CS218264B1 - Method of preparation of the dibenzylsulphide - Google Patents

Description

The invention relates to a process for preparing the dibenzyl sulfide of Formula I

(By reacting benzyl chloride with an aqueous solution of sodium sulfide in the presence of anionic, nonionic or cationic surfactants, the reaction is carried out with the addition of NaOH in an amount of 0.1 to 1.0 mol per 1 mol of benzyl chloride. Diibenzyl sulfide is used as a corrosion inhibitor and as a semi-finished product. for the preparation of dibenzyl sulfoxide.

The invention relates to a process for the preparation of dibenzyl sulfide. Dibenzyl ¹ sulfide, 1,1-thio-bis- (methylbenzene) of formula (I) is prepared in a known manner by reacting benzyl chloride with potassium sulfide in an alcoholic solution at boiling (LiebigS Annaen der Chemie 136, 88). with an aqueous Na 2 S solution at 80 ° C with the addition of sodium diisobutylnaphthalenesulfonate (Nekal BX) as an emulsifier to increase the surface of both immiscible phases (BIOS 1154, 26). Since the production of diisoΡηίγ1ηηίτ &1βη3η1'ίοιΐ3ηη was stopped for ecological reasons, this surfactant had to be replaced by another, more easily degradable agent.

The available anionic surfactants either have low solubility in the concentrated reaction mixture, are very foaming, or the ester sulfated compositions are partially saponified in the reaction. Non-ionic surfactants appear to be poor because in concentrated electrolyte solutions, even with ethylene oxide adducts with a high oxyethylation degree, such as domestic Slovasol O, the clouding temperature is lowered below the reaction temperature and the compositions lose their emulsifying ability. As a result, the sulfidation reaction slows and a significant portion of the benzyl chloride is hydrolyzed to the benzyl alcohol. Preferably, the sulfidation is performed using tZv. phase transfer catalysts. They are essentially quaternary ammonium salts or phosphonium salts with at least one alkyl of at least C 1. By their action, the reaction is transferred from the interphase surface to the organic phase by forming a reactive aniorite to form an organic compound soluble in the organic phase. As a result, the reaction itself is greatly accelerated and the competitive hydrolysis is relatively slow.

It also describes the synthesis diberizylsulfidu reacting benzyl chloride with an aqueous solution of 0.6 mol barer presence of 0.1 mole of hexadecyl tributylfosfoniumbromidu that at 70 ^Q C proceeds completely in <10 min. (Synthesis 1974, 505).

It has now been found that the quaternary ammonium salts of formula II are equally effective for carrying out the reaction,

R2

AND

R1-N-R4X-,

AND

R 3 (II) wherein R 1 is an alkyl having a carbon number of C 10 to C 20, R 2, R 3 are the same or different lower alkyls having a carbon number of C 1 to C 4, or glycol ether chains - (C ₂ H 4 O) - _n H R 4 is lower alkyl having a carbon number of C 1 to C 4, or benzyl; X ^- is a halogen or methylsulfate anion. They provide a sufficient reaction rate at a concentration of 0.1 mole per mole of benzyl chloride, comparable to that of anionic surfactants, which are used at substantially (up to 100 times) higher dosages.

Due to the different mechanism, it is not necessary for the organic phase to be emulsified, so that foaming problems are also eliminated.

Due to the increased reaction rate, the reaction temperature can be lowered below 80 ° C, thereby reducing the hydrolysis of benzyl chloride.

At the same time, it has been found that reactions carried out with both anionic and nonionic emulsifiers or cationic phase transfer catalysts require a relatively large excess (about 30%) of Na 2 S to provide a yield of> 90%.

By reducing the excess Na 2 S or even at an equivalent ratio of 0.5 moles Na 2 per mole of benzyl chloride, the yields of crystalline diberisylsulfide greatly decrease and a byproduct produces a liquid benzylmethaptan of an unpleasant garlic odor which dissolves a considerable proportion of dibenzylsulfide. This is due to the fact that technical sodium sulfide often contains a fairly large proportion of NaSH, which can be analytically detectable. However, even with crystalline Na 2 S. 9 HzO, which according to the analysis contains up to 15 mol%. free NaOH, the formation of benzylmercaptan occurs and the yield of dilbenisylsulfide decreases even at a 10% excess of Na2S below 90%. Apparently, the alkalinity is blunted by hydrolysis or other side reaction of benzyl chloride.

High yields of very pure diberisylsulfide can be achieved by the process according to the invention even with an equivalent ratio of 1 mol of benzyl chloride: 0.5 moles of sodium sulfide while suppressing the formation of benzyl mercaptan by adding sufficient alkali, preferably in the form of hydroxides. A process for preparing a dibenzyl sulfide of formula I by reacting 1 mole of benzyl chloride with an aqueous solution of sodium sulfide in an amount of 0.5 to 0.7 mole in the presence of anionic, nonionic or cationic surfactants in an amount of 0.01 to 10 g per mole of benzyl chloride The reaction is carried out with the addition of sodium hydroxide in an amount of 0.1 to 1.0 mol per 1 mol of benzyl chloride at a temperature of 70 to 100 ° C and a reaction of the dihenzyl sulfide formed after cooling the melt below 40 ° C and crystallizing. Against expectations, even after the addition of 0.5 mol of NaOH (per 1 mol of benzyl chloride) at a reaction temperature of 85 [deg.] C., the proportion of hydrolysis is not appreciably provided that sufficient Na2S is present in the reaction mixture. The advantage of preparing the dibenzylsulfide according to the invention is that

a) obtains a very pure product without the mercap218264 tannate fraction in a practically theoretical yield that, when using phase transfer catalysts, their wastewater pollution is reduced at low dosage. Due to the higher reaction rate, the overall reaction time can be significantly shortened and the NazS concentration increased, resulting in higher productivity and that

c) removing a large excess of Na 2 S, thereby facilitating waste water treatment. It will not be necessary to regenerate unreacted Na2S, it will be sufficient to dispose of a small amount of the sulphite in an acidic environment.

Dibenzylsulfide is used as a corrosion inhibitor, but mainly serves as a semi-finished product for the preparation of dilbenzylsulfoxide, a known inhibitor of steel pickling.

The following examples illustrate the zip method according to the invention. Parts and percentages given ^! are mass.

He did

Dissolve 0.1 mole (4.0 g) of NaOH, 0.1 g of dodecylbenzenesulfonic acid in a solution of NazS 20% containing 0.575 mol (50.0 g) of NazS 100% and stir for 20 minutes at 80 ° C with stirring for aSl. The reaction mixture was charged with 1 mol (12.6.6 g) of benzyl chloride. After stirring at 80 ° C for 5 hours, the mixture was cooled to 30 ° C and the melt crystallized upon seeding. Suction and washing with water gave 103.2 g of ditoenzylsulfide with a pour point of 47.5 ° C. Under the same conditions, but without the addition of NaOH, only 75.0 g of ditoenzylsulfide crystallized and the filtrate contained a considerable amount of garlic odorous benzyl mercaptan.

If the same amount of octadecenyl alcohol adduct with 20 moles of ethylene oxide was used instead of 0.1 g of dodecylbenzenesulfonic acid under the same conditions, only 78.0 g of dibenzylsulfide and benzyl methanesters oil were obtained without the addition of NaOH. If 0.1 mole of NaOH is added simultaneously to the reaction mixture, the yield of crystallized dibenzylsulfide is increased to 94.8 g. Although benzylmercaptan is not formed under these conditions, the mixture contains less benzyl alcohol and the reaction proceeds slowly.

Example 2

Dissolve 0.5 mol (20 g) of NaOH and 0.1 g of the ammonium salt obtained by adding 7 my ethylene oxide per mole of octadeicylamine and quaternizing the adduct with dimethyl sulfate in a solution of 20% Na 2 S (0.575 mol, 50.0 g). To the obtained ro / solution, with stirring and eventual re-cooling, it takes about 20 min. of benzyl chloride (126.6 g) was added at 70 ° C. The reaction is complete after stirring for 2 hours at 70 ° C and treatment according to Example 1 gives 103.2 g of pure dibenzylsulfide. Without the use of NaOH, only 82.9 g of dibenzylsulfide crystallized from the mixture and the mixture contained a considerable amount of benzyl mercaptan. Instead of the ammonium salt, an equivalent amount of the tertiary amine starting material (octadecylamine adduct with 7 moles of ethylene oxide) can be used, from which the quaternary salt is formed by the henzyl chloride in the reaction.

Example 3

0.20 mole (10 g) of NaOH and 0.1 g of dodecyl dimethyl-ibenzylammonium chloride are dissolved in Na 2 S solution of 20% (0.50 mol) and benzyl chloride (1 mol, 126.6 g) is allowed at 100 ° C. By the same treatment as in Example 1, 103.3 g of dibenzylsulfide having a pour point of 47.5 ° C with a low benzyl alcohol content is obtained.

Claims (1)

SUBJECT Process for the preparation of dibenzyl sulfide of formula I by reacting 1 mole of benzyl chloride with an aqueous solution of sodium sulfide in an amount of 0.5 to YNALEZU 0.7 mol in the presence of anionic, nonionic or cationic surfactants in an amount of 0.01 to 10 g per 1 mol of benzyl chloride, characterized in that the reaction is carried out with the addition of sodium hydroxide in an amount of 0.1 to 1.0 mol per 1 mol of benzyl chloride at 70 DEG-100 DEG C. and the benzylsulfide formed by the reaction is separated by filtration after cooling the melt below 40 DEG C. and crystallization.