DE741109C - Process for the preparation of thioarylamides - Google Patents

Description

Process for the preparation of thioarylamides For the preparation of thioarylamides, especially thioacetanilides; one carries into the warm solution of the acetanilide in Benzene, toluene or xylene finely powdered phosphorus pentasulphide. After implementation is in this known process in the warm benzene liquid the thioacetanilide dissolved in a yield of about 30% o of theory. On the Bathing the reaction vessel there is a tough, dark mass that besides the Conversion product of phosphorus pentasulfide still contains plenty of thioacetanilide. Obtaining this portion of the converted product is not, however, technical possible because the viscous mass cannot be worked up economically. This share the product was therefore lost. In addition, the mass obtained can be omitted Do not simply remove it from the reaction vessel. One is therefore forced to use them to destroy in the vessel with the effort of a lot of caustic soda if you use the latter want to clean and use again.

It has now been found that significantly better yields of thioarylamides can be obtained comes when you take the phosphorus pentasulfide to be converted with before use completely dry, finely powdered carbonates or oxides of the alkaline earths mixed. Because of the cheapness, magnesium oxide, calcium oxide and are preferred Calcium carbonate, but also strontium carbonate or barium carbonate are suitable. The carbonates or oxides can either be used alone or in a mixture. at The mixture can contain different carbonates or different oxides or mixtures be used by both. Due to the added, specifically light oxides or Carbonates are the formation of viscous masses, which are neither converted nor Include unused phosphorus pentasulfide prevents. At the bottom of the conversion vessel after the reaction there is rather a dry, powdery mixture that Can easily be boiled with benzene or the like and its amide content is almost completely gives away. The powdery residue can easily be cleaned with a Spade or the like can be removed.

Since the specific gravity of phosphorus pentasulfide is higher than that of the alkaline earth oxides or carbonates, becomes the phosphorus pentasulfide to a certain extent diluted and can therefore act in a larger surface. Before alone but these additives prevent caking of the oil from the phosphorus peritoneal oil resulting phosphorus pentaoxide or the as yet unspecified oxysulfides. The: mass therefore remains porous. The compound obtained can therefore by solvent can be easily extracted.

Whether the added oxides still have a chemical or catalytic effect exercising is not safe, but possible.

It is known that chemical reactions in the liquid phase can be accelerated by indifferent solid bodies such as sand or infusor earth. In this case, however, the reaction is accelerated by the fact that the reaction surface becomes larger and capillary forces act within the kieselguhr, which is soaked with the liquid reaction components. In contrast, the new process involves a reaction in which one of the two components, namely phosphorus pentasulfide, is essentially in solid, undissolved form. The physical conditions are therefore different in the new process. The situation here must be more complicated. It has been shown that substances that merely increase the surface area, such as infusoric cores, etc., have practically hardly any influence on the process to be improved according to the invention. `run z. B. in the implementation of iog acet-p-plienetidid with 6 g of P. S; If a yield of 3.5 g is obtained without addition, then no change in yield can be achieved with the addition of 6 g of sand during the reaction. When 6 g of kieselguhr were added, a yield of 3.9 g was found. If, however, 6 g of magnesite oxide are added according to the invention, the yield increases by leaps and bounds to 6.5 g. It was therefore not foreseeable that alkaline earth carbonates and oxides would bring about a considerable improvement in yields. This must be a new effect, for which, however, no specific explanation can be given for the time being. Example 100 g of acet-p-plienetidide (absolutely dry) are dissolved warm in i 1 benzene. An intimate mixture of 60 g of phosphorus pentasulphide and 6o- 1lagnesium oxide (very finely powdered and absolutely dry) is introduced into the boiling solution. After your last entry, it is boiled for an hour, then filtered or vacuumed. The powdery residue is boiled with 200 cc of benzene. The combined benzene extracts are extracted with 3 1 #, ° toiger cold sodium hydroxide solution. The benzene is separated and recovered. The filtered liquor is cooled with pieces of ice and the Tliioacet-p-plienetidid dissolved in it as the sodium salt is precipitated by introducing carbonic acid or by throwing in sodium bicarbonate. The compound is almost white and easy to filter.

Example: 2 10 g of acet-p-phenetidide are dissolved in 100 cc of boiling benzene; the batch is cooled to about 60 °, with individual crystals separating out again. An intimate mixture of 6 g of P = S ,; and 6- MgO (both finely powdered) added in proportions with stirring. The temperature rises as a result of the reaction up to the boiling point of the benzene.

The approach now remains at 50 ° for about 12 hours. After this Time is filtered off. The sandy residue is boiled twice with a little benzene. The combined benzene solutions "earth finitely 300 ccm of cold 20" sodium hydroxide solution shaken out. Sufficient sodium bicarbonate is added to the alkaline solution, that the excess sodium hydroxide solution is converted into sodium carbonate, whereby (read Thioacet-p-pliet.etidid precipitates as a light-colored precipitate.

Example 3 As example 2; Instead of the 6 g _NIg0, 6g finely powdered Ca 0 is used. Example As in Examples 2 and 3, with 6 g Ba CO being used instead of 6 g MgO.

The amides of the monocarboxylic acids, such as acetic and propionic acid, suitable, which are represented by alkvl, aryl or naphthatlvl in the Amide group can be substituted.

Example 5 2 Soog x Acetnaphtbalid (sharp dried) are placed in a reaction vessel, 18 l of dry benzene are added cold and heated to the boil (it dissolves only a little); then it is cooled down a little (70 °). The following are then added, with stirring, in proportions: an intimate mixture of 18oo g of phosphorus peptasulfide + goo g of magnesium oxide. The approach boils by itself. The acetone goes into solution, the thio product remains dissolved. Cooking takes 3 to 4 hours, including the entry. The approach has pulp consistency. It is then cooled to 70 ° and suctioned off. The residue is first washed with 2 to 31 warm benzene, the residue is returned to the reaction vessel, boiled again with 10 1 benzene, filtered off with suction and the residue is washed with a little warm benzene. The residue is a dry, sandy powder of a brownish color which can be easily removed. The benzene filtrates (approx. 251) are combined and, if necessary, filtered again. The benzene solution is then shaken out with a total of 25 15% cold sodium hydroxide solution (shake out each quantity of benzene solution three to four times). The entire liquor is cooled to 0 ° by throwing in a few kilograms of ice, then finely powdered sodium bicarbonate is introduced with turbines. As soon as the first precipitation occurs, ample solid, moist thioacetnaphthalide from an earlier production is thrown in for inoculation; then continue with the addition of bicarbonate: an initially sticky, yellowish precipitate develops after a short time. After 16 hours it is filtered off with suction (dilute acetic acid is added to the waste liquor, no more precipitation may occur), washed with cold water and squeezed off sharply.

Appearance: Light brownish yellow, dry, sandy powder.

Very high degree of purity (due to oxidation with alkaline ferricyanide solid 2-methyl-a-naphthothiazole is formed immediately: Example 6 350 g hot 10 1 benzene are poured over dried acetanilide and heated to 70 ° (es not everything dissolves). While stirring vigorously, add small portions within entered about 1/2 hour: an intimate mixture of Soo g of finely powdered phosphorus pentasulfide and 400 g of finely powdered Mg O.

After a short time, the batch will boil by itself. After entering, the mixture is allowed to boil gently for a further 2 hours. The approach has pulp consistency. It is then cooled to 70 ° and suctioned off. The residue is covered with 1 1 of warm benzene, then again boiled with 61 benzene, filtered off with suction again and -ausgewaschen with little warm benzene. The remaining residue, a yellow sandy mass, is easy to remove.

The combined benzene solutions are strongly cooled (about 10 °) and shaken exhaustively with 3% ice-cold sodium hydroxide solution.

The combined extracts are cooled to 0 ° by throwing in ice and mixed with sodium bicarbonate while turbineing. The result is a finely crystalline one Precipitation of thioacetanilide.

After vacuuming, it is dried at about 60 ° until the weight is not more decreases.

65o g of dry product of a slightly yellow color are obtained. F1. P. 750. Cleaning: The product is dissolved in a little warm benzene, decolorized with animal charcoal, filtered, cooled and the resulting crystallization by adding petroleum ether made even more abundant; suction takes place last.

An almost snow-white product is obtained in the form of fine needles. The product is used to prepare 2-methylbenzothiazole.

The phenylthioacetanilide is obtained analogously from the formula The yield is even better in this case (up to about 70% of theory).

Example ? The connection 4-Thioacetaminothiophenol methyl ether is prepared as follows: 84g of sharply dried monoacet compound of 4-aminothiophenol methyl ether are made. dissolved in 840 cc of dry boiling benzene; An intimate mixture of 55 g of finely powdered phosphorus pentasulphide and 27 g of finely powdered magnesium oxide is added in proportions to the warm solution. The mixture is boiled for a further 3 hours, then filtered off with suction while warm and the residue is boiled out with a little benzene. The combined benzene extracts are shaken out several times with cold 4 ° Joiger sodium hydroxide solution. The combined extracts are ice-cold precipitated with sodium bicarbonate. The precipitate is washed with cold water and dried.

Yield: 36 g (this is about .1.2% of theory ')

Claims (1)

PATENT CLAIM: Process for the preparation of thioarylamides by Reaction of aryl amides with phosphorus pentasulfide, characterized in that one phosphorus pentasulphide mixed with finely powdered, alkaline earth carbonates and / or alkaline earth oxides.