HU203531B - Process for producing dithio-carbamate in aquous medium with phasis-transfer catalysis - Google Patents

Abstract

Primary or secondary amines in a water suspension react with carbon disulphide at 0-50 deg. C at pH 7-14 in the presence of 0.1-10 %w/w (in relation to amines) of a phase transfer catalyst.

Description

The present invention relates to a process for the preparation of dithiocarbamates in aqueous media, more particularly to a process for the preparation of dithiocarbamates in aqueous media by phase transfer catalysis.

Dithiocarbamates, as a group of compounds, have been prepared previously. Debus described the synthesis of some dithiocarbamic acid in 1850, providing a comprehensive review of industrially important processes in the following summaries: and Related Compounds, Elsevier, Amsterdam, 1962.)

The reaction between carbon disulfide and primary or secondary amines produces the amino salt of N-substituted-dithiocarbamic acid.

2R-NH ₂ + GS ₂ → (R-NH-CS ₂ ) - (R-NH ₃ ) ⁺

In the presence of an alkali metal hydroxide, the corresponding alkali metal dithiocarbamate is formed. The advantage of this process is that half of the more valuable amine can be replaced by alkali.

3-NH ₂ + CS ₂ + NaOH- (R-NH-CS ₂ ) Na + H ₂ O

In water, the reaction proceeds in a heterogeneous phase because neither carbon disulphide nor amines containing more than four carbon atoms are soluble in water. Therefore, the reaction is slow and side reactions occur (G.Gattow, W.Behrendt, Carbon Sulfides and Their Inorganic and Complex Chemistry, Georg Thieme, Stuttgart, 1977). Thus, the carbon disulfide reacts with the hydroxyl ion in the aqueous solution of the alkali, the dithiocarbonate ion formed is not stable in a strongly basic medium, and further reacts with the carbon disulfide to form trithiocarbonate.

_H ⁺ CS

CS ₂ + OH- - »S ₂ CO ² - - ² CS ² - ₃ + COS.

This by-product often contaminates the dithiocarbamate solution depending on the rate of reaction between the amine and the carbon disulfide. Several procedures have been developed to avoid heterogeneity and side reactions.

Thus, the preparation can also be carried out in alcohol, but here, another contaminating by-product, the corresponding xantogenate, can be formed.

Sodium diethyl dithiocarbamate was prepared in aqueous medium by adding carbon disulphide to a solution of diethylamine and sodium hydroxide at 0-10 ° C. After stirring for a quarter hour, the same amount of amine, carbon disulfide and caustic soda was added once more. Even after stirring for 3 hours, only 80% yield was achieved, so the process was slow and complicated. (Houben-Weyl, Methoden d Organischen Chemie, 4th Aufl., Georg Thime, Stuttgart, 1963).

To accelerate the reaction, the aqueous solution of the amine and alkali was reacted with steam-phase carbon disulphide at a temperature above the boiling point of the carbon disulfide.

However, only dimethylamine and ethylenediamine were well recovered. For isopropylamine, only 80% purity was obtained in 65% yield (German Patent 1118186). Therefore, the process is not applicable in general, vapor-phase carbon disulphide poses an increased risk of fire and explosion.

No. 748,291. In the Dutch patent process, the corresponding amine and carbon disulfide were first reacted to form the amino salt. After the mixture was nearly neutral, an aqueous solution of NaOH equivalent to the amine in the salt was added, liberating the amine, which reacted again with the carbon disulfide. This was repeated until all the amines were exhausted. The process is cumbersome, lengthy, and difficult to control.

Similarly, the carbon disulphide was gradually added to the double stoichiometric amount of amine, followed by the addition of a strong base to the amine salt formed, which liberated the amine (U.S. Pat. No. 2,559,389). However, this requires twice as much amine and even alkali, which makes the process more expensive and environmentally disadvantageous.

The formation of a by-product can also be avoided by using ammonia instead of a strong base for salt formation (Hungarian Patent Nos. 163,885 and 2,854,188). However, the main reaction slows down significantly and requires intensive stirring for several hours.

However, since carbon disulphide is only slightly soluble in water, the use of water is necessary to provide the appropriate hydroxyl ion concentration, often a water-miscible solvent, usually alcohol (Thom, Irwing, 1962) dioxane (Japanese Patent No. 3357 [57]). employed. However, the carbon disulfide is still insoluble and there is a risk of formation of xanthogenates. Other solvents have been tried with water and diethyl ether for morpholine and cyclohexylamine (U.S. Patent 2,563,007), and water and toluene have also been found to be advantageous (Hungarian Patent No. 174,485). Reaction of the amine with the carbon disulfide occurred in the solvent phase, and the resulting amine salt, when passed into the alkaline aqueous phase, was liberated again.

The main disadvantage of these processes is that the reaction continues to proceed in two liquid phases and is therefore slow. It also has the disadvantage that the solvents are highly flammable, expensive and need to be regenerated by distillation. Because they are soluble in water, the mother liquor must be de-solvented before being allowed to enter the recipient.

Thus, state of the art, for the preparation of dithiocarbamates, a technique which is easy to carry out and which is economically easy to obtain while providing good yield has not been developed, particularly for water-insoluble amines containing more than four carbon. Thus, it was necessary to develop a simple process, which is easy to industrially implement and provides a pure product with good yield.

This is also important because dithiocarbamates and their derivatives are widely used as an oil additive for crosslinking elastomers or for flotation of ores.

EN 203 531 Β as an analytical reagent, as a plant protection product and also in human medicine, where high purity of the products is of particular importance.

Our aim was to develop a process that overcomes the drawbacks of the above processes and provides a high purity product with a simple, industrially easy to implement technology with good yield.

It has been found that the preparation of dithiocarbamates in aqueous media, with surprisingly high reaction rates, good selectivity and yield, using industrially readily applicable phase transfer catalysts, in the range of 0.1-10% by weight of the expected product. The above advantages over the disclosed methods also exist when using a water immiscible solvent.

The invention comprises a dithiocarbamate of the formula to (I) in the preparation of (Π) primary or secondary formula amine and carbon disulfide in water or water with immiscible solvent mixture - where R ¹ and R ² are the same or different methyl, ethyl , propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isoamyl, hexyl, dodecyl, cyclohexyl, R ¹ or R ² may also represent a hydrogen atom, in which case the another may also be phenyl or benzyl, or R ¹ and R ² may be taken together to form tetramethylene, pentamethylene or hexamethylene; wherein R ¹ and R ² are as defined above, wherein the process comprises from 0.1 to 10% by weight of tetrabenzylphosphonium bromide, 1000 to 2000 molar masses, based on the amount of product expected. monoethyleneglycol or quaternary ammonium halide of formula (ΙΠ) wherein R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different (C 1 -C 16) alkyl or benzyl and X is chlorine, bromine or iodine - phase transfer in the presence of a catalyst.

The process may be carried out in water or in a mixture of water and immiscible solvent.

The process also provides selectivity and reaction rates for any mixture of water and water-immiscible solvents, preferably in the range of 20-80% solvent. Preferably, such solvents include methylene chloride, chloroform, carbon tetrachloride, gasoline with a boiling point between 30 ° C and 170 ° C, toluene, xylene, chlorobenzene, dichlorobenzene, 1,3,5-trichlorobenzene.

According to our process, both the water-soluble and the water-insoluble primary or secondary amines of formula (Π) are preferably converted to the dithiocarbamate of formula (I).

The bases may be potassium, sodium hydroxide, aqueous ammonia, or the amine (H).

Phase Transfer The quaternary ammonium saltAt as an analyzer - wherein R ³ , R ⁴ , R ⁵ , R ⁶ may be different or the same, is C 1 -C 16 alkyl or benzyl, and X is chlorine, bromine, or iodine, preferably trimethyldodecylammonium bromide, tetrabenzylphosphonium bromide, or polyethylene glycol having a molecular weight of from 1000 to 2000 can be used in an amount of 0.52% by weight of the product.

The process is carried out at a temperature of 0-40 ° C.

A further advantage of the process according to the invention is that it can be carried out intermittently but preferably in continuous operation due to the short reaction times.

In batch operation, the reactor is charged with water or solvent mixture, the desired amount of primary or secondary amine, the desired amount of Atalizer, and the salt-forming base, and with sufficient stirring, the necessary amount of carbon disulfide is introduced. After the desired reaction time, the dithiocarbamate is obtained in the aqueous phase.

In continuous operation, the solvents and reactants are continuously fed to the desired temperature at a desired temperature with the appropriate dosing equipment. This system is a cool cascade, a film reactor, a static mixing reactor, but definitely a device that can provide the desired short residence time. In this case too, the product enters the aqueous phase. jg.

Recovery of dithiocarbamates by conventional means; crystallization and vacuum evaporation, but the solution is also suitable for further use, such as the preparation of other metal salts. gj

Embodiments of the process of the present invention are illustrated in the following examples:

1-6. examples

The effect of the different analyzers was investigated. 200 ml of water, 0.2 moles of dipentylamine and 0.2 moles of sodium hydroxide were added to a space-shifted glass reactor and the expected product was transferred to a 1% w / w phase transfer catalyst. we started stirring. At 20 'C, an equivalent amount of carbon disulphide was added to the measured amine and alkali.

Changes in product concentration were monitored by UV spectrophotometry.

Our results are tabulated (See next page) »1

HU 203 531 Β

Table 1

Preparation of Dipentynodium Sodium Dithiocarbamate Using Various Phase Transfer Catalysts in Water at 20 ° C with 1% Phase Transfer Catalyst

Example number phase transfer catalyst Half-life (min) Yield (%) (180min) First - 210 38 Second Tetrabutylammonium bromide 60 97 Third · Adogen 41 98 4th Cetyl trimethyl ammonium bromide 18 100 5th Tetrabenzyl phosphonium bromide 33 100 6th Polyethylene glycol 1500 60 94

®: Adogen proprietary trade name, methyl-trialkyl (C ₈ -C ₁₀ ) -ammonium chloride.

7-24. examples

1-6. Examples 1 to 4 except that 1% by weight of cetyltrimethylammonium bromide catalyst was used in each case, but the amine quality was changed.

F Table 2 «Preparation of various sodium dithiocarbamates in the presence of 1% by weight of cetyltrimethylammonium bromide phase transfer catalyst at 20 ° C in water

Example ^ ID Starting amine Half-life (min) Yield (%) After 15 ' 7-7. ethylamine 4 100 8th diethylamine 2 100 9th propyl-amine 6 100 10th dlpropü amine 5 100 11th isopropyl-amine 14 67 12th diisopropylamine 13 78 13th butyl amine 13 75 14th pentyl-amine 13 75 15th dipentü amine 18 72 16th izoamü amine 9 87 17th diizoamü-amm 15 91 18th cyclohexylamine 4 100 19th dicyclohexylamine 12 90 20th dodecyl amine 14 55 21st didodecyl amine 12 61 22nd N, N-pentametUén amine 6 95 23rd aniline 16 64 24th benzyl-amine 4 100

HU 203 531 Β

Example 25

1-6. The procedure was as described in Example 1, except that 100 ml of water and 100 ml of chlorobenzene were used as the solvent, and the phase transfer catalyst used was 0.5% by weight of cetyltrimethylammonium bromide, based on the expected product. The half-life. 19 min, yield after 3 h was 100%.

The examples show the advantage of the process: the reaction rate increases with the phase transfer catalyst, resulting in a reduced half-life, and the yield obtained in 15 minutes is significantly higher than that obtained in Example 1 after 180 'without catalyst.

Claims (1)

Patent Claim Point Process for the preparation of dithiocarbamate of formula (I) from primary or secondary amine of formula (I) and carbon disulphide in water or in a mixture of water and an immiscible solvent - wherein R ¹ and R ² is the same or different methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isoamyl, hexyl, dodecyl or cyclohexyl group, R ¹ or R ² may also be hydrogen, in which case the other may be phenyl or benzyl, or R ¹ and R ² may be taken together to form tetramethylene, pentamethylene or hexamethylene; M is sodium, potassium, an ammonium ion or a mono- or disubstituted ammonium ion of the formula (HA), wherein R ¹ and R ² are as defined above, characterized in that the process is 0.5 to 2% by weight of tetrabenzylphosphonium bromide, Polyethylene glycol of average molecular weight 10002000 or quaternary ammonium halide of the formula: wherein R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different C 1 -C 16 alkyl or benzyl groups and X is chlorine, bromine or iodine - in the presence of a phase transfer catalyst.