RU2768934C1 - METHOD OF PRODUCING ADDUCTS OF S,S-DIMER OF 2,5-DIMERCAPTO-1,3,4-THIADIAZOLE (bis-DMTD) WITH ESTERS OF α, β-UNSATURATED ACIDS - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to organic chemistry, namely to a method of producing adducts S,S-dimer of 2,5-dimercapto-1,3,4-thiadiazole (bis-DMTD) with ethers α,β-unsaturated acids of general formula given below, which can be used as multifunctional additives for petroleum and synthetic oils, in particular as extreme pressure additives. Method involves interaction 2,5-dimercapto-1,3,4-thiadiazole with a dialkyl ester of maleic acid, where alkyl is n-butyl, iso-butyl, 2-ethylhexyl, or with 2-ethylhexyl ester of acrylic acid in presence of 1 wt.% of a tertiary amine of formula NR₃, where R is C₂-C₄ alkyl, followed by treatment with 33–35% hydrogen peroxide.

EFFECT: disclosed method enables to obtain said adducts with virtually quantitative output (98–99%) without formation of polymer by-products.

1 cl, 2 ex

Description

The invention relates to the field of organic chemistry, namely, to a method for obtaining adducts of S,S-dimer 2,5-dimercapto-1,3,4-thiadiazole (bis-DMTD) with esters of α,β-unsaturated acids of general formula I

,

,

which can be used as multifunctional additives for petroleum and synthetic oils.

The use of compounds with a similar structure as multifunctional additives to petroleum and synthetic oils, including corrosion inhibitors of non-ferrous metals, extreme pressure and antioxidant additives is known, for example, from the reference book [Rudnik L.R. Lubricant additives. Properties and application / Per. from English. lang. 2nd edition ed. A.M. Danilova. - S.Pb: Profession, - 2013, - 928 p.].

A known method for producing S-derivatives of 2,5-dimercapto-1,3,4-thiadiazole by the reaction of a maleic compound and 2,5-dimercapto-1,3,4-thiadiazole, followed by the use of the obtained products as multifunctional additives to petroleum and synthetic oils, general formula II (mono-DMTD) (US 5055584, 1991):

where R ₁ \u003d R ₂ \u003d alkyl, cycloalkyl, H, etc.

These compounds contain an insufficient amount of sulfur atoms (≤ 25% wt.) to achieve good extreme pressure properties, therefore, the possibilities of obtaining derivatives containing two thiadiazole rings were studied.

Compounds of formulas III and IV (US 2016201001 A1) are declared and investigated as extreme pressure additives:

where n=l-2; R ₁ and R ₂ \u003d H, iso-alkyl C ₁ -C ₁₂ , n-alkyl C ₁ -C ₁₂ , arom., heteroarom.

However, only the 2,5-dimercapto-1,3,4-thiadiazole derivative under the trade name ADDITIN RC8210 (RHEIN CHEMIE) is given as an example. According to the safety data sheet (SDS), this derivative is the product of the reaction of 2,5-dimercapto-1,3,4-thiadiazole with hydrogen peroxide H ₂ O ₂ and tert-dodecanethiol (tert-C ₁₂ H ₂₅ SH) and has the formula V :

This compound already contains sufficient sulfur atoms (ca. 29 wt. %) to achieve good extreme pressure properties, but is used primarily as a non-ferrous corrosion inhibitor. In addition, the use of tert-dodecanethiol (dodecylmercaptan) in industrial synthesis poses a threat to the environment and requires the adoption of special measures to ensure safety against leakage of this compound.

The claimed compounds with enhanced extreme pressure properties can be obtained by modifying the S,S-dimer of DMTD. Numerous papers have been published in the chemical literature relating to the production of S,S-dimer DMTD by a wide range of oxidizing agents since the late 19th century (Bush M., Ziegele E., J. Prakt. Chem., vol. 60, 1899 , p. 25). In more recent works, the processes of dimerization of DMTD under the action of iodine have been studied in detail (Shouji E. Yokoyama, Y., Pope, J. M., Oyama, N., Buttry, DA Electrochemical and Spectroscopic Investigation of the Influence of Acid-Base Chemistry on the Redox Properties of 2,5-Dimercapto-l,3,4-thiadiazole//The Journal of Physical Chemistry B. - 1997. - T. 101. - No. 15. - C. 2861-2866.) and hydrogen peroxide (US 4246126). Already in the first works on the synthesis of the DMTD dimer, the authors noted the ambiguity of the results of this process. A fundamental study of the composition of DMTD polymerization products under various conditions was carried out in (Li C, Huang S., Min C, Du P., Xia Y., Yang, C, Huang Q. Highly Productive Synthesis, Characterization, and Fluorescence and Heavy Metal Ion Adsorption Properties of Poly (2,5-dimercapto-1,3,4-thiadiazole) Nanosheets//Polymers. - 2018. - V. 10. - No. 1. - C. 24.). According to physicochemical research methods, especially mass spectrometry (MALDI-TOF method), in such reactions a mixture of oligomers, including cyclic ones, is always obtained, and the linear S,S dimer is often not the main product.

The only chemoselective method for obtaining S,S-dimer DMTD that matters is the synthesis method proposed in the patent (US 10316005 B2, 2019). This patent proposes to obtain an unsubstituted S,S-dimer starting from hydrazine and carbon disulfide through the mono-sodium salt of DMTD without isolating the intermediate, followed by its oxidation with H ₂ O ₂ to the desired bis-DMTD with a total yield of 92%. This preparation method contains an additional step of forming the 1,3,4-thiadiazole ring:

At the same time, further modification of the product by SH groups is difficult due to the low reactivity of the dimer (Fields E. K. Addition of l,3,4-thiadiazole-2,5-dithiol to Olefinic Compounds//The Journal of Organic Chemistry. - 1956 - T. 21. - No. 5. - C. 497-499).

The objective of the present invention is to develop a method for obtaining S,S-dimer 2,5-dimercapto-1,3,4-thiadiazole (bis-DMTD), modified by substituents on the remaining SH groups, having a sufficient number of sulfur atoms (S≤29% of the mass .) to achieve good extreme pressure properties, in high yield, without the formation of polymer by-products.

The problem is solved by developing a two-stage method for obtaining adducts of S,S-dimer of 2,5-dimercapto-1,3,4-thiadiazole (bis-DMTD) with esters of α, β-unsaturated acids, in which mono-S- derivatives of DMTD, by the interaction of 2,5-dimercapto-1,3,4-thiadiazole with a dialkyl ester of maleic acid, where alkyl: n-butyl, iso-butyl, 2-ethylhexyl, or with 2-ethylhexyl ester of acrylic acid, in the presence of 1 wt % of a tertiary amine of the formula NR ₃ , where R is C ₂ -C ₄ alkyl, which are doubled in the second stage under the action of 33-35% hydrogen peroxide into the target products.

At the same time, to increase the yields of monoadducts, the reaction at the first stage is carried out in the presence of catalytic amounts of organic bases - tertiary amines (1% wt, tertiary amine of the formula NR ₃ , where R is alkyl C ₂ -C ₄ ).

The process of obtaining target products was carried out both without a solvent and in an organic solvent.

Example 1 Synthesis without solvent.

A mixture of 0.4 mol 2,5-dimercapto-1,3,4-thiadiazole and 0.4 mol maleic acid dialkyl ester (alkyl=n-butyl, n-butyl, 2-ethylhexyl) or acrylic acid 2-ethylhexyl ester was heated at 70-130°C (depending on the structure of the reagents) in the presence of 1 wt%, trialkylamine with the appropriate boiling point for 1-3 hours with vigorous stirring until complete dissolution of DMTD. The resulting oil was cooled and dissolved in 500 ml. glacial acetic acid or absolute ethyl alcohol. 100 ml of 33% hydrogen peroxide (0.4 mol) was added dropwise to the resulting solution with vigorous stirring for one hour, cooling the flask in an ice bath (0–10°C), and then stirring was continued for another hour at room temperature. The resulting mixture was poured into water, extracted with chloroform, ethyl acetate or other suitable solvent (3 x 150 ml) and the organic layer was washed several times with water. In the case of alcohol, rinsing is not necessary. The organic fraction was dried over anhydrous sodium sulfate, the solvent was removed on a rotary evaporator. The resulting substances are thick yellow-brown oils. Yields are almost quantitative 98-99%.

Example 2 Solvent Synthesis

A mixture of 0.4 mol of 2,5-dimercapto-1,3,4-thiadiazole and 0.4 mol of maleic acid dialkyl ester (alkyl=n-butyl, iso-butyl, 2-ethylhexyl) or 2-ethylhexyl acrylic acid ester was boiled in 500 ml of ethyl acetate, toluene, butyl acetate or dioxane in the presence of 1% of the mass, a tertiary amine with the appropriate boiling point for 1-3 hours with vigorous stirring. The solvent was then removed in vacuo. The resulting oil was cooled and dissolved in 500 ml of glacial acetic acid or absolute ethanol. 100 ml of 35% hydrogen peroxide (0.4 mol) was added dropwise to the resulting solution with vigorous stirring for half an hour, while cooling the flask in an ice bath (0–10°C), and then stirring was continued for another hour at room temperature. The resulting mixture was poured into water, extracted with chloroform, ethyl acetate or other suitable solvent (3 x 25 ml) and the organic layer was washed several times with water. In the case of alcohol, rinsing is optional. The organic fraction was dried with anhydrous sodium sulfate. Then the solvent was removed on a rotary evaporator. The resulting substances are thick yellow-brown oils. Yields are almost quantitative 98-99%.

The characteristics of the obtained compounds are given below.

1. Tetra-butyl-2,2'-[dithio-bis-(1,3,4-thiadiazole-5,2-dithio)]-disuccinate (SS-tetra-Vi). ¹ H NMR spectrum (DMSO-d6, σ ppm): 0.70-0.90 (12 H, m, 4 CH ₃ ); 1.15-1.40 (16 N, m., 8 CH ₂ ); 1.40-1.50 (8 H, m., 4 CH ₂ ); 3.00-3.10 (2 H, m., 2 CH); 3.80-4.20 (8 H, m., 4 CH ₂ ); IR spectrum (Vaseline oil, cm ^-1 ): 1730 (non-conjugated group CO ₂ Bu).

2. Tetra-(iso-butyl)-2,2'-[dithio-bis-(1,3,4-thiodiazole-5,2-dithio)]-disuccinate (SS-tetra-iso-Bu). ¹ H NMR spectrum (DMS0-d6, σ ppm): 0.75-0.90 (24 H, m., 8 CH ₃ ); 1.75-2.00 (4 H, m., 2 CH ₂ ); 3.05-3.55 (4 H, m., 2 CH ₂ ); 3.55-3.80 (8 N, m, 4 CH ₂ ); 4.60-4.90 (2 H, m, 2 CH); IR spectrum (wm, cm ^-1 ): 1745 (non-conjugated group CO ₂ -iso-Bu).

3. Tetra-(2-ethylhexyl)-2,2'-[dithio-bis-(1,3,4-thiodiazole-5,2-dithio)]-disuccinate (SS-tetra-2-EtHex). ¹ H NMR spectrum (DMSO-d6, σ ppm): 0.75-0.95 (24 H, m, 8 CH ₃ ); 1.20-1.70 (32 N, m., CH+CH ₂ ); 3.00-3.10 (4H, m. 2 CH ₂ ); 4.00-4.20 (14 N, m. 2 CH + 6 CH ₂ ); IR spectrum (wm, cm ^- ): 1740 (unconjugated group CO ₂ - 2-EtHexyl).

4. Di-(2-ethylhexyl)-3,3'-[dithio-bis-(1,3,4-tnadiazol-5,2-dithio)]-dipropionate (SS-di-2-EtHex). ¹ H NMR spectrum (DMSO-d6, σ ppm): 0.75-0.90 (12 H, m, 8 CH ₃ ); 1.20-1.65 (16 H, m., CH ₂ ); 1.45-1.55 (2H, m., 2 CH) 2.80-2.90 (4H, m. 2 CH ₂ ); 3.45-3.55 (4 H, m., 2 CH ₂ ); 3.95-4.05 (4 H, m, 2 CH ₂ ); IR spectrum (wm, cm ^-1 ): 1750 (non-conjugated group CO ₂ - 2-EtHexyl).

Thus, a method has been developed for the preparation of adducts of S,S-dimer 2,5-dimercapto-1,3,4-thiadiazole (bis-DMTD) with esters of α,β-unsaturated acids of general formula I

practically in quantitative yields of 98-99%, having a sufficient amount of sulfur atoms (S ≤ 29% wt.) to achieve good extreme pressure properties, without the formation of polymer by-products.

Claims (4)

1. Method for obtaining adducts of S,S-dimer 2,5-dimercapto-1,3,4-thiadiazole (bis-DMTD) with esters of α,β-unsaturated acids of the general formula

interaction of 2,5-dimercapto-1,3,4-thiadiazole with a dialkyl ester of maleic acid, where alkyl is n-butyl, iso-butyl, 2-ethylhexyl, or with 2-ethylhexyl ester of acrylic acid in the presence of 1 wt.% tertiary amine of the formula NR ₃ where R is C ₂ -C ₄ alkyl, followed by treatment with 33-35% hydrogen peroxide. 2. The method according to p. 1, characterized in that the reaction is carried out in the presence of an organic solvent selected from the group: ethyl acetate, toluene, butyl acetate, dioxane.