DE2120194A1 - Chloroacetyl chloride prodn - by reacting a soln of acetyl chloride in acetic anhydride with gaseous chlorine - Google Patents

Abstract

Title cpd. is prepd. by reacting a mixt. of 5-50 pbw acetyl chloride in acetic anhydride with chlorine at 70-110 degrees C and separating by known methods. The process is simple and cheaper than known methods.

Description

Process for the preparation of chloroacetyl chloride The invention relates to a process for the preparation of chloroacetyl chloride in which acetyl chloride is in the presence of acetic acid hydride is treated with chlorine and the chloroacetyl chloride formed is separated from the reaction mixture oh in a manner known per se.

It is known to produce chloroacetyl chloride by reacting monochloroacetic acid by reaction with a chlorinating agent such as a phosphorus chloride, a sulfur chloride or to produce phosgene. According to the German Offenlegungsschrift 1 804 43G at 1100G in a melt of chloroacetic acid, in which 0.05 - 0.3 percent by weight Palladium chloride are dissolved, phosgene introduced0 The intestinal reaction product is then condensed and must be repeated to obtain pure chloroacetyl chloride be distilled. Processes are also known in which chloroacetyl chloride is obtained by treating acetyl chloride with chlorine. As the for this process the optimal temperature is well above the boiling point of acetyl chloride (51 ° C), this reaction usually takes too long for an application on an industrial scale.

By simultaneous UV irradiation or by adding iodine to the reaction mixture the chlorination time can be shortened, but the process is reduced by the J3 radiation or

the necessary separation of the iodine or its reaction products uneconomical.

It has now been found that acetyl chloride dissolved in acetic anhydride reacts spontaneously with chlorine introduced at temperatures of 70 ° and 110 ° C. to form chloroacetyl chloride. According to the reaction equation (1) Hydrogen chloride formed reacts immediately with acetic anhydride to form new acetyl chloride and acetic acid. The acetic acid formed reacts with primarily formed chloroacetyl chloride to form chloroacetic acid and acetyl chloride. The acetyl chloride formed in these subsequent actions is converted into chloroacetyl chloride according to equation (1).

In the gross reaction, acetyl chloride is completely converted into chloroacetyl chloride and acetic anhydride in equal parts in chloroacetyl chloride and chloroacetic acid convicted. From the reaction mixture obtained, which is neither acetic acid nor water contains, chloroacetyl chloride can easily be separated off in a known manner will.

The invention accordingly relates to a method of production of chloroacetyl chloride, which is characterized in that a solution of 5 - 50 percent by weight acetyl chloride in acetic anhydride at temperatures between Treated 70 and 110 ° C with chlorine and from the reaction mixture in a known manner Way separates the chloroacetyl chloride Expediently according to the invention Process carried out in such a way that initially acetic anhydride with 5 - 50, preferably mixed with 10-15 percent by weight acetyl chloride and add this mixture to one Temperature between 70 and 110 ° C, preferably 75-90 ° C is heated. The mixture the components and the heating can be inside or outside the chlorination reactor used. In a corrosion-resistant reactor is then introduced chlorine into the hot mixture.

The initially exothermic reaction is excepted by the regulation the supply of chlorine is expediently carried out by distilling off part of the reaction partuers and the re-supply of this distillate controlled so that the temperature does not 110 ° C exceeds.

Already during the second phase of the procedure, when the Chlorination of acetyl chloride no longer released by the hydrogen chloride Reaction with acetic anhydride is intercepted, distilled part of the formed Chloracetyl chloride with the hydrogen chloride atom at a temperature of 30 - 60 ° C and can be condensed in pure form.

The supply of chlorine to the reaction mixture is stopped as soon as the calculated Amount of chlorine is absorbed. Then that is still contained in the reaction mixture Separated chloroacethyl chloride in a conventional manner. This can be done by distillation under reduced pressure, for example between 10 and 400 Torr, with the sump temperature should not exceed 100 ° C .; it is still possible the liquid chloroacetyl chloride from that by cooling to room temperature or lower Temperature to decant crystallized chloroacetic acid.

A large part of the chloroacetyl chloride formed can be in very pure form can also be isolated from the reaction mixture by removing this after the chlorination has ended treated with enough water that part of the chlorine formed to acetyl chloride Chloroacetic acid is hydrolyzed; the remaining chloroacetyl chloride with the released Hydrogen chloride distilled off; this work-up way is especially there preferred, where also possible uses for the pure chloroacetic acid formed in the process exist.

Example In a mixture of 600 kg acetic anhydride and 60 kg Acetyl chloride ground 900 kg of chlorine at 75 ° C. at a rate of 40 - 45 kg / hour initiated. The temperature is thereby reduced by cooling and refluxing the kept cooled distillate between 70 and 110 ° C; if, especially in the first stage of the reaction, the mixture begins to foam heavily, becomes temporary a part of the i) estillate consisting essentially of acetyl chloride was removed and only re-entered into the chlorination mixture in the second reaction phase. When the stated amount of chlorine has reacted, the reaction mixture is heated to 10.degree cooled and left to stand at this temperature for 20 hours, with 470 kg of chloroacetic acid crystallize.

The chloroacetyl chloride made from chloroacetyl chloride containing very little chloroacetic acid Existing mother liquor is poured off and distilled at 100-130 Torr. The yield of pure distilled chloroacetyl chloride is 706 kr (94.1% of theory).

Claims (1)

Claim Process for the production of chloroacetyl chloride, characterized in that that a solution of 5-50 parts by weight of acetyl chloride in acetic anhydride at 70-110 ° C is treated with chlorine and the chloroacetyl chloride formed from the reaction mixture is separated in a per se belcanned manner.