DE10218595A1 - Production of highly pure trichloroacetamide for use e.g. in anti-tumour agents and herbicides involves reaction of ammonia gas with a solution of trichloroacetyl chloride in methyl tert.-butyl ether - Google Patents

Abstract

A method for the production of highly pure trichloroacetamide from trichloroacetyl chloride and ammonia gas involves carrying out the reaction at 0-60 degrees C and 1-4 bar with methyl tert.-butyl ether as solvent and then working up by filtration and distillation of solvent. A method for the production of highly pure crystalline trichloroacetamide (I) with a minimum assay of 99 wt% from trichloro-acetyl chloride (II) and ammonia gas involves passing ammonia into a 20-300% solution of (II) in methyl tert.-butyl ether MTBE at 0-60 degrees C and 1-4 bar (under inert gas, with or without external cooling) until the end of the exotherm, stirring for 45-75 minutes at reaction temperature, filtering off ammonium chloride, washing with 1/8-1/12 of the original volume of MTBE used, combining the filtrate and washings, removing MTBE by distillation under normal pressure, cooling the residue to 20-0 degrees C, filtering off pure (I) and drying at 40-80 degrees C under vacuum. The MTBE is recycled several times and precipitated NH4Cl is suspended in 1/8-1/12 of the original volume of MTBE, while off-gas and solvent removed from circulation are disposed of harmlessly by burning to provide energy.

Description

The invention relates to a simple, efficient and technically safe method for Production of high-purity crystalline trichloroacetamide (2,2,2-trichloroacetic acid amide CAS number 594-65-0) with an active substance content of at least 99% by weight from trichloroacetyl chloride (2.2.2 Trichloroacetic acid chloride CAS number 76-02-8) and gaseous ammonia using methyl t butyl ether as a solvent.

Trichloroacetamide is used in pharmaceutical chemistry, for example, as an active ingredient in Antitumor agents (JP 11322593 A2) or as a component of herbicide compositions (JP 55102505 A2, 69008578 B and 680 148 13 B) used or used for the synthesis of cephalosporins, such as described in US 4258183. This results in very high requirements for its purity, in particularly high in pharmaceutical and medical applications.

Trichloroacetamide, which is suitable for the abovementioned applications, must be high-purity crystalline product with an active ingredient content of at least 99% by weight and largely be free of contaminants that could interfere with its use.

Such are, for example, trichloroacetic acid, trichloroacetyl chloride as the starting material for the Production, mono- and dichloroacetyl chloride, trichloroacetic acid esters, monochloroacetamide, organic Acids, organic alcohols, ammonium chloride, solvents, water, catalysts and the like. a. Highly pure trichloroacetamide may add the impurities mentioned as a sum in the amount of contain at most 1% by weight, so that when used as an intermediate product from the above Impurities no undesirable by-products are formed in significant amounts can. The demands for a crystalline product are usually based on technological Because of its use and especially because of the associated chemical purity posed.

Products occurring in crystalline form additionally experience a desired one during crystal formation Purification and have a significantly smaller surface area than the amorphous solids; Amorphous solids can cause unwanted and difficult to separate by-products, solvents u. s. w. adsorb, however, crystalline substances to a much lesser extent.

A number of proposals for the production of trichloroacetamide have emerged from the literature various starting materials known, e.g. B. from an ester of trichloroacetic acid.

Japanese Patent 2000-09541 A or the publications in the technical literature, for example by E. T. McBee in Industrial and Engineering Chemistry, Vol. 37 (1947), P. 391 and by M. M. Joullie in Journal of the American Chemical Society, Vol. 76 (1954), p. 2990. a fundamental disadvantage of these proposals is that a derivative of trichloroacetic acid is used, which is usually prepared from the trichloroacetyl chloride, thus an additional Process stage represents and can not be as economical as the direct production from the Trichloroacetyl. In addition, completely anhydrous (absolute) solvents such as ethanol or diethyl ether recommended, the production of which already has a high technological and expenditure on materials management means. In the case of diethyl ether there is still the risk of Accumulation of peroxides is added, which always carries the risk of explosive decomposition salvage, especially in cases where the diethyl ether is to be removed to dryness, as the above Suggest descriptions.

In the Japanese patent application 440 28 889 B4 the production of trichloroacetamide is carried out Cyanoacetic acid and sulfuryl chloride are described.

In this process, a very low molar yield of 57% is achieved; beyond that cleaned up over water, which is associated with the shortcomings explained below. Furthermore, the production of trichloroacetamide from trichloroacetonitrile is used various catalysts, for example in Canadian Patent 860366 A Use of hydrogen fluoride as a catalyst or, for example, in US Pat. No. 2443291 Use of concentrated hydrochloric acid described. Common disadvantage of exemplary mentioned method is the use of the starting material trichloroacetonitrile, the sooner and better from which the amide itself can be produced than vice versa. Another disadvantage is that first-mentioned method of dealing with the extremely aggressive hydrogen fluoride, which both attacks metallic as well as glass-like (e.g. enamel) materials. The second mentioned Process requires a workup with water, which is a great disadvantage.

Another suggestion for the production of trichloroacetamide is from B. Sukornick in Organic Synthesis, Verlag Wiley, New York, Collective Volume V from 1973 on the pages 1074-1076 called as a synthetic route, with hexachloroacetone to be reacted with ammonia without however, to disclose how to do this. Basic data on synthesis such as e.g. B. Solvent, temperature, type of processing and. s. w.

In the US patent specification 232 1823 (also GB 534 732) there are indications of a possible production of trichloroacetamide from trichloroacetyl chloride and gaseous ammonia.

The patent claims the oxidation of perchlorethylene to trichloroacetyl chloride, which then enriched or can be used in the mixture of substances obtained, according to Example III with Ammonia gas to be processed into trichloroacetamide. The reaction with ammonia takes place at this example III consisting largely of within 7 hours in a mixture Trichloroacetyl chloride, perchlorethylene and trichlorethylene, after which the reaction products Trichloroacetamide and ammonium chloride together with the adhering solvent and unreacted starting compounds are separated. It is only possible to process such a mixture of substances with profound and extensive water washing. Information about the purity of the so obtained Trichloroacetamids as defined by the by-products or Usability instructions are missing. The proposed method of application of the patent US 232 1823 have the following disadvantages; a) The reaction with ammonia gas is 7 hours tedious; b) the product coincides with the reaction product ammonium chloride and others halogen-containing ingredients; c) extensive water washing is absolutely necessary, whereby even with this measure it is unclear how far the content of impurities, e.g. B. Ammonium chloride and the water-insoluble halogenated hydrocarbons can be reduced can.

For the production of trichloroacetamide from trichloroacetyl chloride are in the chemical literature to find a number of suggestions. These are laboratory methods.

For example, C. Bachand in the Journal of Organic Chemistry, Vol. 39 (1974), p. 3136 propose to react trichloroacetyl chloride with concentrated aqueous ammonia. The specified 71% yield is too low to develop a powerful process on this basis, quite apart from the wastewater problem explained below.

G. R. Aliev made two further suggestions in the magazine Azerbajdshankij chimiceskij Zumal Issue 3 from 1986 on pages 39 to 44 and D.S. Tarbell in Journal of the American Chemical Society, Vol. 63 (1941), pp. 2939 to 2942. Both propose the use of absolute diethyl ether as Solvent before, the removal of the ammonium chloride and the isolation of the product by Removal of the diethyl ether to dryness. Disadvantages when using absolute Diethyl ether as a solvent has already been explained above, including the necessary ones Drying and the risk of the accumulation of explosive peroxides. It should also be mentioned low ignition temperature of diethyl ether of about 160 ° C, which does not allow it in conventional chemical Systems, but only in specially equipped and approved systems. But even the use of diethyl ether as a solvent does not appear to be of sufficient purity ensure, since D. S. Tabell in the article mentioned above a subsequent recrystallization Benzene performs and ultimately also achieved an unsatisfactory yield of 54%.

In summary, it should be noted that none of the above patent and technical literature described methods sufficiently meets the following requirements for a method for the production of high purity crystalline trichloroacetamide with a minimum active ingredient content of 99% by weight are to be provided.

The object of the invention is therefore a new method while eliminating the shortcomings known Develop methods and methods and make them available according to the high-purity crystalline Trichloroacetamide with an active ingredient content of at least 99% by weight is technically safe to produce and subsequent process conditions are met in an advantageous manner.

The process to be developed should be in a technologically simple manner in a comparatively straightforward manner Plants that are economically feasible with a good space-time yield, but the target product is still in the very high desired purity. The process is said to be low in waste and without that Use of peroxide-forming solvents such. B. diethyl ether, which is always a risk Enrich the explosive peroxides, get by. In addition, that should For ecological reasons, processes avoid the disposal of waste products via waste water, since the biological activity of the trichloroacetamide against microorganisms has already been mentioned above and is well known (usually biological wastewater treatment is carried out and the microorganisms exposed to the action of trichloroacetamide). But at the same time this means that the high-purity recyclable to be produced does not at all with the process to be developed Water may be brought into contact.

Surprisingly for the person skilled in the art it has now been found that only the use of Methyl t-butyl ether, also called t-butyl methyl ether or 2-methylbutan-2-ol, with CAS number 1634-04-4, in ordinary technical quality as a solvent all disadvantages of existing processes and Methods for the production of trichloroacetamide from trichloroacetyl chloride and gaseous ammonia eliminated and solves the task.

According to the invention, a 20-30% solution is used in a double-walled stirred reactor or autoclave of trichloroacetyl chloride in methyl t-butyl ether and with or without external cooling of the Reaction vessel of gaseous ammonia under an inert gas atmosphere at an absolute pressure of 1 up to 4 bar and a reaction temperature of 0 to 60 ° C until the heat of reaction subsides and the set reaction temperature begins to drop noticeably.

To complete the reaction, 45 to 75 min. stirred at reaction temperature, the The resulting ammonium chloride is filtered off and washed with methyl t-butyl ether, main filtrate and Wash filtrate united, a certain amount of methyl t-butyl ether distilled from the filtrates, the Cooled distillation residue, the precipitated trichloroacetamide filtered off and dried, whereby according to the process conditions according to claim 1 and preferably according to claims 2-7 is worked. The trichloroacetamide produced by the process according to the invention has one Active substance content of at least 99% by weight, as can be seen in Tables 1 and 2.

The process according to the invention can be carried out practically without pressure or under slight pressure absolute pressures between 1 and 4 bar are used sensibly. commercial Reactors and equipment for chemical purposes are designed for these pressures.

The conversion of trichloroacetyl chloride in the form of the 20-30% solution (% by weight) in methyl-t- Butyl ether with gaseous ammonia is carried out in the temperature range from 0 to 60 ° C, wherein preferably the reaction is carried out at 15 to 30 ° C and working with 25% solutions.

The reaction is exothermic and while the ammonia is being fed in it is cooled or so much Ammonia abandoned that the desired temperature limits are maintained. The one among the Conditions of the heat of reaction occurring according to the invention is neither strongly still uncontrollable. The process allows it by the amount of ammonia added control the speed of implementation. A particularly intensive cooling is not necessary already about 10 to 15 ° C temperature difference between the outer surface (cooling surface) and Internal temperatures are sufficient to allow the main reaction to proceed in 1 to 2 hours. To The reaction subsides at about 45 to 75 minutes, preferably 60 minutes, at the reaction temperature stirred and the batch placed on a filter.

The filter residue, ammonium chloride, is repeatedly, preferably three times, with the solvent Methyl t-butyl ether washed, the respective wash volume 1/8 to 1/12, preferably 1/10 of Batch volumes of the solvent is. The main and wash filtrates are combined below, concentrated by distillation under normal pressure, the distillation residue to about 0 to 20 ° C. cooled, the resulting compact and crystalline product on a suitable filter apparatus filtered and to a high-purity trichloroacetamide, for example in a scoop or Filter dryer dried in a vacuum at temperatures between 40 and 80 ° C.

The distillate can be used for the subsequent batch without further post-treatment. His crowd is for the procedure is not particularly significant and may well be so large that the After cooling, the residue just remains stirrable. But it can also be significantly less be distilled off. In this case, the filtrate is concentrated again after the target product has been separated off or the larger amount of filtrate is taken over to the next batch. In this regard, that leaves The method according to the invention offers great possibilities for variation. After separation of the product the filtrate is not only used in one but in several subsequent batches. Only after about At least four times of use for the subsequent batches, it is removed and burned destroyed while generating heat.

The separated and washed ammonium chloride is with a 1/8 to 1/12 of Batch volume of the solvent methyl t-butyl ether stirred, drained as a suspension and also supplied for thermal disposal. The filter device is without subsequent cleaning reusable.

The entire process takes place in closed equipment under nitrogen, for example with thermal exhaust gas cleaning is coupled so that pollutants do not get into the environment. Alternatively, the exhaust gases are subjected to cryogenic cooling and residual gas in an absorption eliminated with, for example, sulfuric acid. The product never comes into contact with water or product-containing solutions or suspensions are disposed of via wastewater.

The methyl t-butyl ether to be used for carrying out the process is technically sufficient Quality and is available from several manufacturers.

For the technical implementation of the process, for example, only four main apparatuses are necessary: a synthesis apparatus and a distillation apparatus and two filter apparatuses, one of which has a drying function. Since the synthesis time takes about 4 hours and the distillation (concentration of the product solution) also takes about 4 hours, the crystalline product is filtered within 30 minutes. and drying is completed in about 3 to 4 hours, the cycle times are very short and consequently high throughputs per unit of time. It is Z. B. possible when using two 6.3 m ³ apparatus in the configuration proposed here to produce about 3000 kg of high-purity crystalline trichloroacetamide per day. The configuration shown here is only an example and can be designed differently depending on operational requirements or possibilities, without this restricting the method according to the invention.

The crystalline trichloroacetamide produced by the process according to the invention shows excellent purity. The total amount of impurities in the product is less than 1.0% by weight, as can be seen from Tables 1 and 2. So were analytical Studies, for example, of ammonium chloride in an amount well below 0.1% by weight, Trichloroacetic acid in an amount well below 0.1% by weight as well as other by-products overall found below 0.7% by weight. The starting material trichloroacetyl chloride was up to a detection limit of 0.01% by weight was not found in the end product. These purities are only through the Carried out the method according to the invention in methyl t-butyl ether.

When the method is carried out according to the invention, the molar yield is more than 90%.

The use of methyl t-butyl ether according to the invention not only leads to an excellent Product quality, but allows a very safe process. This is because the ignition temperature of methyl t-butyl ether at 460 ° C is very high and the fact that that of many ethers known formation of dangerous, explosive ether peroxides with methyl t-butyl ether watch is. As a result, the method according to the invention is conventional in the chemical industry Apparatus and equipment feasible.

• 1. Es wird ein kristallines und hochreines Trichloracetamid mit einem Gehalt von mindestens 99 Gew.% gewonnen.
• 2. Es wird nur ein Lösungsmittel, nämlich Methyl-t-butylether mit hoher Zündtemperatur verwendet, das keine explosionsfähigen Peroxide bildet und somit eine technisch sichere Verfahrensweise gewährleistet.
• 3. Die Hauptreaktion läßt sich gefahrlos in kurzer Zeit durchführen.
• 4. Die molare Ausbeute beträgt über 90%.
• 5. Produkt und produkthaltige Gemische kommen nicht mit Wasser in Kontakt und werden nicht über Abwasser entsorgt.
• 6. Es fallen nur gut handhabbare Abprodukte an, die unter Energiegewinnung entsorgt werden können.
• 7. Der Großteil des während der Herstellung verwendeten Methyl-t-butylethers wird recycliert und mehrfach für Folgeansätze eingesetzt.
• 8. Die für das Verfahren notwendigen Apparate sind für die chemische Industrie üblich.
• 9. Das Verfahren zeichnet sich durch eine gute Raum-/Zeitausbeute aus und ist dadurch wirtschaftlich.

The method according to the invention has the following advantages over known methods or synthesis methods:

• 1. A crystalline and high-purity trichloroacetamide with a content of at least 99% by weight is obtained.
• 2. Only a solvent, namely methyl t-butyl ether with a high ignition temperature, is used which does not form explosive peroxides and thus ensures a technically safe procedure.
• 3. The main reaction can be carried out safely in a short time.
• 4. The molar yield is over 90%.
• 5. Product and product-containing mixtures do not come into contact with water and are not disposed of via wastewater.
• 6. There are only easily manageable waste products that can be disposed of using energy.
• 7. The majority of the methyl t-butyl ether used during production is recycled and used several times for subsequent batches.
• 8. The apparatus necessary for the process are common in the chemical industry.
• 9. The process is characterized by a good space / time yield and is therefore economical.

The method according to the invention is explained below using some exemplary embodiments, without that the examples are a limitation. A technical implementation in plants of chemical industry is possible in principle according to the same or a similar configuration. Exhaust gases can be subjected to thermal exhaust gas cleaning in order to comply with environmental standards become. Alternatively, the exhaust gases can be subjected to cryogenic cooling and residual gas in one Absorption can be eliminated with, for example, sulfuric acid.

With the method according to the invention, a simple, powerful and technically safe process for the production of high-purity crystalline Trichloroacetamide provided.

Example 1

The apparatus used for this embodiment consists of a double jacket vessel 1.25 l capacity, temperature-controlled via a thermostat, equipped with a Bottom outlet valve, a reflux condenser operated with bath liquid at -5 ° C, one Stirrer, a thermometer, a gas supply for ammonia and an overpressure protection from 1.1 bar absolute. This system is called vessel 1 below.

Another part of the apparatus (vessel 2) consists of the same arrangement as vessel 1, however without overpressure protection. A dephlegmator is used instead of a reflux condenser. Vessel 2 will operated without pressure.

Furthermore, a Nutsche (Filter 1), a temperature-controlled pressure Nutsche (Filter 2) and a Vacuum rotary evaporator used for drying. The main apparatuses are gas absorption connected with dilute sulfuric acid.

Vessel 1 is rendered inert with nitrogen, with 800 ml of methyl t-butyl ether and 182 g of trichloroacetyl chloride filled, the jacket temperature is set to 11 ° C, the apparatus is closed and is stirred Ammonia abandoned in such an amount that the overpressure protection does not respond and the Temperature of the batch is about 16 to 20 ° C. After about 110 min. the inside temperature begins drop, which suggests that the reaction is essentially complete. The Jacket temperature is now increased to 20 ° C and the mixture is stirred at this temperature for 1 h. The The resulting easily stirrable suspension is drained onto filter 1, filtered and the filter content with 3 Portions of 67 ml of methyl t-butyl ether washed with stirring. The combined filtrates are in the transferred with vessel 2 inertized with nitrogen.

The solid on filter 1 is stirred with 70 ml of methyl t-butyl ether and the content in the form of a good flowable suspension removed, leaving the filter for the subsequent batch without further cleaning can be used. This procedure is carried out on each of Examples 1 to 4.

The combined filtrates in vessel 2 are heated and 660 ml of distillate are removed. The Distillation is interrupted by cooling, the batch is cooled to + 2 ° C and to 0 ° C Pre-cooled filter 2 drained. Nitrogen is added to filter 2 for 10 seconds to complete Filtration abandoned. The trichloroacetamide on filter 2 is left without further treatment removed and stored moist for further processing. Filter 2 can be used without further Cleaning can be used for the subsequent test. The filtrate of about 200 ml is in the Follow-up test (example 2) used.

Example 2

The same apparatus as in Example 1 is used.

The reaction of the trichloroacetyl chloride (182 g) is used as described in Example 1 of 660 ml of distillate from Example 1 + 140 ml of fresh methyl t-butyl ether, as well as the Treatment of the filter cake on filter 1 analogous to example 1. In vessel 2, the filtrate from filter 1 and the filtrate from filter 2 of the preliminary test (example 1) is initially introduced and distilled analogously to example 1. 960 ml are now distilled off; the batch is cooled to + 3 ° C and the product on filter 2 filtered off. The trichloroacetamide on filter 2 is removed without further treatment and moist kept for further processing. Filter 2 can be used for further testing without further cleaning be used. The filtrate of about 100 ml is used in the follow-up experiment (example 3).

Example 3

The same apparatus as in Example 1 is used.

The reaction of the trichloroacetyl chloride (182 g) is similar to that described in Example 1 under Using 800 ml of distillate from Example 2, with the difference that the Jacket temperature was set to 9 ° C and ammonia fed somewhat faster than in Example 1 was so that the internal temperature of the batch rose to 25 ° C. The main reaction was roughly Completed for 80 min and the temperature started to drop. Then was at 20 ° C for 1 h stirred, filtered off, the precipitate with a portion of 100 ml of distillate from the preliminary experiment (Example 2) washed under a further portion of 100 ml of fresh methyl t-butyl ether, the Precipitate as in Example 1 suspended with 70 ml of methyl t-butyl ether (consisting of 60 ml of distillate from preliminary experiment +10 ml of fresh methyl t-butyl ether) and removed. The combined are in vessel 2 Filtrates from filter 1 and the filtrate from filter 2 of the preliminary test (example 2) are presented and analogously Example 1 distilled. 880 ml are now distilled off; the batch is cooled to + 3 ° C and that Product filtered off on filter 2. The trichloroacetamide on filter 2 is left without further treatment removed and stored moist for further processing. Filter 2 can go without further Cleaning can be used for the subsequent test. The filtrate of about 85 ml is in the Follow-up test (Example 4) used.

Example 4

The same apparatus as in Example 1 is used.

The reaction of the trichloroacetyl chloride (182 g) is, similar to that described in Example 3, under Use of 800 ml of distillate from Example 3, with the difference that the Jacket temperature was set to 10 ° C and ammonia fed somewhat faster than in Example 1 was so that the internal temperature of the batch rose to 24 ° C. The main reaction was in about 85 min. finished and the temperature started to drop. The mixture was then stirred at 20 ° C. for 1 h, filtered off, the precipitate with a portion of 100 ml, consisting of 80 ml of distillate from a preliminary test (Example 3) +20 ml of fresh methyl t-butyl ether and a further portion of 100 ml of fresh methyl washed t-butyl ether. After the end of the experiment, the precipitate was mixed with the Completion of the distillation and filtration resulting filtrate suspended and removed. Be in vessel 2 the combined filtrates from filter 1 and the filtrate from filter 2 of the preliminary test (example 3) and distilled analogously to Example 1. 865 ml are now distilled off, in subsequent batches if necessary can be used; the distillation residue is cooled to + 3 ° C and the product on Filter 2 filtered. The trichloroacetamide on filter 2 is removed without further treatment and stored moist for further processing. Filter 2 can be used for one without further cleaning any subsequent attempt can be used. The filtrate of about 85 ml was used to suspend the Precipitation from filter 1 used.

Analytical studies to determine the purity of the according to the invention Process produced trichloroacetamides

• 1. Bestimmung des Gehaltes an Ammoniumchlorid (durch Chloridtitration): etwa 10 g Produktprobe wird in Methanol/Reinstwasser gelöst und die Chloridionen mit Silbernitrat titriert. Das Ergebnis wird in Gewichts-% Ammoniumchlorid angegeben.
• 2. Bestimmung des Gehaltes weiterer Verunreinigungen (gaschromatographisch): 150 mg des Produktes werden in 1 ml Dioxan gelöst und auf einer schwach polaren Säule chromatographiert. Die ermittelten Verunreinigungen werden in Gewichts-% angegeben.
• 3. Bestimmung des Wassergehaltes (nach Karl Fischer): 5 g Produkt werden in Methanol gelöst und mit Hydranal Composite 5 titriert. Das Ergebnis wird in Gewichts-% angegeben.
• 4. Bestimmung des Gehaltes an Trichloracetamid (Ammoniakdestillation): in einer dichten Destillationsapparatur werden 300 mg Produkt, gelöst in 50 ml Wasser vorgelegt, 75 ml einer 20%igen Natronlauge zugegeben und 20 min erwärmt, wobei Ammoniakwasser überdestilliert. Das Destillat wird in 50 ml 0,05 molare Schwefelsäure eingeleitet; die überschüssige Schwefelsäure wird mit 0,1 m Natriumhydroxidlösung zurücktitriert. Das Ergebnis wird als Gewichts-% Trichloracetamid angegeben.

The moist trichloroacetamide obtained from Examples 1 to 4 was transferred to a vacuum rotary evaporator and dried in each case for 1 h at 30.40 or 50 ° C. under a vacuum of 100 mbar. 598 g of trichloroacetamide were obtained, corresponding to an average molar yield of 92%, which was subjected to some analytical investigations to determine the purity, which are described in brief below.

• 1. Determination of the ammonium chloride content (by chloride titration): about 10 g of product sample is dissolved in methanol / ultrapure water and the chloride ions are titrated with silver nitrate. The result is given in% by weight ammonium chloride.
• 2. Determination of the content of further impurities (gas chromatography): 150 mg of the product are dissolved in 1 ml of dioxane and chromatographed on a weakly polar column. The impurities determined are given in% by weight.
• 3. Determination of the water content (according to Karl Fischer): 5 g of product are dissolved in methanol and titrated with Hydranal Composite 5. The result is given in% by weight.
• 4. Determination of the content of trichloroacetamide (ammonia distillation): 300 mg of product, dissolved in 50 ml of water, are added to a dense distillation apparatus, 75 ml of a 20% sodium hydroxide solution are added and the mixture is heated for 20 minutes, with ammonia water being distilled over. The distillate is introduced into 50 ml of 0.05 molar sulfuric acid; the excess sulfuric acid is back-titrated with 0.1 M sodium hydroxide solution. The result is reported as% by weight trichloroacetamide.

Table 1 below summarizes the analysis results.

All substances whose contents are marked with the symbol "<" could not be detected become. The result shown is only the detection limit.

Example 5

This example shows the production of trichloroacetamide according to the invention under increased pressure.

A stainless steel autoclave with a volume of 2.25 l and a temperature-controlled jacket was used to manufacture it. equipped with a stirrer with mechanical seal, thermometer, pressure gauge, overpressure protection up to 6 bar, drain and inlet valve used.

1600 ml of methyl t-butyl ether and 364 g of trichloroacetyl chloride were introduced, with nitrogen inertized, the temperature set to + 11 ° C with stirring and so much ammonia gas added, that the absolute pressure is 1.1 to 2.5 bar. The internal temperature fluctuated between 12 and 24 ° C. After about 85 min. the main reaction was over; the mixture was at 21 to 23 ° C for 1 h stirred, the overpressure is released and the contents drained onto a suction filter. The precipitation was washed with 2 portions of 200 ml of methyl t-butyl ether and the combined filtrates in a Distillation apparatus transferred. A sample of the combined filtrates was added before the distillation started subjected to a gas chromatographic analysis for trichloroacetyl chloride. Found was only 0.02% (area percent), indicating that the reaction was virtually complete has expired. It was then distilled without pressure until trichloroacetamide was already massive in the heat fails. The mixture was cooled to 0 ° C., the product was filtered off and the filtrate was again Subjected to distillation until the stirrability of the residue was just guaranteed. The The residue was cooled to 2 ° C. and the product was filtered off.

The distillates can also be carried out when the process according to the invention is carried out under pressure and reuse residues analogous to that shown in Examples 1-4.

The combined product amounts from both crystallizations (pre-precipitation and post-precipitation) were dried as described in the section on analytical tests. 302 g of trichloroacetamide were obtained, corresponding to a molar yield of 93%, which was subjected to the same analytical tests as the amounts from Examples 1 to 4. The results are summarized in Table 2 below. Table 2

All substances whose contents are marked with the symbol "<" could not be detected become. The result shown is only the detection limit.

Claims (8)

1. Process for the production of high-purity crystalline trichloroacetamide with a minimum content of active ingredient of 99% by weight from trichloroacetyl chloride and gaseous ammonia Use of methyl t-butyl ether as a solvent under an inert gas atmosphere, in which submitted 20-300% solution of trichloroacetyl chloride in methyl t-butyl ether Reaction temperatures of 0 ° -60 ° C and an absolute pressure of 1-4 bar gaseous ammonia with or is introduced without external cooling until the heat of reaction subsides and the Reaction temperature drops, then the reaction suspension 45-75 min. at Reaction temperature is stirred and then the suspension through a filter to separate Ammonium chloride is given several times with a solvent volume of 1/8 to 1/12 of the batch volume of methyl t-butyl ether is washed and subsequently main and Wash filtrates are combined and the solvent methyl t-butyl ether under normal pressure distilled off and the distillation residue is cooled to 20 ° -0 ° C and filtered and that as Filter residue obtained from high-purity trichloroacetamide filtered off at temperatures of 40-80 ° C is dried under vacuum, the solvent methyl t-butyl ether being circulated several times is performed and resulting ammonium chloride suspended in 1/8 to 1/12 volumes of Batch volume of methyl t-butyl ether, exhaust gases and solvents in a circle Incineration for energy recovery and safe disposal. 2. The method according to claim 1, characterized in that methyl t-butyl ether as the solvent technical quality can be used. 3. The method according to claim 1 and 2, characterized in that nitrogen is used as the inert gas becomes. 4. The method according to claim 1 to 3, characterized in that preferably with a 25% Solution of trichloroacetyl chloride in methyl t-butyl ether is worked. 5. Process according to claims 1-4, characterized in that the implementation of the Starting materials are preferably carried out in the temperature range of 15 ° -25 ° C. 6. Process according to claims 1-5, characterized in that the reaction suspension preferably about 60 min. is stirred. 7. The method according to claim 1-6, characterized in that the filter residue ammonium chloride preferably washed three times with methyl t-butyl ether. 8. The method according to claims 1-7, characterized in that the trichloroacetamide-containing Distillation residue is preferably cooled to 5 ° -0 ° C.