CS254238B1 - Method of morpholine regeneration - Google Patents

Abstract

A method for recovering morphine from a solution is solved the production of N- (3-oxa-pentamethylene) -2-benzothiazylsulfenamide, at which increased efficiency of morpholine recovery. At producing said vulcanizer accelerator by reacting 2-mercaptobenzothiazole with morpholine in the presence of an oxidizing agent excess morpholine from solution after separation product recovers and returns to the process. The recovery of morpholine recovery is increased when regeneration occurs in the presence a small amount of hydroxide and / or carbonate sodium and / or hydroxide and / or oxide and / or calcium carbonate. preferred is to perform at least part of the regeneration after adding said substances under vacuum and in the presence boiling point substances above 150 ° C.

Description

The present invention provides a process for the recovery of morpholine from the production of N (3-oxa-pentamethylene) -2-benzthiazylsulphenamide, which results in an improved morpholine recovery efficiency.

N- (3-pxa-pentamethylene) -2-benzthiazylsulfenamide, marketed as Sulfenamide M, Sulfenax MOR and the like, is one of the most important rubber vulcanization accelerators and is produced from 2-mercaptobenzothiazole (2-MBljj and morpholine) an oxidizing agent such as sodium hypochlorite or hydrogen peroxide according to the equation

Sf-7 • t

C H - C i i i i o c> 1f C

Cu.

W · _0:> to achieve high yields of the product is the reaction of an excess of morpholine, as mercaptobenzothiazole in the presence of an oxidizing agent is reacted on the one hand to the disulfide, first, the mixture of sulfenic, sulfinic and sulfenic acid and the undesired side reactions can be an excess of morpholine, to a large extent, The morpholine / 2-MBT molar ratio used, according to the method of reaction, is between 4: 1 and 14: 1 and unreacted morpholine needs to be recovered from the reaction mixture by a suitable procedure. However, even with these morpholine remnants, the reacting 2-mercaptobenzothiazole cannot be completely protected from the oxidative effect.

In addition to the main product, which falls out of the reaction mixture as a crystalline phase, a pitch-like condensation waste material, a mixture of acids and their compounds with morpholine, which must be removed from the process during regeneration, is formed.

After separating the solid phase and rinsing the filter cake with morpholine and water, a moist but relatively very pure product is obtained, while the filtrates of these operations contain morpholine, water, unreacted 2-MBT and pitch condensates, representing a varied mixture of substances. The economics of the whole process is determined by the efficiency with which morpholine can be recovered from these filtrates for careful use. The waste pitch is environmentally harmful (high sulfur and nitrogen content) and must therefore be separated from the water and incinerated or used in an appropriate manner.

While the water and the major portion of the morpholine can be separated from the pitch relatively easily, theological properties of the pitch make it difficult to completely separate the morpholine from the concentrated residues, with some of the morpholine bound chemically. In known separation modes (normal or azeotropic rectification, optionally in the presence of CO 2, atmospheric or vacuum evaporation, film evaporation), the recovery efficiency of morpholine is 75 to 90% depending on the working temperature, pressure and regeneration method. valuable waste of raw material is lost and the economy of production is burdened with increased morpholine consumption.

According to the invention, the recovery of morpholine from the production of N- (3-oxa-pentamethylphene) -2-benzthiazylsulphenamide by reaction of 2-mercaptobenzothiazole with morpholine in the presence of an oxidizing agent is carried out such that after completion of the reaction 3.0 to 50.0 wt. %, preferably 10.0 to 20.0 wt. % sodium hydroxide and / or sodium carbonate and / or hydroxide and / or oxide and / or calcium carbonate, preferably in the form of an aqueous solution and / or suspension, based on the final amount of concentrated pitch, and water and / or morpholine are separated from the mixture .

In view of the thermal lability of the thickened pitches and their tendency to decompose, it is desirable that the separation of water and / or morpholine after the addition of sodium and / or calcium hydroxide and / or calcium carbonate is carried out gently, preferably by film evaporation, preferably under reduced pressure. In smaller-sized plants, it is advantageous to operate at a pressure of about 1.3 kPa, a slight vacuum can be selected for the operating evaporator and a working pressure of 20 to 30 kPa.

The rheological properties of thickened pitches are relatively unfavorable, pitches are viscous and difficult to transport. It is therefore advantageous to add a so-called liner when separating the water and / or morphine 254238. Exorcist, i.e. a substance or mixture of substances with a boiling point at atmospheric pressure above 150, preferably in the range of ³ 180 to 200 C. The boiling point at atmospheric pressure is referred to as the normal boiling point. Even under vacuum, these substances have a lower saturated vapor pressure than water or morpholine, facilitate their separation and improve the flow properties of the concentrated residue.

In contrast to the processes used hitherto, the method of morpholine regeneration has in this way a number of technological and economic advantages. In the presence of hydroxides and / or sodium and / or calcium carbonates, not only a recovery yield of unreacted morpholine close to 100% can be achieved, but chemically bound morpholine, which has reacted by undesired reactions, in particular with the sultan, sulfine and sulfonic acids. Morpholine is displaced from these salts by the addition of an inorganic substance and can be recovered for careful use, which is an important contribution to the process economy at its high cost.

However, any alkali metal or alkaline earth metal hydroxides or carbonates are not suitable for this process. The use of sodium or calcium or calcium carbonate or calcium oxide or mixtures thereof gave positive results, while using similar potassium compounds the yields were not significantly better and generally remained at the level of the additive process (recovery efficiency 85-90%). This is probably due to the general differences observed with the potassium salts of organic sulfuric acids, eg compared to sodium or calcium salts.

Some of the advantages of the process of the present invention are illustrated in the accompanying examples.

Example 1 (comparative)

127.2 g of combined filtrates containing morpholine (determined by titration of 24.93% by weight) were placed in a laboratory flask. A cooler, distillate vessel, freezer and vacuum apparatus were added to the flask. The flask was heated to 60 ° C and gradually decreased pressure so that the mixture of water and morpholine gradually and uniformly distilled, the pressure was reduced to 1.33 kPa and maintained at this value for 2 hours to obtain 95.3 g of distillate (a mixture of water and morpholine) having a morpholine concentration of 24, 91 wt%, a further 17.3 g with a morpholine concentration of 10.11 wt% were collected in the freezer A total of 28.21 g of morpholine was passed into the aqueous distillates, which represents an efficiency of 88.98% Example 2 (comparative)

A batch of 110.6 g of combined filtrates having a morpholine content of 24.93 wt. %, the same procedure was followed, but after collecting the major portion of water and morpholine, 5.9 g of a 20% aqueous KOH solution was added to the flask and the procedure was completed as in Example 1. A total of 25.08 g of morpholine was obtained in the combined distillates. , which corresponds to an efficiency of 90.96%.

Example 3

120.05 g of combined filtrates having a morpholine concentration of 23.11 wt. % as described in Example 2, but instead of an aqueous KOH solution, 4.10 grams of a 20% aqueous NaOH solution was added to the primary thickened flask. A total of 28.92 g of morpholine was obtained in the combined distillates, representing a recovery efficiency of 104.24% based on the free morpholine used. An additional amount above 100% has been chemically dissolved.

In the same procedure, using Ca (OH) 2 [1.69 g Ca (QH) 2 and 5 g water] or CaO (1.28 g) instead of NaOH, achieved a relative regeneration efficiency

103.52%. Here again, additional amounts of bound morpholine were released by chemical means.

Example 4

To 120 g of the morpholine concentration of 41.03% was added 2.2 g of Na 2 CO 3 and 3.3 g of water, and the resulting mixture was treated as in Example 1, except that a laboratory rotary evaporator was used for evaporation. A total of 49.89 g of morpholine was obtained in the combined distillates (117.1 gj), corresponding to a recovery efficiency of 101.3%.

When 1.0 g of CaCO3 was added in place of Ma2CO3 and treated in the same manner, 116.05 g of combined distillates were obtained with a total morpholine content of 50.24 g, which represents a recovery efficiency of 102.0%. In both cases, another fraction of bound morpholine was chemically released.

Claims (3)

SUBJECT Process for the recovery of morpholine from the production of N- (3-oxa-pentamethylene) -2-benzthiazylsulphenamide by reaction of 2-mercaptobenzothiazole with morpholine in the presence of an oxidizing agent, characterized in that after completion of the reaction but at least after separation of water and a major proportion of morpholine 3.0 to 50.0% by weight, preferably 10.0 to 20.0% by weight, are added to the mixture to be treated. hydroxide and / or sodium carbonate and / or hydroxide and / or calcium oxide and / or carbonate, preferably in the form of an aqueous solution and / or suspension based on the final amount of concentrated pitch, and water and / or morpholine are separated from the mixture. We claim: Method according to claim 1, characterized in that the water and / or the morpholine are separated by film evaporation, preferably under reduced pressure, after addition of sodium hydroxide and / or sodium carbonate and / or hydroxide and / or calcium carbonate and / or preferably 1 to 30 · kPa. 3. The process as claimed in claim 1, wherein the water and / or the morpholine are separated by evaporation in the presence of substances having a nominal content of sodium hydroxide and / or sodium carbonate and / or hydroxide and / or calcium carbonate and / or calcium carbonate. a boiling point above 150 ° C, preferably 180 to 200 ° C. Severografia, n. p. Race 7, Moat Price 2,40 KCs