DE2427204C3 - Process for the preparation of an amide from a nitrile - Google Patents

Description

The invention relates to a method for producing an amide by reacting a nitrile, for example Acrylonitrile, methacrylonitrile, benzonitrile, nicotine nitrile or propionitrile, with water in the presence of a metallic copper catalyst and a nitrate as an activator.

Process for converting a nitrile, for example acrylonitrile, into the corresponding amide, for example Acrylamide, by hydrating the nitrile in the presence of a metallic copper catalyst are described, for example, in US Pat. No. 3,631,104 and in BE-PS 7 53 365. The catalysts that These processes are used, metallic copper catalysts with a comparatively large Surface, such as reduced copper, Raney copper and Ullmann copper, which by appropriate reduction processes, specially designed to be obtained. Despite the effectiveness of the metallic There is a copper catalyst in the conversion of nitriles into the corresponding amides Need to improve the catalytic effects when used on an industrial scale.

In a known method using a metallic copper catalyst, there is the improvement in having a cupric salt to increase the conversion of the nitrile to the amide an inorganic acid, for example copper nitrate, or the cupric salt of a fatty acid, for example Copper acetate, is present in the reaction mixture as an activator for the metallic copper catalyst. This process is described in FR-PS 21 18 517. It is taught that the transmutation of the Amides is increased to more than 70% when using a metallic copper catalyst along with the Copper (II) salt activator is used, whereas the conversion is done using a metallic one Copper catalyst alone without activator is only 50%. However, there is still a need that when working on an industrial scale, an activator is available that increases the rate of conversion of the nitrile in the amide increased, while at the same time the catalytic life of the metallic Copper catalyst is retained for longer periods of time.

Further processes for the production of an amide from a nitrile are given in DT-OS 22 56 238 and 20 01 903 and in US Pat. No. 3,674,848.

Compared to the methods known from the DT-OS mentioned, the method according to the invention allows it surprisingly to produce higher amounts of amide per unit weight of the catalyst. As Table I of US Pat. No. 3,674,848 shows the conversion and selectivity of acrylonitrile to Acrylamide is considerably lower than in the process according to the invention. According to the invention compared to the Teaching of FR-PS 21 18 517 surprisingly achieved technical progress is based on the following Comparative example 1 and reference to example 8.

The present invention is based on the object of an improved method for transferring of a nitrile to the corresponding amide using an improved catalyst system create.

The inventive method of the type mentioned is characterized in that as Activator ammonium nitrate, sodium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, zinc nitrate, aluminum nitral, Manganese nitrate, iron nitrate, cobalt nitrate and / or nickel nitrate in an amount of 3 to 200 ppm, calculated as the weight ratio of nitrate ion to the gross weight of the reaction mixture, used.

The corresponding amides are obtained in high yield at a higher rate of hydration and the catalyst is in no way affected by factors influencing the catalytic activity reduced or by which the effective service life of the metallic copper catalyst is shortened.

Preferred compounds to be used according to the invention are ammonium, sodium, calcium, zinc and iron nitrate. The addition of the nitrate to the reaction system can be done by adding the nitrate dissolves in water or the nitrile. Alternatively, the nitrate can be dissolved separately and then fed into the reactor or added to the circulation system of the reaction liquid.

The amount of nitrate added to the reaction mixture is in the range of 3 to 200 ppm, calculated and expressed as the weight ratio of nitrate ion to the gross weight of the reaction mixture made of nitrile and water. If the amount of nitrate is less than 3 ppm, none or none will be obtained sufficiently favorable activator effect. If the amount of activator is over 200 ppm, the Long-term activity of the metallic copper catalyst can be adversely affected compared with that catalytic activity without activator, even if you can still see a temporary improvement in activity of the catalyst observed.

The metallic copper catalyst that can be used in the process of the invention is one that contains metallic copper as a main component of the catalyst. The following specific Catalysts are examples of suitable metallic copper catalysts:

(1) Copper dust (ground), made from a metallic copper bar, a microfine one Pieces of copper wire and the like

(2) Reduced copper such as that obtained by using a copper compound such as copper oxide, Copper hydroxide or copper chloride, reduced using hydrogen and / or carbon monoxide applies at temperatures in the range of 0 to 500 ° C.

(3) Reduced copper such as that obtained by reducing a copper compound such as copper oxide, Copper hydroxide or copper chloride,

if the reducing agent used is hydrazine or sodium borohydride in the liquid phase.

(4) Reduced copper such as that obtained by treating a copper compound such as copper oxide, Copper hydroxide or copper chloride is obtained when using a metal that has a higher It has a tendency to ionize as copper, such as zinc, aluminum, iron, tin and the like, and in liquid form Phase works

(5) Raney copper such as that obtained by properly developing a Raney alloy called copper and contains aluminum, zinc or magnesium.

(6) Copper like that which is obtained when a copper compound, such as copper formate or copper oxalate, is thermally cleaved ^{at a temperature in the range from 100 to 400 ° C., for example.}

(7) A multi-element catalyst like the one you see obtained when you combine other metals such as chromium, zinc, nickel, manganese or molybdenum with one of the the aforementioned copper metal compounds mixed during the preparation of the catalyst.

(8) Other supported copper catalysts of essentially inert material such as aluminum oxide, Silicon dioxide, kieselguhr, pumice stone, diatomaceous earth, etc., produced by the deposition of the Catalyst on the inert support.

A suitable process for the production of a Raney copper catalyst is the Raney process, which is similar to what is commonly used to make Raney nickel. Commercially available Formulations that can be used in preparing these catalysts are easy available, for example an alloy of aluminum and copper. These catalysts are known according to Process developed or activated to obtain metallic copper catalysts that are used for the Process according to the invention are suitable. Usually in these processes, the alloy is treated with a strong base under such conditions which the aluminum or other metal is leached out.

The differences between the catalysts described above from one another are not so much in the selectivity of the implementation as in the intensity of their Activation. For example, when acrylonitrile is a hydration reaction below the usual Is subjected to reaction conditions, which will be explained in more detail below, and if you the Selects the catalysts described above and produces catalysts with outstanding purity that Selectivity for acrylamide 97% or more and the selectivity for ethylene cyanohydrin 2% or less.

The amount of metallic copper catalyst that is usually used in the process of the invention used, is in the range of 0.01 to 1000 g / mole of nitrile, for example, if a reaction mixture in contact with the metallic copper catalyst in a suspension layer or fluidized bed layer brings. The metallic copper catalysts according to the invention can be used both in batches Method as well as used in continuous flow methods. Both procedures will be treating the nitrile and water with the catalyst under suitable reaction conditions, and that Amide product is recovered.

The reaction mixture is treated with the metallic copper catalyst in the liquid phase. the Proportions of nitrile and water in the reaction mixture can vary widely as any amount of water will leads to hydration, is acceptable. It is important that the nitrile to water ratio be greater than that Implementation between the respondents and that good contact is ensured, to get the greatest yield and efficiency. It is believed, however, that certain amounts are helpful can be to ensure intimate contact of the nitrile and the water, for example 'one dissolves the nitrile in the water or dissolves water in the nitrile. Outside the solubility limits of a reactant in the other, the reaction mixture can be stirred, and a suitable compatible one Solvent can be added or other measures can be taken. Suitable, inert, tolerable Solvents include alkanols such as methanol, dioxane, dimethyl sulfoxide, acetone, dimethyl ether of ethylene glycol and tetrahydrofuran. The ratio of nitrile to water is generally used recommended in which the water is present in excess by weight, based on the nitrile compound is, d. That is, water is used in an amount ranging from 50 to 90 percent by weight, based on the Reaction mixture.

The temperature of the reaction mixture can vary widely since various nitriles can be used in the process of the invention. In general, the reaction is carried out within a temperature range of about 0 to 400 ⁰ C. At temperatures below this level the reaction is impractically slow and above this range an increased amount of undesirable by-products can be formed. The preferred temperature is in the range from 50 to 300 ^° C. However, in reactions in which a side reaction can occur or in which polymerization can take place, such as in the conversion of acrylonitrile to acrylamide, the preferred temperature range is 50 to 150 ^° C., for example .

The nitriles that can be used in the process of the invention include compounds the formula

R- (CN) _n

wherein R is an alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 3 to 12 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a cycloalkyl group with 5 to 15 carbon atoms, an aralkyl group having 7 to 15 carbon atoms; an aryl group having 6 to 15 carbon atoms or represents a substituted aryl group having 7 to 15 carbon atoms.

The substituents in the substituted alkyl or substituted aryl groups can be halogen, for example Chlorine, be. Specific examples of suitable nitriles include such alkyl nitriles as propionitrile, substituted alkyl nitriles such as chloroacetonitrile, alkenyl nitriles such as acrylonitrile or methacrylonitrile, cycloalkyl nitriles, such as cyclohexanecarbonitrile, aralkyl nitriles such as benzyl cyanide, aryl nitriles such as benzonitrile, substituted Aryl nitriles, such as p-methylbenzonitrile, polynitriles, such as Succinonitrile or phthalonitrile, and other nitriles such as nicotine nitrile.

Water solutions of the amides which are obtained by the process according to the invention contain only negligible amounts of the nitrates used and can therefore be used directly as intermediates

can be used with no need to clean them. It goes without saying to the person skilled in the art known that ions which have been added in the method according to the invention, in a suitable manner can be removed if necessary, for example by using an ion exchange resin used If a water solution of acrylamide is obtained as a product, this can be used as a water solution for Production of polymers used as agents in paper processing or as soil stabilizers are suitable, and can also be used to produce acrylamide crystals by known procedures are carried out. If you get nicotinamide as a product, it can be effective as a Material used for agricultural chemicals and for pharmaceutical preparations.

Other advantages obtained in the process of the invention reside in the fact that the The service life of the metallic copper catalyst can be extended considerably.

The combination of metallic copper catalyst and Nitrataktiva tor according to the present Invention causes that in contrast to the known combinations of metallic copper catalyst and copper (I I) salt activator the activity of the catalyst is greatly elongated, and accordingly the amount of metallic copper catalyst that is consumed can be decreased, thereby improving the economic value of the process.

The following examples illustrate the invention. In the examples, unless otherwise noted, are all Parts expressed by weight and all weights on a dry weight basis. In all tables is the amount of activator in ppm as the weight ratio of nitrate ion to the gross weight of the raw material liquid, which contains nitrile and water, calculated and expressed.

Copper ions resulted in the raw material liquid was added in place of the sodium nitrate. A third implementation and analysis was carried out, no activator was used. The results of all of these implementations and analyzes are listed in Table I.

example 1

150 g of Raney copper catalyst was placed in a reaction vessel by a known method made of stainless steel with a capacity of 1 l, the reaction vessel having a stirrer and a Contained catalyst separator. Water and acrylonitrile, which make up about 90% of dissolved oxygen had previously removed by placing the dissolved oxygen in a deoxidizer of a deoxidation had subjected, were continuously introduced into the reactor in amounts of 700 g / h and 300 g / h, and then the reaction was carried out at 120 ° C. The Water contained 39 ppm sodium nitrate, which had been added beforehand, which corresponds to 20 ppm activator, based on the gross weight of the raw material liquid containing acrylonitrile and water. The implementation was carried out for a period of 14 consecutive days, and the reaction liquid was analyzed using gas chromatography and the results were expressed as the conversion of Acrylonitrile to acrylamide expressed as listed in Table I. The conversion into impurities, especially in acrylic acid, acrylate, ethylene cyanohydrin and / J-hydroxypropionic acid amide, was each 0.5% or lower.

For comparison purposes, the reaction and analysis were repeated except that copper sulfate, a known activator, in an amount that is 10 ppm

Table I. Conversion (%) Copper ion *) No Days of analysis Nitrator. Activator present (10 ppm) (20 ppm) 70 47 68 61 41 Start day 62 54 35 After 2 days 58 47 30th After 4 days 53 41 26th After 6 days 50 32 23 After 8 days 47 26th 18th After 10 days 43 21 15th After 12 days 40 After 14 days Comparative example 1 *) Made of copper sulfal.

Example 1 was repeated, but using copper nitrate as an activator. The copper nitrate concentration was 20 ppm (which corresponds to about 10 ppm copper ions) expressed as nitrate ions, based on the raw material liquid. The results are expressed as the conversion of acrylonitrile to acrylamide Expressed analogously to Example 1 and are summarized in the table below:

4 ^C conversion

First day
Second day
fourth day
sixth day
Eighth day
Tenth day
Twelfth day
Fourteenth day

71 67 55 51 48 42 36 30

From the above, it follows that copper nitrate has a greater conversion effect than copper sulfate according to Example !, but lower than sodium nitrate, delivers.

55

Example 2

The procedure of Example 1 was repeated for 6 consecutive days, with the exception that the sodium nitrate activator by different Amounts of ammonium nitrate was replaced, each 4 to 1000 ppm activator in the Maintained reaction fluids. The results are given in Table II, in which the results in Column “no activator present” from Table I have been taken over.

Table II

Conversion (%) 20th too 400 1000 Nitration no 4 Activator (ppm) present

Analysis day
Start day
After 2 days
After 4 days
After 6 days

Example 3

The procedure of Example 1 was repeated for 14 consecutive days except that the sodium nitrate activator has been replaced by calcium nitrate, zinc nitrate and iron nitrate, and although in amounts that resulted in 20 ppm of activator in the reaction mixtures. The results are in Table III listed.

Table III

47 59 67 68 65 62 41 51 61 60 52 14th 35 45 57 53 43 5 30th 40 54 44 35 1

Analysis day

Conversion (%)

Calcium nitrate

Zinc nitrate

Iron nitrate

Start day
After 2 days
After 4 days
After 6 days
After 14 days

70 71 4th 65 61 64 60 58 60 56 53 54 52 38 43 40 example

Days of analysis

Conversion (%)

Nitration is not an activator

(ppm) present

Start day
After 2 days
After 4 days
After 6 days

75
65
57
52

Example 5

49
43
38
35

separator was equipped. Water and acrylonitrile, from which about 90% of the dissolved oxygen had previously been removed by passing them through a deoxidizer, were continuously introduced into the reactor in amounts of 700 g / h and 300 g / h, respectively, and then at a temperature of 120 ° C implemented. The water contained 39 ppm sodium nitrate which corresponds to 20 ppm activator in the reaction mixture, which contained both acrylonitrile and water. The results of this reaction were analyzed over a period of 6 consecutive days and are shown in Table V. The conversion to impurities, particularly acrylic acid, acrylate, ethylene cyanohydrin and ^ -hydroxypropionamide, was each 0.5% or less. Further tests were carried out for comparison purposes, not using sodium nitrate: the results are also shown in Table V.
Table V

Days of analysis

300 g of copper oxide tablets were distributed so as to ^{fill a metal reaction tube with a volume of 300 cm 3} , and then they were ^{reduced to metallic copper at 200 to 250 °} C. using hydrogen diluted with nitrogen to 2%. The reaction tube was then continuously charged with water and acrylonitrile, from which approximately 90% of the dissolved oxygen was previously removed by passing them through a deoxidizer using charges of 700 g / h and 300 g / h, respectively, and then the Mixture in the reaction tube at 120 ⁰ C implemented. The water originally contained 39 ppm sodium nitrate, which corresponds to 20 ppm activator in the reaction mixture, which contains both acrylonitrile and water. The results of the reaction, observed for 6 consecutive days, are given in Table IV. Another experiment was carried out for comparison purposes, in which no sodium nitrate was added.

Table IV

5 kg of copper dust was placed in a stainless steel reaction vessel with a capacity of 101, that with a stirrer and a catalyst conversion (%)

Nitraiion is not an activator

(ppm) present

Start day 74 51 After 2 days 66 44 After 4 days 59 38 After 6 days 54 33

Example 6

The procedure of Example 1 was repeated for 6 consecutive days, with the exception that methacrylonitrile and benzonitrile were used in place of acrylonitrile. The amount of sodium nitrate, which was used gave 20 ppm activator in the reaction mixtures. For comparison purposes further reactions carried out in which no activator was added. The analysis results all these reactions are listed in Table VI.

Table Vl Conversion (%)
Nitration is not an activator
(20 ppm) present 51
42
36
33 Days of analysis Methacrylonitrile 74
66
61
57 69
59
50
44 Start day
After 2 days
After 4 days
After 6 days Benzonitrile 88
81
76
69 Starting position
After 2 days
After 4 days
After 6 days

Days of analysis

Conversion (%)

Nitration is not an activator

(20 ppm) present

Propionitrile 62 44 Start day 56 37 After 2 days 51 32 After 4 days 49 29 After 6 days 40 22nd After 10 days 33 10 After 14 days

Example 7

The procedure of Example 1 was repeated except that propionitrile and nicotine nitrile (3-cyanopyridine) were used in place of acrylonitrile. The amounts of sodium nitrate used resulted in 20 ppm activator in the reaction mixtures. For comparison purposes, further reactions were carried out in which no activator was added. The analytical results of all these ₎ reactions are shown in Table VI! listed.

Table VII

10

Tiifii: animal Ainilwe llmwi.iHll.HuM %) Ni Iriiiion no acliviilur (20 ppm) present Nicotine nitrile Start day 81 51 After 2 days 72 40 After 4 days 67 37 After 6 days 65 32 After 10 days 33 22nd After 14 days 37 13th

'5 Example 8

Example 1 was repeated, but using different nitrates. The attempt was made Performed for 14 days. In the experiment, the nitrate concentration was 20 ppm, expressed as nitrate groups, based on the raw material liquid. The test results, expressed as the conversion of Acrylonitrile to acrylamide according to Example 1 are summarized in the table below:

Potassium nitrate

Magne- manganese nitrate nitrate aluminum nitrate

Cobalt nitrate

Nickel nitrate

I. day 69 70 66 70 67 66 2 day 60 62 59 61 58 58 4th day 57 59 58 60 57 56 6th day 53 56 55 54 53 54 H. day 44 45 42 45 42 41

Claims (1)

Claim: Process for the preparation of an amide from a nitrile by reacting the nitrile with water in Presence of a metallic copper catalyst and a nitrate as activator, characterized in that that the activator is ammonium nitrate, sodium nitrate, potassium nitrate, magnesium nitrate. Calcium nitrate, zinc nitrate, aluminum nitrate, manganese nitrate, iron nitrate, cobalt nitrate and / or Nickel nitrate in an amount of 3 to 200 ppm, calculated as the weight ratio of nitrate ion to Gross weight of the reaction mixture was used. '5