 and 2 are cooled and the temperature is maintained at 30-35 ° C. By adjusting the temperature of the reactor 3, we control the equilibrium molar ratio of the reaction (secondary amine): COS.

The reactor 3 does not release a significant amount of reaction heat, so keeping the temperature at 65 'Con can be achieved through a thermostat. The reaction temperature of 65-66'C corresponds to a molar ratio of COS: amine of 0.49: 1.0. At this temperature, pure thiourea di (n-propyl) amine salt leaves reactor 3. According to the conductivity value in reactor 1, 116 g / h of carbonyl sulfide gas is introduced into reactor 3.

To the pure thiocarbamic acid (n-propyl) amine salt leaving reactor 3, diethyl sulfate (2.1 mol / h = 3.24 g / h) was added to reactor 4. The temperature of the reactor 4 is maintained at 30-50 ° C by cooling with alkylation. Reactor 5 is heated to 80 ° C to complete alkylation. The crude product leaving the reactor 5, having a mass flow rate of 842 g / h, is batchwise processed.

The crude product (842 g) was washed with water (500 ml) at 60 ° C in apparatus 6. The aqueous phase is separated from the organic phase below and sodium hydroxide is added to the aqueous phase to recover the di (n-propyl) amine. The separated organic layer was washed with water (2 x 500 mL), then heated to 120 ° C at 100 mbar to remove volatiles. After purification from the hourly crude product, 362 g of S-ethyl-N, N-di (n-propyl) thiocarbamate are obtained, which is 98.2% pure.

The yield was 97.28% based on the introduced carbonyl sulfide.

Example 2

In the apparatus of Figure 1, 404 g / h (4 mol / h) of di (n-propyl) amine is introduced into the reactor 1 and 116 g / h of carbonyl sulfide gas is introduced into the reactor 3. Alkylation in reactor 4 is carried out with 260 g / h of n-propyl bromide in 500 g / h of xylene. The temperature of the reactor 3 is maintained at 64 ° C.

The alkylation temperature is 40-50 ° C and is maintained under cooling. In Reactor 5, the alkylation of the reaction mixture is completed at 80 'C. The crude product (1280 g) is washed with water (3 x 500 ml) every hour and the separated organic phase is freed from the xylene by fractional distillation at 100 mbar. 377.5 g of S- (n-propyl) -N, N-n-dipropylthiocarbamate are obtained hourly with a purity of 97.3%. Yield 93.5% based on amine input.

Example 3

Reactor 1 is charged with a mixture of 254 g of N-ethylcyclohexylamine and 202 g of diethylamine, and reactor 3 is charged with 116 g of carbonyl sulfide gas. In reactor 1, the thiourea acid amine salt and. The amine salt concentration of the amine mixture is maintained at 25 to 30 moles based on electrical conductivity.

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Reactor 1 and reactor 2 are cooled to 40-50 ° C. The temperature of the reactor 3 is adjusted to 62 ° C. In Reactor 4, the thiourea acid amine salt is alkylated with 324 g / h diethyl sulfate at 40-50 ° C, and then in Reactor 5, the alkylation is completed at 80'C. After working up in Example 1, 394.2 g of S-ethyl-Nethyl-N-cyclohexylthiocarbamate are obtained, with a purity of 96.8% per hour. Yield 91.8% based on amine.

Example 4

The reaction is carried out in the operating apparatus of Figure 1. Reactors 1-5 have a useful capacity of 500 liters and are equipped with continuous washing, separation, fractionation, amine regeneration and dewatering equipment.

To the reactor 1 is added 101 kg / h of fresh di (n-propyl) amine and 106 kg / h of anhydrous regenerated di (n-propyl) amine (95% by weight of amine).

Carbonyl sulfide gas (58 kg / h) was introduced into reactor 3. The electrical conductivity is maintained at 5-30 pS and the temperature of the reactor 3 is adjusted to 65 ° C.

The leaving intermediate in reactor 4 is alkylated with 162 kg / h diethyl sulfate at 30-50 ° C. In Reactor 5, the alkylation is completed at 80 ° C.

The crude product leaving the alkylation reactor was washed with 250 L / hr of water and the organic and aqueous phases were separated continuously. To the organic phase was added 120 kg / h of 40% w / w sodium hydroxide solution to liberate the di (npropyl) amine used for salt formation and to separate the organic phase. The water content of the regenerated amine is continuously removed by azeotropic distillation.

After washing with water, the crude product was fractionated at 120'C in a continuous distillation column at 100 mbar. The apparatus discharges 180 kg / h of S-ethyl-N, N-di (n-propyl) thiocarbamate with a purity of 96-97%. Yield 95-96% based on carbonyl sulfide.

Example 5 (Comparative)

The example illustrates the modification of electrical conductivity and yield when more than the stoichiometric amount is introduced from COS.

Example 1 except that 128 grams of carbonyl sulfide gas was introduced into reactor 3 per hour. At this time, the electrical conductivity of the reaction mixture in reactor 1 is continuously increased until it reaches 31.8 pS / cm, which corresponds to the electrical conductivity of the 100% di (n-propyl) thiocarbamic acid di (npropyl) amine salt. . Thereafter, 12 g of carbonyl sulfide gas is continuously discharged from reactor 1 through the airway.

361 g of di (n-propyl) thiourea acid ethyl ester are obtained hourly, corresponding to a yield of 97% for di-n-propylamine and 87% for carbonyl sulfide. The product is 98%.

Example 6 (Comparative)

This example illustrates how electrical conductivity and yield change when less than stoichiometric amount is introduced from COS.

The procedure of Example 1 was followed except that 105 g of carbonyl sulfide gas was introduced into reactor 3 per hour. The electrical conductivity of the material in Reactor I is then constant at 0.06 pS / cm, which corresponds to the electrical conductivity of 100% di (n-propyl) amine. This gives 325 g of di (n-propyl) thiocarbamic acid ethyl ester per hour, which corresponds to 88% yield of di (n-propyl) amine and 97% yield of COS. . The product is 98%.

Patent claims

Claims (3)

A process for the preparation of thiocarbamic acid esters having the herbicidal properties of the compounds of formula (I) - R, ethyl or n-propyl; - R _{2 is} n-propyl or cyclohexyl; - R _{3 is} ethyl or n-propyl; By reacting the secondary amines of formula (II) wherein R and R are as defined above and the carbonyl sulfide in a 2: 1 ratio and alkylating the amine salt of the thiocarbamic acid formed, wherein the secondary amines of formula (II) and continuously feeding the carbonyl sulfide countercurrently into a reactor such that the reaction mixture is saturated with carbonyl sulfide at a temperature of 30-50 ° C in the vicinity of the amine introduction, and 60-65 ° C in the vicinity of the carbonyl sulfide introduction. the amine salt of the thiourea formed is introduced in the vicinity of the carbonyl sulfide introduction and then alkylated in a known manner with a dialkyl sulfate or an alkyl halide of formula (II) wherein R 1 is as defined above; the salt obtained after alkylation is removed from the lyocarbamic acid ester by washing with water and the ester is dried by fractional distillation. A process according to claim 1, characterized by. keeping the molar ratio of the starting materials at 2: 1 by measuring the electrical conductivity in the environment of the amine introduction and, if necessary, adjusting the molar ratio of the starting materials It is maintained between 5.5 and 7.5 pS. 3 page drawing 88-0645 - Dabasi Nyomda, Budapest - Dabas ---- Responsible leader: Csaba Bálint director Published by the National Office for Inventions - Winter for Publication. Zoltán Himer Head of Department Taken by the Printing Pickup Plant (877667 (W) -5.187 632 NGO ₄ : The Leg N 47/10 C 07 C 155/02 feet