EP0288818B1 - Bor-tris-(dialkyl-dithiocarbamates) and process for their preparation - Google Patents

Abstract

Boron tris-(dialkyl-dithiocarbamate) of the general formula <IMAGE> (I) wherein R and R' represent the same or different branched- or straight-chain saturated or unsaturated alkyl radicals having from 1 to 16 carbon atoms and a process for preparing the same, comprising reacting 3 moles of an alkali dialkyl-dithiocarbamate of the general formula <IMAGE> wherein R and R' are as defined in claim 1 and Me+ represents Na+, K+ or NH4+ with one mole boron tribromide, boron trichloride or boron trifluoride in an inert medium, separating the so-formed alkali metal or ammonium halide and isolating the boron dithiocarbamates are suitable as additives for hydraulic oils or permanent gear lubricant oils.

Description

Dithiocarbamates of metals are described in large numbers, see Elsevier Monographs "The Dithiocarbamates and related Compounds" by Thorn and Ludwig (1962), Table I, pages 12 to 34.
Nöth and Schweizer published a possibility in 1969 in the chemical reports (102), pages 161-166, to produce dimethylthiocarbamoyl mercaptoborane. However, the compound could only be obtained from sodium dimethyldithiocarbaminate (NaSC (S) NMe₂) and boron trichloride under extreme conditions (-45 ° C). Higher boron dialkyldithiocarbamates are not known.

The object of the present invention is to be able to synthesize these higher homologues and also the known boron tris (dithiocarbamate) in a simple manner.

The invention relates to boron tris (dialkyl dithio

in der R und R' gleiche oder verschiedene, verzweigte oder unverzweigte, gesättigte oder ungesättigte Alkylreste mit 1 bis 12 Kohlenstoffatomen oder beide Tridecyl bedeuten, mit der Ausnahme, daß sowohl R als auch R' Methylreste sind. Diese Alkylreste können auch Cycloalkylreste wie z.B. Cyclohexyl sein. Insbesondere können R und R' 2-Ethylhexyl oder Pentyl bedeuten.carbamates) of the general formula

in which R and R 'are identical or different, branched or unbranched, saturated or unsaturated alkyl radicals having 1 to 12 carbon atoms or both tridecyl mean, with the exception that both R and R 'are methyl radicals. These alkyl radicals can also be cycloalkyl radicals such as cyclohexyl. In particular, R and R 'can mean 2-ethylhexyl or pentyl.

In einem ersten Verfahren haben R und R' die obige Bedeutung, und können auch beide Methyl sein. X steht für Fluorid und M⁺ für Na⁺, K⁺, NH₄⁺, vorzugsweise das Natriumion. In diesem Verfahren wird ein Mol des Komplexes aus Bortrifluorid mit Dimethylether oder Methanol in einem wasserhaltigen Medium mit 3 Mol des Alkali-dialkyl-dithiocarbamats umgesetzt, das gebildete Alkali- oder Ammoniumflourid abgetrennt und das Bor-tris-(dialkyl-dithiocarbamat) isoliert.The invention further relates to processes for the preparation of boron tris (dithiocarbamates), which proceed according to the following equations:

In a first method, R and R 'have the above meaning, and can both be methyl. X stands for fluoride and M⁺ for Na⁺, K⁺, NH₄⁺, preferably the sodium ion. In this process, one mole of the complex of boron trifluoride with dimethyl ether or methanol in a water-containing medium is reacted with 3 moles of the alkali dialkyl dithiocarbamate, the alkali metal or ammonium fluoride formed is separated off and the boron tris (dialkyl dithiocarbamate) is isolated.

The production of the alkali dialkyldithiocarbamates is known in principle. The procedure for the preparation of the sodium dialkyl dithiocarbamates is generally as follows:
A 50% sodium hydroxide solution is introduced into methanol. The secondary amine is added and carbon disulphide is added dropwise. All reaction components are used in stoichiometric amounts, carbon disulfide can also be used in excess. The mixture is stirred mechanically for 1 to 3 hours. Then the formation of sodium dithiocarbamate is complete.

This solution can be used directly as a starting product for the subsequent preparation of boron tris (dialkyl dithiocarbamates) and the reaction can be continued in the same vessel if 1 mol of a solution of the complex of boron trifluoride with diethyl ether or Methanol added dropwise in diethyl ether.

Instead of methanol, other water-miscible solvents such as ethylene glycol monoalkyl ether, tetrahydrofuran, dioxane, ethanol, propanol or isopropanol can also be used. The boron trifluoride complex compounds are not as sensitive to hydrolysis as the free boron halides, so that it is possible to work in aqueous-alcoholic solution, but the water content in the reaction medium should not exceed 15 percent by weight.

The reaction is weakly exothermic in both stages. Additional heating or external cooling is therefore generally not necessary. The reaction is therefore preferably carried out at 0 to 90, in particular at 20 to 70 ° C.

After the reaction with the boron trifluoride complex has ended, the mixture is stirred for a few more hours. The alkali metal fluoride which has crystallized out is then suctioned off. The mixture of water and solvent is distilled off from the filtrate. A temperature of 70 ° C should not be exceeded here either. Residual amounts of solvent are therefore expediently distilled off in vacuo. Pale yellowish to amber-colored oils are obtained, which are preferably filtered again clearly.

If one wants to use boron tribromide, boron trichloride or boron trifluoride as the reaction component instead of the boron fluoride-diethyl ether or methanol complex, the corresponding alkali dialkyl dithiocarbamate is used in anhydrous form in another process. The aqueous solution initially obtained must therefore be evaporated to dryness before the alkali dialkyl dithiocarbamate can be reacted with the boron halide in an anhydrous inert solvent, such as aliphatic or aromatic hydrocarbons or lower alkyl ethers. The production takes place at 0 ° C to 90 ° C, preferably between 20 ° C and 70 ° C.

Suitable inert solvents for the reaction in the anhydrous medium are aliphatic or aromatic hydrocarbons or lower dialkyl ethers. The same applies to the temperature profile and the temperatures to be observed as when working in a water-containing environment.

In both cases, the so-called "one-pot process" can be used, i.e. the boron tris (dialkyl dithiocabamate) can be prepared in the same reaction vessel in which the alkali metal or ammonium dialkyldithiocarbamate was prepared in the first stage from a corresponding secondary amine, carbon disulfide and alkali metal hydroxide or by another known process.

The new bordithiocarbamates of the general formula I are suitable as additives for hydraulic oils or gear oils.

The preparation of compounds according to the invention is illustrated using a few examples:

Example 1 : Boron tris (di-2-ethylhexyl dithiocarbamate).

15 kg of a 50% sodium hydroxide solution are added to 94 liters of methanol in a 200 liter glass apparatus with mechanical stirring. Then 45 kg of di-2-ethylhexylamine are added. 15 kg of carbon disulfide are added dropwise in the course of 30 minutes. The mixture is then stirred for a further 2 hours. The solution of 7.5 kg of boron trifluoride-diethyl ether complex (50% strength) in 19 liters of ether is then added dropwise over the course of 90 minutes. The mixture is stirred for a further 3 hours and then remains closed overnight. The next morning, the precipitated sodium fluoride is sucked off through an earthenware filter. The mixture of methanol, water and ether is distilled off from the filtrate, at the end in a vacuum, heating not above 70 ° C. After cooling, the oil is sucked off again. 46.6 kg of a clear, amber-colored oil were obtained, which has a content of 100.1%, based on total nitrogen. The yield was 77.62% of theory, based on BF₃.

Example 2 : Boron tris (di-2-ethylhexyl dithiocarbamate).

24 g of a 50% sodium hydroxide solution are added to 250 ml of water. 72.3 g of di-2-ethylhexylamine are added. With mechanical stirring, 20 ml of carbon disulfide are added dropwise in the course of 20 minutes. The mixture is stirred for a further 30 minutes. The mixture is then evaporated to dryness in a rotary evaporator at a bath temperature of 50 ° C. The dust-dry powder is mixed with 200 ml of di-isopropyl ether dried over molecular sieves. To this end, with mechanical stirring, the solution of 25 g of boron tribromide in 100 ml of di-isopropyl ether dried over molecular sieve is added dropwise over the course of one hour. The mixture is stirred for a further 3 hours and then remains overnight. The sodium bromide is suctioned off with a weak negative pressure. The di-isopropyl ether is distilled off. The residue is dried in vacuo at 70 ° C. 44 g of a yellowish oil are obtained, which has a content of 96.9%, based on nitrogen.

Example 3 : Boron tris (di-2-ethylhexyl dithiocarbamate).

40 g of sodium hydroxide, granulated, are dissolved in 350 ml of methanol. 241 g of di-2-ethylhexylamine are added. To do this with mechanical stirring 64 ml of carbon disulphide were dropped in 20 minutes. The mixture is stirred for a further 2 hours. Then 171 g of boron trifluoride-methanol complex (14% BF₃) are added dropwise over the course of one hour. The mixture is stirred for a further 2 to 3 hours and remains closed overnight. The sodium fluoride is suctioned off. The solvent is distilled off and the residue is dried in vacuo. Finally, it is suctioned off again. 223 g of a yellowish oil are obtained, which has a content of 97.3%, based on nitrogen. The yield was 69.7% of theory, based on BF₃.

Example 4 : Boron tris (diamyl dithiocarbamate).

150 g of a 50% sodium hydroxide solution are introduced into 940 ml of methanol. Add 293 g of diamylamine. 120 ml of carbon disulfide are added dropwise with mechanical stirring over the course of 30 minutes. The mixture is stirred for a further 2 hours. 75 g of boron trifluoride-diethyl ether complex are introduced into 190 ml of ether. This solution is added dropwise to the solution of the sodium dithiocarbamate within 90 minutes. The mixture is stirred for a further 3 hours. The sodium fluoride is suctioned off. The solvent mixture is distilled off from the filtrate. The residue is dried in vacuo in a water bath at 70 ° C for one hour. Then it is suctioned off again. 325 g of a yellowish-colored oil are obtained, which has a content of 98.45%, based on N. The yield is 83% of theory, based on boron trifluoride.

Example 5 : Boron tris (ditridecyl dithiocarbamate)

80 g of a 50% sodium hydroxide solution are added to 500 ml of methanol. 381 g of ditridecylamine are added. With mechanical stirring on the reflux condenser, 64 ml of carbon disulfide are added dropwise over the course of 30 minutes. The mixture is stirred for a further 2 hours. The solution of 45 ml of boron trifluoride-ethyl ether complex in 100 ml of ether is then added dropwise over the course of 1 hour. The mixture is stirred for a further 3 hours. It then remains closed overnight. The sodium fluoride is suctioned off. The solvent mixture is distilled off from the filtrate. The residue is dried in vacuo in a rotary evaporator at a bath temperature of 70 ° C. The oil obtained is suctioned off again after cooling. 393 g of an amber-colored, viscous oil are obtained, which has a content of 98.7%. The yield is 85.4% of theory.

Claims (10)

1. A method for the production of boron-tris-(dialkyl-dithiocarbamates) of the general formula

   

   in which R and R' are identical or different, branched or unbranched, saturated or unsaturated alkyl radicals having 1 to 12 carbon atoms, characterised in that 3 moles of an alkali dialkyl-dithiocarbamate of the general formula

   

   in which R and R' have the above meanings and M⁺ stands for Na⁺, K⁺ or NH₄⁺, are reacted at 0°C to 90°C, preferably 20°C to 70°C, with one mole boron tribromide, boron trichloride or boron trifluoride in aliphatic or aromatic hydrocarbons or ethers, the resulting alkali halide or ammonium halide is separated off and the boron-tris-(dialkyl-dithiocarbamate) is isolated.
2. A method for the production of boron-tris- potential;(dialkyl-dithiocarbamates) of the general formula

   

   in which R and R' are identical or different, branched or unbranched, saturated or unsaturated alkyl radicals having 1 to 12 carbon atoms or both stand for tridecyl, characterised in that
   3 moles of an alkali dialkyl-dithiocarbamate of the general formula

   

   in which R and R' have the above meanings and M⁺ stands for Na⁺, K⁺ or NH₄⁺, are reacted with one mole of the complex of boron trifluoride with diethyl ether or methanol in a water-containing medium, the resulting alkali halide or ammonium halide is separated off and the boron-tris-(dialkyl-dithiocarbamate) is isolated.
3. A method according to Claim 2, characterised in that the reaction is performed in methanol, ethanol, propanol, isopropanol, ethylene glycol monoalkyl ether, tetrahydrofuran or dioxane.
4. A method according to Claim 2 or 3, characterised in that the water content of the water-containing medium is not more than 15%.
5. A method according to one of Claims 2 to 4, characterised in that the reaction is performed at temperatures of 0 to 90°C, preferably 20 to 70°C.
6. A method according to one of Claims 1 to 5, characterised in that the reaction is carried out in the same reaction vessel in which the alkali-dialkyl-dithiocarbamate has previously been produced.
7. Boron-tris-(dialkyl-dithiocarbamates) of the general formula

   

   in which R and R' are identical or different, branched or unbranched, saturated or unsaturated alkyl radicals having 1 to 12 carbon atoms or both stand for tridecyl, with the exception that both R and R' are methyl radicals.
8. A compound according to Claim 7, characterised in that R and R' are 2-ethylhexyl.
9. A compound according to Claim 7, characterised in that R and R' are pentyl.
10. The use of the compounds according to one of Claims 7 to 9 as additives for hydraulic oils or long-life gear oils.