JPS6232746B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing substituted thiocarbamates in continuous cycles.

The following is known in the literature. That is, thiocarbamates can be prepared by reacting a secondary amine with carbon monoxide and sulfur in a suitable solvent and alkylating the reaction product thus obtained. It is known that it is possible.

The reaction is as follows: However, in the formula, R ₁ and R ₂ may be the same or different and consist of an alkyl group, a cycloalkyl group, or an aralkyl group, or together form a divalent polymethylene group. Good too.

R ₃ represents an alkyl group, a cycloalkyl group, or an aralkyl group.

X is a substitutable group consisting of halide, sulfate, or sulfonate.

Essentially, the following happens. First, in reaction (1), the secondary amine reacts with carbon monoxide and sulfur to form a substituted ammonium salt of thiocarbamic acid, and then in reaction (2), this salt is alkylated. reacts with the agent to form a substituted thiocarbamate.

As a result of deep research into the mechanism by which the above-mentioned known reactions occur and a series of long experiments,
The present inventors have now developed an improved method and apparatus for producing substituted thiocarbamates.

In fact, so far the first of the reactions mentioned above has always been carried out in the presence of an excess of sulfur.
This has been done by mixing equimolar amounts of secondary amines and sulfur in the presence of carbon monoxide.

Furthermore, these two reactions were always carried out separately, and neither of these reactions were carried out sequentially.

For example, US Pat. No. 3,151,119 discloses a method for producing a thiocarbamate by reacting a secondary amine, carbon monoxide, and sulfur to obtain a thiocarbamate, which is then alkylated. However, very unsatisfactory results have been obtained, especially in terms of yield. For example, in Example 1, the yield was only 60%, and in Example 4, the yield was only 62%. In Example 5
A yield of 78% is obtained, which is the only example in which the sulfur is soluble in the amine used.

However, in the present invention, on the contrary, the secondary amine and sulfur are used in a stoichiometric ratio (1 mole of amine + 0.5 mole of sulfur), and this is carried out in a reaction column pressurized with carbon monoxide. is continuously supplied with a suitable solvent, and the reaction solution is maintained in continuous circulation within the column, in which case the column is
It forms part of the device. This device is
Downstream thereof, an alkylation reactor is included, from which the desired substituted thiocarbamate is continuously removed.

Furthermore, the device basically consists of: In addition to the reaction column described above, which is preferably a column packed with Raschschig rings, and the alkylation reactor described above, a circulation pump for the liquid reactants and temperature control means.

The reacted solution is removed from the alkylation reactor in an amount equal to that of the reactants fed.

According to the present invention, when amine and sulfur are to be reacted successively in stoichiometric proportions, the sulfur must be completely dissolved in the reaction mass introduced into the reaction column. It is essential that this is the case; in fact, it must not be treated otherwise or supplied as a slurry. This is because, if such a thing were done, technical difficulties would arise in carrying out the supply process and achieving the conditions of the stoichiometric ratio.

In the present invention, sulfur may be dissolved in the amine itself, for example, when hexamethyleneimine is used, or, for example, di-
If the amount of amine specified by the stoichiometric reaction is not sufficient to dissolve the sulfur, such as when N-propylamine or ethylcyclohexylamine is used, the reaction has already occurred in the column. The sulfur may be dissolved by adding the required amount of the finished solution.

In the second case above, this is
This is carried out by utilizing the sulfur-dissolving property of the thiocarbamate solution obtained in the first reaction of this method. That is, this stipulates that the product produced by the first reaction is used to dissolve sulfur, one of the substances to be reacted. This shows that the number and types of amines that can be used to carry out the reaction effectively can be clearly and considerably expanded.

As more carbon monoxide is consumed, more carbon monoxide is added to the column. The amount of carbon monoxide circulating is very small. This is because the free volume within the reaction column is small. As a result, the method and device according to the invention offer, in addition to the usual advantages of continuous processes (high potential, low labor, etc.), the advantage of extremely high safety. It will be done.

According to the method of the present invention, a very high yield of 90% or more can be obtained as shown in the Examples below, which is a surprising result.

The invention will now be described in more detail with reference to the accompanying drawings and with the aid of the examples described below. The accompanying drawing diagrammatically shows an embodiment of the device according to the invention.

The illustrated device is equipped with two mixing tanks SA1 and SA2, which are alternately connected to the line CO by means of a pump P1. This conduit CO then leads to the top of the reaction column C packed with Raschchiring RA. Tank B1, which contains carbon monoxide under pressure, is also connected to the reaction column.

At its bottom, this reaction column C has a collection tank SC, and from the bottom of this collection tank a delivery conduit CE emerges.
This delivery conduit is bifurcated, one side of which is connected to the conduit CO upstream of the circulation pump P2, and the other side connected to the heat exchanger F1. At the top of column C there is a gas conduit CG leading to venting means SR2, SR3. The conduit CO is, for the most part, equipped with a heating jacket R.

Exchanger F1 (its purpose is to cool the solution coming out of the collection tank SC so that the product does not decompose when transferred to normal pressure) is connected to the alkylation reactor SA3. ing.
The alkylation reactor includes a stirrer and an overflow
A TP is installed, and from the overflow comes a pipe TS, which connects to storage tank SR1.

Example 1 S-ethyl-N.N-hexamethylene thiocarbamate is prepared according to the following formula: Into one of the mixing tanks SA1 or SA2 of capacity 10, reactants are introduced alternately in the following proportions: 99% hexamethyleneimine 1000 g (10 mol) Sulfur 160 g (5 mol) The sulfur is completely dissolved. Continue vigorous stirring until then add: 2600 g of anhydrous toluene Continue stirring gradually throughout this addition.

Column C has a diameter of 5 cm and a height of 400 cm, is filled with a Raschich ring, and is heated and maintained by a jacket at 95-105°C, with a carbon monoxide pressure of 8-10°C. A quantity of the mixture is pumped into this column C, which is maintained at atmospheric pressure, using pump P1 to reach the level (L1) of the collection tank SC. Pump P2 is rotated to circulate the mixture within the column. The pump delivery rate is adjusted from 60 to 200/hour.

This mixture is circulated for 30-60 minutes at a temperature of 95-105°C, and then pump P1 pumps the mixture.
Feed to the column at a rate of 15-20 kg/hour to compensate for what is consumed.

At the same time, the same amount of reaction product as the supplied raw material is taken out from the collection tank SC, keeping its level (L1) constant.

Carbon monoxide is fed from the top and bottom of the column and is consumed in virtually the stoichiometric amount; however, to avoid contamination by gaseous impurities within the column, venting
means) Remove a certain amount of gas (1 or 2 bubbles per second) through SR2 and SR3. It is preferred to maintain the temperature in column C between 95 and 105°C by applying heat to the jacket R in the circulation conduit CO; the lower the temperature, the slower the reaction. On the other hand, if the temperature is higher than this, there is a possibility that the obtained product will decompose.

The pressure inside the column is preferably maintained at 8 to 10 atmospheres, and this level of pressure is sufficient for the reaction to proceed well. The removed product is cooled to 30-40° C. in exchanger F1 (it does not need to be lower than this temperature so that salt crystallization does not occur). This is then combined into 10 ethylation reactors.
I'll send you to SA3.

At the same time, diethyl sulfuric acid was added to this reactor SA.
Supply within 3 minutes (3.1÷4.1Kg/hour).

In the ethylation reactor SA3, the temperature is 35~
Maintain at 40°C. The reactor is equipped with a side outlet (residence time in the reactor is approximately 30
), from this exit,
The reacted mass is removed by overflowing and sent to storage tank SR1. By this method, about 23% S-ethyl-
A toluene solution of N.N-hexamethylene thiocarbamate is obtained.

The overall yield is more than 90% of theory.

Example 2 S-ethyl-dipropylthiocarbamate is prepared according to the following formula: The same equipment as described in Example 1 was used.

The reactants consisting of the following proportions are introduced alternately into a 10 volume mixing tank SA1 or SA2: - 3000 ml of dipropylammonium salt of dipropylthiocarbamic acid, an approx. 23% solution (in toluene) - 98% di- N-Propylamine 678ml - Sulfur 84g Stir until the sulfur is completely dissolved (di-N-
It must be noted that propylamine alone does not dissolve all of the sulfur in it, so it is necessary to recycle the thiocarbamate. ), then add 1500ml of toluene.

The amount of thiocarbamate solution to be added is not critical and is determined so that the sulfur is completely dissolved.

The operating conditions are as follows: Column temperature 80-85°C Output temperature 35-40°C CO pressure in the column 8-10 atm Delivery rate of recycle pump P2
80-200/h Delivery rate of metering pump P1 approx. 13/h The ethylation of this salt-containing solution produced in column C is carried out, as in Example 1, in the reactor or tank SA3 at approx. This is done by feeding diethyl sulfuric acid at a rate of 860 ml/h. By this method a toluene solution containing about 23% S-ethyldipropylthiocarbamate is obtained. The overall yield is more than 85% of theory. If a second finishing column similar to this column is connected to the bottom of the reaction column, this yield can be increased to over 95%.

(Note) By using this second method, S-propyl dipropyl thiocarbamate can be produced according to the following reaction formula: However, the alkylating agent is different from that described above: propyl iodide is fed into the alkylation reactor.

Yield is more than 85%.

Example 3 S-ethylcyclohexylethylthiocarbamate is prepared according to the following reaction formula: The same equipment as described in Example 1 is used.

Reactants consisting of the following proportions are introduced alternately into a 10 volume mixing tank: - ethylcyclohexylammonium salt of ethylcyclohexylthiocarbamic acid, approximately 23% solution.
2000 g - 640 g of 97% ethylcyclohexylamine - 80 g of sulfur Stir vigorously until the sulfur is completely dissolved in the salt and the amine, then add: - 1500 ml of anhydrous toluene The operating conditions are: As follows: Column temperature 80-100℃ Take-out temperature 30-40℃ CO pressure in column 8-10 atm Delivery rate of recycle pump P2
80-200/h Delivery rate of metering pump P1 10-15/h Ethylation of this salt produced in the column was carried out by adding diethyl sulfate at a rate of 760-1140 ml/h, as in Examples 1 and 2. Do this continuously by feeding. By this method, approximately 23
A toluene solution containing % is obtained.

The overall yield will be more than 85%.

In order to increase the yield, it is necessary, as in Example 2, to connect a second finishing column similar to the first column.

[Brief explanation of the drawing]

The drawings schematically illustrate one embodiment of the apparatus for producing substituted thiocarbamates according to the present invention. C...Reaction column, B1...Carbon monoxide tank, SA1 and SA2...Mixing tank, SR2 and
SR3...discharge means, SA3...alkylation reactor, SR1...storage tank, RA...Rashchiring.

Claims (1)

[Claims] 1. Sulfur is continuously dissolved in a stoichiometric ratio in a liquid consisting of a secondary amine or a mixture of the secondary amine and a thiocarbamate, and the resulting solution is appropriately dissolved. This mixture is continuously fed into a reaction column pressurized with carbon monoxide, and this reaction mixture is kept continuously circulating in the reaction column to remove the produced thiocarbamate. continuously subjecting the effluent containing the alkylation reaction to an alkylation reaction,
A method for continuously producing a substituted thiocarbamate, which comprises: and continuously taking out the newly generated substituted carbamate from the substituted carbamate. 2. An apparatus for carrying out a method for continuously producing a substituted thiocarbamate, which comprises a pair of mixing tanks, a reaction column packed with a Raschschring ring, and a collection tank provided at the bottom of the reaction column. , a conduit externally connecting the collection tank and the top of the column;
A circulation pump is connected in this conduit, and the conduit is supplied with the contents of the mixing tank by a second pump, and the conduit is branched from the conduit to connect the bottom of the collection tank via a heat exchanger. Said apparatus consisting of a pipe connecting to an alkylation reactor, said alkylation reactor comprising an overflow and a stirrer connecting to a storage tank. 3. A device according to claim 2, characterized in that the external conduit is provided with a heating jacket over at least part of its length.