DE1155769B - Process for the production of adipic dinitrile - Google Patents

Description

Process for the production of adipic acid dinitrile Addition to the patent application K 43829 Vb / 12o (Auslegeschrift 1151791) The present invention relates to a method for the production of adipic dinitrile (adiponitrile), which is used as a starting material for the manufacture of synthetic fibers is a product of great technical importance.

According to the main patent application K 43829 IVb / 12o (German Auslegeschrift 1151791) you can get adiponitrile with very good yields, based on both consumed Acrylonitrile as well as used, d. H. used amalgam, to manufacture, if you have a mixture of a jB-halopropionitrile, which is expedient by Addition of hydrogen halide to acrylonitrile is obtained, and acrylonitrile treated with an alkali and / or alkaline earth amalgam.

This process is characterized in that it is used as the starting material a mixture of 20 to 90 mole percent, preferably 50 to 80 mole percent, β-halopropionitrile and 10 to 80 mole percent, preferably 20 to 50 mole percent of acrylonitrile.

When carrying out the process according to the main patent application yields of adiponitrile of 904 / o, based on the total consumed Acrylonitrile achieved. The amalgam used is up to 60% for the adiponitrile synthesis exploited; the rest is for the technically undesirable formation, however Usable propionitrile consumed; also the sometimes onset of hydrogen evolution as well as the formation of resinous distillation residues occurring in smaller quantities are at the expense of the amalgam or Energy consumption.

The highest yields of adiponitrile, calculated on both total used acrylonitrile as well as used, d. H. used amalgam, are obtained according to Example 7 and 8 of the main patent application, if the reaction mixture from about 3 moles of chloropropionitrile, 2 moles of acrylonitrile, 1 gram atom of sodium in Form of 0.54% liquid sodium amalgam and about 0.5 weight percent water composed.

Surprisingly, however, it is also possible to use the Amalgam-related yield of adiponitrile can be increased considerably over 60% if instead of, as before, preferably with a molar excess of β-halopropionitrile over acrylonitrile - now with a molar excess of acrylonitrile over ß-Halopropionitrile works. This inverse relationship seemed like the previous one Less favorable experience, as excess acrylonitrile polymerizes easily.

According to the invention, however, this polymerization can be made more suitable by adding Inhibitors can be effectively prevented.

At least one is preferably used as the polymerization inhibitor Connection with one or two unpaired electrons, for example nitrogen oxide (NO) or oxygen (see H. Remy, "Textbook of Inorganic Chemistry", 9th edition, 1957, Vol. I, pp. 159 to 167 and 811 to 812). Is particularly suitable the use of nitrogen oxide in an inert gas atmosphere, for example in a mixture with hydrogen or nitrogen.

According to the invention, the reaction mixture used should be 10 to 80 mol percent, Contain B-halopropionitrile and 20 to 90 mole percent acrylonitrile.

Expediently, mixtures of 20 to 50 mol percent ß-halopropionitrile are used and 50 to 80 mole percent acrylonitrile.

As ß-halopropionitrile is the use of the chlorine compound particularly economical.

To achieve good adiponitrile yields, it is expedient to use each Gram atom of alkali metal in the form of amalgam about 3 moles of ß-halopropionitrile and about 3 to 9 moles of acrylonitrile.

Otherwise, under the same reaction conditions as in Main patent application worked.

When the process according to the invention is carried out, yields are obtained of adiponitrile up to 90%, based on total acrylic acid tril consumed, achieved. The amalgam used is up to about 75% for the adiponitrile synthesis exploited.

In the following examples, the Temperature-jacketed stirred vessel a mixture of ß-chloropropionitrile, acrylonitrile and water submitted and at the temperature given in the table under intense Stirring sodium as 0.5% liquid amalgam added dropwise in portions. Simultaneously one passes about 15 bubbles of nitrogen oxide per minute, corresponding to about 0.41 NO per hour, into the reaction mixture; through the gas space becomes a weak nitrogen or preferably hydrogen stream (about 2 to 51 N2 or NH2 per hour) passed. To When the sodium reacts thoroughly, the mercury is separated off before the amalgam becomes fresh flows in. The reaction time is also given in the table. After completion the reaction is the separated sodium chloride from the reaction liquid centrifuged and with the help of the released mercury, which as The cathode functions according to the so-called mercury process for the purpose of recovery electrolyzed by amalgam. Receives in the distillative work-up of the approaches one adiponitrile, propionitrile and distillation residue.

Acrylic acid nitrile is also obtained, which with hydrogen chloride is converted back to (-chloropropionitrile.

The yields are given, as in the main patent application, calculated.

To identify the amount of amalgam used and used Yields the percentages are given for the sodium, which in each case for the To spend synthesis of the adiponitrile obtained and the propionitrile reversible was.

The remainder - at least 15 "/ o sodium - is made in a manner which is not known in detail irreversible in the formation of the distillation residue and the hydrogen consumed.

The examples show that, in the presence of nitrogen oxide, with increasing acrylonitrile content in the reaction mixture, both the acrylonitrile and amalgam-related yields of n-adiponitrile increase. example 1 2 3 Raw materials β-chloropropionitrile (g) ............... 716 268.5 268.5 (Mole) ........... 8 3 3 Acrylonitrile (g) ................. 106 159 318 (Mole) ........... 2 3 6 Sodium as 0.5% amalgam (g) ........... 23 23 23 (Gram atom) ...... 1 1 1 Added water (g) 4, 11 2, 14 2, 93 (Percent by weight) 0.5 0.5 0.5 Reaction conditions Temperature (° C) .. 47 to 52 46 to 52 47 to 53 Time (hours) .. 1, 85 1, 3 1, 67 Reaction products (g) Adiponitrile ................................... 27 34.5 39 Propionitrile .................................... 11.4 3.9 3.1 Distillation residue .......................... 1 2.5 2 Total ..... 39, 4 40, 9 44, 1 Material yield, calculated on the total consumed Acrylonitrile (° / o) Adiponitrile. 68, 5 84, 5 88, 5 Propionitrile .. 29 9, 5 7 Backlog 2, 5 6 4, 5 Material yield, calculated on the amalgam consumed (° / o) Adiponitrile ... 50 64 72 Propionitrile .. 41, 5 14 11, 5

Claims (3)

PATENT CLAIMS: 1. Further development of the manufacturing process of adiponitrile by reacting a mixture of ß-halopropionitrile and Acrylonitrile with an alkali and / or alkaline earth amalgam according to patent application K 43 829 IVb / 12o, (German interpretation 1151791), characterized in that the starting material is a mixture of 10 to 80 mol percent, preferably 20 to 50 mole percent ß-halopropionitrile and 20 to 90 mole percent, preferably 50 to 80 mole percent acrylonitrile used and in the presence of a polymerization inhibitor for acrylonitrile works. 2. The method according to claim 1, characterized in that as Polymerization inhibitor at least one compound with one or two unpaired Electrons, for example nitrogen oxide or oxygen, are used. 3. The method according to claim 2, characterized in that as Polymerization inhibitor nitrogen oxide in the presence of an inert gas, for example Hydrogen or nitrogen, is used.