SU889660A1 - Method of isolating 2-mercaptobenzthiazole - Google Patents

Description

(54) METHOD FOR THE ADMINISTRATION OF 2-MERCAPTOBENZIAZOLE

one

This invention relates to an improved process for the separation of 2-mercaptobenzthiazole (captax), which is widely used as a rubber vulcanization accelerator.

In the production of 2-mercaptobenzthiazole (2-MBT) from aniline, sulfur and carbon disulfide receive 85-90% of the target product and 8-15% resinous substances, which are usually thrown out.

In industry, when cleaning a captax from tar, consisting of dissolving raw 2-MW melt in alkali, separating the resin after settling, the resin irretrievably loses from 10 to 20% captax.

Methods for recovering captax from resinous captax production are not described in the literature.

The closest in technical essence and the achieved effect is a method for separating captax from a mixture containing 2-mercaptobenzthiazole, aniline, benzthiazole and tarry wastes, which implies that the crude product is dissolved in an aromatic hydrocarbon at a temperature above 200 ° C, the solution is added alkalis in water, the layers are separated and the target product is isolated by acidification with sulfuric acid. Get the product with so pl. 178-180, and the content of the basic substance is 98.8% 1.

The disadvantage of this method is the need to dissolve the melts of captax at high temperatures due to the difficulty of dissolution, as a result of which the risk of the process is increased. In addition, this method does not solve the problem of the use of tarry waste.

The purpose of the invention is to increase the efficiency of the process.

This goal is achieved by the process of 2-mercaptobenzthiazole injection, KOtoptiA consists in that a sap of the captax production after the separation of the captax alkaline solution is dissolved at 30-60 ° C in an organic solvent, not mixed with water, and then extracted with ammonia water, the layer is separated -Ammonium solution, the captax salt and the captax were acidified with a mineral acid.

Aromatic, aliphatic or cycloaliphatic hydrocarbons can be used as solvents. Preferably

use o- or p-xylene, -Toluene; or a toluene-xylene mixture, a waste product from the production of synthetic rubber, the production of isobutane dehydrogenation, which has the best dissolving power. When the resin is dissolved in an organic solvent, a homogeneous solution of a dark brown color is formed. When alkali is added at 10–25 ° C and then water, with stirring, captal of the resin solution is immediately extracted into the solvent. After stirring has ceased, two distinct layers are formed after 1 mi: a dark brown resin layer in a solvent and a light yellow aqueous layer of an alkaline captax solution.

If caustic soda solution is used as alkaline extragate, then the layers are difficult to separate, since they differ slightly in color from each other, and so pl. The selected captax is low at 150-165 ° C. When using ammonium hydroxide as the extractant, a clear phase separation occurs: the layer containing the resin and organic solvent is dark brown in color, and the ammonia captax solution is light yellow. Kaptaks isolated at PRU 9.2-9.5 from the filtered ammonium salt Kaptax, high quality. M.p. captax 177-iaO ° C. The yield of captax is 95-100%.

The difference of this method from the known one is that the process of growing resinous waste in an organic solvent is carried out at a temperature of 30-60 ° C, and an aqueous ammonia solution is used as the aqueous base solution.

Example 1. A resin in an amount of 100 g, containing 25% captax, is dissolved at 60 ° C in 50 ml of toluene, after which the solution is cooled to room temperature and shifted from 25 ml of a 20% aqueous solution of ammonia. After stirring, 200 ml of water was added to the mixture. After 1 min after stopping the stirring, the layers are separated on a separatory funnel: the top is a light yellow ammonia captax solution, the bottom is a dark brown resin solution in a solvent. After separation of the layers, 1 g of activated carbon is added to the ammonia solution of the captax salt with stirring and filtered on a Buchner funnel through a paper filter. Then a captaxa is precipitated from the filtered ammonia solution during acidification with sulfuric acid. After filtering the captax suspension, washing and drying the captax, the precipitate is weighed. Draft weight 24 g. Captax yield 96% based on initial content.

captax in resin. T. pl. Kaptaks1 118 ° C,

PRI mme R 2. A resin in an amount of 100 g, containing 25% captax, is dissolved in 200 ml of o-xylene, and then sequentially mixed with 25 MP of a 20% aqueous solution of ammonia and 300 ml of distilled water. After mixing, the layers are separated in a separatory funnel, the top is a dark brown toluene resin layer, and the bottom is a light yellow ammonium captax solution. After filtration on a Büchner funnel, the captax is divided through a filter paper of a solution of ammonium salt of captax when acidifying the solution with sulfuric acid. After filtering the captax suspension, washing and drying the captax, the precipitate is weighed. The weight of the precipitate captax 25 g, the yield of captax 100% in terms of the initial content of captax in the resin. M.p. captax

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Froze The resin in the amount of 100%, containing 25% captax at 30-60 ° C in 150 ml of para-xylene-toluene fraction - waste of production of synthetic rubber Ski-3 {isobutane-methanol method), and then mixed with 30 ml of 20% solution of ammonia After stirring, the layers are separated on a separatory funnel: the top is a solution of the resin in a dark brown organic solvent, and the bottom is a solution of the light yellow captaxon ammonium salt. After filtration on a Büchner funnel through a filter paper of a solution of the ammonium salt of captax, captax is isolated upon acidification with sulfuric acid, which is filtered off, washed with water and dried. The weight of the dry precipitate of captax is 25 g. The yield of captax is 100% calculated on the initial content of captax. T. pl. captax 177 ° C.

Claims (2)

1. A method for separating 2-mercaptobenzthiazole from resinous waste produced by 2-mercaptobenzthiazole by the interaction of aniline, sulfur and carbon disulfide, dissolving them in an organic solvent that is not miscible with water, when heated, extracting with an aqueous base solution, separating the aqueous layer and acidifying it with glineral acid, It is distinguished by the fact that, in order to increase the efficiency of the process, the process of dissolving resinous wastes in an organic solvent is carried out at a temperature of 30 ° C, and as an aqueous solution 5 use ammonia solution. 58896606 2. The method according to p. 1, about tl and h and y-sources of information y and with the fact that as an organ, taken into account in the examination of a nical solvent, use 1. US Patent 3,770,759, or toluene, or xylene, or their mixture. 260-306, published. 1970 (prototype)