HU201522B - Improved process for producing s-ethyl-n,n-diisobutylthio-carbamate - Google Patents

Abstract

The present invention relates to the preparation of S-ethyl-N, N-diisobutylthiocarbamate by reaction of diisobutylamine and carbonyl sulfide at ambient temperature and alkylation of the resulting thiocarbamic acid amine with diethyl sulfate. The essence of the process is that the reaction and alkylation is carried out in the presence of at least 10% by weight of the starting diisobutylamine in the presence of 1 to 3 carbon atoms of aliphatic alcohol. After alkylation, the alcohol is distilled off and the reaction mixture is poured into water and the desired product is recovered from the resulting organic phase. Scope of the description: 8 pages, Figure 1 CM CM 10 O CM

Description

The present invention relates to the preparation of S-ethyl-N, N-diisobutylthiocarbonate by reacting diisobutylamine with COS gas and diethyl sulfate esterification of the resulting thiocarbamic acid amine salt, which can be carried out batchwise or continuously.

S-ethyl-N, N-diisobutylthiocarbamate (hereafter butylate) is used to control broadleaf and herbaceous weeds in maize because it is not persistent. Usually in combination with other herbicides, its use is advantageous.

Thiocarbamate-type herbicides are economically prepared from amine and carbonyl sulfide (COS-gas). The corresponding secondary amine is reacted with COS gas in the presence of an alkali and the resulting thiocarbamic acid salt is esterified with an alkyl halide or dialkyl sulfate. The COS gas and the amine can be reacted without solvent in an organic or aqueous medium. 52-78.832 / 1977. According to the Japanese patent, diisobutylamine is dissolved in four times the amount of acetonitrile to produce butylate, and COS gas is introduced at room temperature in the presence of triethylamine. The resulting N-diisobutylamine thiocarbamic acid triethylamine salt is esterified with ethyl chloride in hexamethylphosphoramide (5 times its weight). The yield is 94.4%, but the product quality is unknown. However, the process requires relatively large amounts of expensive solvents, and it is disadvantageous that ethyl chloride is less reactive and therefore, due to the slow reaction time, the process cannot be made continuous. The use of two types of solvents also makes the reaction difficult.

The object of the present invention is to simplify the process for the preparation of butylate, to increase the reaction rate and to make the processing more economical. We also aim to develop a continuous process technology for the product.

It has now been found that reacting amine and carbonyl sulfide gas in the presence of a C 1-3 aliphatic alcohol in the preparation of the butylate, followed by diethyl sulfate ester formation, increases the reaction rate, decreases the viscosity of the reaction partners, and it can be played continuously without the use of special equipment. The increased reaction rate and the homogeneous reaction medium may contribute to the purity of the product.

The process of the present invention for the preparation of S-ethyl-N, N-diisobutylthiocarbamate by reaction of diisobutylamine and carbonyl sulfide gas at ambient temperature and esterification of the resulting thiocarbamic acid amine salt with diethyl sulfate is characterized in that the reaction and esterification at least 10% by weight of diisobutylamine, preferably 30-50% by weight of a C 1-3 aliphatic alcohol. Preferred aliphatic alcohols are methanol. In the continuous reaction, diisobutylamine and carbonyl sulfide are passed in countercurrent, in a multi-member cascade reactor, followed by diethyl sulfate alkylation at ambient or elevated temperature. The alkylation (esterification) is carried out by distilling off the alcohol used, and then adding water to separate the organic and aqueous phases. The aqueous phase can be regenerated with sodium hydroxide solution to remove the diisobutylamine salt and the organic phase containing butylate to remove the volatile material.

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The advantages of our process over known methods are summarized below:

1. The process according to the invention can increase the reaction rate compared to both the solvent-free process and the solvent-free process.

2. A homogeneous medium is formed and the increased reaction rate allows continuous production of the production technology, which is not known for the production of butylate.

3. The reaction mixture has a favorable viscosity, which not only has the advantage of being easier to handle, but also has a better yield.

4. Due to the homogeneous reaction medium and the increased reaction rate, the quality of the product can be improved.

The continuous installation is schematically illustrated in Figure 1. A metered amount of gas from a gas cylinder 1 is introduced into the second 2 members of a gas absorption reactor connected in two rows. Simultaneously, diisobutylamine is added to the first 3 members of the gas-absorbing cascade from the diisobutylamine dispenser 4 by means of a piston metering pump. A methanolic solution of the thiocarbamic acid amine salt leaving reactor 2 is passed through a liquid seal to the alkylation reactor 6, and diethyl sulfate is added from the feed vessel 5 to the alkylator 6.

The reaction mixture flows from the alkylation reactor 6 to the post-alkylation reactor 7, where the reaction is completed at a higher temperature. From the post-alkylator 7, methanol is distilled off, which is transferred to the recovered methanol collecting tank 8, and from there to the diisobutylamine feeder 4.

The reaction mixture is then worked up. After completion of the reaction, the reaction mixture flows from the post-alkylator 7 to the washer 9 to which water is added from the meter 10. Two phases are formed in the washing vessel. The phases are separated in the phase separator 11. The upper organic phase is the butylate and the lower aqueous phase is the aqueous solution of the diisobutylamine ethyl hydrosulfate salt. The butylate is introduced into the collecting vessel 12 and the aqueous phase into the alkaline digester 13, where a 20% solution of sodium hydroxide is added from a dispensing vessel 14. Diisobutylamine is liberated from its salt by sodium hydroxide and is in a separate phase. The phases are separated again in the phase separator 15 into organic and aqueous phases. The upper organic phase, which is the regenerated diisobutylamine, is passed to a 16 packed distillation column for dewatering. The distillation column was heated to 140 ° C, the water and methanol distilled and recycled to the alkaline digester 13. The anhydrous regenerated diisobutylamine leaving the vessel 18 is collected in the collecting vessel 19 and returned to the dispenser 4 at the beginning of the process. The effluent from the phase separator 15 is passed through the collecting vessel 20 through a continuous distillation column to remove methanol.

/. example

A mixture of 130 g (1 mole) of diisobutylamine and 50 g of methanol is absorbed at 25-30 ° C into 30 g (0.5 mole) of COS gas.

Thereafter, 81 g (0.502 mole) of diethyl sulfate was added at the above temperature to ca. in half an hour. The methanol is distilled off using a slow-heating condenser to a temperature of 110 ° C. brought back

HU 201522 Β 'C and 100 ml of water was added, then cooled to room temperature and the organic phase separated from the first aqueous phase. The organic phase was 96 g of butylate (90% by weight). To the aqueous phase was added 22 g of sodium hydroxide (0.55 mol) dissolved in 50 ml of water to form the diisobutylamine as a separate phase. The amine weighs 71 g with an amine content of 92% and a butylate content of 5.7%. The recovered amine is recycled in the manufacturing process. Total yield 100.1 g (92% of theory). The product is 96% volatile. Example 2

A mixture of fresh diisobutylamine (130 g, 1 mole), regenerated diisobutylamine (165 g, 1.28 mol) and methanol (100 g) was charged with 520 ml / h to a two-stage cascade reactor and reacted with COS gas in countercurrent. The volume of gas introduced is 29 l and 70 g per hour, respectively. The gas is absorbed at 26-28 ° C. The absorbing reactors were cooled with a 20 ° C thermostat. The gas feed rate is controlled so that the rate of heat generation in the two reactors is approximately the same. Thus, in the second section of the cascade reactor, approx. A 50% excess COS gas allows for a high degree of conversion, while a 50% amine excess in the first member ensures the absorption of the total amount of COS gas introduced. The total volume of reactors is approximately 720 ml, with amine feed of 520 ml. An average residence time of 1.35 hours is obtained. A solution of the prepared thiocarbamic acid amine salt in methanol was treated with 175 g (1.14 mol) of diethyl sulfate per hour. The reaction is carried out in a two-membered cascade. The first member of the cascade is cooled with a 20 'C thermostat to maintain the reaction temperature at 30' C. The second reactor was maintained at 110 ° C to effect alkylation. At 110 'C, methanol is ca. half of it is distilled off, which is returned to the beginning of the production anhydrous. The total useful volume of the alkylation reactor is 1420 ml, in which ca. Alkylation occurs with an average residence time of 2 hours.

The reaction mixture was washed with water (200 mL) per hour in the wash vessel. The mixture separates into two phases at 60-70 ° C. From the phase separator, 210-230 g of butylate, 90%, are removed per hour. The aqueous solution from the butylate phase separator was stirred with 244 g of sodium hydroxide solution (20%, 1.22 mol) per hour in the alkaline decomposer. Excess alkali causes the diisobutylamine to be liberated from the hydrosulphate salt and to form ethyl sodium sulphate. The diisobutylamine is separated from the waste water in the continuous phase separator. The diisobutylamine thus obtained was ca. Contains 80% methanol, water and butylate as impurities. The amine is dehydrated by adding the amine to be dehydrated to the center of a column of 6 theoretical plates before being reused, with a reflux of 1: 2 in the head. The product decreases to a water content of less than 0.1% by weight at a temperature of 145-147 ° C. In practice, with a water content of less than 0.3%, the regenerated amine can be recycled to the manufacturing process. The amount of crude butylate leaving the continuous butylate production plant is approx. 90%. The methanol and diisobutylamine contents are distilled off batchwise. Distil off the volatiles to a temperature of 120 ° C with aeration, leaving 96% butylate in the pan. At 130-140'C and 126-136'C, the butylate can also be distilled off. This gave a pale yellow product of 98% purity.

Example 3

For the continuous production of butylate, a cascade reactor line consisting of 3 300 liters continuous tank reactors with stirrer, gas inlet, liquid and outlet is used to react the di-i-butylamine with carbon monoxide.

260 kg / hr di-i-butylamine, 300 kg / hr regenerated di-i-butylamine (containing 87% di-i-butylamine) and 200 kg / hr methanol are added to the first member of the reactor 3 connected in series. The reaction mixture, which overflows from the first reactor, is reacted with carbon oxysulfide gas in a countercurrent flow through the second and third reactors. The 120 kg / h carbon oxysulfide is introduced at the gas inlet of the third reactor below the surface of the liquid in the reactor, the unreacted gas being introduced into the second reactor and hence into the first reactor. In the first reactor, the introduced di-i-butylamine only contained about 10% of the added di-i-butylamine. The reaction is carried out at 50 mol%, so that an excess of the amine present here can react to the total amount of carbon oxysulfide introduced therein. In the second reactor, the total amount of di-i-butylamine introduced is reacted with the presence of 50 mol% excess carbon oxysulfide. The first and second reactors are maintained at 25-30 ° C by cooling and, as described above, the reaction heat is also distributed in a 50-50% ratio between the two reactors. Prior to the alkylation reaction, the molar ratio of di-i-butylamine: carbon oxysulfide should be exactly 2: 1. To adjust the molar ratio accurately, the third reactor is brought to 45 ° C, because at this temperature the desired molar ratio of 2: 1 di-butylamine: carbon oxysulfide can be adjusted.

The resulting mixture of N, N-i-butylthiocarbamic acid di-i-butylamine salt and methanol was alkylated with diethyl sulfate in two further 300 L stirred tank reactors. Half of the total diethyl sulfate (325 kg / h) was added to the first and the other half to the second alkylation reactor, both reactors being cooled to 30-40 ° C. The monoethyl sulfate di-butylamine salt formed in the alkylation reaction is crystalline. The reaction mixture leaving the second alkylation reactor in a tubular steam-exchanged heat exchanger is ca. Heat to 80 ° C.

The reaction mixture is decomposed in a stirred tank reactor. Mix with 800 l / h of water at 60 ° C. On a continuous phase separator, the final product can be separated from the aqueous solution of monoethyl sulfate di-i-butylamine salt. The yield of 430 kg of butylate is 96-97%, which corresponds to a yield of 95-96%.

The aqueous solution leaving the phase separator is reacted with 220 kg / h 40% sodium hydroxide solution and then passed through another continuous phase separator to recover the di-butylamine as an organic phase and return to the beginning of the process after drying.

Claims (2)

Claims 1. A process for the preparation of S-ethyl-N, N-diisobutylthiocarbamate by reacting diisobutylamine and carbonyl sulfide in a 2: 1 molar ratio at ambient temperature and alkylating the resulting thiocarbamic acid amine salt with diethyl sulfate. and alkylation is carried out in the presence of at least 10% by weight of the starting diisobutylamine, preferably 30-50% by weight of a C 1-3 aliphatic alcohol, followed by alkylation of the aliphatic alcohol -3ι HU 201522 Β and distillate the reaction mixture to water Process according to claim 1, characterized in that it is processed after casting in a known manner. methanol is used as the aliphatic alcohol.